Search

Compression tests have been performed on solid neon to determine Young's modulus and compressive strengths in the temperature range from 8 to 23 K. This data was used for structural analysis of the X-Ray Spectrometer's (XRS) solid neon dewar. The dewar is nearly full of a 2.5% dense aluminum foam, so measurements were made for samples where solid neon was formed within the aluminum matrix as well as pure solid neon samples. The latter measurements were made in order to determine, at least qualitatively, how the mechanical properties of solid neon are affected by the aluminum foam and to allow direct comparisons with Young's moduli obtained from literature data as a check on the experimental technique. As a further check and to verify the structural model, thermal cycle tests were conducted on a small-scale toroidal dewar filled with solid neon. Mechanical properties measurements and data are described, along with model predictions and actual performance of both the engineering unit XRS dewar and the sub-scale dewar.

NASA is developing the NICMOS Cooling System (NCS) for deployment during Servicing Mission 3 of the Hubble Space Telescope (HST) in late 1999. The NCS is intended to provide mechanical cryocooling for the near IR camera and multi- object spectrometer (NICMOS) instrument that was installed during servicing mission 2 in February 1997. The NICMOS with NCS can potentially continue the near-IR capability of HST through the currently scheduled end-of-mission in 2010. The NCS hardware is currently in final integration and will soon start a series of rigorous ground and flight test that will prepare it for installation in the HST.

We describe the engineering design and operational concept for a series of three complementary top mounted balloon- borne experiments to measure the Cosmic Microwave Background Radiation anisotropy, culminating in a two week circumpolar flight from McMurdo Station, Antarctica. Each experiment is designed to provide a maximum science return in addition to acting as a pathfinder to the successor flights of top- mounted balloon-borne experiments. The experiment program, named TopHat, will involve the launch and operation of the first far-infrared and microwave telescope flown entirely from the top of a 28 million cubic foot balloon. It utilizes a two axis gimbal pointing system, a one meter Cassegrain optical system with a chopping secondary mirror, and a 3He evaporation cryostat designed to maintain a bolometer detector temperature of 0.25 K for 30 days without cycling. The series of flights will begin with an engineering test flight scheduled for launch in July 1996 from Palestine, Texas, followed by a pointing experiment to be flown from Ft. Sumner, New Mexico in April 1997. A spinning experiment will be launched from Ft. Sumner in April 1998 and Antarctica in December 1998.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.