The next generation of geostationary meteorological satellites is being developed in the frame of Meteosat Third Generation (MTG) ESA program where Thales Alenia Space is prime.

The Institute of Optical Sensor Systems (OS) at the Robotics and Mechatronics Center of the German Aerospace Center (DLR) has more than 30 years of experience with high-resolution imaging technology. This paper shows the institute’s scientific results of the leading-edge detector design in a BTDI (Bidirectional Time Delay and Integration) architecture. This project demonstrates an approved technological design for high or multi-spectral resolution spaceborne instruments. DLR OS and BAE Systems were driving the technology of new detectors and the FPA design for future projects, new manufacturing accuracy in order to keep pace with ambitious scientific and user requirements. Resulting from customer requirements and available technologies the current generation of space borne sensor systems is focusing on VIS/NIR high spectral resolution to meet the requirements on earth and planetary observation systems. The combination of large swath and high-spectral resolution with intelligent control applications and new focal plane concepts opens the door to new remote sensing and smart deep space instruments. The paper gives an overview of the detector development and verification program at DLR on detector module level and key parameters like SNR, linearity, spectral response, quantum efficiency, PRNU, DSNU and MTF.

We have developed a novel radiation hard photon detector concept based on Modified Internal Gate Field Effect Transistor (MIGFET) wherein a buried Modified Internal Gate (MIG) is implanted underneath a channel of a FET. In between the MIG and the channel of the FET there is depleted semiconductor material forming a potential barrier between charges in the channel and similar type signal charges located in the MIG. The signal charges in the MIG have a measurable effect on the conductance of the channel. In this paper a radiation hard double MIGFET pixel is investigated comprising two MIGFETs. By transferring the signal charges between the two MIGs Non-Destructive Correlated Double Sampling Readout (NDCDSR) is enabled.

The radiation hardness of the proposed double MIGFET structure stems from the fact that interface related issues can be considerably mitigated. The reason for this is, first of all, that interface generated dark noise can be completely avoided and secondly, that interface generated 1/f noise can be considerably reduced due to a deep buried channel readout configuration.

Electrical parameters of the double MIGFET pixel have been evaluated by 3D TCAD simulation study. Simulation results show the absence of interface generated dark noise, significantly reduced interface generated 1/f noise, well performing NDCDSR operation, and blooming protection due to an inherent vertical anti-blooming structure. In addition, the backside illuminated thick fully depleted pixel design results in low crosstalk due to lack of diffusion and good quantum efficiency from visible to Near Infra-Red (NIR) light. These facts result in excellent Signal-to-Noise Ratio (SNR) and very low crosstalk enabling thus excellent image quality. The simulation demonstrates the charge to current conversion gain for source current read-out to be 1.4 nA/e.

Both ESA and the EC have identified the need for a supply chain of CMOS imagers for space applications which uses solely European sources. An essential requirement on this supply chain is the platformization of the process modules, in particular when it comes to very specific processing steps, such as those required for the manufacturing of backside illuminated image sensors. This is the goal of the European (EC/FP7/SPACE) funded project EUROCIS. All EUROCIS partners have excellent know-how and track record in the expertise fields required. Imec has been leading the imager chip design and the front side and backside processing. LASSE, as a major player in the laser annealing supplier sector, has been focusing on the optimization of the process related to the backside passivation of the image sensors. TNO, known worldwide as a top developer of instruments for scientific research, including space research and sensors for satellites, has contributed in the domain of optical layers for space instruments and optimized antireflective coatings. Finally, Selex ES, as a world-wide leader for manufacturing instruments with expertise in various space missions and programs, has defined the image sensor specifications and is taking care of the final device characterization. In this paper, an overview of the process flow, the results on test structures and imagers processed using this platform will be presented.

With the aim to expand its capability to offer state-of-the-art space qualified multispectral optical filters assemblies, Sodern continues its effort to evaluate and incorporate new technologies in its designs. For many years, Sodern has been developing complex optical devices incorporating spectral filters.

We present hereafter the results on the fabrication of complex optical filters within the Institut Fresnel in close collaboration with CILAS. Bandpass optical filters dedicated to astronomy and space applications, with central wavelengths ranging from ultraviolet to near infrared, were deposited on both sides of glass substrates with performances in very good congruence with theoretical designs. For these applications, the required functions are particularly complex as they must present a very narrow bandwidth as well as a high level of rejection over a broad spectral range. In addition to those severe optical performances, insensitivity to environmental conditions is necessary. For this purpose, robust solutions with particularly stable performances have to be proposed.

Stray light is an important issue in optical systems and may be responsible for huge limitation of final performances. Use of black coated surfaces is known to be an efficient means to reduce such parasitic light sources and various solutions exist that can be applied to mechanical surfaces such as black paints or black anodization; these coatings are relatively thick and to produce thin, black baffle edges, a thin layer technology is thus needed. In this paper, we show how thin film multilayer coatings can be a solution to answer this problematic as it is possible to design accurate spectral response that present a very low level of reflectance with a zero value of transmittance.

Today high angular resolution telescopes for space observation satellites require primary mirrors with larger and larger dimensions. For such mirrors, high-performance silver coating is required and is a key part of the component. For more than 20 years, CILAS has developed an expertise in the field of thin film optical coatings in order to answer a wide range of spectral performances and produce high quality thin film coatings. Among the various coating technologies that may answer such demand, magnetron sputtering is particularly well-suited to produce dense layers with improved mechanical performances and a high level of uniformity.

The Methane Remote Sensing LIDAR Mission (MERLIN) is a joint French-German cooperation on the development, launch and operation of a climate monitoring satellite, executed by the French Space Agency CNES and the German Space Administration DLR.

For a prediction of the rate of climate change during the 21^st century, there is an urgent need to better understand the global carbon cycle, in particular the processes that control the carbon flows between the various reservoirs, and their interactions with the climate system. Atmospheric carbon dioxide (CO₂) represents the main atmospheric phase of this biogeochemical cycle. Due to human activities, the concentration of this most important of the Earth’s greenhouse gases has grown from a pre-industrial average atmospheric mole fraction of about 280 parts per million volume (ppm) to 390.5 ppm in 2011 which is an increase of 40%. CO₂ contributes to ~63% to the overall global radiative forcing.

In the framework of CO₂ monitoring in the Atmospheric Boundary Layer (ABL), a ground-based 2-μm Differential Absorption Lidar (DIAL) has been developed at the Laboratoire de Météorologie Dynamique (LMD) in Palaiseau. In order to derive flux information, this system has been set up with coherent detection, which allows to combine CO₂ density measurements with wind velocity measurements. On the other hand, new advances in the field of Mercury Cadmium Tellure (MCT) Avalanche Photodiodes (APDs) open the way for high-precision measurements in direct detection ultimately from space. In this study, we first report on state of the art measurements obtained with the current coherent DIAL system before presenting expected results for a similar laser transmitter equipped with MCT APDs. For this latter part, we use a numerical model which relies on APDs performance data provided by the Laboratoire d'Électronique et de Technologie de l'Information (LETI).

Carbon dioxide (CO₂) is an important greenhouse gas that significantly contributes to the carbon cycle and global radiation budget on Earth. CO₂ role on Earth’s climate is rather complicated due to different interactions with various climate components that include the atmosphere, the biosphere and the hydrosphere.

The European Data Relay System (EDRS) will provide optical and microwave data relay services between Low Earth Orbit (LEO) satellites at altitudes up to 2000 km and the ground through geostationary (GEO) satellite nodes. Currently, two such nodes have been procured as part of a Public Private Partnership (PPP) between Astrium (now Airbus Defence and Space) and ESA. The first node (EDRS-A) is a hosted payload embarked upon the Eutelsat 9B satellite and scheduled for launch in early 2015.

Optical instruments, sensitive to contamination, impose stringent cleanliness requirements for spacecraft missions. The contamination aspects and the subsequent possible performance degradation of the optical instruments have to be considered and controlled all along the spacecraft manufacturing and operative life.

In October 2013 the Lunar Laser Communications Demonstration (LLCD) made communications history by successfully demonstrating 622 megabits per second laser communication from the moon’s orbit to earth. The LLCD consisted of the Lunar Laser Communication Space Terminal (LLST), developed by MIT Lincoln Laboratory, mounted on NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft and a primary ground terminal located in New Mexico, the Lunar Laser Communications Ground Terminal (LLGT), and two alternate ground terminals.

This paper presents the optical layout of the LLST, the approach for testing the optical subsystems, and the results of the optical qualification of the LLST. Also described is the optical test set used to qualify the LLST. The architecture philosophy for the optics was to keep a small, simple optical backend that provided excellent boresighting and high isolation between the optical paths, high quality wavefront on axis, with minimal throughput losses on all paths. The front end large optics consisted of a Cassegrain 107mm telescope with an f/0.7 parabolic primary mirror and a solar window to reduce the thermal load on the telescope and to minimize background light received at the sensors.

We describe the design of a compact free-space optical communications module for use on a nanosatellite and present results from a detailed trade study to select an optical fine steering mechanism compatible with our stringent size, weight and power (SWaP) constraints. This mechanism is an integral component of the compact free-space optical communications system that is under development at the MIT Space Systems Laboratory [1]. The overall goal of this project is to develop a laser communications (lasercom) payload that fits within the SWaP constraints of a typical “3U” CubeSat. The SWaP constraints for the entire lasercom payload are 5 cm × 10 cm × 10 cm, 600 g and 10W. Although other efforts are underway to qualify MEMS deformable mirrors for use in CubeSats [2], there has been very little work towards qualifying tip-tilt MEMS mirrors [3].

Sec. II provides additional information on how the fast steering mechanism is used in our lasercom system. Performance requirements and desirable traits of the mechanism are given. In Sec. III we describe the various types of compact tip-tilt mirrors that are commercially available as well as the justification for selecting a MEMS-based device for our application. Sec. IV presents an analysis of the device's transfer function characteristics and ways of predicting this behavior that are suitable for use in the control processor. This analysis is based upon manufacturer-provided test data which was collected at standard room conditions. In the final section, we describe on-going work to build a testbed that will be used to measure device performance in a thermal chamber.

Optoelettronica Italia Srl, better known as Optoi, is an Italian Company dealing with optoelectronics and microelectronics and focusing on back-end technologies. The growing volume of activities concerning the aerospace field has recently brought to the creation of a company unit, with collaborations with ESA, CNES and ASI. In this context, Optoi’s key partner for the microelectronic front-end is Fondazione Bruno Kessler (FBK) and specifically its Micro Nano Facility (MNF).

The development and testing of the MSI PFM for the first Sentinel-2 satellite is now completely achieved, in particular tests and characterization of the VNIR FPA and of the whole instrument. This paper provides main results obtained for the 12 VNIR detection chains of the Sentinel-2 Multi-Spectral Instrument and highlights some of the most outstanding characteristics and performances achieved.

Hybridized image sensors are actually the only solution for image sensing beyond the spectral response of silicon devices. By hybridization, we can combine the best sensing material and photo-detector design with high performance CMOS readout circuitry. In the infrared band, we are facing typically 2 configurations: high background situation and low background situation. The performance of high background sensors are conditioned mainly by the integration capacity in each pixel which is the case for mid-wave and long-wave infrared detectors. For low background situation, the detector’s performance is mainly limited by the pixel’s noise performance which is conditioned by dark signal and readout noise. In the case of reflection based imaging condition, the pixel’s dynamic range is also an important parameter. This is the case for SWIR band imaging. We are particularly interested by InGaAs based SWIR image sensors.

Infrared detection is widely used in astrophysics and plays a key role in several space missions aiming for example at scanning the sky to discover new objects (coolest stars, dust-obscured galaxies, exo-planets …) or studying the evolution of the universe, where light is redshifted in the infrared range. In many cases the space telescope involves an HgCdTe infrared detector operating at low frame rate over long integration time. Due to the very low input signal, dark current and readout noise are essential figures that must be minimized to get the best detector sensitivity. This kind of application also requires very large focal plane array (FPA) often relying on a butting arrangement of large detectors. The trend is to increase the single detector format from 1Kx1K to 2Kx2K and 4Kx4K. For very large formats, material quality and detector process may affect the production yield and the global infrared FPA cost. As a result the detector format could result from a trade-off taking into account producibility.

Multispectral or hyperspectral images allow acquiring new information that could not be acquired using colored images and, for example, identifying chemical species on an observed scene using specific highly selective filters.

High-reflective coatings are indispensable in order to manufacture mirrors with highest possible reflectivity. The maximum reflectivity can be achieved by all-dielectric coatings; however, the spectral bandwidth of these mirrors is limited. For astronomical applications metal based coatings (Al, Au, Ag) are commonly applied, as they allow high reflectivity and at the same time a broad spectral bandwidth.

Contamination control research activities for space optics projects in JAXA R&D are described. More accurate contamination control techniques are requested because of intensified recent science mission requirements. One approach to control the contamination effects is analysis by software. JAXA has been developing a contamination analytical tool “J-SPICE” (Japanese Spacecraft Induced Contamination analysis software) as well as experiment facilities to improve the J-SPICE. A reflection model in J-SPICE has been experimentally verified and outgassing model data has been acquired by a facility. JAXA has developed a facility which could determine the influence of the contamination at a specific wavelength by combining a vacuum chamber with an I-R spectrometer and performed an experiment to inspect the effect of baking. Space material exposure experiment results reveal the actual thickness of the contamination layer in ISS orbit.

