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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Vacuum Strength of Two Candidate Glasses for a Space Observatory

The strengths of two candidate glass types for use in a space observatory were measured. Samples of ultra-low expansion glass (ULE) and borosilicate (Pyrex) were tested in air and in vacuum at room temperature (20 C) and in vacuum after being heated to 200 C. Both glasses tested in vacuum showed an increase in strength over those tested in air. However, there was no statistical difference between the strength of samples tested in vacuum at room temperature and those tested in vacuum after heating to 200 C.

Manning, T. a.↗
NASA NTRS2007

Vacuum Strength of Two Candidate Glasses for a Space Observatory

The strengths of two candidate glass types for use in a space observatory were measured. Samples of ultra-low expansion glass (ULE) and borosilicate (Pyrex) were tested in air and in vacuum at room temperature (20 degrees C) and in vacuum after being heated to 200 degrees C. Both glasses tested in vacuum showed a significant increase in strength over those tested in air. However, there was no statistical difference between the strength of samples tested in vacuum at room temperature and those tested in vacuum after heating to 200 degrees C.

Manning, Timothy Andrew↗
NASA NTRS2012

Low-Cost, Rugged High-Vacuum System

A need exists for miniaturized, rugged, low-cost high-vacuum systems. Recent advances in sensor technology have led to the development of very small mass spectrometer detectors as well as other analytical instruments such as scanning electron microscopes. However, the vacuum systems to support these sensors remain large, heavy, and power-hungry. To meet this need, a miniaturized vacuum system was developed based on a very small, rugged, and inexpensive-to-manufacture molecular drag pump (MDP). The MDP is enabled by a miniature, very-high-speed (200,000 rpm), rugged, low-power, brushless DC motor optimized for wide temperature operation and long life. The key advantages of the pump are reduced cost and improved ruggedness compared to other mechanical hig-hvacuum pumps. The machining of the rotor and stators is very simple compared to that necessary to fabricate rotor and stator blades for other pump designs. Also, the symmetry of the rotor is such that dynamic balancing of the rotor will likely not be necessary. Finally, the number of parts in the unit is cut by nearly a factor of three over competing designs. The new pump forms the heart of a complete vacuum system optimized to support analytical instruments in terrestrial applications and on spacecraft and planetary landers. The MDP achieves high vacuum coupled to a ruggedized diaphragm rough pump. Instead of the relatively complicated rotor and stator blades used in turbomolecular pumps, the rotor in the MDP consists of a simple, smooth cylinder of aluminum. This will turn at approximately 200,000 rpm inside an outer stator housing. The pump stator comprises a cylindrical aluminum housing with one or more specially designed grooves that serve as flow channels. To minimize the length of the pump, the gas is forced down the flow channels of the outer stator to the base of the pump. The gas is then turned and pulled toward the top through a second set of channels cut into an inner stator housing that surrounds the motor. The compressed gas then flows down channels in the motor housing to the exhaust port of the pump. The exhaust port of the pump is connected to a commercially available diaphragm or scroll pump.

Sorensen, Paul↗
NASA NTRS2013

Very-Low-Cost, Rugged Vacuum System

NASA, DoD, DHS, and commercial industry have a need for miniaturized, rugged, low-cost vacuum systems. Recent advances in sensor technology have led to the development of very small mass spectrometer detectors as well as other miniature analytical instruments. However, the vacuum systems to support these sensors remain large, heavy, and power-hungry. To meet this need, a miniaturized vacuum system was created based on a very small, rugged, and inexpensive- to-manufacture molecular drag pump (MDP). The MDP is enabled by the development of a miniature, veryhigh- speed, rugged, low-power, brushless DC motor optimized for wide temperature operation and long life. Such a pump represents an order-of-magnitude reduction in mass, volume, and cost over current, commercially available, state-ofthe- art vacuum pumps. The vacuum system consists of the MDP coupled to a ruggedized rough pump (for terrestrial applications or for planets with substantial atmospheres). The rotor in the MDP consists of a simple smooth cylinder of aluminum spinning at approximately 200,000 RPM inside an outer stator housing. The pump stator comprises a cylindrical aluminum housing with one or more specially designed grooves that serve as flow channels. To minimize the length of the pump, the gas is forced down the flow channels of the outer stator to the base of the pump. The gas is then turned and pulled toward the top through a second set of channels cut into an inner stator housing that surrounds the motor. The compressed gas then flows down channels in the motor housing to the exhaust port of the pump. The exhaust port of the pump is connected to a diaphragm or scroll pump. This pump delivers very high performance in a very small envelope. The design was simplified so that a smaller compression ratio, easier manufacturing process, and enhanced ruggedness can be achieved at the lowest possible cost. The machining of the rotor and stators is very simple compared to that necessary to fabricate TMP (turbo molecular pump) rotor and stator blades. Also, the symmetry of the rotor is such that dynamic balancing of the rotor is greatly simplified. Finally, because of the simplified design, the number of parts in the unit is cut by nearly a factor of three. In fact, there are only five parts, not counting the motor and off-the-shelf screws and O-rings. This reduces the amount of machining and also makes fit-up much simpler while allowing the maintenance of close tolerances.

