Electroforming replication technology at the Marshall Space Flight Center has a long heritage of producing high-quality, full-shell X-ray mirrors for various applications. Nickel alloys are electroformed onto a super-polished mandrel in the electroforming process and then separated to form the replicated full-shell optic. Various parameters in the electroplating configuration could result in the non-uniformity of the shell’s thickness. Thickness non-uniformities primarily occur due to the non-uniform electric field distribution in the electroforming tank during deposition. Using COMSOL Multiphysics simulations, we studied the electric field distributions during the deposition process. Using these studies, we optimized the electric field distribution and strength inside the tank using customized shields and insulating gaskets on the mandrel. These efforts reduced the thickness non-uniformity from over 20% to under 5%. Improving the thickness uniformity of the shell aids in better mounting and aligning shells in the optics module. Optimization of the electroforming process, in some cases, improved the optical performance of the shells. Using finite element modeling, we estimated the effect of electroforming stress on the figure errors of the replicated optics. We observed that the electroforming stress predominantly affects the figure toward the ends of the optics. We presented COMSOL optimization of the electroforming process and the experimental results validating these simulations. We also discuss modeling experimental results of the replication figure errors due to electroforming stresses.
NASA / MSFC has been preparing for X-ray calibration of the large
optic for the future ESA Athena mission at the 500 meter XRCF
beamline. Improvements include new facility X-ray detectors (Six
Amptek C2 window SDDs and a PI-MTE3 4k CCD camera), stages, and
verification of the facility's operation to the level reached for the
ground calibration of the Chandra X-ray telescope. The XRCF 1.5
meter beam size requires that a flight Athena optic be calibrated by
combining measurements from the six individual sub-sectors of the full
optic. New XRCF capabilities for the Athena measurement include the
ability to measure 12 meter focal length optics with the focal point
not co-linear with the facility optical axis.
As part of these preparations, in January 2023 we tested an SPO module
at the XRCF, aligning the optic in the facility and measuring the
point spread function and effective area at two separate energies.
Our results agree well with previous measurements of this module taken
at the MPE PANTER X-ray beamline. We present a synopsis of the
XRCF facility and its X-ray testing equipment, results from the
XRT#4 testing campaign in January 2023, and show that the XRCF is
currently capable of testing and calibrating large optics for the next
generation of flagship and probe class X-ray observatories.
NASA / MSFC has made new full-shell NiCo replicated hard X-ray optics
for the fourth flight of the Focusing Optics X-ray Solar Imager
sounding rocket set to observe the sun in March 2023. The new FOXSI-4
high resolution optics were made using enhanced
mandrel polishing techniques incorporating a Zeeko CNC deterministic
polishing machine and an improved module assembly station with in-situ metrology.
FOXSI-4 will fly three new 2-meter focal length high
resolution mirror modules with two shells each. The previous FOXSI-3
optics achieved an angular resolution of 20 arcsec HPD (5 arcsec FWHM) for
ten-shell modules. Initial X-ray measurements of FOXSI-4 shells
before module integration show a performance of 8 arcsec HPD and 3
arcsec FWHM, a substantial improvement over the FOXSI-3 optics. We present the
advances made in the polishing, replication, and assembly processes, and
measurements of the performance of the completed modules taken in the
Marshall 100 meter X-ray beam line.
The Focusing Optics X-ray Solar Imager 4 (FOXSI-4) is a heliophysics sounding rocket experiment that is currently in its fourth launch campaign. The payload is comprised of seven x-ray telescopes, which each consist of a 2 m focal length grazing incidence mirror module that focuses x-rays onto an imaging detector. For this fourth flight, Marshall Space Flight Center (MSFC) designed, built, and tested three new high-angular-resolution mirror module assemblies (MMAs). This paper describes the design and assembly of the FOXSI-4 MMAs.
The Marshall 100-Meter x-ray Beamline is a user facility for x-ray and EUV optics and instrumentation calibration, located at NASA’s Marshall Space Flight Center in Huntsville, Alabama. Also known as the Stray Light Test Facility, the Marshall-100 provides a range of focal plane detectors, x-ray sources, translation stages, cleanrooms, and high-vacuum level capability to the high-energy astrophysics community. Facility time is made available to Astronomy and Physics Research and Analysis (APRA) funded projects and is also available to the broader community upon request made to beamline management. The beamline has successfully been employed in the calibration of larger scope projects such as the Spectrum-Roentgen-Gamma Astronomical Röentgen Telescope X-ray Concentrator (ART-XC) telescope and the Small Explorer (SMEX) class Imaging X-ray Polarimetry Explorer (IXPE) Space Telescope. Additionally, the Marshall-100 is instrumental in supporting testing related to MSFC’s high-angular resolution optics development program.