In order to study the dark universe (energy and matter), EUCLID space mission will collect near infrared spectra and images of millions of galaxies. This massive measurement survey requires a slitless spectroscopic channel including GRISMs (for “Grating pRISMs”) in NISP (Near Infrared SpectroPhotometer). Very special technical specifications are required for the grating manufacturing: large aperture, low groove frequency and blaze angle, line curvature. In addition, it has to withstand space environment. Therefore, in the frame of a R&D project funded by the CNES, we developed bulk silica gratings in close collaboration with the French company SILIOS Technologies. SILIOS delivered two resin-free blazed gratings with curved lines engraved directly into the fused silica substrate of 80mm and 108mm useful aperture. At LAM, we measured very high optical performances of these prototypes: <80% transmitted efficiency, <30nm RMS wavefront error, groove shape and roughness very close to theory and uniform over the useful aperture. In this paper, we give specifications of these gratings, we describe the manufacturing process developed by SILIOS Technologies, we present briefly optical setups and models allowing optical performances verifications at LAM and we show very encouraging results obtained on the two gratings.

The diffraction gratings are widely used in Space-flight satellites for spectrograph instruments or in ground-based telescopes in astronomy. The diffraction gratings are one of the key optical components of such systems and have to exhibit very high optical performances.

HORIBA Jobin Yvon S.A.S. (part of HORIBA Group) is in the forefront of such gratings development for more than 40 years. During the past decades, HORIBA Jobin Yvon (HJY) has developed a unique expertise in diffraction grating design and manufacturing processes for holographic, ruled or etched gratings.

We will present in this paper an overview of diffraction grating technologies especially designed for space and astronomy applications. We will firstly review the heritage of the company in this field with the space qualification of different grating types. Then, we will describe several key grating technologies developed for specific space or astronomy projects: ruled blazed low groove density plane reflection grating, high-groove density holographic toroidal and spherical grating, and finally transmission Fused Silica Etched (FSE) grism-assembled grating. We will not present the Volume Phase Holographic (VPHG) grating type which is used in Astronomy.

For atmospheric LIDAR instruments in space, a manifold of scientific applications exists. But due to the lack of high energy laser sources providing the performance, reliability and lifetime necessary to operate such instruments in space, realization is currently seen as still very critical in the community.

The accurate determination of the atmospheric distribution of carbon dioxide (CO₂) on planetary scale is a key requirement for setting up modeling tools able to make reliable predictions of Earth climate dynamics which are essential for the understanding of such important issues as climate change and global warming. Nowadays, the concentrations of CO₂ are mainly measured in-situ at a number of surface stations that are unevenly distributed over the planet. Air-borne and space-borne missions have the potential to provide a denser and better distributed set of observations to complement those provided by the surface network.

In the absence of climate change policies, the fossil fuel emissions are projected to increase in the next decades. Depending on how the current carbon sinks change in the future, the atmospheric CO₂ concentration is predicted to be between 700–1000 ppmv by 2100, and global mean surface temperature between 1.1–6.4°C, with related changes in sea-level, extreme events and ecosystem drifts. Keeping the atmospheric CO₂ concentration at a level that prevents dangerous interference with the climate system poses an unprecedent but necessary challenge to humanity. Beyond this point, global climate change would be very difficult and costly to deal with. There are two main approaches that are currently analysed: (1) to reduce emissions; (2) to capture CO₂ and store it, i.e. sequestration. For these two ways, some monitoring at different scales ultimately from space would be needed. Lidar remote sensing is a powerful technique that enables measurements at various space and time resolution.

High energy fiber lasers emitting around 1579nm is seen as a possible technology for the laser unit of a spaceborn CO₂ DIAL system. We are developing an all fiber system with the following expected performances: pulse energy of 260μJ, pulse duration 150ns, beam quality M² <2, pulse linewidth <60 MHz, laser stability 200 kHz. One of our main concerns has been the radiation induced attenuation mitigation. Various fiber compositions have been investigated.

Nowadays the interest in high power semiconductor devices is growing for applications such as telemetry, lidar system or free space communications. Indeed semiconductor devices can be an alternative to solid state lasers because they are more compact and less power consuming. These characteristics are very important for constrained and/or low power supply environment such as airplanes or satellites.

Lots of work has been done in the 800-1200 nm range for integrated and free space Master Oscillator Power Amplifier (MOPA) [1]-[3]. At 1.5 μm, the only commercially available MOPA is from QPC [4]: the fibred output power is about 700 mW and the optical linewidth is 500 kHz.

In this paper, we first report on the simulations we have done to determine the appropriate vertical structure and architecture for a good MOPA at 1.58 μm (section II). Then we describe the fabrication of the devices (section III). Finally we report on the optical and electrical measurements we have done for various devices (section IV).

Quantum teleportation is a quintessential prerequisite of many quantum information-processing protocols.

The performance of sensors for Earth Observation Missions is constantly improving. This drives the need for a reliable, high-speed data transfer capability from a Low Earth Orbit (LEO) spacecraft (S/C) to ground. In addition, for the transfer of time-critical data to ground, a low latency between data generation in orbit and data reception at the respective mission control center is of high importance. Laser communication between Satellites for high data transmission in combination with a GEO data relay system for reducing the latency time addresses these requirements.

NASA and other space agencies around the world are currently developing free space optical communication systems for both space-to-ground links and space-to-space links. This paper provides an overview of NASA's current activities in free space optical communications with a focus on Near Earth applications. Activities to be discussed include the Lunar Laser Communication Demonstration, the Laser Communications Relay Demonstration, and the commercialization of the underlying technology. The paper will also briefly discuss ongoing efforts and studies for Deep Space optical communications. Finally the paper will discuss the development of international optical communication standards within the Consultative Committee for Space Data Systems.

Recently, the free space optical (FSO) communications have been widely studied as an alternative for large capacity communications and its possible implementation in satellite and terrestrial laser links. In satellite communications, clouds can strongly attenuate the laser signal that would lead to high bit-error rates or temporal unavailability of the link. To overcome the cloud coverage effects, often site diversity technique is implemented. When using multiple ground stations though, simplified optical system is required to allow the usage of more flexible approaches. In terrestrial laser communications, several methods for optical system simplification by using a multimode fiber (MMF) have been proposed.

Inter-satellite and ground to satellite optical communications have been successfully demonstrated over more than a decade with several experiments, the most recent being NASA’s lunar mission Lunar Atmospheric Dust Environment Explorer (LADEE). The technology is in a mature stage that allows to consider optical communications as a high-capacity solution for future deep-space communications [1][2], where there is an increasing demand on downlink data rate to improve science return. To serve these deep-space missions, suitable optical ground stations (OGS) have to be developed providing large collecting areas. The design of such OGSs must face both technical and cost constraints in order to achieve an optimum implementation. To that end, different approaches have already been proposed and analyzed, namely, a large telescope based on a segmented primary mirror, telescope arrays, and even the combination of RF and optical receivers in modified versions of existing Deep-Space Network (DSN) antennas [3][4][5]. Array architectures have been proposed to relax some requirements, acting as one of the key drivers of the present study. The advantages offered by the array approach are attained at the expense of adding subsystems. Critical issues identified for each implementation include their inherent efficiency and losses, as well as its performance under high-background conditions, and the acquisition, pointing, tracking, and synchronization capabilities. It is worth noticing that, due to the photon-counting nature of detection, the system performance is not solely given by the signal-to-noise ratio parameter.

To start with the analysis, first the main implications of the deep space scenarios are summarized, since they are the driving requirements to establish the technical specifications for the large OGS. Next, both the main characteristics of the OGS and the potential configuration approaches are presented, getting deeper in key subsystems with strong impact in the performance. The different configurations are compared from the technical point of view, taking into account the effect of atmospheric conditions. Finally a very preliminary cost analysis for a large aperture OGS is presented.

One of the main challenges of modern astronomical instruments like adaptive optics (AO) systems or fringe trackers is to deal with the very low photons flux detection scenarios. The typical timescale of atmospheric turbulences being in the range of some tens of milliseconds, infrared wavefront sensors for AO systems needs frame rates higher than 1 KHz leading to integration times lower than 1 ms. This integration time associated with a low irradiance results in a few number of integrated photons per frame per pixel. To preserve the information coming from this weak signal, the focal plane array (FPA) has to present a low read out noise, a high quantum efficiency and a low dark current. Up to now, the output noise of high speed near infrared sensors is limited by the silicon read out circuit noise. The use of HgCdTe avalanche photodiodes with high gain at moderate reverse bias and low excess noise seems then a logical way to reduce the impact of the read noise on images signal to noise ratio. These low irradiance passive imaging applications with integration times in the millisecond range needs low photodiode dark current and low background current. These requirements lead to the choice of the photodiode cut off wavelength. The short wave infrared (SWIR) around 3 μm is a good compromise between the gain that can be obtain for a given APD bias and the background and dark current. The CEA LETI HgCdTe APD technology, and a fine analysis of the gain curve characteristic are presented in [1] and won’t be detailed here. The response time of the APD is also a key factor for a high frame rate FPA. This parameter has been evaluated in [2] and the results shows cut off frequencies in the GHz range.

In this communication we report the performances of a SWIR APD FPA designed and fabricated by CEA LETI and SOFRADIR for astrophysical applications. This development was made in the frame of RAPID, a 4 years R&D project funded by the French FUI (Fond Unique Interministériel). This project involves industrial and academic partners from the field of advanced infrared focal plane arrays fabrication (SOFRADIR and CEA LETI) and of astronomical/defense institutes (IPAG, LAM, ONERA). The goal of this program is to develop a fast and low noise SWIR camera for astronomical fast applications like adaptive optics wavefront sensing and fringe tracking for astronomical interferometers [3].

The first batch of FPA’s was based on liquid-phase epitaxy (LPE) grown photodiode arrays with 3 μm cut off wavelength. In order to get higher avalanche gain for a given photodiode reverse bias voltage, we have made a second batch with a cadmium composition leading to 3.3 μm cut off wavelength (λ_c). This paper described the read out circuit in the next section. The aim section III is to find the critical parameter that has to be measured to evaluate the signal to noise ratio (SNR) of an APD FPA. The main electro optical characteristics of an FPA based on 3.3μm cut off wavelength APDs are reported in “Rapid FPAs characterisation” section. The dark current evolution with temperature of a 3 μm FPA high and low APD bias is also detailed in this section.

Large format near infrared HgCdTe 2Kx2K and 4Kx4K MBE arrays have reached a level of maturity which meets most of the specifications required for near infrared (NIR) astronomy. The only remaining problem is the persistence effect which is device specific and not yet fully under control. For ground based multi-object spectroscopy on 40 meter class telescopes larger pixels would be advantageous.

For high speed near infrared fringe tracking and wavefront sensing the only way to overcome the CMOS noise barrier is the amplification of the photoelectron signal inside the infrared pixel by means of the avalanche gain. A readout chip for a 320x256 pixel HgCdTe eAPD array will be presented which has 32 parallel video outputs being arranged in such a way that the full multiplex advantage is also available for small sub-windows. In combination with the high APD gain this allows reducing the readout noise to the subelectron level by applying nondestructive readout schemes with subpixel sampling. Arrays grown by MOVPE achieve subelectron readout noise and operate with superb cosmetic quality at high APD gain. Efforts are made to reduce the dark current of those arrays to make this technology also available for large format focal planes of NIR instruments offering noise free detectors for deep exposures. The dark current of the latest MOVPE eAPD arrays is already at a level adequate for noiseless broad and narrow band imaging in scientific instruments.

Selex ES produces a wide range of infrared detectors from mercury cadmium telluride (MCT) and triglycine sulfate (TGS), and has supplied both materials into space programmes spanning a period of over 40 years. Current development activities that underpin potential future space missions include large format arrays for near- and short-wave infrared (NIR and SWIR) incorporating radiation-hard designs and suppression of glow. Improved heterostructures are aimed at the reduction of dark currents and avalanche photodiodes (APDs), and parallel studies have been undertaken for low-stress MCT array mounts. Much of this development work has been supported by ESA, UK Space, and ESO, and some has been performed in collaboration with the UK Astronomy Technology Centre and E2V.

This paper focuses on MCT heterostructure developments and novel design elements in silicon read-out chips (ROICs). The 2048 x 2048 element, 17um pitch ROIC for ESA’s SWIR array development forms the basis for the largest cooled infrared detector manufactured in Europe. Selex ES MCT is grown by metal organic vapour phase epitaxy (MOVPE), currently on 75mm diameter GaAs substrates. The MCT die size of the SWIR array is 35mm square and only a single array can be printed on the 75mm diameter wafer, utilising only 28% of the wafer area. The situation for 100mm substrates is little better, allowing only 2 arrays and 31% utilisation. However, low cost GaAs substrates are readily available in 150mm diameter and the MCT growth is scalable to this size, offering the real possibility of 6 arrays per wafer with 42% utilisation.

A similar 2k x 2k ROIC is the goal of ESA’s NIR programme, which is currently in phase 2 with a 1k x 1k demonstrator, and a smaller 320 x 256 ROIC (SAPHIRA) has been designed for ESO for the adaptive optics application in the VLT Gravity instrument. All 3 chips have low noise source-follower architecture and are enabled for MCT APD arrays, which have been demonstrated by ESO to be capable of single photon detection. The possibility therefore exists in the near future of demonstrating a photon counting, 2k x 2k SWIR MCT detector manufactured on an affordable wafer scale of 6 arrays per wafer.

Compared with the other Infrared detector materials, such as HgCdTe (or MCT) and lead salts (e.g.: PbS, PbSe, PbSnTe, …), the history of InGaAs FPA’s is not that old. Some 25 years ago the first linear detectors were used for space missions [1,2]. During the last 15-20 years InGaAs, grown lattice matched on InP, has become the work horse for the telecommunication industry [3] and later on for passive and active imagery in the SWIR range. For longer wavelengths than 1.7 μm, III-V materials are in strong competition with SWIR MCT and till now the performance of MCT is better than high In-content InGaAs. During the last years some alternatives based on quaternary materials [4] and on Superlattice structures [5] are making gradual progress in such a way that they can yield performing Focal planes in the (near) future.

