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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS2018

JWST Optical Telescope Element Center of Curvature Test

The James Webb Space Telescope (JWST) Optical Telescope Element (OTE) and Integrated Science Instrument Module (ISIM) completed element level integration and test programs and were integrated to the next level of assembly called OTE/ISIM (OTIS) at Goddard Space Flight Center (GSFC) in Greenbelt, Maryland in 2016. Before shipping the OTIS to Johnson Space Center (JSC) for optical test at cryogenic temperature a series of vibration and acoustic tests were performed. To help ensure that the OTIS was ready to be shipped to JSC an optical center of curvature (CoC) test was performed to measure changes in the mirror's optical performance to verify that the telescope's primary mirror was not adversely impacted by the environmental testing and help us in understanding potential anomalies identified during the JSC tests. The primary is a 6.5 meter diameter mirror consisting of 18 individual hexagonal segments. Each segment is an off-axis asphere. There are a total of three prescriptions repeated six times each. As part of the CoC test each segment was individually measured using a high-speed interferometer (HSI) designed and built specifically for this test. This interferometer is capable of characterizing both static and dynamic characteristics of the mirrors. The latter capability was used, with the aid of a vibration stinger applying a low-level input force, to measure the dynamic characteristic changes of the PM backplane structure. This paper describes the CoC test setup and both static and dynamic test results.

interferometer↗
NASA NTRS1998

Initial Evaluation of Space Environmental Effects on the NGST Sunshield

The "Next Generation Space Telescope" (NGST), the follow-on telescope to the Hubble Space Telescope, will carry on exploration of the early universe with a primary mirror 6-8 meters in diameter optimized to operate in the infrared. The mirror and its instruments will perform extremely deep exposures at near infra-red wavelengths (0.5-30 microns), and will operate for 5-10 years. In order to achieve the requirements, cryogenic temperatures between 30-60 Kelvin must be maintained on the telescope (OTA) and in the science module (SIM). A primary feature for passive cooling in the designs presented is that of an enormous, light-weight deployable sunshield. As a result, issues of contamination from the sunshield and space environmental effects on the sunshield itself present a critical matter: if the sunshield becomes a source of contamination, or if environmental effects damage the sunshield, the NGST mission could be compromised or could fail completely. A molecular redistribution analysis has been performed on the Goddard Space Flight Center (GSFC) design for NGST. The analysis revealed that because the shield will initially cool down faster than the OTA, the shield would not be a significant source of molecular contamination during the cooling phase. However, if the shield were ever to warm up, it would be a very large source of molecular contamination. The sunshield itself is susceptible to degradation from an external source of contamination: the space environment at L2 or at 1 x 3 AU. It is therefore necessary to design the sunshield to withstand the space environment. Thin films and coatings on the sunshield have been evaluated and testing has begun so that a suitable film and/or coating can be chosen or developed for the NGST mission. The evaluation and test results will be presented.

Wooldridge, Eve M.↗
NASA NTRS1984

Temperature stability limits for an isothermal demagnetization refrigerator

It is pointed out that magnetic refrigeration can provide additional cooling for infrared detectors on space missions, taking into account the Shuttle Infrared Telescope Facility (SIRTF) and the Large Deployable Reflector (LDR). From a temperature of 2 K provided by the primary cryogens, magnetic refrigerators could cool bolometers or pumped photoconductors to 0.1 K or below. Such a reduction in operating temperature would increase the sensitivity for bolometers, while the response at longer wavelengths for pumped photoconductors would be improved. Two types of magnetic refrigeration cycles have been proposed. One type uses a complete demagnetization. The present investigation is concerned with the second type, which uses a feedback-controlled isothermal demagnetization, taking into account the temperature stability limits. Attention is given to control system resolution, thermometer noise, reaction time, and thermal time constants.

Kittel, P.↗
NASA NTRS2014

New Method for Characterizing the State of Optical and Opto-Mechanical Systems

James Webb Space Telescope Optical Telescope Element (OTE) is a three mirror anastigmat consisting of a 6.5 m primary mirror (PM), secondary mirror (SM) and a tertiary mirror. The primary mirror is made out of 18 segments. The telescope and instruments will be assembled at Goddard Space Flight Center (GSFC) to make it the Optical Telescope Element-Integrated Science Instrument Module (OTIS). The OTIS will go through environmental testing at GSFC before being transported to Johnson Space Center for testing at cryogenic temperature. The objective of the primary mirror Center of Curvature test (CoC) is to characterize the PM before and after the environmental testing for workmanship. This paper discusses the CoC test including both a surface figure test and a new method for characterizing the state of the primary mirror using high speed dynamics interferometry.