Kline-Schoder, Robert↗
NASA NTRS2014

Maximum Expected Wall Heat Flux and Maximum Pressure After Sudden Loss of Vacuum Insulation on the Stratospheric Observatory for Infrared Astronomy (SOFIA) Liquid Helium (LHe) Dewars

The aircraft-based Stratospheric Observatory for Infrared Astronomy (SOFIA) is a platform for multiple infrared observation experiments. The experiments carry sensors cooled to liquid helium (LHe) temperatures. A question arose regarding the heat input and peak pressure that would result from a sudden loss of the dewar vacuum insulation. Owing to concerns about the adequacy of dewar pressure relief in the event of a sudden loss of the dewar vacuum insulation, the SOFIA Program engaged the NASA Engineering and Safety Center (NESC). This report summarizes and assesses the experiments that have been performed to measure the heat flux into LHe dewars following a sudden vacuum insulation failure, describes the physical limits of heat input to the dewar, and provides an NESC recommendation for the wall heat flux that should be used to assess the sudden loss of vacuum insulation case. This report also assesses the methodology used by the SOFIA Program to predict the maximum pressure that would occur following a loss of vacuum event.

Ungar, Eugene K.↗
NASA NTRS2017

Coil-On-Plug Ignition for LOX/Methane Liquid Rocket Engines in Thermal Vacuum Environments

A coil-on-plug ignition system has been developed and tested for Liquid Oxygen (LOX) / liquid methane rocket engines operating in thermal vacuum conditions. The igniters were developed and tested as part of the Integrated Cryogenic Propulsion Test Article (ICPTA), previously tested as part of the Project Morpheus test vehicle. The ICPTA uses an integrated, pressure-fed, cryogenic LOX/methane propulsion system including a reaction control system (RCS) and a main engine. The ICPTA was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. In order to successfully demonstrate ignition reliability in the vacuum conditions and eliminate corona discharge issues, a coil-on-plug ignition system has been developed. The ICPTA uses spark-plug ignition for both the main engine igniter and the RCS. The coil-on-plug configuration eliminates the conventional high-voltage spark plug cable by combining the coil and the spark-plug into a single component. Prior to ICPTA testing at Plum Brook, component-level reaction control engine (RCE) and main engine igniter testing was conducted at NASA Johnson Space Center (JSC), which demonstrated successful hot-fire ignition using the coil-on-plug from sea-level ambient conditions down to 10(exp.-2) torr. Integrated vehicle hot-fire testing at JSC demonstrated electrical and command/data system performance. Lastly, Plum Brook testing demonstrated successful ignitions at simulated altitude conditions at 30 torr and cold thermal-vacuum conditions at 6 torr. The test campaign successfully proved that coil-on-plug technology will enable integrated LOX/methane propulsion systems in future spacecraft.

Melcher, John C.↗
NASA NTRS2019

Discrete Lattice Material Vacuum Airship

Vacuum airships fueled by renewable energy would reduce reliance on fossil fuel-based modes of transport, lessen the need for limited and non-renewable lifting gases, and can be achieved using novel manufacturing techniques for ultra-light, discrete lattice material systems.The Discrete Lattice Material Vacuum Airships (DLMVA) system combines novel material science and manufacturing technologies for new modes of mass transportation, resulting in a disruptive approach to reduce national resource consumption and emissions. Through the use of high performance building block elements, modular, scalable and extensible aircraft can be rapidly assembled into positive net-buoyancy systems utilizing a vacuum instead of a lifting gas. By using architected lattice material principles, show that lattice materials can overcome stability limitations of previous vacuum balloon designs. Additionally, we show that lattice vacuum balloons are strength limited, rather than stability limited. As a result,airborne infrastructure can be developed to support the proliferation of modern systems such as e-commerce and distributed communications, while simultaneously reducing dependence on finite, non-renewable, emission-heavy resources.