As the SWIR wavelengths range covers a large variety of applications, also the FPA characteristics and mainly the ROIC properties need to be adjusted to fulfil the mission requirements with the requested performance. Additionally one has to bear in mind that the nature of SWIR radiation is completely different from what is usually encountered in IR imaging. Whereas the signal of thermal imagery in the Middle Wavelength (MWIR: [3 – 5 μm]) or Long Wavelength (LWIR: [8 – 10 μm] or [8 – 12 μm]) band is characterized by a large DC pedestal, caused by objects at ambient temperature, and a small AC signal, due to the small temperature or emissivity variations, SWIR range imagery is characterized by a large dynamic range and almost no DC signal. In this sense the SWIR imagery is resembling more the nature of Visible and NIR imaging than that of thermal imagery.

In the frame of recent studies and missions, ESA has been performing various pre-developments of optical gratings for instruments operating at wavelengths from the UV up to the SWIR. The instrument requirements of Sentinel-4, Sentinel-5, CarbonSat and FLEX are driving the need for advanced designs and technologies leading to gratings with high efficiency, high spectral resolution, low stray light and low polarization sensitivities. Typical ESA instruments (e.g. Sciamachy, GOME, MERIS, OLCI, NIRSpec) were and are based on ruled gratings or gratings manufactured with one holographic photoresist mask layer which is transferred to an optical substrate (e.g. glass, glass ceramic) with dry etching methods and subsequently either coated with a reflective coating or used as a mold for replication. These manufacturing methods lead to blazed grating profiles with a metallic reflective surface. The vast majority of spectrometers on ground are still based on such gratings. In general, gratings based on grooved metallic surfaces tend for instance to polarize the incoming light significantly and are therefore not always suitable for ESA’s needs of today. Gratings made for space therefore evolved to many other designs and concepts which will be reported in this paper.

Monolithic diffraction gratings are one of the key components of high sensitive spectral imaging systems including spectrometer used in space instruments. These gratings are optimized for high efficiency, lowest line spacing errors and low scattering values to improve the performance of a spectral imaging system. Spectral imaging systems lead to enhanced remote sensing properties when the sensing system provides sufficient spectral resolution to identify materials from its spectral reflectance signature comprising low signal-to-noise ratios.

For space born Astronomy as well as Earth Observation from space, more and more focal plane instruments are operating in the near or mid infrared and require therefore optics operating at cryogenic temperature (down to liquid nitrogen temperature or less).

Through several examples of typical past or on-going realizations for different projects requiring such cryogenics optics (e.g. MTG=Meteosat Third Generation program for ESA), the presentation will point out the main technical issues and corresponding solutions for design, manufacturing and testing of necessary lens assemblies, mirrors and relevant optical coatings.

A brief review of the corresponding existing “state of the art” for these technologies in Thales Seso will conclude the presentation.

The SCF_Lab (Satellite/lunar/gnss laser ranging and altimetry Characterization Facility Laboratory) of INFNLNF is designed to cover virtually LRAs (Laser Retroreflector Arrays) of CCRs (Cube Corner Retroreflectors) for missions in the whole solar system, with a modular organization of its instrumentation, two redundant SCF (SCF_Lab Characterization Facilities), and an evolutionary measurement approach, including customization and potentially upgrade on-demand. See http://www.lnf.infn.it/esperimenti/etrusco/ for a general description.

Monitoring the concentration of greenhouse gases from space is an important need. It can be achieved via a precise analysis of the chemical gaseous species (CO2, CH4, CO, etc.) signature in the spectrum of the reflected sunlight. The MICROCARB project aims to reach a very high quality measurement from on board a small volume Microsat platform, in 4 different spectral bands (O2 spectral band, 2 CO2 spectral bands and a CH4 spectral band), in order to locate and characterize the CO2 sinks and sources and to have a better understanding of the carbon cycle. But this is a very tricky measurement especially for the CO2 monitoring as its concentration in the atmosphere is about 380ppm and we need to measure it with accuracy better than +/− 1ppm. Another presentation is fully dedicated to the MICROCARB instrument design (see [1]).

PHI is a diffraction limited, wavelength tunable, quasi-monochromatic, and polarization sensitive imager. These capabilities are needed to infer the magnetic field and line-of-sight (LOS) velocity of the region targeted by the spacecraft (spacecraft (S/C)).

PHI will consist of two telescopes: The High Resolution Telescope (HRT)[1] and the Full Disk Telescope (FDT). The HRT and the FDT will view the Sun through entrance windows located in the S/C heat shield. These windows act as heat rejecting filters with a transmission band of about 30 nm width centered on the science wavelength, such that the total transmittance (integral over the filter curve weighted with solar spectrum, including white leakage plus transmission profile of the pass band) does not exceed 4% of the total energy falling onto the window [2][3].

The HREW filter has been designed by SELEX in the framework of an ESA led technology development activity under original ESTEC contract No. 20018/06/NL/CP[4], and extensions thereof. For FDT HREW SLEX will provide the windows and it coatings.

The HREW consists of two parallel-plane substrate plates (window 1 & window 2)[5] made of SUPRASIL 300 with a central thickness of 9 mm and a wedge of 30 arcsec each. These two substrates are each coated on both sides with four different coatings. These coatings and the choice of SUPRASIL help to minimize the optical absorptivity in the substrate and to radiatively decouple the HREW, which is expected to run at high temperatures during perihelion passages, from the PHI instrument cavity.

The temperature distribution of the HREW is driven by two main factors: the mechanical mounting of the substrates to the feedthrough, and the radiative environment within the heat-shield/feedthrough assembly.

The mechanical mount must ensure the correct integration of both suprasil substrates in its correct position and minimize the loads in windows due to thermal induced deformations and launching vibration environment.

All the subsystem must survive to a launching vibration environment and fulfill optical requirements in an environmental conditions according o its position in the external part of the spacecraft with a pressure of 0.0013Pa and a temperature -163°C<T<230°C.

Fibre Optic Sensing is a rapidly growing application field for Photonics Integrated Circuits (PIC) technology. PIC technology is regarded enabling for required performances and miniaturization of next generation fibre optic sensing instrumentation. So far a number of Application Specific Photonics Integrated Circuits (ASPIC) based interrogator systems have been realized as operational system-on-chip devices. These circuits have shown that all basic building blocks are working and complete interrogator on chip solutions can be produced. Within the Saristu (FP7) project several high reliability solutions for fibre optic sensing in Aeronautics are being developed, combining the specifically required performance aspects for the different sensing applications: damage detection, impact detection, load monitoring and shape sensing (including redundancy aspects and time division features). Further developments based on devices and taking into account specific space requirements (like radiation aspects) will lead to the Space Gator, which is a radiation tolerant highly integrated Fibre Bragg Grating (FBG) interrogator on chip. Once developed and qualified the Space Gator will be a giant leap for fibre optic sensing in future space applications.

Striving constantly to reduce mass, AIT effort and overall cost of the classical point-to-point wired temperature sensor harness on-board telecommunication satellites, OHB System (formerly Kayser-Threde) has introduced the Hybrid Sensor Bus (HSB) system. As a future spacecraft platform element, HSB relies on electrical remote sensor units as well as fiber-optical sensors, both of which can serially be connected in a bus architecture. HSB is a modular measurement system with many applications, also thanks to the opportunities posed by the digital I²C bus. The emphasis, however, is on the introduction of fiber optics and especially fiber-Bragg grating (FBG) temperature sensors as disruptive innovation for the company’s satellite platforms.

The light weight FBG sensors are directly inscribed in mechanically robust and radiation tolerant fibers, reducing the need for optical fiber connectors and splices to a minimum. Wherever an FBG sensor shall be used, the fiber is glued together with a corresponding temperature transducer to the satellites structure or to a subsystem. The transducer is necessary to provide decoupling of mechanical stress, but simultaneously ensure a high thermal conductivity.

HSB has been developed in the frame of an ESA-ARTES program with European and German co-funding and will be verified as flight demonstrator on-board the German Heinrich Hertz satellite (H2Sat). In this paper the Engineering Model development of HSB is presented and a Fiber-optical Sensor Multiplexer for a more flexible sensor bus architecture is introduced. The HSB system aims at telecommunication satellite platforms with an operational life time beyond 15 years in geostationary orbit. It claims a high compatibility in terms of performance and interfaces with existing platforms while it was designed with future applications with increased radiation exposure already in mind.

In its basic configuration HSB consists of four modules which are the Power Supply Unit, the HSB Controller Module, the Interrogator Controller Module and the Analog Front-End for the fiber-optical interrogation. The Interrogator Controller Module handles both, the electrical and fiber-optical sensor network. For the latter it is to be completed by the Analog Front-End. On this front-end, a tunable laser diode is implemented for the scanning of the FBG sensors. The reflected spectra are measured on multiple fiber channels and are then evaluated by use of a peak detection algorithm in order to obtain a precise temperature measurement. The precise operation of the photonic system on long terms can be guaranteed thanks to an inorbit calibration concept.

The Hybrid Sensor Bus (HSB) is a modular system for housekeeping measurements for space applications. The focus here is the fiber-optical module and the used fiber-Bragg gratings (FBGs) for temperature measurements at up to 100 measuring points. The fiber-optial module uses a tunable diode laser to scan through the wavelength spectrum and a passive optical network for reading back the reflections from the FBG sensors. The sensors are based on FBGs which show a temperature dependent shift in wavelength, allowing a high accuracy of measurement.

The temperature at each sensor is derivated from the sensors Bragg wavelength shift by evaluating the measured spectrum with an FBG peak detection algorithm and by computing the corresponding temperature difference with regard to the calibration value. It is crucial to eliminate unwanted influence on the measurement accuracy through FBG wavelength shifts caused by other reasons than the temperature change. The paper presents gamma radiation test results up to 25 Mrad for standard UV-written FBGs in a bare fiber and in a mechanically housed version. This high total ionizing dose (TID) load comes from a possible location of the fiber outside the satellite's housing, like e.g. on the panels or directly embedded into the satellites structure. Due to the high shift in wavelength of the standard written gratings also the femto-second infrared (fs- IR) writing technique is investigated in more detail.

Special focus is given to the deployed fibers for the external sensor network. These fibers have to be mechanically robust and the radiation induced attenuation must be low in order not to influence the system's performance. For this reason different fiber types have been considered and tested to high dose gamma radiation. Dedicated tests proved the absence of enhanced low dose rate sensitivity (ELDRS). Once the fiber has been finally selected, the fs-IR grating will be written to these fibers and the FBGs will be tested in order to investigate the radiation induced wavelength shift.

The FBGs react on temperature and strain change, so a decoupling of both physical effects must be assured to allow a precise measurement over large temperature ranges and corresponding potential mechanical stress, passed from the structure to the sensor. This potential source of error is addressed with the design of a strain-decoupled temperature transducer to which the FBGs are glued. The design of the transducer and measurement results of a bending test are provided within this paper.

An outlook of the usage of fiber-optical sensing in space applications will be given. One promising field of application are the so called photonically-wired spacecraft panels, where optical fibers with integrated FBGs are being integrated in panels for temperature measurements and high-speed data transfer at the same time.

Fiber Optic Sensor (FOS) technology presents long recognized advantages which enable to mitigate deficient performance of conventional technology in hazard-environments common in spacecraft monitoring applications, such as: multiplexing capability, immunity to EMI/RFI, remote monitoring, small size and weight, electrical insulation, intrinsically safe operation, high sensibility and long term reliability. A key advantage is also the potential reduction of Assembly Integration and Testing (AIT) time achieved by the multiplexing capability and associated reduced harness.

In the frame of the ESA’s ARTES5.2 and FLPP-Phase 3 programs, Airbus DS-Crisa and FiberSensing are developing a Fiber Bragg Grating (FBG) – based temperature monitoring system for application in space telecommunication platforms and launchers. The development encompasses both the interrogation unit and the FBG temperature sensors and associated fiber harness.

In parallel Airbus DS - Crisa is developing a modular RTU (RTU2015) to provide maximum flexibility and mission-customization capability for RTUs maintaining the ESA’s standards at I/O interface level [1]. In this context, the FBG interrogation unit is designed as a module to be compatible, in both physical dimensions and electrical interfaces aspects, with the Electrical Internal Interface Bus of the RTU2015, thus providing the capability for a hybrid electrical and optical monitoring system.

In this paper we present a newly developed Fiber Optic measurement system, consisting of Fiber Bragg Grating (FBG) sensors and an FBG interrogator. The development of the measuring system is part of the PiezoElectric Assisted Smart Satellite Structure (PEASSS) project, which was initiated at the beginning of 2013 and is financed by the Seventh Framework Program (FP7) of the European Commission. Within the PEASSS project, a Nano-Satellite is being designed and manufactured to be equipped with new technology that will help keep Europe on the cutting edge of space research, potentially reducing the cost and development time for more accurate future sensor platforms including synthetic aperture optics, moving target detection and identification, and compact radars. After on ground testing the satellite is planned to be launched at the end of 2015.

Within the satellite, different technologies will be demonstrated on orbit to show their capabilities for different in-space applications. For our application the FBG interrogator monitors the structural and thermal behaviour of a so called “smart panel”. These panels will enable fine angle control and thermal and vibration compensation in order to improve all types of future Earth observations, such as environmental and planetary mapping, border and regional imaging. The Fiber Optic (FO) system in PEASSS includes four FBG strain sensors and two FBG temperature sensors.

The 3 channel interrogator has to have a small footprint (110x50x40mm), is low cost, low in mass and has a low power consumption. In order to meet all these requirements, an interrogator has been designed based on a tunable Vertical-Cavity Surface-Emitting Laser (VCSEL) enabling a wavelength sweep of around 7 nm. To guarantee the absolute and relative performance, two reference methods are included internally in the interrogator. First, stabilized reference FBG sensors are used to obtain absolute wavelength calibrations. This method is used for the temperature sensors in the system, which will be measured with an accuracy of ±1°C. Second, the strain sensors will be used to monitor deformation of piezo actuators (bimorph plates) in a way that temperature compensation is not required. Using FBGs on top and on the bottom of the plates, relative wavelength differences are measured. In order to have a high accuracy, inside the interrogator a fiber interferometer is used to track the wavelength change. Using this reference technology we are able to measure the (relative) wavelength difference between two FBGs well below 0.1pm.