Optical Testing↗
NASA NTRS2009

Ka-Band High-Rate Telemetry System Upgrade for the NASA Deep Space Network

The NASA Deep Space Network (DSN) has a new requirement to support high-data-rate Category A (Cat A) missions (within 2 million kilometers of Earth) with simultaneous S-band uplink, S-band downlink and Ka-band downlink. The S-band links are required for traditional TT&C (Telemetry, Tracking, and Command) support to the spacecraft, while the Ka-band link is intended for high-data-rate science returns. The new Ka-band system combines the use of proven DSN cryogenic designs, for low system temperature, and high data rate capability using commercial telemetry receivers. The initial Cat A support is required for the James Webb Space Telescope (JWST) in 2013 and possibly other missions. The upgrade has been implemented into 3 different 34-meter Beam Waveguide (BWG) antennas in the DSN, one at each of the complexes in Canberra (Australia), Goldstone (California) and Madrid (Spain). System test data is presented to show that the requirements were met and the DSN is ready for Cat A Ka-band operational support.

space communications↗
NASA NTRS1990

SIRTF primary mirror design, analysis, and testing

The primary mirror assembly (PMA) requirements and concepts for the Space Infrared Telescope Facility (SIRTF) program are discussed. The PMA studies at NASA/ARC resulted in the design of two engineering test articles, the development of a mirror mount cryogenic static load testing system, and the procurement and partial testing of a full scale spherical mirror mounting system. Preliminary analysis and testing of the single arch mirror with conical mount design and the structured mirror with the spherical mount design indicate that the designs will meet all figure and environmental requirements of the SIRTF program.

Sarver, George L., III↗
NASA NTRS2001

Comparison of satellite ozone observations in coincident air masses in early November 1994

Ozone observed by seven satellite instruments, the Atmospheric Trace Molecule Spectroscopy instrument (ATMOS), Stratospheric Aerosol and Gas Experiment (SAGE) II, Polar Ozone and Aerosol Measurement (POAM) II instrument, Halogen Occultation Experiment (HALOE), Microwave Limb Sounder (MLS), Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA), and Millimeter-wave Atmospheric Sounder (MAS), during early November 1994 is mapped in equivalent latitude/potential temperature (EqL/ theta )space to facilitate nearly global comparisons of measurements taken in similar air masses.

atmospheric↗
NASA NTRSDate not supplied

Capability Improvements at Marshall Space Flight Center's X-Ray and Cryogenic Facility

The X-Ray & Cryogenic Facility (XRCF) at Marshall Space Flight Center is the world’s largest x-ray optic calibration facility and NASA’s premier cryogenic optical test facility. Built specifically to calibrate the Chandra telescope, the facility contributed to several other x-ray missions until 2005 when it became dedicated to normal incidence optical testing at cryogenic temperatures. Recently the facility’s x-ray test capability has been returned to service and updated. New beam monitors, focal plane detectors, and test article and instrument positioning systems have been added. The x-ray data acquisition system has been updated. A real-time position monitoring metrology system is being developed that will enable calibration of large diameter optics via partial illumination in a diverging beam. The newly expanded x-ray test capabilities of the facility will be discussed.

XRCF↗
NASA NTRS1989

Proceedings of the Third Infrared Detector Technology Workshop

This volume consists of 37 papers which summarize results presented at the Third Infrared Detector Technology Workshop, held February 7-9, 1989, at Ames Research Center. The workshop focused on infrared (IR) detector, detector array, and cryogenic electronic technologies relevant to low-background space astronomy. Papers on discrete IR detectors, cryogenic readouts, extrinsic and intrinsic IR arrays, and recent results from ground-based observations with integrated arrays were given. Recent developments in the second-generation Hubble Space Telescope (HST) infrared spectrometer and in detectors and arrays for the European Space Agency's Infrared Space Observatory (ISO) are also included, as are status reports on the Space Infrared Telescope Facility (SIRTF) and the Stratospheric Observatory for Infrared Astronomy (SOFIA) projects.

Mccreight, Craig R.↗
NASA NTRS2013

Creating the Deep Space Environment for Testing the James Webb Space Telescope at NASA Johnson Space Center's Chamber A