Jenett, Benjamin E.↗
NASA NTRSDate not supplied

Augmenting the Space Environment Complex's Thermal Vacuum Capabilities for Artemis 1 Orion Spacecraft Testing

The Space Environments Complex at Glenn Research Center’s Neil A Armstrong Test Facility (formerly Plum Brook Station) recently successfully completed Artemis 1 thermal vacuum testing. The Space Environments Complex boasts the world’s largest thermal vacuum chamber with a 122-foot tall, 100-foot diameter aluminum assembly vacuum chamber. The fifty-year old chamber has been adapted over its history to conduct several unique test campaigns in a variety of test environments. Artemis 1 Orion spacecraft testing is the most complex test campaign the Space Environments Complex has undergone to date, with temperature limits between -250 F to +300F in a high vacuum with significant requirements for quality data and contamination control of a flight vehicle. This presentation covers the improvements and innovations in the cryoshroud and thermal systems, data acquisition, as well as contamination and cleanliness to accommodate the rigors of a flight vehicle during a six-week thermal vacuum test. Additionally, the presentation covers successes and lessons learned from the testing.

Erin Reed↗
NASA NTRS2023

Reliable Ignition of LOX Methane Propellants in Thermal Vacuum Environment

The goal of this project is to demonstrate reliable ignition of liquid oxygen-liquid methane at thermal vacuum conditions using a coil-on-plug (COP) sparking exciter. Testing will be performed using EP’s Frost-Mint cryogenic propellant test stand, using an engine updated based on data collected from previous engine testing at Plum Brook Station, to determine conditions under which the cryogenic propellants will consistently and reliably ignite. In FY22 the project successfully completed the following milestones. The cryogenic test stand Frost-Mint was upgraded to include an integrated vacuum tube and liquid nitrogen cooling system enabling cold vacuum ignition testing. The Integrated GN2/LN2 Ultra-Low-temperature Enclosure (IGLUE), a custom-built close-coupled heater exchanger shroud was designed, fabricated, tested and integrated into the test stand. The vacuum tube and IGLUE enabled the thruster body and propellants to be conditioned to temperatures and pressures desired. This work recreated the no-light conditions experienced during vehicle-level thermal vacuum testing and obtained thruster performance data and ignition imagery.