DAS Photonics and Airbus Defence and Space (Spain) have been working for more than six years in the concept of an Active Optical Cable (AOC) for copper cable substitution. The main advantages that AOC offers are significant mass and size saving, better flexibility and routing of the cable and immunity to EMI.

OTOS is a DGA and CNES technology program dedicated to the preparation of the next generation space telescopes.

Dealing with ceramic materials for more than two decades, Thales Alenia Space – France has identified Silicon Nitride Si3N4 as a high potential material for the manufacturing of stiff, stable and lightweight truss structure for future large telescopes. Indeed, for earth observation or astronomic observation, space mission requires more and more telescopes with high spatial resolution, which leads to the use of large primary mirrors, and a long distance between primary and secondary mirrors. Therefore current and future large space telescopes require a huge truss structure to hold and locate precisely the mirrors. Such large structure requires very strong materials with high specific stiffness and a low coefficient of thermal expansion (CTE). Based on the silicon nitride performances and on the know how of FCT Ingenieurkeramik to manufacture complex parts, Thales Alenia Space (TAS) has engaged, in cooperation with FCT, activities to develop and qualify silicon nitride parts for other applications for space projects.

Space telescopes pupil diameter increases continuously to reach higher resolutions and associated optical scheme become more sensitive. As a consequence the size of these telescopes but also their stability requirements increase. Therefore, mass of space telescopes becomes a strong design driver to be still compatible with price competitive launcher capabilities. Moreover satellite agility requirements are more and more severe and instruments shall be compatible with quick evolution of thermal environment.

Metal optics is an inherent part of space instrumentation for years. Diamond turned aluminum (Al6061) mirrors are widely used for application in the mid- and near-infrared (mid-IR and NIR, respectively) spectral range. Aluminum mirrors plated with electroless nickel (NiP) expand the field of application towards multispectral operating instruments down to the ultraviolet wavelengths. Due to the significant mismatch in the coefficient of thermal expansion (CTE) between aluminum and NiP, however, this advantage occurs at the cost of bimetallic bending. Challenging requirements can be met by using bare beryllium or aluminum beryllium composites (AlBeMet) as a CTE tailored substrate material and amorphous NiP as polishable layer. For health reasons, the use of beryllium causes complications in the process chain. Thus, the beryllium approach is subjected to specific applications only. Metal optics has proven to be advantageous in respect of using conventional CNC and ultra-precision fabrication methods to realize complex and light-weighted instrument structures. Moreover, the mirror designs can be effectively optimized for a deterministic system assembly and optimization. Limitations in terms of dimensional stability over temperature and time are mainly given by the inherent material properties (figures of merit) of the substrate material in interaction with the polishing layer.

To find an optimal compromise, a thermal matched aluminum-silicon alloy (silicon contents ≈ 40 wt%) plated with NiP (AlSi40/NiP ) was investigated in a joined project of the Max Planck Institute for Astronomy MPIA and the Fraunhofer Institute for Applied Optics and Precision Engineering IOF. The main tasks of the project were the minimization of the bimetallic bending, the development of reliable stabilizing and aging procedures, and the establishment of a proven fabrication method.

This paper describes fundamental results regarding the optimization of the athermal material combination. Furthermore, the developed production chain for high quality freeform mirrors made of AlSi40/NiP is pointed out.

The next great leap forward in space-based far-infrared astronomy will be made by the Japanese-led SPICA mission, which is anticipated to be launched late 2020’s as the next large astrophysics mission of JAXA, in partnership with ESA and with key European contributions. Filling in the gap between JWST and ALMA, the SPICA mission will study the evolution of galaxies, stars and planetary systems. SPICA will utilize a deeply cooled 3m-class telescope, provided by European industry, to realize zodiacal background limited performance, high spatial resolution and large collecting area.

Making full advantage of the deeply cooled telescope (<6K), the SAFARI instrument on SPICA is a highly sensitive wide-field imaging photometer and spectrometer operating in the 34-210 μm wavelength range. Utilizing Nyquist-sampled focal-plane arrays of very sensitive Transition Edge Sensors (TES), SAFARI will offer a photometric imaging (R ≈ 2), and a low (R = 100) and medium resolution (R = 2000 at 100 μm) imaging spectroscopy mode in three photometric bands within a 2’x2’ instantaneous FoV by means of a cryogenic Mach-Zehnder Fourier Transform Spectrometer.

In this paper we will provide an overview of the SAFARI instrument design and system architecture. We will describe the reference design of the SAFARI focal- plane unit, the implementation of the various optical instrument functions designed around the central large-stroke FTS system, the photometric band definition and out-of-band filtering by quasioptical elements, the control of straylight, diffraction and thermal emission in the long-wavelength limit, and how we interface to the large-format FPA arrays at one end and the SPICA telescope assembly at the other end.

We will briefly discuss the key performance drivers with special emphasis on the optical techniques adopted to overcome issues related to very low background operation of SAFARI. A summary and discussion of the expected instrument performance and an overview of the astronomical capabilities finally conclude the paper.

The CHaracterising ExOPlanet Satellite (CHEOPS) is a joint ESA-Switzerland space mission dedicated to search for exoplanet transits by means of ultra-high precision photometry whose launch readiness is expected end 2017. The CHEOPS instrument will be the first space telescope dedicated to search for transits on bright stars already known to host planets. By being able to point at nearly any location on the sky, it will provide the unique capability of determining accurate radii for a subset of those planets for which the mass has already been estimated from ground-based spectroscopic surveys. CHEOPS will also provide precision radii for new planets discovered by the next generation ground-based transits surveys (Neptune-size and smaller). The main science goals of the CHEOPS mission will be to study the structure of exoplanets with radii typically ranging from 1 to 6 Earth radii orbiting bright stars. With an accurate knowledge of masses and radii for an unprecedented sample of planets, CHEOPS will set new constraints on the structure and hence on the formation and evolution of planets in this mass range. To reach its goals CHEOPS will measure photometric signals with a precision of 20 ppm in 6 hours of integration time for a 9th magnitude star. This corresponds to a signal to noise of 5 for a transit of an Earth-sized planet orbiting a solar-sized star (0.9 solar radii). This precision will be achieved by using a single frame-transfer backside illuminated CCD detector cool down at 233K and stabilized within ~10 mK . The CHEOPS optical design is based on a Ritchey-Chretien style telescope with 300 mm effective aperture diameter, which provides a defocussed image of the target star while minimizing straylight using a dedicated field stop and baffle system. As CHEOPS will be in a LEO orbit, straylight suppression is a key point to allow the observation of faint stars. The telescope will be the only payload on a spacecraft platform providing pointing stability of < 8 arcsec rms, power of 60W for instrument operations and downlink transmission of at least 1.2GBit/day. Both CHEOPS paylaod and platform will rely mainly on components with flight heritage. The baseline CHEOPS mission fits within the technical readiness requirements, short development time and the cost envelope defined by ESA in its first call for S-missions. It represents a breakthrough opportunity in furthering our understanding of the formation and evolution of planetary systems.

METIS coronagraph is designed to observe the solar corona with an annular field of view from 1.5 to 2.9 degrees in the visible broadband (580-640 nm) and in the UV HI Lyman-alpha, during the Sun close approaching and high latitude tilting orbit of Solar Orbiter. The big challenge for a coronagraph is the stray light rejection. In this paper after a description of the present METIS optical design, the stray light rejection design is presented in detail together with METIS off-pointing strategies throughout the mission. Data shown in this paper derive from the optimization of the optical design performed with Zemax ray tracing and from laboratory breadboards of the occultation system and of the polarimeter.

METIS is the Multi Element Telescope for Imaging and Spectroscopy for the ESA Solar Orbiter. Its target is the solar corona from a near-Sun orbit in two different spectral bands: the HI UV narrow band at 121.6 nm, and the VL visible light band. METIS adopts a novel inverted externally occulted configuration, where the disk light is shielded by an annular occulter, and an annular aspherical mirror M1 collects the signal coming from the corona. After M1 the coronal light passes through an internal occulter and is then reflected by a second annular mirror M2 toward a narrow filter for the 121.6 nm HI line selection. The visible light reflected by the filter is used to feed a visible light (580 − 640 nm) polarimetric channel. The photospheric light passing through the entrance aperture is back-rejected by a spherical rejection mirror.

Since the coronal light is enormously fainter than the photospheric one, a very tough suppression is needed for the internal stray light, in particular the requirement for the stray light suppression is more stringent in the VL than in the UV, because the emission of the corona with respect to the disk emission is different in the two cases, and the requirements are a suppression of at least 10^-9 times for the VL and a suppression of at least 10^-7 times for the UV channel.

This paper presents the stray light analysis for this new coronographic configuration.

The complexity of the optomechanical design of METIS, combined with the faintness of the coronal light with respect to the solar disk noise, make a standard ray tracing approach not feasible because it is not sufficient to stop at the first generation of scattered rays in order to check the requirements. Also scattered rays down to the fourth generation must be treated as sources of new scattering light, to analyze the required level of accuracy. If used in a standard ray tracing scattering analysis, this approach is absolutely beyond the computational capabilities today available; therefore we opted for a scattering ray generation with a Montecarlo method in which after a father ray hits a surface, only one ray is generated, randomly selected according to the distribution of the transmitted energy. These rays bring with them all the energy that is otherwise distributed between all the rays of second generation, making the model more realistic and avoiding loss of energy due to the rays sampling. The stray light has been studied in function of the mechanical roughness of the surfaces and the obtained results indicate an instrument stray light blocking performance well within the requirements in both channels.

Following our previous article about Optical fiber connectors for space at the previous ICSO2012 conference, we present here optical connector will be qualified using the ESCC system and report on the final qualification of the AVIM and Mini-AVIM.

Among the different optical modulator technologies available such as polymer, III-V semiconductors, Silicon, the well-known Lithium Niobate (LN) offers the best trade-off in terms of performances, ease of use, and power handling capability.

This paper presents a new European optocoupler type. This component has been developed by Optoi in the framework of ESA’s European Component Initiative (Phase 2). The most recent results are reported, specifically related to a full ESCC Evaluation Testing.

Pyrotechnics components and subsystems are employed for ignition, valve operation, separation systems and many other functions on both launchers and satellites. Other technologies exist, for example thermal or magnetically driven initiators and electric initiators. The choice of technology is mainly driven by application, cost and the environmental requirements to be met, such as shock and thermal requirements. The bulk of the initiator functions on board, including neutralization, are driven by the pyrotechnic chain.

For scientific and earth observation space missions, weight and power consumption is usually a critical factor. In order to obtain better vehicle integration, efficiency and controllability for large format NIR/SWIR detector arrays, a prototype ASIC is designed. It performs multiple detector array interfacing, power regulation and data acquisition operations inside the cryogenic chambers. Both operation commands and imaging data are communicated via the SpaceWire interface which will significantly reduce the number of wire goes in and out the cryogenic chamber. This “ASIC” prototype is realized in 0.18um CMOS technology and is designed for radiation hardness.

HgCdTe avalanche photodiode focal plane arrays (FPAs) and single element detectors have been developed for a large scope of photon starved applications. The present communication present the characteristics of our most recent detector developments that opens the horizon for low infrared (IR) photon number detection with high information conservation for imaging, atmospheric lidar and free space telecommunications. In particular, we report on the performance of TEC cooled large area detectors with sensitive diameters ranging from 30- 200 μm, characterised by detector gains of 2- 20 V/μW and noise equivalent input power of 0.1-1 nW for bandwidths ranging from 20 to 400 MHz.

Europe’s next fleet of geostationary meteorological satellites, MeteoSat Third Generation, will introduce new functions in addition to continuity of high-resolution meteorological data. The atmosphere Infrared Sounder (IRS), as high –end instrument, is part of this challenging program.

IRS principle is a Fourier Transform Interferometer, which allows recomposing atmospheric spectrum after infrared photons detection. Transmission spectrums will be used to support numerical weather prediction. IRS instrument is able to offer full disk coverage in one hour, an on-ground resolution of 4 by 4 km, in two spectral bands (MWIR: 1600 to 2175cm-1 and LWIR: 700 to 1210cm-1) with a spectral resolution of 0.6cm-1.

Among critical technologies and processes, IRS detection chain shall offer outstanding characteristics in terms of radiometric performance like Signal to Noise Ratio (SNR), dynamic range and linearity. Selected detectors are HgCdTe two-dimensions arrays, cooled at 55 Kelvins, hybridized on snapshot silicon read-out circuit at 160x160 format. Video electronics present 16 bits resolution, and the whole detection chain (Detectors and electronics) permits to reach SNR between 2 000 and 10 000 as requested by the application. Radiometric onground test results performed on design representative detection chains are presented and are confirming the challenging phase A design choices.

For the last ten years, SOFRADIR space activity has considerably grown and strengthened relying on 25 years of experience in development and production of 2nd and 3rd generation MCT (Mercury Cadmium Telluride) infrared detectors. Indeed, around 60 persons are now full-time involved in IRFPAs development and/or manufacturing for space applications.

The Laboratoire Electronique et Traitement de l’Information (LETI) of the Commissariat à l’Energie Atomique (CEA, Grenoble, France) has been involved in the development of infrared detectors based on HgCdTe (MCT) material for over 30 years, mainly for defence and security programs [1]. Once the building blocks are developed at LETI (MCT material process, diode technology, hybridization, …), the industrialization is performed at SOFRADIR (also in Grenoble, France) which also has its own R&D program [2].
In past years, LETI also developed infrared detectors for space astrophysics in the mid infrared range – the long wave detector of the ISOCAM camera onboard ISO – as well as in the far infrared range – the bolometer arrays of the Herschel/PACS photometer unit –, both instruments which were under the responsibility of the Astrophysics department of CEA (IRFU/SAp, Saclay, France).