Technology for a large-area, high-angular resolution mirror module for a future Great Observatory x-ray mission is progressing along different paths. To date, none of these are fully developed. Work at the Marshall Space Flight Center (MSFC) seeks to leverage the benefits of full shell optics while exploring the limits of using shell replication technology for optics production. Here, we provide an updated accounting of spatial-resolution-constraining error terms to give context to recent improvements in MSFC replicated optics, as well as guidance and justification for current and future directions of research and development. Content includes straw-man error allocations for an optical system that is parametrically Lynx-like, where the replicated-optics technology stands relative to these allocations, and methodology for mapping development plans to efficiently identify the limiting factors, and approaches to overcoming these.
IXPE, the first observatory dedicated to imaging x-ray polarimetry, was launched on Dec 9, 2021 and is operating successfully. A partnership between NASA and the Italian Space Agencey (ASI) IXPE features three x-ray telescopes each comprised of a mirror module assembly with a polarization sensitive detector at its focus. An extending boom was deployed on orbit to provide the necessary 4 m focal length. A three-axis-stabilized spacecraft provides power, attitude determination and control, and commanding. After one year of observation IXPE has measured statistically significant polarization from almost all the classes of celestial sources that emit X-rays. In the following we describe the IXPE mission, reporting on its performance after 1.5 year of operations. We show the main astrophysical results which are outstanding for a SMEX mission.
The lunar environment heliospheric x-ray imager (LEXI) is a wide field-of-view soft x-ray imager built to monitor the shape and motion of Earth’s magnetopause over multiple days. Set to land on the lunar surface as part of NASA’s commercial lunar payload services (CLPS) program, LEXI will measure soft x-rays (0.1-2 keV) produced by the charge exchange between the solar wind and neutral atoms in the near-earth environment. LEXI focuses x-rays in its 9.1° by 9.1° field of view using a tiled 3 by 3 array of “lobster-eye” micropore optics (MPOs). LEXI’s MPOs were first tested individually with a short range x-ray source to characterize the optics and select the best MPOs for flight. Once assembled into a flight array, the MPOs were tested in the PANTER x-ray beamline facility at multiple energies to determine the array’s point spread function and effective area as a function of off-axis angle. We present preliminary calibration results of LEXI’s individual MPO elements and assembled MPO array to qualify the instrument optics for flight.
The X-ray and Cryogenic Facility (XRCF) at the NASA Marshall Space
Flight Center (MSFC) is the baselined facility for X-ray testing of
the Athena X-ray optics. Here we give an overview of the planned
testing, including the XRCF facility and its 500-meter X-ray
beamline, the required facility X-ray sources and detectors,
testing requirements, and the GSE required for X-ray testing and
calibration of the Athena mirror assembly module demonstrator (MAMD),
the qualification model mirror (QM), and the flight model mirror (FM).
Of special interest is the metrology system needed for the
calibration: because the large Athena optic (the Mirror Assembly
Module, or MAM) is too large for full illumination in the XRCF 1.5m
diameter X-ray beam, the six sectors of the MAM will be tested
separately, requiring precise knowledge of the optic and detector
positions during the calibration to enable the stitching together of
the full MAM point spread function from measurements of the individual
sectors.
The Imaging X-ray Polarimetry Explorer, a NASA small explorer mission, will be the first mission dedicated to x-ray polarimetry. The payload consists of three identical telescopes, each comprising a mirror module assembly (MMA) with a polarization-sensitive detector at its focus. We describe all aspects of the MMA, from initial optical and mechanical design considerations to meet program requirements through mirror shell fabrication, mirror shell integration and module assembly, environmental testing, x-ray calibration, and on-ground and on-orbit alignment.
Launched on 2021 December 9, the Imaging X-ray Polarimetry Explorer (IXPE) is a NASA Small Explorer Mission in collaboration with the Italian Space Agency (ASI). The mission will open a new window of investigation—imaging x-ray polarimetry. The observatory features three identical telescopes, each consisting of a mirror module assembly with a polarization-sensitive imaging x-ray detector at the focus. A coilable boom, deployed on orbit, provides the necessary 4-m focal length. The observatory utilizes a three-axis-stabilized spacecraft, which provides services such as power, attitude determination and control, commanding, and telemetry to the ground. During its 2-year baseline mission, IXPE will conduct precise polarimetry for samples of multiple categories of x-ray sources, with follow-on observations of selected targets.
