KEYWORDS: Sensors, James Webb Space Telescope, Cryogenics, Switches, Electronics, Staring arrays, Control systems, Space operations, Image processing, Space telescopes
The Integrated Science Instrument Module of the James Webb Space Telescope is described from a systems perspective
with emphasis on unique and advanced technology aspects. The major subsystems of this flight element are described
including: structure, thermal, command and data handling, and software.
KEYWORDS: James Webb Space Telescope, Space telescopes, Mirrors, Sensors, Telescopes, Space operations, Stars, Observatories, Hubble Space Telescope, Galactic astronomy
The JWST project at the GSFC is responsible for the development, launch, operations and science data processing for the James Webb Space Telescope. The JWST project is currently in phase B with its launch scheduled for August 2011. The project is a partnership between NASA, ESA and CSA. The U.S. JWST team is now fully in place with the selection of Northrop Grumman Space Technology (NGST) as the prime contractor for the telescope and the Space Telescope Science Institute (STScI) as the mission operations and science data processing lead. This paper will provide an overview of the current JWST architecture and mission status including technology developments and risks.
KEYWORDS: Mirrors, Observatories, James Webb Space Telescope, Space telescopes, Telescopes, Image segmentation, Actuators, Space operations, Wavefronts, Stars
JWST will be used to help understand the shape and chemical composition of the universe, and the evolution of galaxies, stars and planets. With a 6.5 meter primary mirror, the Observatory will observe red shifted light from the early history of the universe, and will see objects 400 times fainter than those seen from large ground-based telescopes or the current generation of space-based infrared telescopes. NASA Goddard Space Flight Center (GSFC) manages JWST with contributions from a number of academic, government, and industrial partners. The contract to build the space-based Observatory for JWST was awarded to the Northrop Grumman Space Technology (NGST)/Ball/Kodak/ATK team.
KEYWORDS: James Webb Space Telescope, Sensors, Cryogenics, Staring arrays, Image processing, Optical filters, Space telescopes, Control systems, Interfaces, Data storage
The Integrated Science Instrument Module of the James Webb Space Telescope is described from a systems perspective with emphasis on unique and advanced technology aspects. The major subsystems of this flight element are described including: structure, thermal, command and data handling, and software.
The Advanced camera for Surveys (ACS), installed in the Hubble Space telescope in March 2002, has significantly extended HST’s deep, survey imaging capabilities. ACS comprises three cameras: the Wide Field Camera (WFC) is designed for deep, near-IR survey imaging programs; the High Resolution Camera (HRC) is a high angular resolution imager/coronagraph, which fully samples the HST point spread function in the visible; and the Solar Blind Camera (SBC) is a far-UV imager. ACS has met, or exceeded all of its key performance specification. In this paper we briefly review the in-flight performances of the instrument's CCD detectors. We present an overview of the performance of the ACS CCD detectors, based on the first year of flight science operations.
We present an overview of the Advanced Camera for Surveys (ACS) CCD detectors performance based on the ground testing and the calibration observations taken during the first four months of ACS operation. ACS has been installed into the Hubble Space Telescope in March 2002 and consists of three different cameras. Two of them employ CCD detectors: the Wide Field Camera a mosaic of two 4096 x 2048 CCDs and the High Resolution Camera a single 1024 x 1024 chip. A review of the on-orbit performance is presented here and also comparison is made with the instrument specifications, published performance expectation and ground test results.
We present an overview of the ACS on-orbit performance based on the calibration observations taken during the first three months of ACS operations. The ACS meets or exceeds all of its important performance specifications. The WFC and HRC FWHM and 50% encircled energy diameters at 555 nm are 0.088" and 0.14", and 0.050" and 0.10". The average rms WFC and HRC read noises are 5.0 e- and 4.7 e-. The WFC and HRC average dark currents are ~ 7.5 and ~ 9.1 e-/pixel/hour at their operating temperatures of - 76°C and - 80°C. The SBC + HST throughput is 0.0476 and 0.0292 through the F125LP and F150LP filters. The lower than expected SBC operating temperature of 15 to 27°C gives a dark current of 0.038 e-/pix/hour. The SBC just misses its image specification with an observed 50% encircled energy diameter of 0.24" at 121.6 nm. The ACS HRC coronagraph provides a 6 to 16 direct reduction of a stellar PSF, and a ~1000 to ~9000 PSF-subtracted reduction, depending on the size of the coronagraphic spot and the wavelength. The ACS grism has a position dependent dispersion with an average value of 3.95 nm/pixel. The average resolution λ/Δλ for stellar sources is 65, 87, and 78 at wavelengths of 594 nm, 802 nm, and 978 nm.