Nowadays, the infrared detectors used in space and ground based astronomical instruments all come from vendors in the US. For programmatic reasons – increase the number of available vendors, decrease the cost, mitigate possible export regulations, …– as well as political ones – spend european money in Europe –, the European Space Agency (ESA) defined two roadmaps (one in the NIR-SWIR range, one in the MWIR-LWIR range) that will eventually allow for the procurement of infrared detectors for space astrophysics within Europe.
The French Space Agency (CNES) also started the same sort of roadmaps, as part of its contribution to the different space missions which involve delivery of instruments by French laboratories. It is important to note that some of the developments foreseen in these roadmaps also apply to Earth Observations.
One of the main goal of the ESA and CNES roadmaps is to reduce the level of dark current in MCT devices at all wavelengths. The objective is to use the detectors at the highest temperature where the noise induced by the dark current stays compatible with the photon noise, as the detector operating temperature has a very strong impact at system level. A consequence of reaching low levels of dark current is the need for very low noise readout circuits.

CEA and SOFRADIR are involved in a number of activities that have already started in this framework. CEA/LETI does the development of the photo-voltaic (PV) layers – MCT material growth, diode technologies–, as well as some electro-optical characterisation at wafer, diode and hybrid component levels, and CEA/IRFU/SAp does all the electro-optical characterisation involving very low flux measurements (mostly dark current measurements). Depending of the program, SOFRADIR can also participate in the development of the hybrid components, for instance the very low noise readout circuits (ROIC) can be developed either at SOFRADIR or at CEA/LETI.
Depending of the component specifications, the MCT epitaxy can be either liquid phase (LPE, which is the standard at SOFRADIR for production purposes) or molecular beam (MBE), the diode technology can be n/p (standard at LETI and SOFRADIR) or p/n (under development for several years now) [3], and the input stage of the ROIC can be Source Follower per Detector (SFD for very low flux low noise programs) or Capacitive Trans Impedance Amplifier (CTIA for intermediate flux programs) [4].

This paper will present the different developments and results obtained so far in the two NIR-SWIR and MWIR-LWIR spectral ranges, as well as the perspectives for the near future. CEA/LETI is also involved in the development of MCT Avalanche Photo Diodes (APD) that will be discussed in other papers [5,6].

Berliner Glas developed and manufactured the plane elliptical shaped mirrors for the Synopta Coarse Pointing Assembly (CPA) being one of the key elements of the TESAT Spacecom Laser Communication Terminals (LCT's). The first TESAT LCT containing a Synopta CPA was embarked on Sentinel 1A and is in orbit since April 2014. TESAT Spacecom LCT's have been successfully tested in space since 2007 and are now operationally used in commercial satellite communication systems.

In the framework of the “Earth Explorer” program, the European Space Agency had foreseen the PREMIER mission intended to monitor the three-dimensional distribution of trace gasses in the atmosphere.

Silicon Carbide is a material of high interest in the design and manufacturing of space telescopes, thanks to its mechanical and thermal properties. Since many years, Reosc has gathered a large experience in the polishing, testing, integration and coating of large size Silicon Carbide mirrors as well as in the integration of full SiC TMAs.

The X-ray optics is a key element of space X-ray telescopes, as well as other X-ray imaging instruments. The grazing incidence X-ray lenses represent the important class of X-ray optics. Most of grazing incidence (reflective) X-ray imaging systems used in astronomy but also in other (laboratory) applications are based on the Wolter 1 (or modified) arrangement. But there are also other designs and configurations proposed, used and considered for future applications both in space and in laboratory. The Kirkpatrick-Baez (K-B) lenses as well as various types of Lobster-Eye optics and MCP/Micropore optics serve as an example. Analogously to Wolter lenses, the X-rays are mostly reflected twice in these systems to create focal images. Various future projects in X-ray astronomy and astrophysics will require large segments with multiple thin shells or foils. The large Kirkpatrick-Baez modules, as well as the large Lobster-Eye X-ray telescope modules in Schmidt arrangement may serve as examples. All related space projects will require high quality and light segmented shells (bent or flat foils) with high X-ray reflectivity and excellent mechanical stability. The Multi Foil Optics (MFO) approach represent a promising alternative for both LE and K-B X-ray optical modules. Several types of reflecting substrates may be considered for these applications, with emphasis on thin float glass sheets and, more recently, high quality silicon wafers. This confirms the importance of non-Wolter X-ray optics designs for the future. The alternative designs require novel reflective substrates which are also discussed in the paper.

For several decades, the field of X-ray astronomy has been playing a major role in understanding the processes in our universe. From binary stars and black holes up to galaxy clusters and dark matter, high energetic events have been observed and analysed using powerful X-ray telescopes like e.g. Rosat, Chandra, and XMM-Newton [1,2,3], giving us detailed and unprecedented views of the high-energy universe.

In November 2013, the theme of “The Hot and Energetic Universe” was rated as of highest importance for future exploration and in June 2014 the ATHENA Advanced Telescope for High Energy Astrophysics was selected by ESA for the second large science mission (L2) in the ESA Cosmic Vision program, with launch foreseen in 2028 [4]. By combining a large X-ray telescope with state-of-the-art scientific instruments, ATHENA will address key questions in astrophysics, including: How and why does ordinary matter assemble into the galaxies and galactic clusters that we see today? How do black holes grow and influence their surroundings?

In order to answer these questions, ATHENA needs a powerful mirror system which exceed the capabilities of current missions, especially in terms of collecting area. However, current technologies have reached the mass limits of the launching rocket, creating the need for more light-weight mirror systems in order to enhance the effective area without increasing the telescope mass. Hence new mirror technologies are being developed which aim for low-weight systems with large collecting areas. Light material like glass can be used, which are shaped to form an X-ray reflecting system via the method of thermal glass slumping.

When we talk about planetary exploration missions most people think spontaneously about fascinating images from other planets or close-up pictures of small planetary bodies such as asteroids and comets. Such images come in most cases from VIS/NIR- imaging- systems, simply called ‘cameras’, which were typically built by institutes in collaboration with industry. Until now, they have nearly all been based on silicon CCD sensors, they have filter wheels and have often high power-consuming electronics.

The question is, what are the challenges for future missions and what can be done to improve performance and scientific output. The exploration of Mars is ongoing. NASA and ESA are planning future missions to the outer planets like to the icy Jovian moons. Exploration of asteroids and comets are in focus of several recent and future missions. Furthermore, the detection and characterization of exo-planets will keep us busy for next generations.

The paper is discussing the challenges and visions of imaging sensors for future planetary exploration missions. The focus of the talk is monolithic VIS/NIR- detectors.

Meteosat Third Generation is the next ESA Program of Earth Observation dedicated to provide Europe with an operational satellite system able to support accurate prediction of meteorological phenomena until the late 2030s. The satellites will be operating from the Geostationary orbit using a 3 axes stabilized platform. The main instrument is called the Flexible Combined Imager (FCI), currently under development by Thales Alenia Space France. It will continue the successful operation of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on Meteosat Second Generation (MSG) with improved performance.

This instrument will provide full images of the Earth every 10 minutes in 16 spectral channels between 0.44 and 13.3 μm. The ground resolution is ranging from 0.5 km to 2 km. The FCI is composed of a telescope developed by Kayser-Threde, which includes a Scan mirror for the full Earth coverage, and a calibration mechanism with an embedded black body dedicated to accurate in-flight IR radiometric calibration. The image produced by the telescope is split into several spectral groups by a spectral separation assembly (SSA) thanks to dichroïc beamsplitters. The output beams are collimated to ease the instrument integration before reaching the cryostat. Inside, the cold optics (CO-I) focalize the optical beams onto the IR detectors. The cold optics and IR detectors are accurately positioned inside a common cold plate to improve registration between spectral channels. Spectral filters are integrated on top of the detectors in order to achieve the required spectral selection.

This article describes the FCI optical design and performances. We will focus on the image quality needs, the high line-of-sight stability required, the spectral transmittance performance, and the stray-light rejection. The FCI currently under development will exhibit a significant improvement of performances with respect to MSG.

In order to ensure continuity and further enhancement of the European operational meteorological observations in the timeframe of 2020 to 2040, the MetOp-SG programme has been initiated by ESA in collaboration with EUMETSAT. ESA develops the prototype MetOp-SG satellites (including associated instruments) and procures, on behalf of EUMETSAT, the recurrent satellites (and associated instruments). EUMETSAT is responsible for the overall mission, funds the recurrent satellites, develops the ground segment, procures the launch and LEOP services and performs the satellites operations. The corresponding EUMETSAT Programme is termed the EUMETSAT Polar System – Second Generation or EPS-SG.

Sound policymaking requires high confidence in climate predictions verified against decadal change observations with robustly known accuracy. Yet, our ability to monitor and predict the future of the climate is inadequate as we currently do not possess sufficient accuracy in our observing capability to confidently observe the small but critical climate change signals that are expected to occur over decadal time scales. These signals are fundamental to assessing the accuracy of climate change projections made by models and for the unambiguous attribution of climate change.

JEM-EUSO (Extreme Universe Space Observatory on the Japanese Experiment Module)[1][2] is an advanced observatory that will be on-board the International Space Station (ISS) to observe the UV photon tracks produced by Ultra High Energy Cosmic Rays (UHECR) with energy above 10¹⁹ eV. JEM-EUSO will detect the electromagnetic and hadronic components of the Extensive Air Showers (EAS) generated as the result of the UHECR colliding with atmospheric nuclei. Atmospheric monitoring to obtain data, us cloud coverage and cloud top altitude, is crucial for energy estimation of an extreme energy particle. Accordingly JEM-EUSO will include and Atmospheric Monitoring System (AMS)[3] to observe the Earth atmosphere continuously in the FOV of the main telescope. The AMS will comprise an InfraRed CAMera (IRCAM), a LIDAR and JEM-EUSO slow data.

Optical laser communications (OLC) has been identified as the technology to enable high-data rate, secure links between and within satellites, as well as between satellites and ground stations with decreased mass, size, and electrical power compared to traditional RF technology.

This paper reports the radiation performance results of several new product types designed for high radiation environments. The products tested include radiation hardened highly birefringent (HiBi) passive products for polarised applications and radiation tolerant active erbium doped fiber products for amplifiers.

Radiation hardened, short beatlength HiBi fiber products have been developed for high accuracy polarisation maintaining (PM) gyros and sensors at both 1310nm and 1550nm operation in the space environment. The fibers have been tested up to 5kGy (500krad) – levels which could be expected in extreme, extra-terrestrial space environments. Results show a consistently low Radiation Induced Attenuation (RIA) of <7dB/km at 5kGy, giving a RIA value of 1.37×10^-2 dB/km/krad at 1550nm for this product range.

Radiation tolerant EDF AstroGain™ fibers are intended for use in multichannel amplifiers in optical intersatellite communications. The structure of the fibers have been designed to deliver an accelerated recovery of radiation damage through photo-annealing using only the residual energy already available in an amplifier using a 980nm pumping regime. These products have been tested up to 200Gy (20krad) – levels which can be expected in Earth orbit environments over a 20-30 mission lifetime. Results show up to 100% recovery under continuous use for dose rates of 0.11rad/hr. It has also been demonstrated through analysis of the optical spectral output that this effect reverses the gain tilt, or spectral narrowing, induced by radiation damage through the C and L band. These combined fiber characteristics allow performance stability of the amplifier over the lifetime of the space mission.

Using fiber optical components and assemblies for space flight applications brings several challenges for the design and the qualification process. Good knowledge of the system and environmental requirements is needed to derive design decisions and select suitable components for the fiber optical subsystem. Furthermore, the manufacturing process and integration limitations are providing additional constraints, which have to be considered at the beginning of the design phase. Besides Commercial off the shelf (COTS) components, custom made parts are often necessary.

Optical fibers are used routinely in harsh environments for signal transmission or sensing applications [1]. Whereas the individual challenges originating from very high or very low temperatures, vacuum or ionizing radiation were extensively studied, the effects of combinations of these conditions were not investigated widely.

In these ICSO proceedings, we review recent advances from our group concerning the radiation hardening of optical fiber and fiber-based sensors for space applications and compare their benefits to state-of-the-art results. We focus on the various approaches we developed to enhance the radiation tolerance of two classes of optical fibers doped with rare-earths: the erbium (Er)-doped ones and the ytterbium/erbium (Er/Yb)-doped ones. As a first approach, we work at the component level, optimizing the fiber structure and composition to reduce their intrinsically high radiation sensitivities. For the Erbium-doped fibers, this has been achieved using a new structure for the fiber that is called Hole-Assisted Carbon Coated (HACC) optical fibers whereas for the Er/Ybdoped optical fibers, their hardening was successfully achieved adding to the fiber, the Cerium element, that prevents the formation of the radiation-induced point defects responsible for the radiation induced attenuation in the infrared part of the spectrum. These fibers are used as part of more complex systems like amplifiers (Erbium-doped Fiber Amplifier, EDFA or Yb-EDFA) or source (Erbium-doped Fiber Source, EDFS or Yb- EDFS), we discuss the impact of using radiation-hardened fibers on the system radiation vulnerability and demonstrate the resistance of these systems to radiation constraints associated with today and future space missions. Finally, we will discuss another radiation hardening approach build in our group and based on a hardening-by-system strategy in which the amplifier is optimized during its elaboration for its future mission considering the radiation effects and not in-lab.

Infrared photodetectors based on type-II InAs/GaSb superlattice (T2SL) material has been given a lot of attention this past decade, in particular by U.S. laboratories. Among the advantages of this material system, one can cite the possibility to span a large Infrared (IR) range (3μm to 30 μm) by tailoring the band-gap independently from the lattice constant, allowing addressing many applications by the same fabrication process and the realization of multi-color IR sensors for high performance imaging systems. Recently, the maturity of the growth of the quantum structure by molecular beam epitaxy (MBE) and progress on the processing resulted in the demonstration of high-performance mega-pixel focal plane arrays (FPA) in both the mid-wavelength (MWIR) and the long-wavelength (LWIR) infrared spectral bands [1]. Consequently, InAs/GaSb T2SL photodetector can be now considered as a new infrared technology which can be complementary to InSb, MCT or QWIPs technologies.