Expected to launch in Fall 2021, the Imaging X-ray Polarimetry Explorer (IXPE) is a NASA Astrophysics Small Explorer Mission with significant contributions from the Italian space agency (ASI). Three identical x-ray telescopes combine to form the IXPE observatory. Each is comprised of a 4-m-focal length mirror module assembly (MMA, provided by NASA MSFC) that focuses x-rays onto a polarization-sensitive, imaging detector (contributed by ASI-funded institutions). This paper describes the now-completed assembly process for the 3 flight mirror modules and spare, and compares as-tested calibrated performance with as-built metrology data. Unexpected challenges and lessons-learned are also discussed.
The Gamow Explorer will use Gamma Ray Bursts (GRBs) to: 1) probe the high redshift universe (z < 6) when the first stars were born, galaxies formed and Hydrogen was reionized; and 2) enable multi-messenger astrophysics by rapidly identifying Electro-Magnetic (IR/Optical/X-ray) counterparts to Gravitational Wave (GW) events. GRBs have been detected out to z ~ 9 and their afterglows are a bright beacon lasting a few days that can be used to observe the spectral fingerprints of the host galaxy and intergalactic medium to map the period of reionization and early metal enrichment. Gamow Explorer is optimized to quickly identify high-z events to trigger follow-up observations with JWST and large ground-based telescopes. A wide field of view Lobster Eye X-ray Telescope (LEXT) will search for GRBs and locate them with arc-minute precision. When a GRB is detected, the rapidly slewing spacecraft will point the 5 photometric channel Photo-z Infra-Red Telescope (PIRT) to identify high redshift (z < 6) long GRBs within 100s and send an alert within 1000s of the GRB trigger. An L2 orbit provides < 95% observing efficiency with pointing optimized for follow up by the James Webb Space Telescope (JWST) and ground observatories. The predicted Gamow Explorer high-z rate is <10 times that of the Neil Gehrels Swift Observatory. The instrument and mission capabilities also enable rapid identification of short GRBs and their afterglows associated with GW events. The Gamow Explorer will be proposed to the 2021 NASA MIDEX call and if approved, launched in 2028.
Scheduled to launch in late 2021 the Imaging X-ray Polarimetry Explorer (IXPE) is a Small Explorer Mission designed to open up a new window of investigation -- X-ray polarimetry. The IXPE observatory features 3 identical telescope each consisting of a mirror module assembly with a polarization-sensitive imaging x-ray detector at its focus. An extending beam, deployed on orbit provides the necessary 4 m focal length. The payload sits atop a 3-axis stabilized spacecraft which among other things provides power, attitude determination and control, commanding, and telemetry to the ground. During its 2-year baseline mission, IXPE will conduct precise polarimetry for samples of multiple categories of x-ray sources, with follow-on observations of selected targets. IXPE is a partnership between NASA and the Italian Space Agency (ASI).
The Lobster Eye X-ray Telescope (LEXT) is one of the payloads on-board the Gamow Explorer, which will be proposed to the 2021 NASA Explorer MIDEX opportunity. If approved, it will be launched in 2028, and is optimised to identify high-z Gamma Ray Bursts (GRBs) and enable rapid follow-up. The LEXT is a two module, CCD focal plane, large field of view telescope utilising Micro Pore Optics (MPOs) over a bandpass of 0.2 - 5 keV. The geometry of the MPOs comprises a square packed array of microscopic pores with a square cross-section, arranged over a spherical surface with a radius of curvature of 600 mm, twice the focal length of the optic, 300 mm. Working in the photon energy range 0.2 - 5 keV, the optimum L/d ratio (length of pore L and pore width d) is 60, and is constant across the whole optic aperture. This paper details the baseline design for the LEXT optic in order to full the science goals of the Gamow mission. Extensive ray-trace analysis has been undertaken and we present the development of the optic design along with the optimisation of the field of view, effective area and focal length using this analysis. Investigations as to the ideal MPO characteristics, e.g. coatings, pore size, etc., and details of avenues for further study are also given.
