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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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Variable-temperature cryostats developed to study radiation damage to, and annealing of, germanium gamma-ray detectors. Two styles: one accommodates large single detector and one accommodates two medium-sized detectors. New cryostats allow complete testing of large-volume germanium gamma-ray detectors without breaking cryostat vacuum and removing detectors for annealing.
The Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) will employ a wide variety of spectral filtration components including narrow band, medium band, wide band, and far ultraviolet (FUV) long pass filters, spatially- variable filters (ramp filters), VIS/IR polarizers, NUV polarizers, FUV prisms, and a grism. These components are spread across ACS's Wide Field, High Resolution, and Solar Blind channels which provide diffraction-limited imaging of astronomical targets using aberration-correcting optics which remove most aberrations from HST's Optical Telescope Assembly (OTA). In order for ACS to be truly advanced, these filters must push the state-of-the-art in performance in a number of key areas at the same time. Important requirements which these filters must meet include outstanding transmitted wavefront, high transmittance, uniform transmittance across each filter, spectrally structure-free bandpasses, exceptionally high out of band rejection, and a high degree of parfocality. These constitute a very stringent set of requirements indeed, especially for filters which are up to 90 mm in diameter. The development of optical metrology stations used to demonstrate that each ACS filter will meet its design specifications is discussed. Of particular note are specially-designed spectral transmissometers and interferometers.
Over the past 20 years, NASA Goddard has successfully developed space-based lidar for remote sensing studies of the Earth and planets. The lidar in all missions to date have used diode pumped Nd:YAG laser transmitters. Recently we have been concentrating work on developing integrated path differential absorption (IPDA) lidar to measure greenhouse gases, with the goal of measurements from space. Due to the absorption spectrum of CO2 a fiber-based master oscillator power amplifier (MOPA) laser with a tunable seed source is an attractive laser choice. Fiber-based lasers offer a number of potential advantages for space, but since they are relatively new, challenges exist in developing them. In order to reduce risks for new missions using fiber-based lasers, we developed a 30- month plan to mature the technology of a candidate laser transmitter for space-based CO2 measurements to TRL-6. This work is also intended to reduce development time and costs and increase confidence in future mission success.