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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Electronically Controlled Mechanical Seal for Aerospace Applications -- Part 1: Design, Analysis, and Steady State Tests

An electronically-controlled mechanial seal, for use as the purge gas seal in a liquid oxygen turbopump, has been designed, analyzed, and built. The thickness of the lubricating film between the faces is controlled by adjusting the coning of the carbon face. This is done by applying a voltage across a piezoelectric element to which the carbon face is bound. Steady state tests have shown that the leakage rate (and film thickness) can be adjusted over a substantial range, utilizing the available range of voltage.

Salant, Richard F.↗
NASA NTRSDate not supplied

Microwave Structure Construction Capability Year One Accomplishments

The Microwave Structure Construction Capability (MSCC) element, part of the Moon to Mars Planetary Autonomous Construction Project (MMPACT) was initiated in 2020. MSCC is responsible for creating horizontal and vertical infrastructure on the moon using microwave energy. Microwave energy was selected since it is the only method to volumetrically heat the regolith. All other sintering/melting methods rely on thermal conduction through the very low conductivity surface, resulting in an inefficient process. Advances were achieved in materials characterization and understanding, microwave sintering in vacuum, and microwave design and analyses. Two dielectric property testing systems have been developed at Radiance Technologies and JPL. These will examine dielectric properties at cryogenic temperatures and over a broad frequency range. Permittivity and permeability testing at -60 ̊C in vacuum from 0.05 to 3 GHz has been generated at JPL. Additional modifications will be made to go to -190 ̊C (LN2). Radiance Technologies created a test system to measure dielectric properties at greater than 10 GHz and initiated work on developing a vacuum capable, portable test system to measure dielectric properties of Apollo regolith and simulants from 100 MHz to 18 GHz. These tests are to identify optimal heating frequencies and protocols. During microwave sintering at about 1100 ̊C, volatiles were creating difficulty in achieving a reasonably dense specimen. Due to processing in vacuum and the nature of the lunar regolith, some volatiles and porosity are expected. However, the Earth produced simulants have non-lunar materials in them that create volatiles that aren’t representative of lunar regolith. Therefore, a five month effort was conducted to establish a heat treat method to remove these non-lunar materials. Tests were conducted using TGA mass spectrometry, heating in vacuum and conducting mass spectrometry, dielectric and DTA, Raman, BET, particle size analysis, morphological analysis, carbon and sulfur chemical content determination and microscopy. The process has been scaled-up to 6 kg batch size and undergoing evaluation. A 36 kg batch size is the target for JSC-1A and other limited availability simulants. These calcining protocols will be standard for NASA and beyond. MSCC has also created scalable processes for fabricating synthetic lunar materials. Processes to fabricate Anorthite (plagioclase CaAl2Si2O8), Diopside (pyroxene CaMgSi₂O₆), and Enstatite (pyroxene Mg2Si2O6) have been generated. These materials will enable generation of microwave sintering models to bound various composition ranges anticipated on the Moon, therefore mitigating the need for a precise simulant with respect to location on the Moon. Successful microwave sintering in air using a horn applicator was demonstrated. All previous microwave vacuum sintering in the literature was at small scale and in a contained enclosure thus taking advantage of reflections. This is the first to use a lunar like microwave applicator to sinter ceramic in a bed as it would be done on the Moon. Small scale and inert sintering were conducted to assist in developing protocols with quicker turnaround times than larger scale testing. Testing has anchored thermal analysis predicting heat flow in vacuum during microwave sintering. Thermal conductivity testing was also initiated. Microwave coupling to the regolith has been modeled by multiple organizations and with different software packages. At least six horn designs and applicator configurations for both magnetron and solid state sources are being examined. Optimal simulant container designs for microwaves have also been generated. The power and electronics design for the solid state microwave system has been initiated. Concept designs for a lander based microwave sintering have been evaluated.