The Marshall 100-Meter X-ray Beamline is a world class facility utilized for testing X-ray and EUV optics and instrumentation. Also known as the Stray Light Test Facility, the beamline has been consequential in the calibration of flight missions such as ART-XC and IXPE. Additionally, the beamline is effectively used for APRA-funded projects and in MSFC own internal optic development campaigns. The Marshall 100-Meter X-ray Beamline a flexible and affordable facility that easily accommodates many of the astrophysical community’s needs. With its recent and upcoming improvements, the Marshall 100-Meter X-ray Beamline will continue to be a user-friendly calibration resource for decades to come.
The Imaging X-ray Polarization Explorer (IXPE) is a NASA Small Explorer mission to measure the polarization of astrophysical objects in the X-ray (2-8 keV) band set for launch in 2021. The calibration of three three flight optics took place in June-Aug 2020 at the NASA/MSFC Stray Light Test Facility (SLTF), a 100-meter vacuum beam line. One flight telescope (optic + detector: Mirror Module Assembly [MMA] + Detector Unit [DU]) and the flight spare were also calibrated at SLTF. We describe the calibration program and present results, including the measurement of the PSF and effective area of the MMAs at several energies, and the response of the telescope to incident polarized X-rays, including measurement of the Detector Modulation Factor (the response of the telescope to 100% polarized X-rays) and the telescope spurious modulation (response to an unpolarized X-ray source).
IXPE, the Imaging X-ray Polarimetry Explorer, is a NASA SMEX mission with an important contribution of ASI that will be launched with a Falcon 9 in 2021 and will reopen the window of X-ray polarimetry after more than 40 years. The payload features three identical telescopes each one hosting one light-weight X-ray mirror fabricated by MSFC and one detector unit with its in-orbit calibration system and the Gas Pixel Detector sensitive to imaging X-ray polarization fabricated by INAF/IAPS, INFN and OHB Italy. The focal length after boom deployment from ATK-Orbital is 4 m, while the spacecraft is being fabricated by Ball Aerospace. The sensitivity will be better than 5.5% in 300 ks for a 1E-11 erg/s/cm2 (half mCrab) in the energy band of 2-8 keV allowing for sensitive polarimetry of extended and point-like X-ray sources. The focal plane instrument is completed, calibrated and it is going to be delivered at MSFC. We will present the status of the mission at about one year from the launch.
An attitude determination system for balloon-borne experiments is presented. The system provides pointing information in azimuth and elevation for instruments flying on stratospheric balloons over Antarctica. In-flight attitude is given by the real-time combination of readings from star cameras, a magnetometer, sun sensors, GPS, gyroscopes, tilt sensors and an elevation encoder. Post-flight attitude reconstruction is determined from star camera solutions, interpolated by the gyroscopes using an extended Kalman Filter. The multi-sensor system was employed by the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol), an experiment that measures polarized thermal emission from interstellar dust clouds. A similar system was designed for the upcoming flight of Spider, a Cosmic Microwave Background polarization experiment. The pointing requirements for these experiments are discussed, as well as the challenges in designing attitude reconstruction systems for high altitude balloon flights. In the 2010 and 2012 BLASTPol flights from McMurdo Station, Antarctica, the system demonstrated an accuracy of < 5’ rms in-flight, and < 5” rms post-flight.
We present the thermal model of the Balloon-borne Large-Aperture Submillimeter Telescope for Polarimetry (BLASTPol). This instrument was successfully own in two circumpolar flights from McMurdo, Antarctica in 2010 and 2012. During these two flights, BLASTPol obtained unprecedented information about the magnetic field in molecular clouds through the measurement of the polarized thermal emission of interstellar dust grains. The thermal design of the experiment addresses the stability and control of the payload necessary for this kind of measurement. We describe the thermal modeling of the payload including the sun-shielding strategy. We present the in-flight thermal performance of the instrument and compare the predictions of the model with the temperatures registered during the flight. We describe the difficulties of modeling the thermal behavior of the balloon-borne platform and establish landmarks that can be used in the design of future balloon-borne instruments.