Chamber A is the largest thermal vacuum chamber at the Johnson Space Center and is one of the largest space environment chambers in the world. The chamber is 19.8 m (65 ft.) in diameter and 36.6 m (120 ft.) tall and is equipped with cryogenic liquid nitrogen panels (shrouds) and gaseous helium shrouds to create a simulated space environment. It was originally designed and built in the mid 1960 s to test the Apollo Command and Service Module and several manned tests were conducted on that spacecraft, contributing to the success of the program. The chamber has been used since that time to test spacecraft active thermal control systems, Shuttle DTO, DOD, and ESA hardware in simulated Low Earth Orbit (LEO) conditions. NASA is now moving from LEO towards exploration of locations with environments approaching those of deep space. Therefore, Chamber A has undergone major modifications to enable it to simulate these deeper space environments. Environmental requirements were driven, and modifications were funded by the James Webb Space Telescope program, and this telescope, which will orbit Solar/Earth L2, will be the first test article to benefit from the chamber s new capabilities. To accommodate JWST, the Chamber A high vacuum system has been modernized, additional LN2 shrouds have been installed, the liquid nitrogen system has been modified to minimize dependency on electrical power and increase its reliability, a new helium shroud/refrigeration system has been installed to create a colder more stable and uniform heat sink, and the controls have been updated to increase the level of automation and improve operator interfaces. Testing of these major modifications was conducted in August of 2012 and this initial test was very successful, with all major systems exceeding their performance requirements. This paper will outline the changes in overall environmental requirements, discuss the technical design data that was used in the decisions leading to the extensive modifications, and describe the new capabilities of the chamber.

Homan, Jonathan L.↗
NASA NTRS2012

Creating the Deep Space Environment for Testing the James Webb Space Telescope at the Johnson Space Center's Chamber A

Chamber A is the largest thermal vacuum chamber at the Johnson Space Center and is one of the largest space environment chambers in the world. The chamber is 19.8 m (65 ft) in diameter and 36.6 m (120 ft) tall and is equipped with cryogenic liquid nitrogen panels (shrouds) and gaseous helium shrouds to create a simulated space environment. It was originally designed and built in the mid 1960's to test the Apollo Command and Service Module and several manned tests were conducted on that spacecraft, contributing to the success of the program. The chamber has been used since that time to test spacecraft active thermal control systems, Shuttle DTO, DOD, and ESA hardware in simulated Low Earth Orbit (LEO) conditions. NASA is now moving from LEO towards exploration of locations with environments approaching those of deep space. Therefore, Chamber A has undergone major modifications to enable it to simulate these deeper space environments. Environmental requirements were driven, and the modifications were funded, by the James Webb Space Telescope program, and this telescope which will orbit Solar/Earth L2, will be the first test article to benefit from the chamber s new capabilities. To accommodate JWST, the Chamber A high vacuum system has been modernized, additional LN2 shrouds have been installed, the liquid nitrogen system has been modified to remove dependency on electrical power and increase its reliability, a new helium shroud/refrigeration system has been installed to create a colder more stable and uniform heat sink and, the controls have been updated to increase the level of automation and improve operator interfaces. Testing of these major modifications was conducted in August 2012 and this initial test was very successful, with all major systems exceeding their performance requirements. This paper will outline the changes in the overall environmental requirements, discuss the technical design data that was used in the decisions leading to the extensive modifications, and describe the new capabilities of the chamber.

Homan, Jonathan L.↗
NASA NTRS2013

Creating the Deep Space Environment for Testing the James Webb Space Telescope (JWST) at NASA Johnson Space Center's Chamber A

Chamber A is the largest thermal vacuum chamber at the Johnson Space Center and is one of the largest space environment chambers in the world. The chamber is 19.8 m (65 ft) in diameter and 36.6 m (120 ft) tall and is equipped with cryogenic liquid nitrogen panels (shrouds) and gaseous helium shrouds to create a simulated space environment. It was originally designed and built in the mid 1960 s to test the Apollo Command and Service Module and several manned tests were conducted on that spacecraft, contributing to the success of the program. The chamber has been used since that time to test spacecraft active thermal control systems, Shuttle DTO, DOD, and ESA hardware in simulated Low Earth Orbit (LEO) conditions. NASA is now moving from LEO towards exploration of locations with environments approaching those of deep space. Therefore, Chamber A has undergone major modifications to enable it to simulate these deeper space environments. Environmental requirements were driven, and modifications were funded by the James Webb Space Telescope program, and this telescope which will orbit Solar/Earth L2, will be the first test article to benefit from the chamber s new capabilities. To accommodate JWST, the Chamber A high vacuum system has been modernized, additional LN2 shrouds have been installed, the liquid nitrogen system has been modified to remove dependency on electrical power and increase its reliability, a new helium shroud/refrigeration system has been installed to create a colder more stable and uniform heat sink, and the controls have been updated to increase the level of automation and improve operator interfaces. Testing of these major modifications was conducted in August of 2012 and this initial test was very successful, with all major systems exceeding their performance requirements. This paper will outline the changes in overall environmental requirements, discuss the technical design data that was used in the decisions leading to the extensive modifications, and describe the new capabilities of the chamber.

