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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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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

New technique for oil backstreaming contamination measurements

Due to the large size and the number of diffusion pumps, space simulation chambers cannot be easily calibrated by the usual test dome method for measuring backstreaming from oil diffusion pumps. In addition, location dependent contamination may be an important parameter of the test. The backstreaming contamination in the Space Power Facility (SPF) near Sandusky, Ohio, the largest space simulation vacuum test chamber in the U.S.A. was measured. Small size clean silicon wafers as contamination sensors placed at all desired measurement sites were used. The facility used diffusion pumps with DC 705 oil. The thickness of the contamination oil film was measured using ellipsometry. Since the oil did not wet uniformly the silicon substrate, two analysis models were developed to measure the oil film: continuous, homogeneous film and islands of oil with the islands varying in coverage fraction and height. In both cases, the contamination film refractive index was assumed to be that of DC 705. The second model improved the ellipsometric analysis quality parameter by up to two orders of magnitude, especially for the low coverage cases. Comparison of the two models for our case shows that the continuous film model overestimates the oil volume by less than 50 percent. Absolute numbers for backstreaming are in good agreement with published results for diffusion pumps. Good agreement was also found between the ellipsometric results and measurements done by x ray photoelectron spectroscopy (XPS) and by scanning electron microscopy (SEM) on samples exposed to the same vacuum runs.

Alterovitz, S. A.↗
NASA NTRS1998

Rocketdyne Advanced Reusable Technologies Program Update

NASA Marshall Space Flight Center Advanced Reusable Technologies/Rocket Based Combined Cycle (RBCC) program has enabled: (1) the creation of unique trajectory simulation facility; (2) development of basic operability and performance data; (3) results to date: (a) rocket thrusters performing as designed (P(sub c), MR, q, etc); (b) AAR performance data measured at M = 0 and 3; (c) rocket mode performance at simulated vacuum conditions; and (d) data reduction in progress; (4) completing testing; M = 0, 3 and trajectory M = 3 to 3.7; and (5) next logical steps: build flight type engine and flight demonstrate RBCC.

Ratekin, Gary↗
NASA NTRSDate not supplied

Managing Spacecraft Risk With Space Environments Testing Via Process Safety Management At The NASA Neil A. Armstrong Test Facility

The NASA Glenn Research Center’s Neil A. Armstrong Test Facility (GRC-ATF) is home to several unique, world class aerospace test facilities, including the In-Space Propulsion (ISP) Facility. The ISP Facility is NASA’s largest chamber designed to store and transfer large quantities of liquid hydrogen and liquid oxygen; and is designed to support developmental testing of upper stage chemical propulsion systems as well as fully integrated stages. The facility is also capable of providing thermal-vacuum simulation services to support testing of aerospace hardware, Cryogenic Fluid Management (CFM) systems and other In-Space propulsion programs. The U.S. Occupational Safety and Health Administration’s (OSHA) Process Safety Management (PSM) of Highly Hazardous Chemicals Standard (29 CFR 1910.119) is an analytical tool focused on preventing the release of chemicals and other energy sources. In a short timeframe, GRC-ATF was required to restore a PSM Program at the Facility. Although the summarized work is specific to the ground testing of rockets and space vehicles, the ISP Facility is used to verify system level requirements, some of these are safety requirements, and thus key to managing risks in space.

Safety↗
NASA NTRSDate not supplied

Managing Spacecraft Risk with Space Environments Testing via Process Safety Management at the NASA Neil A. Armstrong Test Facility (GRC-ATF)

The NASA Glenn Research Center’s Neil A. Armstrong Test Facility (GRC-ATF) is home to several unique, world class aerospace test facilities, including the In-Space Propulsion (ISP) Facility. The ISP Facility is NASA’s largest chamber designed to store and transfer large quantities of liquid hydrogen and liquid oxygen; and is designed to support developmental testing of upper stage chemical propulsion systems as well as fully integrated stages. The facility is also capable of providing thermal-vacuum simulation services to support testing of aerospace hardware, Cryogenic Fluid Management (CFM) systems and other In-Space propulsion programs. The U.S. Occupational Safety and Health Administration’s (OSHA) Process Safety Management (PSM) of Highly Hazardous Chemicals Standard (29 CFR 1910.119) is an analytical tool focused on preventing the release of chemicals and other energy sources. In a short timeframe, GRC-ATF was required to restore a PSM Program at the Facility. Although the summarized work is specific to the ground testing of rockets and space vehicles, the ISP Facility is used to verify system level requirements, some of these are safety requirements, and thus key to managing risks in space.

Safety↗
NASA NTRS1992

Behavior of compacted lunar simulants using new vacuum triaxial device

The objectives of this study are to create a lunar simulant locally from a basaltic rock and to design and develop a vacuum triaxial test device that can permit testing of compacted lunar simulant under cyclic loading with different levels of initial vacuum. Triaxial testing is performed in the device itself without removing the compacted specimen. Preliminary constrained compression and triaxial shear tests are performed to identify effects of initial confinements and vacuums. The results are used to define deformation and strength parameters. At this time, vacuum levels up to 0.0001 are possible. The research can aid in the development of compacted materials for various construction applications.

