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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Durability of Intercalated Graphite Epoxy Composites in Low Earth Orbit

The electrical conductivity of graphite epoxy composites can be substantially increased by intercalating (inserting guest atoms or molecules between the graphene planes) the graphite fibers before composite formation. The resulting high strength, low density, electrically conducting composites have been proposed for EMI shielding in spacecraft. Questions have been raised, however, about their durability in the space environment, especially with respect to outgassing of the intercalates, which are corrosive species such as bromine. To answer those concerns, six samples of bromine intercalated graphite epoxy composites were included in the third Evaluation of Oxygen Interaction with Materials (EOIM-3) experiment flown on the Space Shuttle Discovery (STS-46). Changes in electrical conductivity, optical reflectance, surface texture, and mass loss for SiO2 protected and unprotected samples were measured after being exposed to the LEO environment for 42 hours. SiO2 protected samples showed no degradation, verifying conventional protection strategies are applicable to bromine intercalated composites. The unprotected samples showed that bromine intercalation does not alter the degradation of graphite-epoxy composites. No bromine was detected to have been released by the fibers allaying fears that outgassing could be disruptive to the sensitive electronics the EMI shield is meant to protect.

Gaier, James R.↗
NASA NTRS1981

SEP solar array Shuttle flight experiment

An experiment to verify the operational performance of a full-scale Solar Electric Propulsion (SEP) solar array is described. Scheduled to fly on the Shuttle in 1983, the array will be deployed from the bay for ten orbits, with dynamic excitation to test the structural integrity being furnished by the Orbiter verniers; thermal, electrical, and sun orientation characteristics will be monitored, in addition to safety, reliability, and cost effective performance. The blanket, with aluminum and glass as solar cell mass simulators, is 4 by 32 m, with panels (each 0.38 by 4 m) hinged together; two live Si cell panels will be included. The panels are bonded to stiffened graphite-epoxy ribs and are storable in a box in the bay. The wing support structure is detailed, noting the option of releasing the wing into space by use of the Remote Manipulator System if the wing cannot be refolded. Procedures and equipment for monitoring the array behavior are outlined, and comprise both analog data and TV recording for later playback and analysis. The array wing experiment will also aid in developing measurement techniques for large structure dynamics in space.

Elms, R. V., Jr.↗
NASA NTRS1973

Acid electrolyte fuel cell technology program

The development of an acid electrolyte fuel cell was investigated to provide a cost effective electrical power system for the space shuttle orbiter. Previous investigation showed the life capability of the fuel cell was improved by proper prehumidification of the reactant gases. Breadboard models were developed which incorporate reactant prehumidification and have a life duration time of 2000 hours. Fuel cell performance was found to be invariant with cell life, and reactant consumption was unchanged from start to end of life. Satisfactory start and stop procedures are demonstrated along with scale-up capabilities for the number of cells in a stack, and for cell active areas. Safety design features, which operate to isolate the affected module from the remainder of the system, to eliminate single point failure modes from affecting the entire electrical power system are included.

Source record↗
NASA NTRS1999

Inhibition of root elongation in microgravity by an applied electric field

Roots grown in an applied electric field demonstrate a bidirectional curvature. To further understand the nature of this response and its implications for the regulation of differential growth, we applied an electric field to roots growing in microgravity. We found that growth rates of roots in microgravity were higher than growth rates of ground controls. Immediately upon application of the electric field, root elongation was inhibited. We interpret this result as an indication that, in the absence of a gravity stimulus, the sensitivity of the root to an applied electric stimulus is increased. Further space experiments are required to determine the extent to which this sensitivity is shifted. The implications of this result are discussed in relation to gravitropic signaling and the regulation of differential cell elongation in the root.

short duration↗
NASA NTRS2008

New Materials for the Repair of Polyimide Electrical Wire Insulation

Two viable polyimide backbone materials have been identified that will allow the repair of polyimide electrical wire insulation found on the Space Shuttle and other aging aircraft. This identification is the outcome of ongoing efforts to assess the viability of using such polyimides and polyimide precursors (polyamic acids [PAAs]) as repair materials for aging polyimide electrical wire insulation. These repair materials were selected because they match the chemical makeup of the underlying wire insulation as closely as possible. This similarity allows for maximum compatibility, coupled with the outstanding physical properties of polyimides. The two polyimide backbone materials allow the polymer to be extremely flexible and to melt at low temperatures. A polymer chain end capping group that allows the polymer to crosslink into a nonflowable repair upon curing at around 200 C was also identified.

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NASA NTRS1992

Interference patterns in the Spacelab 2 plasma wave data - Oblique electrostatic waves generated by the electron beam

During the Spacelab 2 mission the University of Iowa's Plasma Diagnostics Package (PDP) explored the plasma environment around the shuttle. Wideband spectrograms of plasma waves were obtained from the PDP at frequencies of 0-30 kHz and at distances up to 400 m from the shuttle. Strong low-frequency (below 10 kHz) electric field noise was observed in the wideband data during two periods in which an electron beam was ejected from the shuttle. This noise shows clear evidence of interference patterns caused by the finite (3.89 m) antenna length. The low-frequency noise was the most dominant type of noise produced by the ejected electron beam. Analysis of antenna interference patterns generated by these waves permits a determination of the wavelength, the direction of propagation, and the location of the source region. The observed waves have a linear dispersion relation very similar to that of ion acoustic waves. The waves are believed to be oblique ion acoustic or high-order ion cyclotron waves generated by a current of ambient electrons returning to the shuttle in response to the ejected electron beam.

