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Nast, T. C.

Publications and source records attributed to Nast, T. C..

13 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Design and performance analysis of the CLAES Ne/CO2 cryostat

The design of the dual-stage Ne/CO2 cryostat, constructed for the Cryogenic Limb Array Etalon Spectrometer (CLAES) for the cooling, to their respective required operation temperatures, of the focal plane (to less than 15 K), spectrometer (to less than 30 K), telescope (to less than 150 K), and baffles (to less than 180 K) is described, and the cryostat's performance is analyzed. The results of this study show that the current cryostat will meet all sensor cooling requirements. The cryostat weighs 2276 lbs, of which 988 lbs are charged to the neon and 484 lbs are charged to the CO2. Schematic diagrams of the CLAES cooler/sensor and of the external plumbing are presented together with the test data.

Naes, L. G.↗
NASA NTRS1985

SIRTF Telescope Instrument Changeout and Cryogen Replenishment (STICCR) Study

The Space Infrared Telescope Facility (SIRTF) is a long-life cryogenically cooled space-based telescope for infrared astronomy from 2 to 700 micrometers. SIRTF is currently under study by NASA-ARC (Reference AP) and planned for launch in approximately the mid 1990s. SIRTF will operate as a multiuser facility, initially carrying three instruments at the focal plane. It will be cooled to below 2 K by superfluid liquid helium to achieve radiometric sensitivity limited only by the statistical fluctuations in the natural infrared background radiation over most of its spectral range. The lifetime of the mission will be limited by the lifetime of the liquid helium supply, and baseline is currently to be 2 years. The telescope changes required to allow in-space replenishment of the 4,000-L superfluid helium tank was investigated. A preliminary design for the space services equipment was also developed. The impacts of basing the equipment and servicing on the space station were investigated. Space replenishment and changeout of instruments required changes to the telescope design. Preliminary concepts are presented.

Nast, T. C.↗
NASA NTRS1985

Long life feasibility study for SIRTF

The Phase A baseline for the Shuttle Infrared Telescope Facility (SIRTF) consists of an 85-cm diameter Cassegrain telescope, cooled to temperatures in the range from 10 to 20 K to provide background limited imaging for up to six instruments contained within a multiple instrument chamber (MIC). Colder temperature zones are also provided. A cryogenics system for a 15-day mission lifetime was first considered. In another study, the feasibility was assessed to extend the lifetime of the baseline SIRTF concept to at least six months, taking into account a mission involving the use of a space platform or a free-flyer configuration. According to the considered requirements, the optics temperature is to be kept below 10 K for at least 30 days. The temperatures are not to exceed 20 K at the end of the six months mission. It is shown that by using solid hydrogen, long-life operation is feasible with present technology.

Naes, L. G.↗
NASA NTRS1984

Development of a para-orthohydrogen catalytic converter for a solid hydrogen cooler

Design features of a tested catalytic converter for altering vented cryogenic parahydrogen used as a coolant on spacecraft into a para-ortho equilibrium for channeling to other cooling functions are described. The hydrogen is expected to be stored in either liquid or solid form. A high surface area Ni-on-Si catalyst was selected for tests at an operating pressure of 2 torr at a ratio of 1000 gr catalyst for a gr/sec hydrogen flow. Cylindrical and radial flow geometries were tried and measurements centered on the converter efficiencies at different operating temperatures when the converter was placed in the vent line of the H2 cooler. Efficiencies ranging from 10-100 percent were obtained for varying flow rates. Further testing is necessary to characterize the converter performance under a wider range of operating temperatures and environments.

Nast, T. C.↗
NASA NTRS1983

Investigation of a para-ortho hydrogen reactor for application to spacecraft sensor cooling

The utilization of solid hydrogen in space for sensor and instrument cooling is a very efficient technique for long term cooling or for cooling at high heat rates. The solid hydrogen can provide temperatures as low as 7 to 8 K to instruments. Vapor cooling is utilized to reduce parasitic heat inputs to the 7 to 8 K stage and is effective in providing intermediate cooling for instrument components operating at higher temperatures. The use of solid hydrogen in place of helium may lead to weight reductions as large as a factor of ten and an attendent reduction in system volume. The results of an investigation of a catalytic reactor for use with a solid hydrogen cooling system is presented. Trade studies were performed on several configurations of reactor to meet the requirements of high reactor efficiency with low pressure drop. Results for the selected reactor design are presented for both liquid hydrogen systems operating at near atmospheric pressure and the solid hydrogen cooler operating as low as 1 torr.

Nast, T. C.↗
NASA NTRS1983

Performance analysis for the cryogenic etalon spectrometer on the Upper Atmospheric Research Satellite

The Upper Atmospheric Research Satellite (UARS) program has the objective of providing an 18-month to 2-year platform for observations of the upper atmosphere, giving particular attention to the stratosphere, mesosphere, and lower thermosphere. The primary aims of the mission are related to the measurement of the solar energy input between 120 and 500 km, the acquisition of global maps of the vertical and horizontal distribution of a series of critical trace and minor species, and the investigation of the dynamics of the upper atmosphere. One of several instruments designed to perform neutral species measurements on board the satellite is the Cryogenic Limb Array Etalon Spectrometer (CLAES). The CLAES experiment is concerned with measurements of concentrations of species of interest to the ozone layer balance. Attention is given to the performance requirements of the instrument and the effects of these requirements on the cryogenic design.

Roche, A. E.↗
NASA NTRS1983

Two-year solid hydrogen cooler for the Cryogenic Limb Array Etalon Spectrometer (CLAES) instrument

The Cryogenic Limb Array Etalon Spectrometer (CLAES) will be one of thirteen instruments on board the Upper Atmospheric Research Satellite (UARS) in late 1988. CLAES is to be employed for the measurement of stratospheric trace species concentrations affecting the ozone layer balance. It is an earth-limb viewing instrument which requires cryogenic cooling in order to obtain the necessary performance sensitivity. The present investigation is concerned with the solid hydrogen cryogen subsystem which provides the instrument temperature needed. Attention is given to the studies which led to the selection of solid hydrogen as cooling agent, the baseline cooler system, aspects of baseline performance sensitivity, and nominal cooler operations.

Naes, L. G.↗
NASA NTRS1979

Cryogenic cooling of instruments in orbit - A standard solid cryogen cooler approach

A study has been conducted to determine the utility and characteristics of a solid cryogen cooler which could meet a variety of instrument and mission requirements. The cooler consists essentially of two stages of solid cryogen and two cooled shields. The inner shield is thermally grounded to the secondary (warmer) cryogen and provides a low temperature boundary around the colder primary stage, while the outer shield reduces the heat loads upon the secondary cryogen. The baseline design provides cooling of approximately 1 watt over the temperature range 60-100 K, 0.5 watts from 15 to 60 K, and 0.2 watts from 8 to 15 K for a one-year lifetime. For low cooling loads (0.1 W) and with use of an optional cooled shield, cooling lifetimes of 8 years are possible.

Nast, T. C.↗
NASA NTRS1976

Orbital cryogenic cooling of sensor systems

Cryogenic cooling of sensors is a means of attaining the high-performance detection characteristics required for orbital missions. Solid cooler technology is reviewed, and its application to helium/liquid helium, solid neon/liquid helium, and solid nitrogen/liquid helium systems, capable of satisfying requirements below 10 K is examined. The impact of these systems on spacecraft design and operation is assessed, and recent orbital experience is discussed.

Nast, T. C.↗