After some reminders on InAs/GaSb T2SL quantum structure properties, we present in this communication the results obtained by the IES laboratory, from Montpellier University, France, for photodiodes operating in the MWIR spectral domains. We then complete the paper by the main results reached by others laboratories for T2SL detectors operating from MWIR to VLWIR spectral ranges.

The ESA EarthCARE satellite mission objective is the observation of clouds and aerosols from low Earth orbit. The key spatial context providing instrument within the payload suite of 4 instruments is the Multi- Spectral Imager (MSI). This paper discusses the test program developed and implemented at SSTL for the formal qualification of the COTS micro-bolometer detectors for the TIR camera of the MSI. The comprehensive test campaign for the qualification of the detectors covered full electro-optical characterisation, life tests, environmental testing (thermal and mechanical), Particle Impact Noise Detection (PIND) tests, destructive physical analysis (DPA) and radiation tolerance assessment. Testing was undertaken at the specialist detector test facilities at SSTL. External facilities were called on for aspects of the programme. We describe the microbolometer arrays tested, the test benches developed for the program, test facilities, the test procedures and a summary of the test results. The qualification programme was completed in May 2014.

Detection for space application is very demanding on the IR detector: all wavelengths, from visible-NIR (2- 3um cutoff) to LWIR (10-12.5um cutoff), even sometimes VLWIR (15um cutoff) may be of interest. Moreover, various scenarii are usually considered. Some are imaging applications where the focal plane array (FPA) is used as an optical element to sense an image. However, the FPA may also be used in spectrometric applications where light is triggered on the different pixels depending on its wavelength. In some cases, star pointing is another use of FPAs where the retina is used to sense the position of the satellite.

In all those configurations, we might distinguish several categories of applications:
• low flux applications where the FPA is staring at space and the detection occurs with only a few number of photons.
• high flux applications where the FPA is usually staring at the earth. In this case, the black body emission of the earth and its atmosphere ensures usually a large number of photons to perform the detection.

Those two different categories are highly dimensioning for the detector as it usually determines the level of dark current and quantum efficiency (QE) requirements. Indeed, high detection performance usually requires a large number of integrated photons such that high QE is needed for low flux applications, in order to limit the integration time as much as possible. Moreover, dark current requirement is also directly linked to the expected incoming flux, in order to limit as much as possible the SNR degradation due to dark charges vs photocharges. Note that in most cases, this dark current is highly depending on operating temperature which dominates detector consumption. A classical way to mitigate dark current is to cool down the detector to very low temperatures.

This paper won't discuss the need for wavefront sensing where the number of detected photons is low because of a very narrow integration window. Rigorously, this kind of configuration is a low flux application but the need for speed distinguishes it from other low flux applications as it usually requires a different ROIC architecture and a photodiode optimized for high response speed.

To push HOT-performance, AIMs existing n-on-p technology has been improved by introducing Gold as an acceptor and reducing its concentration to the lower 10¹⁵/cm³ range as well as by optimizing the passivation process. This results in a substantial reduction in dark current density, a prerequisite for HOT operation. Recent dark current data are compared to ones previously obtained as well as to Tennant`s Rule07 [1], a generally accepted bench mark in this context.

Furthermore, we present electro-optical parameters obtained in the temperature range from 120 K to 170 K on resulting FPAs with 640x512 pixels, a pitch of 15 μm and a typical (80 K) cutoff wavelength of 5.1 μm.

Sensing tiny distance variations interferometrically will be a key task in several future space missions. Interferometric detectors such as (e)LISA will observe gravitational waves from cosmic events such as for instance super novae and extreme mass ratio inspirals. The detection principle of such detectors is sensing phase variations due to tiny distance variations between two free floating test masses aboard two remote spacecraft originating from passing gravitational waves.

This detection principle will be tested for the first time by LISA Pathfinder (launch ~2015), where the interferometric readout of two free floating test masses aboard one single spacecraft will be demonstrated. Future geodesy missions will map Earths Gravity field, by interferometrically measuring distance variations between two spacecraft in low Earth orbit. This will be tested for the first time by the Laser Ranging Instrument (LRI) aboard GRACE Follow-On (launch ~2017).

The low noise laser interferometry of all these missions provides a number of challenging tasks. We will present optical simulations performed for the missions above.

The interferometry of LISA Pathfinder is purely local (there do not exist any received beams from remote spacecraft), such that all beams can be approximated by fundamental Gaussian beams. We will present simulations regarding the coupling of residual test mass jitter (longitudinal and lateral as well as angular) to the phase readout, including Monte Carlo simulations to predict how misalignment affects resulting phase noise and estimate in-flight alignment of the test masses.

In all of the mentioned missions, the local laser beams are delivered to the optical bench by fibers, resulting in laser beams in fiber modes. Besides local laser beams, the interferometry of missions such as (e)LISA and LRI involves also received beams from remote spacecraft. These beams have diameters in the range of tens of meters (LRI) or kilometers (LISA / eLISA and alike), before being clipped down to centimeter scale by the receiving aperture. The resulting top hat beams show strong diffraction effects and are therefore imaged on the optical benches. Key elements for simulations are therefore the propagation with diffraction of top hat beams and fiber modes in vacuum, as well as imaging optics causing aberration and astigmatism, with the central task to characterize the coupling of test mass or spacecraft jitter to optical readout noise, in presence of realistic alignment errors.

A recurring and often limiting noise in the length measurement originates from the cross coupling of angular component jitter. This cross coupling will be briefly introduced with strategies for its mitigation in the various missions.

To overcome the limitations of existing and commercial software, we have written and used for the simulations above as well as for general interferometer design purposes a dedicated software package called IfoCAD which is publicly available and will be presented as well.

PHARAO (Projet d'Horloge Atomique par Refroidissement d'Atomes en Orbite), which has been developed by CNES, is the first primary frequency standard specially designed for operation in space. PHARAO is the main instrument of the ESA mission ACES (Atomic Clock Ensemble in Space). ACES payload will be installed on-board the International Space Station (ISS) to perform fundamental physics experiments. All the sub-systems of the Flight Model (FM) have now passed the qualification process and the whole FM of the cold cesium clock, PHARAO, is being assembled and will undergo extensive tests. The expected performances in space are frequency accuracy less than 3.10^-16 (with a final goal at 10^-16) and frequency stability of 10^-13 τ^-1/2. In this paper, we focus on the laser source performances and the main results on the cold atom manipulation.

The Gravity Recovery and Climate Experiment (GRACE) is a successful Earth observation mission launched in 2002 and consisting of two identical satellites in a polar low-Earth orbit.

The gravitational wave detection will open a new gravitational wave astronomy, which gives a fruitful insight about early universe or birth and death of stars. In order to detect gravitational wave, we planed a space gravitational wave detector, DECIGO (DECi-heltz Interferometer Gravitational wave Observatory), which consists of three drag-free satellites forming triangle shaped Fabry-Perot laser interferometer with the arm length of 1000 km, and whose strain sensitivity is designed to be 2x10^-24 /√Hz around 0.1 Hz. Before launching DECIGO around 2030, a milestone mission named DECIGO pathfinder (DPF) is planed to be launched whose main purpose is the feasibility test of the key technologies for DECIGO. In the present paper, the conceptual design and current status of DECIGO and DPF are reviewed.

The eLISA (evolved Laser Interferometer Space Antenna) mission is an ESA L3 concept mission intended to detect and characterise gravitational radiation emitted from astrophysical sources [1]. Current designs for eLISA [2] are based on the ESA study conducted in 2011 to reformulate the original ESA/NASA LISA concept [3] into an ESA-only L1 candidate named NGO (New Gravitational Observatory) [4]. During this brief reformulation period, a number of significant changes were made to the baseline LISA design in order to create a more costeffective mission. Some of the key changes implemented during this reformulation were:
• A reduction in the inter satellite distance (the arm length) from 5 Gm to 1 Gm.
• A reduction in the diameter of the telescope from 40 cm to 20 cm.
• A reduction in the required laser power by approximately 40%.
• Implementation of only 2 laser arms instead of 3.
Many further simplifications were then enabled by these main design changes including the elimination of payload items in the two spacecraft (S/C) with no laser-link between them (the daughter S/C), a reduction in the size and complexity of the optical bench and the elimination of the Point Ahead Angle Mechanism (PAAM), which corrects for variations in the pointing direction to the far S/C caused by orbital dynamics [4] [5].

In the run-up to an L3 mission definition phase later in the decade, it is desirable to review these design choices and analyse the inter-dependencies and scaling between the key mission parameters with the goal of better understanding the parameter space and ensuring that in the final selection of the eLISA mission parameters the optimal balance between cost, complexity and science return can be achieved.

PROBA-V has been successfully launched on 7^th May 2013 and is providing a global monitoring in the continuity of the SPOT-VEGETATION mission. The progress in terms of ground resolution between Spot VGT and PROBA-V is a factor 3 (1 km to 1/3 km ground resolution product).

SEOSAT/Ingenio (Spanish Earth Observation SATellite) is a high-spatial-resolution optical mission developed, together with PAZ (a synthetic aperture radar satellite), under the Spanish Earth Observation National Program for Satellites (PNOTS).

Current fleet of geostationary Earth orbit (GEO) satellites are used to provide communication in remote areas and to acquire meteorological data that are fed to Numerical Weather Predictions models.

The China-Brazilian Earth Resources Satellite (CBERS) program, (also called ZY-1) the result of a space technology agreement between China and Brazil, was officially signed in 1988 after the first joint work report produced by National Institute for Space Research (INPE) and the Chinese Academy of Space Technology (CAST). During the 26 years of its existence, the program of cooperation between China and Brazil in space has achieved the successful launch of three satellites. It has become a unique example of cooperation in cutting edge technology between emerging nations. CBERS satellite is the first generation data-transferring remote sensing satellite developed by China. CBERS satellite data are widely applied to crop yield estimation, exploration of land and resources, urban planning, environmental protection and monitoring, disaster reduction, and other fields. CBERS series is just like Landsat series of USA and SPOT series of France.

A mid-to-high resolution optical payload, named STREEGO, featuring a compact envelope, reduced mass, and competitive cost has been designed to address Earth Observation applications from low Earth orbit (LEO) small satellites. STREEGO is a fully reflective telescope designed for operation at a nominal altitude of 600 km to provide a ground sampling distance (GSD) of 2.75 m, a field of view of about 1° and a modulation transfer function (MTF) greater than 10% at Nyquist frequency (91 cy/mm) with a telescope aperture of 200 mm. A large two-dimensional CMOS sensor with a pixel size of 5.5 μm has been selected in order to obtain the requested GSD with a focal length of 1.2 m, and a signal-to-noise ratio equal to 75. A demonstration model is in the detailed design phase and will be developed, with completion planned by end of 2015. We present a detailed description of the instrument, which, by leveraging on aspheric surfaces and light-weight solutions, achieves remarkable performance in terms of compactness and image quality with less than 25 kg in mass. The optical design is based on a three mirror anastigmat (TMA) configuration whereby the mirrors are realized in metal with the same coefficient of thermal expansion of the structure in order to obtain an athermal design.

CERN, the European Organization for Nuclear Research (in Geneva, Switzerland), is home to a complex scientific instrument: the 27-kilometre Large Hadron Collider (LHC) collides beams of high-energy particles at close to the speed of light. Optical fibres are widely used at CERN, both in surface areas (e.g. for inter-building IT networks) and in the accelerator complex underground (e.g. for cryogenics, vacuum, safety systems). Optical fibres in the accelerator are exposed to mixed radiation fields (mainly composed of protons, pions, neutrons and other hadrons, gamma rays and electrons), with dose rates depending on the particular installation zone, and with radiation levels often significantly higher than those encountered in space. In the LHC and its injector chain radiation levels range from relatively low annual doses of a few Gy up to hundreds of kGy.

Optical fibres suffer from Radiation Induced Attenuation (RIA, expressed in dB per unit length) that affect light transmission and which depends on the irradiation conditions (e.g. dose rate, total dose, temperature). In the CERN accelerator complex, the failure of an optical link can affect the proper functionality of control or monitoring systems and induce the interruption of the accelerator operation. The qualification of optical fibres for installation in critical radiation areas is therefore crucial. Thus, all optical fibre types installed in radiation areas at CERN are subject to laboratory irradiation tests, in order to evaluate their RIA at different total dose and dose rates. This allows the selection of the appropriate optical fibre type (conventional or radiation resistant) compliant with the requirements of each installation. Irradiation tests are performed in collaboration with Fraunhofer INT (irradiation facilities and expert team in Euskirchen, Germany).

Conventional off-the-shelf optical fibres can be installed for optical links exposed to low radiation levels (i.e. annual dose typically below few kGy). Nevertheless, the conventional optical fibres must be carefully qualified as a spread in RIA of factor 10 is observed among optical fibres of different types and dopants. In higher radiation areas, special radiation resistant optical fibres are installed. For total dose above 1 kGy, the RIA of these special optical fibres is at least 10 times lower than the conventional optical fibres RIA at same irradiation conditions. 2400 km of these special radiation resistant optical fibres were recently procured at CERN. As part of this procurement process, a quality assurance plan including the irradiation testing of all 65 produced batches was set up.

This presentation will review the selection process of the appropriate optical fibre types to be installed in the radiation environment of CERN. The methodology for choosing the irradiation parameters for the laboratory tests will be discussed together with an overview of the RIA of different optical fibre types under several irradiation conditions.