microwave↗
NASA NTRS2008

Aromatic Diimides - Potential Dyes for Use in Smart Films and Fibers

New aromatic diimide fluorescent dyes have been prepared with potential for use as chemical sensors and in chromogenic polymers. These dyes have been designed to utilize excited state electron transfer reactions as the means for sensing chemical species. For example, an aniline en-dcapped anthryl diimides functions effectively as an "on-off" sensor for pH and the detection of phosphoryl halide based chemical warfare agents, such as Sarin. In the absence of analytes, fluorescence from this dye is completely quenched by excited state electron transfer from the terminal amines. Reaction of these amines inhibits electron transfer and activates the fluorescence of the dye. Another substituted anthryl diimide is presented with the capability to detect pH and nitroaromatic compounds, such as TNT. Films prepared by doping small amounts (less than 0.1 weight percent) of several of these dyes in polymers such as linear low density polyethylene exhibit thermochromism. At room temperature, these films fluoresce reddish-orange. Upon heating, the fluorescence turns green. This process is reversible cooling the films to room temperature restores the orange emission.

Meador, Michael A.↗
NASA NTRS1993

Design methods for fault-tolerant finite state machines

VLSI electronic circuits are increasingly being used in space-borne applications where high levels of radiation may induce faults, known as single event upsets. In this paper we review the classical methods of designing fault tolerant digital systems, with an emphasis on those methods which are particularly suitable for VLSI-implementation of finite state machines. Four methods are presented and will be compared in terms of design complexity, circuit size, and estimated circuit delay.

Niranjan, Shailesh↗
NASA NTRS2009

Microwave Temperature Profiler Mounted in a Standard Airborne Research Canister

Many atmospheric research aircraft use a standard canister design to mount instruments, as this significantly facilitates their electrical and mechanical integration and thereby reduces cost. Based on more than 30 years of airborne science experience with the Microwave Temperature Profiler (MTP), the MTP has been repackaged with state-of-the-art electronics and other design improvements to fly in one of these standard canisters. All of the controlling electronics are integrated on a single 4 ~5-in. (.10 ~13- cm) multi-layer PCB (printed circuit board) with surface-mount hardware. Improved circuit design, including a self-calibrating RTD (resistive temperature detector) multiplexer, was implemented in order to reduce the size and mass of the electronics while providing increased capability. A new microcontroller-based temperature controller board was designed, providing better control with fewer components. Five such boards are used to provide local control of the temperature in various areas of the instrument, improving radiometric performance. The new stepper motor has an embedded controller eliminating the need for a separate controller board. The reference target is heated to avoid possible emissivity (and hence calibration) changes due to moisture contamination in humid environments, as well as avoiding issues with ambient targets during ascent and descent. The radiometer is a double-sideband heterodyne receiver tuned sequentially to individual oxygen emission lines near 60 GHz, with the line selection and intermediate frequency bandwidths chosen to accommodate the altitude range of the aircraft and mission.

Mahoney, Michael J.↗
NASA NTRS1982

Advanced technology for earth observation - Data processing

The Experimental Land Observing System (ELOS) is to demonstrate major advances in space-based land observation. Program success will depend upon successful demonstration of both space-segment performance and ground-system capabilities. Increases in data-rate, volume, and processing requirements present substantial challenges to the ground data processing system. ELOS is based on the utilization of the multispectral linear array (MLA) sensor, a solid-state, electronically scanned instrument. Current MLA instrument designs offer a number of capabilities beyond those provided in the Landsat imaging devices. These capabilities include greater resolution, inherent registration, onboard calibration, off-nadir pointing capability, and fore/aft pointing capability. The proposed MLA flight mission scenario will be one of continued growth and will include flights on the Space Transportation System. Attention is also given to ground-to-ground data transport, data capture, and the use of high speed computers.

Heffner, P.↗
NASA NTRS1997

Center for Applied Radiation Research (CARR)

Prairie View A&M University (PVAMU) Center for Applied Radiation Research (CARR) was established in 1995 to address the tasks, missions and technological needs of NASA. CARR is built on a tradition of radiation research at Prairie View A&M started in 1984 with NASA funding. This continuing program has lead to: (1) A more fundamental and practical understanding of radiation effects on electronics and materials; (2) A dialog between space, military and commercial electronics manufacturers; (3) Innovative electronic circuit designs; (4) Development of state-of-the-art research facilities at PVAMU; (5) Expanded faculty and staff to mentor student research; and (6) Most importantly, increased flow in the pipeline leading to expanded participation of African-Americans and other minorities in science and technological fields of interest to NASA.