Homan, Jonathan L.↗
NASA NTRS2006

NASA's Spitzer Space Telescope's Operational Mission Experience

New Generation of Detector Arrays(100 to 10,000 Gain in Capability over Previous Infrared Space Missions). IRAC: 256 x 256 pixel arrays operating at 3.6 microns, 4.5 microns, 5.8 microns, 8.0 microns. MIPS: Photometer with 3 sets of arrays operating at 24 microns, 70 microns and 160 microns. 128 x 128; 32 x 32 and 2 x 20 arrays. Spectrometer with 50-100 micron capabilities. IRS: 4 Array (128x128 pixel) Spectrograph, 4 -40 microns. Warm Launch Architecture: All other Infrared Missions launched with both the telescope and scientific instrument payload within the cryostat or Dewar. Passive cooling used to cool outer shell to approx.40 K. Cryogenic Boil-off then cools telescope to required 5.5K. Earth Trailing Heliocentric Orbit: Increased observing efficiency, simplification of observation planning, removes earth as heat source.

space telescopes↗
NASA NTRS1989

Space Infrared Telescope Facility (SIRTF) science instruments

Concepts of scientific instruments designed to perform infrared astronomical tasks such as imaging, photometry, and spectroscopy are discussed as part of the Space Infrared Telescope Facility (SIRTF) project under definition study at NASA/Ames Research Center. The instruments are: the multiband imaging photometer, the infrared array camera, and the infrared spectograph. SIRTF, a cryogenically cooled infrared telescope in the 1-meter range and wavelengths as short as 2.5 microns carrying multiple instruments with high sensitivity and low background performance, provides the capability to carry out basic astronomical investigations such as deep search for very distant protogalaxies, quasi-stellar objects, and missing mass; infrared emission from galaxies; star formation and the interstellar medium; and the composition and structure of the atmospheres of the outer planets in the solar sytem.

Ramos, R.↗
NASA NTRS1991

Materials technology for SIRTF

A number of studies on materials technologies for the Space Infrared Telescope Facility (SIRTF) intended to enhance SIRTF mission performance are reviewed. Particular attention is given to dewar support straps, dewar structural materials, infrared black coatings, optical mirror materials, cryogenic properties data base, contamination control, and thermal control materials/coatings. It is noted that the alternative to baseline materials offer potential for substantial improvements in reliability, weight, and lifetime.

Coulter, D.↗
NASA NTRSDate not supplied

Molecular Accumulation during JWST’s Optical Telescope Cryogenic Thermal Vacuum Testing

Maintaining molecular cleanliness during the JWST’s Optical Telescope/Instrument Module (OTIS) Cryogenic Thermal Vacuum (TV) test campaign was critical to the success of its optical mission on orbit. In the thermal vacuum tests leading up to the final cryogenic test to validate the OTIS flight hardware, NASA Johnson Space Center’s (JSC’s) TV Chamber A was fully characterized for molecular contamination. It was found to contain common volatile condensable materials (VCM), including hydrocarbons, plasticizers, and silicones, all of which absorb in JWST’s infrared wavelength region. Due to the risks involved, cleaning molecular contamination from the OTIS mirrors was not an option and heating the Primary Mirror (PM) segments would have also been a risky and expensive endeavor. As a result, a monitoring process was developed and implemented during four different Pathfinder or risk reduction tests that were scheduled to occur prior to the flight hardware test. The goal was to quantify and assess the risk of molecular contamination depositing on the PM resulting from relatively warm chamber shrouds “leading” colder PM mirrors during warmup, by a margin of 10-50 Kelvin (K). This was accomplished using Cryogenic Quartz Crystal Microbalances (CQCMs), held at temperatures slightly cooler than the segments to signal the onset of contamination events. Per the JWST Contamination Control Plan (CCP)1, the total Primary Mirror molecular allocation requirement was 50 angstroms. In all tests, the results showed an average accumulated molecular contamination of <10 angstroms.

optics↗
NASA NTRS1992

SiC lightweight telescopes for advanced space applications. I - Mirror technology

A SiC based telescope is an extremely attractive emerging technology which offers the lightweight and stiffness features of beryllium, the optical performance of glass to diffraction limited visible resolution, superior optical/thermal stability to cryogenic temperatures, and the cost advantages of an aluminum telescope. SSG has developed various SiC mirrors with and without a silicon coating and tested these mirrors over temperature ranges from +50 C to -250 C. Our test results show less than 0.2 waves P-V in visible wavefront change and no hysteresis over this wide temperature range. Several SSG mirrors are representative of very lightweight SiC/Si mirrors including (1) a 9 cm diameter, high aspect ratio mirror weighing less than 30 grams and (2) a 23 cm diameter eggcrated mirror weighing less than 400 grams. SSG has also designed and analyzed a 0.6 meter SiC based, on axis, three mirror reimaging telescope in which the primary mirror weighs less than 6 kg and a 0.5 meter GOES-like scan mirror. SSG has also diamond turned several general aspheric SiC/Si mirrors with excellent cryo optical performance.

Anapol, Michael I.↗