liquid oxygen↗
NASA NTRSDate not supplied

Quantifying Leak Rates and Vacuum Impact on Granular Soil Column Pneumatic Seal

Introduction: All In-Situ Resource Utilization (ISRU) regolith reactor systems that aim to extract gases or vapors must maintain a seal along the flow path of the regolith from the inlet hopper to where extracted gases or vapors are generated. Using a column of regolith at the inlet has been proposed as an alternative to systems using series of mechanical valves to reduce mass and complexity. Preliminary investigations into the use of regolith itself as a barrier to escaping fluids have been conducted, which this research seeks to expand upon. Different vertical regolith simulant plug diameters and heights were tested under vacuum with dry nitrogen to observe leak rates and approximate steady state pressure gradient equilibria. The effect of absolute ambient pressure was also studied by repeating tests at incremental pressures ranging from 10e-5 Torr up to 1 atm to corroborate ambient bench tests from previous work. The impact of regolith dynamics was addressed to emulate continuous-feed regolith reaction processes by measuring leak rates through continuously draining simulant columns. OB-1 lunar highlands regolith simulant was used. Experimental Setup: Regolith simulant columns were constructed using a motorized butterfly valve separating upper acrylic tubes of various diameters from a larger, lower aluminum pipe plenum (See Figure 1). The butterfly valve was cracked open such that gas could freely pass through whereas regolith would bridge and stay suspended as a cohesive plug above in the acrylic portion. These assemblies were loaded into a vacuum chamber, and a compressed dry nitrogen line was routed into the lower plenum. Pressure transducers measured the absolute pressure of the lower plenum, which was compared to absolute chamber pressure to monitor the pressure gradient across the regolith simulant. A precision mass flow controller enabled fine control of plenum pressure. The plenum pressure was quasi-statically increased to set points informed by previous work [1] before shutting off the gas supply to allow the now pressurized gas volume to dissipate through the simulant into the chamber in what was referred to as a ‘leak test.’ In a separate set of tests, the pressure was allowed to quasi-statically build until visual disturbances in the soil were observed via remote camera feeds. Initial leak rate tests were repeated on the disturbed soil to observe changes in leak rates between initial as-poured and post-bubbling soil conditions. This test schedule was applied to simulant columns of three different diameters (approximately 2, 4, and 6 inches) as well as two different heights (around 8 and 16 inches) and was repeated at least three times for each configuration. Plenums were also pressurized while the butterfly valves were opened slightly further to facilitate slow, controlled, constant flowrate draining of the simulant to observe the impact that continuous-feed systems might have on leak rate through the regolith column. Finally, the regolith columns were reset and refilled and static leak rate tests were repeated approximately every decade in ambient pressure from 10e-5 Torr up to ambient conditions to observe the impact of transitioning out of the molecular flow regime on regolith column seal performance. Analysis: Trends with respect to each factor examined were constructed and reported alongside commentary on the most likely responsible physical phenomena. Confidence intervals were applied to the predictive findings of the data by quantifying instrumentation error and accounting for probabilistic impacts of curve fitting the generic exponential function onto pressure decay data. The leak rate is assumed directly proportional to the exponential term coefficient, while the steady-state static pressure gradient is assumed to be the asymptotic limit of each curve fit. Finally, a generic model developed by Ogino et al. [2] and later tuned for ambient testing was re-tuned using vacuum data to estimate leak rates on the lunar surface. Results: Pressure decay rates decreased up to 27-fold under vacuum when compared to ambient pressure, as shown in Figure 2. Simulant column diameter was found to exponentially correlate to both regolith column leak rate and steady-state equilibrium pressure delta. Height was found to be linearly related to leak rate –doubling the regolith column height consistently yielded around a 40% reduction in leak rate. Dynamic regolith draining was found to slightly increase leak rate, although to a lower degree than expected. Conclusion: Because of the transition into molecular gas flow through regolith, vacuum testing is required to properly estimate performance. Regolith columns should be designed as narrow as possible to avoid bridging and minimize leak rate, and as tall as is feasible to both further reduce leak rate and to help prevent bubbling, which has been shown to degrade the quality of the regolith seal. Disrupted soil was found to exhibit higher leak rates than pristine, as-poured soil, indicating the need to consider the impact of recovery from depressurization events. Regolith columns appear equally feasible for both dosed and continuous-feed reactors.

ISRU↗
NASA NTRS2018

Modernization of NASA Johnson Space Center's Chamber A to Support Cryogenic Vacuum Optical Testing of the James Webb Space Telescope (JWST)

Final document is attached. NASA is the mission lead for the James Webb Space Telescope (JWST), the next of the "Great Observatories", scheduled for launch in 2021. NASA is directly responsible for the integration and test (I&T) program that culminated in an end-to-end cryo vacuum optical test of the flight telescope and instrument module in Chamber A at NASA Johnson Space Center. Historic Chamber A is the largest thermal vacuum chamber at Johnson Space Center and one of the largest space simulation chambers in the world. Chamber A has undergone a major modernization effort to support the deep cryogenic, vacuum and cleanliness requirements for testing the JWST. This paper describes the upgrades to the Chamber A facility: Thermal Shrouds, Helium Refrigeration, Liquid Nitrogen System, High Vacuum System, Clean Airflow System, and Utilities.

Thermal vacuum testing↗
NASA NTRS2023

Dry Preform Stitching Using Temporary Vacuum Consolidation

Stitched composites (composite parts stitched in a dry preform state that are infused with resin and cured to a final shape) offer a variety of benefits for modern aircraft structures. In this document one means of stitching dry fabric preforms in a state of temporary vacuum consolidation is discussed. This vacuum consolidation allows for the completion of stitching procedures while the dry preform thickness is temporarily reduced to a thickness reflective of its final cured thickness. Here, a temporary vacuum consolidation process enabling stitching of preforms of unconsolidated nominal thickness greater than the maximum allowable stitching thickness for the Integrated Structural Assembly of Advanced Composite (ISAAC) system is explored as a use case for such processes. Temporary vacuum consolidation processes may lead to simplified manufacturing processes or desirable composite material properties in the future.