Fogarty, Thomas N.↗
NASA NTRS1980

The use of the principle of superposition in measuring and predicting the thermal characteristics of an electronic equipment operated in a space environment

The advantages and possible pitfalls of using a generalized method of measuring and, based on these measurements, predicting the transient or steady-state thermal response characteristics of an electronic equipment designed to operate in a space environment are reviewed. The method requires generation of a set of thermal influence coefficients by test measurement in vacuo. A implified thermal mockup isused in this test. Once this data set is measured, temperatures resulting from arbitrary steady-state or time varying power profiles can be economically calculated with the aid of a digital computer.

Gale, E. H.↗
NASA NTRS1994

Atmospheric chemistry of the reaction ClO + O2 reversible reaction ClO (center dot) O2: Where it stands, what needs to be done, and why?

Possible existence and chemistry of ClO (center dot) O2 was originally proposed to explain the Norrish-Neville effect that O2 suppresses chlorine photosensitized loss of ozone. It was also thought that ClO (center dot) O2 might have some atmospheric chemistry significance. Recently, doubts have been cast on this proposal, because certain laboratory data seem to imply that the equilibrium constant of the title reaction is so small that ClO (center dot) O2 may be too unstable to matter. However, those data create only a superficial illusion to that effect, because on a closer analysis they do not disprove a moderately stable and chemically significant ClO (center dot) O2. Furthermore, our state-of-the-science accurate computational chemistry calculations also suggest that ClO (center dot) O2 may be a weakly bound ClOOO radical with a reactive (2)A ground electronic state. There is therefore a need to design and perform definitive experimental tests of the existence and chemistry of the ClO (center dot) O2 species, which we discuss and which have the potential to mediate the chlorine-catalyzed stratospheric ozone depletion.

Prasad, Sheo S.↗
NASA NTRS2002

The IRIS-GUS Shuttle Borne Upper Stage System

This paper describes the Italian Research Interim Stage - Gyroscopic Upper Stage (IRIS-GUS) upper stage system that will be used to launch NASA's Triana Observatory from the Space Shuttle. Triana is a pathfinder earth science mission being executed on rapid schedule and small budget, therefore the mission's upper stage solution had to be a system that could be fielded quickly at relatively low cost and risk. The building of the IRIS-GUS system wa necessary because NASA lost the capability to launch moderately sized upper stage missions fro the Space Shuttle when the PAM-D system was retired. The IRIS-GUS system restores this capability. The resulting system is a hybrid which mates the existing, flight proven IRIS (Italian Research Interim Stage) airborne support equipment to a new upper stage, the Gyroscopic Upper Stage (GUS) built by the GSFC for Triana. Although a new system, the GUS exploits flight proven hardware and design approaches in most subsystems, in some cases implementing proven design approaches with state-of-the-art electronics. This paper describes the IRIS-GUS upper stage system elements, performance capabilities, and payload interfaces.

Tooley, Craig↗
NASA NTRS1999

K-Band Phased Array Developed for Low- Earth-Orbit Satellite Communications

Future rapid deployment of low- and medium-Earth-orbit satellite constellations that will offer various narrow- to wide-band wireless communications services will require phased-array antennas that feature wide-angle and superagile electronic steering of one or more antenna beams. Antennas, which employ monolithic microwave integrated circuits (MMIC), are perfectly suited for this application. Under a cooperative agreement, an MMIC-based, K-band phased-array antenna is being developed with 50/50 cost sharing by the NASA Lewis Research Center and Raytheon Systems Company. The transmitting array, which will operate at 19 gigahertz (GHz), is a state-of-the-art design that features dual, independent, electronically steerable beam operation ( 42 ), a stand-alone thermal management, and a high-density tile architecture. This array can transmit 622 megabits per second (Mbps) in each beam from Earth orbit to small Earth terminals. The weight of the total array package is expected to be less than 8 lb. The tile integration technology (flip chip MMIC tile) chosen for this project represents a major advancement in phased-array engineering and holds much promise for reducing manufacturing costs.

Anzic, Godfrey↗