Desai, Chandra S.↗
NASA NTRS1992

Mechanical properties of compacted lunar simulant using new vacuum triaxial equipment

Mechanical stress-strain strength properties of Arizona Lunar Simulant (ALS) are investigated by using a newly developed vacuum triaxial device that allows compaction under different initial vacuums and confinements. Influence of vacuum and confinement on compaction, strength and deformation characteristics of compacted material are delineated and discussed.

Desai, Chandra S.↗
NASA NTRS1972

Optical properties of thermal control coating contaminated by MMH/N2O4 5-pound thruster in a vacuum environment with solar simulation

Cat-a-lac Black, and S13G thermal control coatings were exposed to the exhaust of a thruster in a simulated space environment. Vacuum was maintained at less than 10 to the minus 5th power torr during thruster firing in the liquid helium cooled facility. The thruster was fired in a 50-millisecond pulse mode and the accumulated firing time was 224 seconds. Solar absorptance (alpha sub s) and thermal emittance (sigma) of the coatings were measured in-situ at intervals of 300 pulses. A calorimetric technique was used to measure alpha sub s and sigma. The tests, technique, and test results are presented. The Cat-a-lac Black coatings showed no change in alpha sub s or sigma. The S13G showed up to 25 percent increase in alpha sub s but no change in sigma.

Sommers, R. D.↗
NASA NTRS1972

Optical properties of thermal control coatings contaminated by MMH/N2O4 5-pound thruster in a vacuum environment with solar simulation.

Cat-a-lac Black and S13G thermal control coatings were exposed to the exhaust of a thrustor in a simulated space environment. Vacuum was maintained at less than 10 microtorr during thrustor firing in the liquid helium cooled facility. The thrustor was fired in a 50-millisecond pulse mode, and the accumulated firing time was 224 seconds. Solar absorptance and thermal emittance of the coatings were measured in-situ at intervals of 300 pulses, using a calorimetric technique. The Cat-a-lac Black coatings showed no change in solar absorptance or thermal emittance. The S13G showed up to 25% increase in solar absorptance but no change in thermal emittance.

Sommers, R. D.↗
NASA NTRS1975

A thermal vacuum-UV solar simulator test system for assessing microbiological viability

Microorganisms were exposed to a simulated space environment in order to assess the photobiological effect of broad spectrum, nonionizing solar electromagnetic radiation in terms of viability. A thermal vacuum chamber capable of maintaining a vacuum of 0.000133n/sq m and an ultraviolet rich solar simulator were the main ingredients of the test system. Results to date indicate the system to be capable of providing reliable microbiological data.

Ross, D. S.↗
NASA NTRS1973

Operation of small rocket engines in the JPL high-vacuum molecular space simulator (Molsink)

The feasibility of operating small rocket engines in the Molsink facility was demonstrated. A 0.44-N (0.1-lbf) hydrazine engine and a 0.18-N (0.04-lbf) thruster using cold gas from a hydrazine plenum system were operated for both flight duty cycles and off-nominal conditions. The exhaust gases from these thrusters contain NH3, N2, and H2. The chamber was also calibrated for larger bipropellant engines using nitrogen tetroxide/monomethyl hydrazine (NTO/MMH). The exhaust products of these engines contain CO2, CO, H2, H2O, and H2. A mixture of cold gases simulating the engine exhaust was injected through a nozzle under conditions simulating thrust levels up to 26.7-N (6 lbf). Pulsing and continuous operations were investigated. The chamber background pressure traces were compared with the traces obtained for the same thrusters operated with pure nitrogen at approximately equivalent thrust. Satisfactory recuperation times were encountered in all the pulsing modes. Test times greater than 20s were obtained in steady state operation before the vacuum chamber back pressure climbed to prohibitive values.

Chirivella, J. E.↗
NASA NTRS1984

Zero-g experiments with a He II active phase separator for space application

An active phase separator (APS) for temperature control of He II space cooling systems was tested in a zero-g environment during a series of parabolic flights on a NASA KC 135 aircraft. The APS provides for liquid-gas separation and features an annular gap, a downstream heat exchanger and an upstream ball closure. The apparatus was operated during acceleration and floating and in two different heat load situations. The tests confirmed that adequate mass flow rates could be maintained using a vacuum pump to simulate space vacuum and that residual liquid could be evaporated from the heat exchanger after closing a ball valve to seal off flows.

Denner, H. D.↗
NASA NTRS2014

Cryogenic Boil-Off Reduction System Testing

The Cryogenic Boil-Off Reduction System was tested with LH2 and LOX in a vacuum chamber to simulate space vacuum and the temperatures of low Earth orbit. Testing was successful and results validated the scaling study model that predicts active cooling reduces upper stage cryogenic propulsion mass for loiter periods greater than 2 weeks.

Zero Boil-Off↗
NASA NTRSDate not supplied

In-Space Laser Forming Simulated Under Thermal Vacuum (TVAC) Conditions

NASA Marshall Space Flight Center is investigating laser forming under thermal vacuum conditions representative of the space environment through a partnership with the DARPA NOM4D program. The thermal gradient mechanism (TGM) is used to bend a metal sheet towards the laser optics. Laser equipment and process parameters are being optimized for thermal vacuum conditions. Such conditions are representative of the extreme cold and hot temperatures and high vacuum that exist on orbit or on the lunar surface. in situ photogrammetry and thermography assess the bend/counterbend and elucidate the TGM in thermal vacuum. Structured light scanning and metallography after bending reveal the macroscopic and microscopic structure after TGM.

thermal vacuum↗