KEYWORDS: Bolometers, Digital signal processing, Analog electronics, Cryogenics, Electronics, Control systems, Physics, Sensors, Telescopes, Signal processing
We present the second generation BLASTbus electronics. The primary purposes of this system are detector readout, attitude control, and cryogenic housekeeping, for balloon-borne telescopes. Readout of neutron transmutation doped germanium (NTD-Ge) bolometers requires low noise and parallel acquisition of hundreds of analog signals. Controlling a telescope's attitude requires the capability to interface to a wide variety of sensors and motors, and to use them together in a fast, closed loop. To achieve these different goals, the BLASTbus system employs a flexible motherboard-daughterboard architecture. The programmable motherboard features a digital signal processor (DSP) and field-programmable gate array (FPGA), as well as slots for three daughterboards. The daughterboards provide the interface to the outside world, with versions for analog to digital conversion, and optoisolated digital input/output. With the versatility afforded by this design, the BLASTbus also finds uses in cryogenic, thermometry, and power systems. For accurate timing control to tie everything together, the system operates in a fully synchronous manner. BLASTbus electronics have been successfully deployed to the South Pole, and own on stratospheric balloons.
Nicholas Thomas, Jenny Carter, Meng Chiao, Dennis Chornay, Yaireska Collado-Vega, Michael Collier, Thomas Cravens, Massimiliano Galeazzi, Dimitra Koutroumpa, Joseph Kujawski, K. Kuntz, Maria Kuznetsova, Susan Lepri, Dan McCammon, Kelsey Morgan, F. Scott Porter, Krishna Prasai, Andy Read, Ina Robertson, Steve Sembay, David Sibeck, Steven Snowden, Youaraj Uprety, Brian Walsh
The objective of the Diffuse X-ray emission from the Local Galaxy (DXL) sounding rocket experiment is to distinguish the soft X-ray emission due to the Local Hot Bubble (LHB) from that produced via Solar Wind charge exchange (SWCX). Enhanced interplanetary helium density in the helium focusing cone provides a spatial variation to the SWCX that can be identified by scanning through the focusing cone using an X-ray instrument with a large grasp. DXL consists of two large proportional counters refurbished from the Aerobee payload used during the Wisconsin All Sky Survey. The counters utilize P-10 fill gas and are covered by a thin Formvar window (with Cyasorb UV-24 additive) supported on a nickel mesh. DXL's large grasp is 10 cm2 sr for both the 1/4 and 3/4 keV bands. DXL was successfully launched from White Sands Missile Range, New Mexico on December 12, 2012 using a Terrier Mk70 Black Brant IX sounding rocket.
The Sheath Transport Observer for the Redistribution of Mass (STORM) instrument is a prototype soft
X-ray camera also successfully own on the DXL sounding rocket. STORM uses newly developed slumped micropore (`lobster eye') optics to focus X-rays onto a position sensitive, chevron configuration, microchannel plate detector. The slumped micropore optics have a 75 cm curvature radius and a polyimide/aluminum filter bonded to its surface. STORM's large field-of-view makes it ideal for imaging SWCX with exospheric hydrogen for future missions. STORM represents the first flight of lobster-eye optics in space.
The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) is a suborbital mapping
experiment designed to study the role played by magnetic fields in the star formation process. BLASTPol uses
a total power instrument and an achromatic half-wave plate to modulate the polarization signal. During its first flight from Antarctica in December 2010, BLASTPol made degree scale maps of linearly polarized dust emission
from molecular clouds in three wavebands centered at 250, 350, and 500 μm. This unprecedented dataset in terms
of sky coverage, with sub-arcminute resolution, allows BLASTPol to trace magnetic fields in star-forming regions
at scales ranging from cores to entire molecular cloud complexes. A second long-duration flight is scheduled for
December 2012.
The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLAST-Pol) is a suborbital mapping
experiment designed to study the role played by magnetic fields in the star formation process. BLAST-Pol is
the reconstructed BLAST telescope, with the addition of linear polarization capability. Using a 1.8m Cassegrain
telescope, BLAST-Pol images the sky onto a focal plane that consists of 280 bolometric detectors in three arrays,
observing simultaneously at 250, 350, and 500μm. The diffraction-limited optical system provides a resolution of
30"at 250μm. The polarimeter consists of photolithographic polarizing grids mounted in front of each bolometer/
detector array. A rotating 4K achromatic half-wave plate provides additional polarization modulation. With
its unprecedented mapping speed and resolution, BLAST-Pol will produce three-color polarization maps for a
large number of molecular clouds. The instrument provides a much needed bridge in spatial coverage between larger-scale, coarse resolution surveys and narrow field of view, and high resolution observations of substructure
within molecular cloud cores. The first science flight will be from McMurdo Station, Antarctica in December
2010.
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