Testing optical fibers for their response to ionizing radiation is unavoidable if their properties in radiation environments need to be known. So far, no model exists that would be able to predict the behavior of optical fibers in the presence of radiation, for example because too many, mostly unknown parameters influence the changes in the fiber.

To obtain reliable results from irradiation tests of optical fibers a well-defined setup and thorough experience is needed to avoid erroneous data that might lead to wrong decisions for the final application.

This presentation tries to introduce basic concepts of radiation testing of optical fibers, focusing on not so well known influences or typical errors. Focus will be laid on the measurement of radiation-induced attenuation (RIA) in optical fibers.

We realized ultra-stable optical frequency references on elegant breadboard (EBB) and engineering model (EM) level utilizing Doppler-free spectroscopy of molecular iodine near 532nm. A frequency stability of about 1•10^-14 at an integration time of 1 s and below 5•10^-15 at integration times between 10 s and 100 s was achieved. These values are comparable to the currently best laboratory setups.

Both setups use a baseplate made of glass material where the optical components are joint using a specific assembly-integration technology. Compared to the EBB setup, the EM setup is further developed with respect to compactness and mechanical and thermal stability. The EM setup uses a baseplate made of fused silica with dimensions of 380 x 180 x 40 mm³ and a specifically designed 100 x 100 x 30 mm³ rectangular iodine cell in nine-pass configuration with a specific robust cold finger design. The EM setup was subjected to thermal cycling and vibrational testing.

Applications of such an optical frequency reference in space can be found in fundamental physics, geoscience, Earth observation, and navigation & ranging. One example is the proposed mSTAR (mini SpaceTime Asymmetry Research) mission, dedicated to perform a Kennedy-Thorndike experiment on a satellite in a sunsynchronous low-Earth orbit. By comparing an iodine standard to a cavity-based frequency reference and integration over 2 year mission lifetime, the Kennedy-Thorndike coefficient will be determined with up to two orders of magnitude higher accuracy than the current best ground experiment. In a current study, the compatibility of the payload with the SaudiSat-4 host vehicle is investigated.

With GRACE (launched 2002) and GOCE (launched 2009) two very successful missions to measure earth’s gravity field have been in orbit, both leading to a large number of publications. For a potential Next Generation Gravity Mission (NGGM) from ESA a satellite-to-satellite tracking (SST) scheme, similar to GRACE is under discussion, with a laser ranging interferometer instead of a Ka-Band link to enable much lower measurement noise. Of key importance for such a laser interferometer is a single frequency laser source with a linewidth <10 kHz and extremely low frequency noise down to 40 Hz / √Hz in the measurement frequency band of 0.1 mHz to 1 Hz, which is about one order of magnitude more demanding than LISA. On GRACE FO a laser ranging interferometer (LRI) will fly as a demonstrator. The LRI is a joint development between USA (JPL,NASA) and Germany(GFZ,DLR). In this collaboration the JPL contributions are the instrument electronics, the reference cavity and the single frequency laser, while STI as the German industry prime is responsible for the optical bench and the retroreflector. In preparation of NGGM an all European instrument development is the goal.

Nowadays cold atom-based quantum sensors such as atom interferometers start leaving optical labs to put e.g. fundamental physics under test in space. One of such intriguing applications is the test of the Weak Equivalence Principle, the Universality of Free Fall (UFF), using different quantum objects such as rubidium (Rb) and potassium (K) ultra-cold quantum gases. The corresponding atom interferometers are implemented with light pulses from narrow linewidth lasers emitting near 767 nm (K) and 780 nm (Rb). To determine any relative acceleration of the K and Rb quantum ensembles during free fall, the frequency difference between the K and Rb lasers has to be measured very accurately by means of an optical frequency comb. Micro-gravity applications not only require good electro-optical characteristics but are also stringent in their demand for compactness, robustness and efficiency. For frequency comparison experiments the rather complex fiber laser-based frequency comb system may be replaced by one semiconductor laser chip and some passive components. Here we present an important step towards this direction, i.e. we report on the development of a compact mode-locked diode laser system designed to generate a highly stable frequency comb in the wavelength range of 780 nm.

Direct detections of gravitational wave (GW) by using a long-baseline laser interferometer have been tried in many countries. In Japan, a space-GW detector named DECIGO (Deci-hertz interferometer Gravitational wave detector), and its milestone mission DPF (DECIGO pathfinder) has been promoted. We have developed a spaceborne highly frequency-stabilized light source for DECIGO and DPF with high mechanical stability, long-term stable operation, high-efficiency and compactness. The frequency of an Yb doped fiber DFB laser at 1030 nm was locked to the saturated absorption signal of the iodine molecule (I₂) at 515 nm. We have developed the breadboard model 1 (BBM1) of the I₂ stabilized Yb:fiber laser, which was installed on a 550x300x20-mm aluminum plate. The frequency noise of the laser was suppressed down to 0.4 Hz/Hz^1/2 at 1 Hz which was evaluated from the frequency error signal. In the present paper, we will report the details and performance of the BBM1 of the light source for DECIGO and DPF.

The payloads for Earth Observation and Universe Science are currently based on very stiff opto-mechanical structures with very tight tolerances. The introduction of active optics in such an instrument would relax the constraints on the thermo-mechanical architecture and on the mirrors polishing. A reduction of the global mass/cost of the telescope is therefore expected. Active optics is based on two key-components: the wave-front sensor and the wave-front corrector.

The next generation of large lightweight space telescopes will require the use of active optics systems to enhance the performance and increase the spatial resolution. Since almost 10 years now, LAM, CNES, THALES and ONERA conjugate their experience and efforts for the development of space active optics through the validation of key technological building blocks: correcting devices, metrology components and control strategies. This article presents the work done so far on active correcting mirrors and wave front sensing, as well as all the facilities implemented. The last part of this paper focuses on the merging of the MADRAS and RASCASSE test-set up. This unique combination will provide to the active optics community an automated, flexible and versatile facility able to feed and characterise space active optics components.

Concepts for future large space telescopes require an active optics system to mitigate aberrations caused by thermal deformation and gravitational release. Such a system would allow on-site correction of wave-front errors and ease the requirements for thermal and gravitational stability of the optical train. In the course of the ESA project "Development of Adaptive Deformable Mirrors for Space Instruments" we have developed a unimorph deformable mirror designed to correct for low-order aberrations and dedicated to be used in space environment. We briefly report on design and manufacturing of the deformable mirror and present results from performance verifications and environmental testing.

A technical development activity was carried out from 2009 to 2011 under ESA supervision to validate the Liquid Crystal Variable Retarders (LCVRs) as polarization modulators for the Solar Orbiter mission. After this, the technology achieved the Technology Readiness Level 5 (TRL5) corresponding to “Component Validation in Relevant Environment”. Afterwards, additional tests and characterizations were performed in order to select the final specifications of the LCVRs cells to optimize their performances under the mission environmental conditions.

The LCVRs will be used to measure the complete Stokes vector of the incoming light in PHI (The Polarimetric and Helioseismic Imager for Solar Orbiter) and the linear polarization in the case of METIS (Multi Element Telescope for Imaging and Spectroscopy). PHI is an imaging spectro-polarimeter that will acquire high resolution solar magnetograms. On the other hand, METIS is a solar coronagraph that will analyze the linear polarization for observations of the visible-light K-corona.

The polarization modulators are described in this work including the optical, mechanical, thermal and electrical aspects. Both modulators will consist of two identical LCVRs with a relative azimuth orientation of 45° for PHI and parallel for the METIS modulator. In the first case, the configuration allows the analysis of the full Stockes vector with maximum polarimetric efficiencies. In the second setup, wide acceptance angles (≤±4°) are obtained.

The polarization modulators will be thermal controlled to reach a stability better than ±0.5°C during the measurement acquisition time (≤60s) under all the operational thermal conditions. This is required to fulfill the required polarimetric accuracy (≤10^-3), because the LCVRs behavior has a dependence on temperature. The mechanical design has been conceived to minimize mass, volume and the thermal conductivity as well as the mechanical stress produced by the mounts to the cells, but taking into account the vibration environment due to the launch loads that the device shall withstand. Additionally, the optical clear aperture has been maximized and the design avoids breaks due to thermo-elastic deformations produced during the thermal cycling.

Finally, the electrical cables and connections have been designed to obtain a very compact, modular and robust device.

The FLuorescence EXplorer (FLEX) mission is one of the two candidates of ESA’s 8^th Earth Explorer opportunity mission. A system feasibility (Phase A/B1) study is about to be completed. The FLuORescence Imaging Spectrometer (FLORIS) is an imaging spectrometer on board of a medium sized satellite flying in tandem with Sentinel-3 in a Sun synchronous orbit at a height of about 814 km. FLORIS will observe vegetation fluorescence and reflectance within a spectral range between 500 and 780 nm, allowing the monitoring of seasonal variations of the vegetation cycles. FLORIS observes the land area including coastal zones (50 km).

In the framework of the Fluorescence Explorer (FLEX) phase A/B1 study, an elegant breadboard (EBB) of an imaging spectrometer is designed, manufactured and aligned by AMOS, with Airbus Defence&Space as the prime Contractor of the study. The FLEX mission is one of the two candidates of the 8^th Earth Explorer mission. The main constituting instrument of the FLEX mission is an imaging spectrometer observing vegetation fluorescence and reflectance with a high- and a low-resolution channels in the 500 nm -780 nm band. As part of the system feasibility study of the mission, a breadboard of the high-resolution channel of the instrument is designed and manufactured with a high representativeness of a future flight concept. The high-resolution channel is referred to as FIMAS (Fluorescence IMAging Spectrometer). The main purpose of the EBB is to demonstrate (1) the manufacturability of the instrument and (2) the compliance of the optical performances with respect to the science requirements (including spatial and spectral resolution and stray-light).

In Earth Observation, Universe Observation and Planet Exploration, scientific return of the instruments must be optimized in future missions. Micro-Opto-Electro-Mechanical Systems (MOEMS) could be key components in future generation of space instruments. These devices are based on the mature micro-electronics technology and in addition to their compactness, scalability, and specific task customization, they could generate new functions not available with current technologies. French and European space agencies, the Centre National d’Etudes Spatiales (CNES) and the European Space Agency (ESA) have initiated several studies with LAM and TAS for listing the new functions associated with several types of MEMS, and developing new ideas of instruments.

Today, optical instruments with FOV of ±30 degrees or more can be achieved by combining several optical modules thus increasing the complexity at instrument level in the design, integration, validation and calibration phases. For instance the MERIS instrument on the ENVIronment SATellite (ENVISAT) has a 68.5 degree FOV shared between 5 identical modules. Each one of those modules needs to be calibrated independently and the modules require to be co-registrated, which leads to stringent constraints at system level in terms of stability. Reducing the number of modules to achieve large FOVs will have potentially beneficial impact on the mass and volume of the instrument and will ease the calibration and co-registration process.

This paper describes the Next Generation Space Interconnect Standard (NGSIS) effort for the Reinventing Space community.

We present fiber optic technology for 850 nm, VCSEL-based embedded optical computing solutions. We introduce concepts for compact, rugged fiber optic transceivers that provide multi-channel operation at 12.5 Gbps per channel. The transceiver can be placed in close proximity to high performance ASICs to provide direct optical I/O between components. The transceiver is packaged with material having match coefficients of thermal expansion (CTE), and expanded beam optical interface – these features offer survivability and operation over wide temperature ranges.

Proba-V is the third mission of ESA’s Programme for In-orbit Technology Demonstration (IOD), based on a small, high performance satellite platform and a compact payload. Besides, the main satellite instrument aiming at Vegetation imaging, Proba-V embarks five technological payloads providing early flight opportunities for novel instruments and space technologies. Successfully launched by the ESA VEGA launcher in May 2013, it has now completed its commissioning and the full calibration of platform, main instrument and additional payloads and is, since last October, fully operational.

The High dEnsity space foRM cOnnector Demonstration or HERMOD is the last payload selected to fly on Proba-V. The payload objective is to validate through an actual launch and in orbit high-density optical fibre cable assembly, cumulate space heritage for fibre optics transmission and evaluate possible degradation induced by the space environment compared to on-ground tests. The future applications of this technology are for intrasatellite optical communications in view of mass reduction, the electrical grounding simplification and to increase the transmission rate. The project has been supported under an ESA GSTP contract. T&G Elektro (Norway) developed and tested the different optical cable assembly to be validated in the payload. The electrooptic modules, control, power and mechanical interfaces have been developed by DAS Photonics (Spain).

The payload contains four optical channels to be studied through the experiment, two assemblies with MTP/PC connectors and two assemblies with MPO/APC connectors. Optical data is transmitted in the four independent channels using two optoelectronic conversion modules (SIOS) working at 100Mbps including 2 full duplex channels each. A FPGA is used to generate, receive and compare the different binary patterns. The number of errors (if any) and Bit Error Rate (BER) is sent to the satellite TM interface. HERMOD successfully went through all mechanical and environmental tests before the integration in a very limited time. The telemetry data is currently sent to ground on daily basis. All the channels have survived the launch and no BER has been measured with the exception of channel 2, currently recording a BER of 3.06*10-16, that exhibits from time to time a burst of errors due to synchronizing issues of the initial data frame. It is expected to observe during the operating life of the payload the first errors within the channel 4 which was designed on purpose with reduced power margin.

This paper will present the full overview of the HERMOD technology demonstrator including the development, testing, validation activity, integration, commissioning and 1 year in-orbit exploitation results.

The satellite telecommunication sector is continuously facing new challenges. Operators turn towards increasing capacity payloads with higher number of beams and broader bandwidth, in order to cope with exhausting orbital positions and to lower the cost of in-orbit delivery of bit. Only satellites able to provide high data rate connections to numerous users are expected to achieve affordable communication prices. On the other hand, as the telecom market grows and the range of offered services (HDTV, Video On Demand, Triple Play), operators call for more versatile solutions to quickly grasp new markets and to adapt to these evolutions over the average 15 years of a satellite lifetime.