Stitched Composites↗
NASA NTRSDate not supplied

Computer Controlled High Vacuum Gas Purification and Analysis Line

Light stable isotope work requires the handling of gasses such a way that does not alter isotopic composition. To do this, there are a large number of analytical and experimental procedures which involve the use of a vacuum line, numerous “egg timers” and a human hand on a valve. Unfortunately, the human hand is inconsistent and inadvertent small, and commonly large, differences in timing can have a measurable effect on outcomes. We have constructed a computer controlled high-vacuum line to be used as an expandable platform for future experimental and analytical procedures. The vacuum line consists of an electropolished 316 stainless steel system of cryogenic u-traps partitioned by pneumatic valves. The code to operate the line has been developed using the LabView platform and will allow for automated timing, consistent valve opening speed and unattended operation of long analytical procedures. The aim of this project is to address a need in the light stable isotope laboratory for a general-purpose vacuum line for handling and manipulation of gasses. When combined with existing instrumentation it allows for a significant expansion of current analytical capabilities. The system allows for better handling of standards, gas conversion techniques and gas sample collection for interlaboratory comparisons. The basic structure of the line, automation hardware and software were chosen and designed to provide a base for future expansion of the system to incorporate new automated analytical techniques as laboratory instrumentation and analytical needs expand.

High vacuum↗
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↗
NASA NTRS1971

A study of LC-39 cryogenic systems. Part 1: A study of the vacuum insulated transfer lines at Kennedy Space Center. Part 2: Cooldown pressure surges

The vacuum liquid hydrogen and liquid oxygen transfer lines at Kennedy Space Center were studied to evaluate the feasibility of using a condensing gas such as CO2 inside the vacuum spaces to achieve a condensing-vacuum. The study indicates that at ambient temperature, a maximum vacuum hyphen space pressure of 4000 microns is acceptable for the LH2 transfer lines. In addition, the cooldown procedures for the 14-inch cross-country liquid oxygen line was studied using a simplified mathematical model. Preliminary cooldown times are presented for various heat leak rates to the line and for two vent configurations.

Ludtke, P. R.↗
NASA NTRS1972

Torsion pendulum measurements on viscoelastic materials during vacuum exposure

A torsional pendulum apparatus designed for testing in situ in vacuum, the dynamic mechanical properties of materials is described. The application of this apparatus to an experimental program to measure the effects of vacuum on the mechanical properties of two ablator materials (a foamed material and a filled elastomer) and a solid rocket propellant (a filled elastomer) is presented. Results from the program are discussed as to the effects of vacuum on the mechanical properties of these three materials. In addition, time-temperature-superposition, as a technique for accelerating vacuum induced changes in mechanical properties, is discussed with reference to the three materials tested in the subject program.

Ward, T. C.↗
NASA NTRS1971

The Effect of Temperature on the Survival of Microorganisms in a Deep Space Vacuum

A space molecular sink research facility (Molsink) was used to evaluate the ability of microorganisms to survive the vacuum of outer space. This facility could be programmed to simulate flight spacecraft vacuum environments at pressures in the .1 nanotorr range and thermal gradients (30 to 60 C) closely associated to surface temperatures of inflight spacecraft. Initial populations of Staphylococcus epidermidis and a Micrococcus sp. were reduced approximately 1 log while exposed to -105 and 34 C, and approximately 2 logs while exposed to 59 C for 14 days in the vacuum environment. Spores of Bacillus subtilis var. niger were less affected by the environment. Initial spore populations were reduced 0.2, 0.3, and 0.8 log during the 14-day vacuum exposure at -124, 34, and 59 C, respectively.

Hagen, C. A.↗
NASA NTRS1973

Test stand system for vacuum chambers

A test stand system for supporting test items in a vacuum chamber is described. The system consists of a frame adapted to conform to the inside of the vacuum chamber and supporting a central vertical shaft. The shaft rotates on bearings located at each end of the shaft. Several vertically spaced plates which fixed to the vertical shaft may be adjusted for height to support the test equipment as required. The test equipment may be rotated during tests without disturbing the vacuum by a manually actuated drive external to the vacuum chamber.

Newman, D. F.↗