The Advanced Camera for Surveys (ACS) is a third generation science instrument scheduled for installation into the Hubble Space Telescope (HST) during the servicing mission 3B scheduled for late February 2002. The instrument has three cameras, each of which is optimized for a specific set of science goals. The first, the Wide Field Camera, is a high throughput (43% at 700 nm, including the HST OTA), wide field (200' X 204'), optical and I-band optimized camera. The second, the High Resolution Channel (HRC) has a 26' X 29' field of view, it is optimized for the near-UV (a peak throughput of 24% at 500 nm) and is critically sampled at approximately 630 nm. The third camera, the Solar-Blind Camera is a far-UV, photon counting array that has a relatively high throughput over a 26' X 29' field of view. Two of the three cameras employ CCD detectors: the WFC a mosaic of two SITe 2048 X 4096 pixel CCDs and the HRC a 1024 X 1024 CCD based on the Space Telescope Imaging Spectrograph 21 micrometers pixel CCD. In this paper we review the performance of the flight detectors selected for ACS.
The Advanced Camera for Surveys (ACS) will fly on the Hubble Space Telescope (HST) Servicing Mission 3b in late-2001 and includes a Solar Blind Channel (SBC) comprising correcting/magnifying relay optics, a far ultraviolet (FUV) filter selection, and a 1K X 1K multi-anode microchannel array (MAMA) detector with cesium iodide photocathode. In order to characterize SBC's flat field response over its full spectral range and to radiometrically calibrate ACS at two FUV lines through as many SBC filters as possible, a sophisticated and automated STimulus for Ultraviolet Flat Fields (STUFF) was developed whose application extends to other vacuum ultraviolet optical instrumentation having similar characterization requirements. Challenges in STUFF's development and resulting design features are presented along with results from in vacuo characterizations carried out before and during thermal vacuum testing of ACS.
The Advanced Camera for Surveys (ACS) is a third generation science instrument scheduled for installation into the Hubble Space Telescope (HST) during the servicing mission 3B scheduled for June 2001. The instrument has three different cameras, each of which is optimized for a specific set of science goals. The first, the Wide Field Camera, will be a high throughput, wide field optical and I-band optimized camera that is half-critically sampled at approximately 570 nm. The second, the High Resolution Channel (HRC) has a 26 inch by 29 inch field of view, it is optimized for the near- UV and is critically sampled at approximately 630 nm. The third camera, the Solar-Blind Camera is a far-UV, photon counting array that has a relatively high throughput over a 26 inch by 29 inch field of view. Two of the three cameras employ CCD detectors: the WFC a mosaic of two SITe 2048 by 4096 pixel CCDs and the HRC a 1024 by 1024 CCD based on the Space Telescope Imaging Spectrograph 21 micrometers pixel CCD. IN this paper we review the performances of the devices baselined as flight candidates.
The Advanced Camera for Surveys (ACS) is a third generation instrument for the Hubble Space Telescope (HST). It is currently planned for installation in HST during the fourth servicing mission in Summer 2001. The ACS will have three cameras.
The advanced camera for surveys (ACS) will be installed in the Hubble Space Telescope during the third servicing mission in May 2000. The ACS has three cameras, each of which is optimized for a specific set of science goals. The wide field camera, is a high throughput, wide field, optical and I-band camera that is half critically sampled at 500 nm. The high resolution camera (HRC) is optimized for the near- UV, has a 26 inch by 29 inch field of view and is critically sampled at 500 nm. The solar-blind camera, is a far-UV, photon counting camera that has a relatively high throughput over a 26 inch by 29 inch field of view. The WFC employs a mosaic of two SITe 2048 by 4096 CCDs with 15 micrometers pixels and a SITe backside treatment, while the HRC channel is designed around a 1024 by 1024 CCD with 21 micrometers pixels, and a near-UV backside treatment developed at the Steward Observatory. In this paper we review the performance of the devices currently selected for flight, and discuss the design of their flight packages.
The Advanced Camera for the Hubble Space Telescope has three cameras. The first, the Wide Field Camera, will be a high- throughput, wide field, 4096 X 4096 pixel CCD optical and I-band camera that is half-critically sampled at 500 nm. The second, the High Resolution Camera (HRC), is a 1024 X 1024 pixel CCD camera that is critically sampled at 500 nm. The HRC has a 26 inch X 29 inch field of view and 29 percent throughput at 250 nm. The HRC optical path includes a coronagraph that will improve the HST contrast near bright objects by a factor of approximately 10 at 900 nm. The third camera, the solar-blind camera, is a far-UV, pulse-counting array that has a relatively high throughput over a 26 inch X 29 inch field of view. The advanced camera for surveys will increase HST's capability for surveys and discovery by a factor of approximately 10 at 800 nm.
During the ground calibration of the Space Telescope Imaging Spectrograph (STIS) large scattered light haloes were identified in images of point sources and long slit spectral images at long wavelengths (greater than 750 nm). The long wavelength scattering was traced to the SITe 1024 X 1024 CCD and its header package, raising concerns for the performance of the Advanced Camera for Surveys (ACS) CCD detectors. ACS is a third generation axial instrument for the Hubble Space Telescope (HST) and will be installed during the 1999 Servicing Mission. Two of the ACS imaging channels employ SITe CCDs, so the ACS team have conducted a study of the long- wavelength scattering, in collaboration with SITe, to assess the impact to the ACS science program and develop a solution. In this paper we discuss our solution, its implementation on ACS CCDs, and describe the results of initial tests.
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