Flexible payloads have found an increasing interest for a number of years. Flexibility is considered as a means for a better commercial exploitation of a satellite fleet and a better allocation of resource in response to traffic evolution and/or changing business plans, with potential advantages such as a wider range of applications, less customization for specific missions, increased production runs of equipment, enhancement of reliability, reduction of equipment cost, reduction of program schedules [1]. Flexibility is expected to be offered in spectrum management and frequency plan, in coverage, or in the repeater power allocation.

The industry is taking up the challenge both by improving current telecom satellites and offering new payload technology, more flexible and able to address the new markets. From a system integrator perspective, flexibility is as an opportunity to design more generic payloads, that can be customized during or after fabrication only, thus shortening the design-to-manufacturing cycle, and improving the industry competitiveness.

Qualification testing of fiber based laser transmitters is required for NASA’s Deep Space Optical Communications program to mature the technology for space applications. In the absence of fully space qualified systems, commercial systems have been investigated in order to demonstrate the robustness of the technology. To this end, a 2.5 W fiber based laser source was developed as the transmitter for an optical communications experiment flown aboard the ISS as a part of a technology demonstration mission. The low cost system leveraged Mil Standard design principles and Telcordia certified components to the extent possible and was operated in a pressure vessel with active cooling. The laser was capable of high rate modulation but was limited by the mission requirements to 50 Mbps for downlinking stored video from the OPALS payload, externally mounted on the ISS. Environmental testing and space qualification of this unit will be discussed along with plans for a fully space qualified laser transmitter.

Satellite-based remote sensing using laser-based lidar techniques provides a powerful tool for global 3-D mapping of atmospheric species (e.g. CO₂, ozone, clouds, aerosols), physical attributes of the atmosphere (e.g. temperature, wind speed), and spectral indicators of Earth features (e.g. vegetation, water). Such information provides a valuable source for weather prediction, understanding of climate change, atmospheric science and health of the Earth eco-system. Similarly, laser-based altimetry can provide high precision ground topography mapping and more complex 3-D mapping (e.g. canopy height profiling). The lidar technique requires use of cutting-edge laser technologies and engineered designs that are capable of enduring the space environment over the mission lifetime. The laser must operate with suitably high electrical-to-optical efficiency and risk reduction strategy adopted to mitigate against laser failure or excessive operational degradation of laser performance.

Several ESA missions incorporate high power laser systems as core constituents of the payload. Instruments based on techniques such as Light Detection And Ranging (LIDAR) can offer extremely accurate measurements of great scientific and industrial interest such as atmosphere composition, wind speed, aerosol presence, topography and water depth, surface backscattering and many more. Other active optical techniques such as Laser Induced Breakdown Spectroscopy (LIBS) enable the remote testing of the composition of rocks. Rendezvous sensors can guide the approach and docking of spacecraft, or assist in the descent of a lander on a surface.

The Aeolus mission is part of ESA’s Earth Explorer program. The goal of the mission is to determine the first global wind data set in near real time to improve numerical weather prediction models.

The only instrument on board Aeolus, Aladin, is a backscatter wind LIDAR in the ultraviolet (UV) frequency domain. Aeolus is a frequency limited mission, inasmuch as it relies on the measure of the backscattered signal frequency shift in order to deduce the wind velocity. As such the frequency stability of the LIDAR laser source is a key parameter for this mission.

In the following, the characterization of the laser frequency stability, reproducibility and agility in vacuum shall be reported and compared to the mission requirements.

Future planetary exploration missions require the support of 3D vision in the GN&C during key spacecraft’s proximity phases, namely: i) spacecraft precision and soft Landing on the planet’s surface; ii) Rendezvous and Docking (RVD) between a Sample Canister (SC) and an orbiter spacecraft; iii) Rover Navigation (RN) on planetary surface. The imaging LiDARs are among the best candidate for such tasks [1-3]. The combination of measurement requirements and environmental conditions seems to find its optimum in the flash 3D LiDAR architecture. Here we present key steps is the evaluation of novelty light detectors and MOEMS (Micro-Opto- Electro-Mechanical Systems) technologies with respect to LiDAR system performance and miniaturization. The objectives of the project MILS (Miniaturized Imaging LiDAR System, Phase 1) concentrated on the evaluation of novel detection and scanning technologies for the miniaturization of 3D LiDARs intended for planetary mission. Preliminary designs for an elegant breadboard (EBB) for the three tasks stated above (Landing, RVD and RN) were proposed, based on results obtained with a numerical model developed in the project and providing the performances evaluation of imaging LiDARs.

Solar System planetology requires a wide use of observing spectroscopy for surface geology to atmosphere climatology. A high-contrast imaging is required to study and to characterize extra-solar planetary systems among other faint astronomical targets observed in the vicinity of bright objects. Two middle class space telescopes projects aimed to observe Solar system planets by a long term monitoring via spectroscopy and polarimetry. Extra solar planets (exoplanets) engineering and scientific explorations are included in science program.

Making use of all Mars observations taken by Herschel-HIFI, we present a detailed comparison of the measured and predicted beam profiles observed in space. Starting with a number of instrument beam profile models, including one based on actual wavefront measurements in the 480 – 1625 GHz frequency range, we developed a forward model predicting the detailed characteristics of the beam profile at the sky. Once convolved with the actual brightness temperature distribution and appearance of Mars, this forward model can be compared in detail with the observed spatial response towards Mars, using the science data of HIFI. Since the HIFI instrument is a single-mode coherent receiver, and given the availability of phase-sensitive measurements at instrument level, the results suggest that it is possible to extract some interesting optical characteristics of the Herschel telescope in addition. We discuss a possible way to extract the location of the telescope focus from these observations, which could provide useful feedback to the thermo-elastic properties of the SiC telescope assembly under zero-g and cryogenic conditions.

In the framework of the FP7 program FISICA (Far Infrared Space Interferometer Critical Assessment), we are developing a cubesat platform which will be used for the validation in space of two technological bricks relevant for FIRI.

The first brick is a high-precision accelerometer which could be used in a future space mission as fundamental element for the dynamic control loop of the interferometer.

The second brick is a miniaturized version of an imaging multi-aperture telescope. Ultimately, such an instrument could be composed of numerous space-born mirror segments flying in precise formation on baselines of hundreds or thousands of meters, providing high-resolution glimpses of distant worlds. We are proposing to build a very first space-born demonstrator of such an instrument which will fit into the limited resources of one cubesat.

In this paper, we will describe the detailed design of the cubesat hosting the two payloads.

Sub-meter resolution imagery has become increasingly important for disaster response, defence and security applications. Earth Observation (EO) at these resolutions has long been the realm of large and heavy telescopes, which results in high image costs, limited availability and long revisit times. Using synthetic aperture technology, instruments can now be developed that can reach these resolutions using a substantially smaller launch volume and mass.

To obtain a competitive MicroSatellite telescope design, a concept study was performed to develop a deployable instrument that can reach a ground resolution of 25 cm from an orbital altitude of 500 km. Two classes of instruments were analysed: the Fizeau synthetic aperture, a telescope that uses a segmented primary mirror, and a Michelson synthetic aperture, an instrument concept that combines the light of a distributed array of afocal telescopes into a final image. In a trade-off the Fizeau synthetic aperture was selected as the most promising concept for obtaining high resolution imagery from a Low Earth Orbit.

The optical design of the Fizeau synthetic aperture is based on a full-field Korsch telescope that has been optimized for compactness and an excellent wavefront quality. It uses three aperture segments in a tri-arm configuration that can be folded alongside the instrument during launch. The secondary mirror is mounted on a deployable boom, further decreasing the launch volume.

To maintain a high image quality while operating in the harsh and dynamic space environment, one of the most challenging obstacles that must be addressed is the very tight tolerance on the positioning of the three primary mirror segments and the secondary mirror. Following a sensitivity analysis, systems engineering budgets have been defined.

The instrument concept features a robust thermo-mechanical design, aimed at reducing the mechanical uncertainties to a minimum. Silicon Carbide mirror segments, the use of Invar for the deployable arms and a main housing with active thermal control, will guarantee a high thermal stability during operations.

Since a robust mechanical design alone is insufficient to ensure a diffraction limited performance, an inorbit calibration system was developed. Post launch, a combination of interferometric measurements and capacitive sensors will be used to characterise the system. Actuators beneath the primary mirror segments will then correct the position of the mirror segments to meet the required operating accuracies. During operations, a passive system will be used. This system relies on a phase diversity algorithm to retrieve residual wavefront aberrations and deconvolve the image data. Using this approach, a good end-to-end imaging performance can be achieved.

The Infrared Atmospheric Sounding Interferometer New Generation (IASI-NG) is a key payload element of the second generation of European meteorological polar-orbit satellites (METOP-SG) dedicated to operational meteorology, oceanography, atmospheric chemistry, and climate monitoring. IASI-NG is designed with a very high level of accuracy being dedicated to operational meteorology, climate monitoring, characterization of atmospheric composition related to climate, atmospheric chemistry and environment. The performance objective is mainly a spectral resolution and a radiometric error divided by two compared with the IASI first generation ones.

The measurement technique is based on wide field passive Fourier Transform Spectrometer (operating in the 3.5 - 15.5 μm spectral range) based on an innovative Mertz compensated interferometer to manage the so-called self-apodization effect and the associated spectral resolution degradation.

We will present an overview of the instrument architecture and ongoing instrument development.

CarbonSat is a candidate mission for ESA's Earth Explorer program, currently undergoing industrial feasibility studies. The primary mission objective is the identification and quantification of regional and local sources and sinks of carbon dioxide (CO₂) and methane (CH₄). The mission also aims at discriminating natural and anthropogenic fluxes. The space-borne instrument will quantify the spatial distribution of CO₂ and CH₄ by measuring dry air column-averaged mixing ratios with high precision and accuracy (0.5 ppm for CO₂ and 5 ppb for CH₄). These products are inferred from spectrally resolved measurements of Earth reflectance in three spectral bands in the Near Infrared (747-773 nm) and Short Wave Infrared (1590-1675 nm and 1925-2095 nm), at high and medium spectral resolution (0.1nm, 0.3 nm, and 0.55 nm). Three spatially co-aligned push-broom imaging spectrometers with a swath width <180 km will acquire observations at a spatial resolution of 2 x 3 km² , reaching global coverage every 12 days above 40 degrees latitude (30 days at the equator). The targeted product accuracy translates into stringent radiometric, spectral and geometric requirements for the instrument. Because of the high sensitivity of the product retrieval to spurious spectral features of the instrument, special emphasis is placed on constraining relative spectral radiometric errors from polarisation sensitivity, diffuser speckles and stray light. A new requirement formulation targets to simultaneously constrain both the amplitude and the correlation of spectral features with the absorption structures of the targeted gases. The requirement performance analysis of the so-called effective spectral radiometric accuracy (ESRA) establishes a traceable link between instrumental artifacts and the impact on the level-2 products (column-averaged mixing ratios). This paper presents the derivation of system requirements from the demanding mission objectives and report preliminary results of the feasibility studies.

CarbonSat is one of the two candidate missions for the 8th cycle of European Space Agency (ESA) Earth Explorers, currently undergoing feasibility studies with two industrial consortia. The mission aims at quantifying the spatial distribution of carbon dioxide (CO₂) and methane (CH₄) with high precision (3.0 ppm for CO₂ and 12.0 ppb for CH₄) and accuracy (0.5 ppm for CO₂ and 5 ppb for CH₄) at a high spatial resolution (2km x 3km) and with global coverage above 40° latitude every 12 days. It consists of three pushbroom spectrometers measuring the Earth reflectance in each of the following bands: NIR (747nm- 773nm @0.1nm resolution), SWIR-1 (1590-1675nm @0.3nm) and SWIR-2 (1925-2095nm @0.55nm).

Although most requirements for the CarbonSat phase A are defined over spatially homogeneous scenes, it is known from previous missions and studies that the observation of real, spatially heterogeneous scenes create specific measurement errors. One obvious mechanism is a distortion of the instrument spectral response function (ISRF) induced by a non-uniform slit illumination in the along-track (ALT) direction. This error has been analysed for several missions (OMI, Sentinel-4, Sentinel-5). The combination of spectrometer smile with across-track (ACT) scene non-uniformities induces similar errors. In this paper, we report about the analysis efforts carried out during CarbonSat preliminary phases to evaluate and mitigate these effects. In a first section, we introduce common concepts and notations for heterogeneous scenes analysis. An exhaustive list of known error mechanisms is presented. In section 2 we discuss the effect of inhomogeneous slit illumination, and describe hardware mitigation with a slit homogeniser. The combination of spectrometer smile and ACT heterogeneities is studied in section 3.

The MicroCarb mission objective is to better understand the carbon cycle and predict its evolution. For that purpose MicroCarb is designed to measure the carbon dioxide (CO₂) mixing ratio column within 1 ppm (a measurement precision of ~0.3%) from a space observatory in low Earth orbit (LEO) so as to locate and characterise the CO₂ sinks and sources.

We present novel immersed grating (IG) based spectrometer designs that can be used in space instrumentation. They are based on the design approach that aims to optimize the optical design using the expanded parameter space that the IG technology offers. In principle the wavefront error (WFE) of any optical system the most conveniently can be corrected in the pupil, where in the case of the IG based spectrometer, the IG itself is positioned. By modifying existing three-mirror based optical systems, which can form the main part of double pass spectrometer designs, a large portion of the WFE of the optical system can be transferred to the pupil and to the IG. In these cases the IG can compensate simple low order aberrations of the system and consequently the main benefit is that the mirrors that tend to be off-axis conical sections can be substituted by spherical mirrors. The WFE budget of such designs has only a minor contribution from the very high quality spherical mirrors and the majority of the WFE can be then allocated to the most complex part of the system, the IG. The latter can be designed so that the errors are compensated by a special grating pattern that in turn can be manufactured using the expertise and experience of the semiconductor industry.