Feng, Wei↗
NASA NTRS1993

A strip chart recorder pattern recognition tool kit for Shuttle operations

During Space Shuttle operations, Mission Control personnel monitor numerous mission-critical systems such as electrical power; guidance, navigation, and control; and propulsion by means of paper strip chart recorders. For example, electrical power controllers monitor strip chart recorder pen traces to identify onboard electrical equipment activations and deactivations. Recent developments in pattern recognition technologies coupled with new capabilities that distribute real-time Shuttle telemetry data to engineering workstations make it possible to develop computer applications that perform some of the low-level monitoring now performed by controllers. The number of opportunities for such applications suggests a need to build a pattern recognition tool kit to reduce software development effort through software reuse. We are building pattern recognition applications while keeping such a tool kit in mind. We demonstrated the initial prototype application, which identifies electrical equipment activations, during three recent Shuttle flights. This prototype was developed to test the viability of the basic system architecture, to evaluate the performance of several pattern recognition techniques including those based on cross-correlation, neural networks, and statistical methods, to understand the interplay between an advanced automation application and human controllers to enhance utility, and to identify capabilities needed in a more general-purpose tool kit.

Hammen, David G.↗
NASA NTRS1979

Cooling a radioisotope power source in the Space Shuttle Orbiter

Radioisotope thermoelectric generators (RTG's), used to generate electrical power on outer planetary spacecraft, are presently planned for a January 1982 launch of Galileo and later for a February 1983 launch. The RTG's will be externally located on a spacecraft to be deployed from the Space Shuttle Orbiter. Each RTG rejects nearly 2.5 kW (8500 Btu/hr) of thermal energy. From the time the RTG's are loaded into the payload bay until the doors are opened one to three hours after launch, active cooling will maintain proper temperature limits. This paper includes a description of two types of RTG's and the various cooling concepts considered. The payload cooling capability of the Shuttle Orbiter and modifications required to accommodate the RTG's are discussed. The analytical technique for determining the heat load split between the orbiter environment and RTG coolant is also presented.

Levine, D. I.↗
NASA NTRS1970

Solid state power management

Analytic and design studies of contactless solid state electric power management systems for space shuttle vehicles

Rakofsky, I.↗
NASA NTRS1972

Astronomy sortie missions definition study. Volume 3, book 2: Appendix: Design analysis and trade studies

Backup or supporting data for the design analyses and trade studies which defined the astronomy sortie missions are presented. The subjects discussed are: (1) configuration of space shuttle orbiter, (2) electronic subsystems, (3) electric power requirements, and (4) payload requirements. Mathematical models are developed to illustrate the orbital rendezvous capabilities.

Source record↗
NASA NTRS1974

Space Shuttle OMS engine valve technology

Valve technology program to determine shutoff valve concepts suitable for the Orbital Maneuvering System (OMS) engine of the Space Shuttle. The tradeoff studies selected the electric torque motor operated dual poppet and ball valves as the most desirable valve concepts for the OMS Engine Shutoff Valve. A prototype of one of these concepts was built and subjected to a design verification program. A number of unique features were designed to include the required contamination insensitivity, operating fluid compatibility, decontamination capability, minimum maintenance requirement and long service life capability.

Wichmann, H.↗
NASA NTRS1978

Space transportation systems, 1980-2000

An overview of projected space transportation systems for the 1980-2000 period is presented. Methods for meeting the requirements in that area are documented through a description of the Space Shuttle and its current upper stages, reusable transfer vehicles, Shuttle uprating, fully reusable and single-stage transports, heavy lift vehicles, and advanced vehicles for orbital transfer and lunar landing. The structure of the liquid oxygen/liquid hydrogen boosters, cryogenic propellants, whose main propulsion system is a derivative of the RL-10 engine used in the Centaur launch, and mixed mode propulsion engine is also described, as is the flyback booster concept and such related issues as propellants and rocket engines, staging velocity, configuration shape, and whether it should be manned or unmanned. Especially noted are proposed propulsion systems going beyond the present Shuttle such as the nuclear and electric propulsion concepts, the resistojet, using liquid hydrogen, ion thruster, using argon, magnetoplasmadynamic thrusters, solar thermal rocket, and solar sail concept where the basic idea is to use a 'sail' of thin reflective material to generate a net force by reflection of solar radiation.

Cohan, C. J.↗
NASA NTRS1985

Preliminary investigation of the electrodynamics of a conducting tether

An introductory study of the properties of an electrically conducting tether flown from the shuttle is presented. Only a single configuration is considered: a vertical conductor moving normally across the Earth's field, connecting the shuttle to a large conducting balloon that passively extracts electrons from the ionosphere. The distortions in the plasma at maximum current collection are described, as are the local and distant wakes. Numerical values are given.

Thompson, W. B.↗
NASA NTRS1989

Igniter Simulator

Report describes electronic circuitry that simulates electrical properties of igniter of Space Shuttle main engine. Circuit used to test software of engine controller, without having to fire real igniter or turn on engine. Circuit used in all igniter simulations and mimics operation of igniter more realistically than did previous versions.

Simon, Richard A.↗
NASA NTRS2005

STS-114 Flight Day 5 Highlights

Highlights of Day 5 of the STS-114 Return to Flight mission (Commander Eileen Collins, Pilot James Kelly, Mission Specialists Soichi Noguchi, Stephen Robinson, Andrew Thomas, Wendy Lawrence, and Charles Camarda) include video coverage of an extravehiclular activity (EVA) by Noguchi and Robinson. The other crew members of Discovery are seen on the flight deck and mid-deck helping the astronauts to suit-up. The objectives of the EVA are to test repair techniques on sample tiles in the shuttle's payload bay, to repair electrical equipment for a gyroscope on the International Space Station (ISS), and to install a replacement GPS antenna on the ISS. Noguchi and Robinson use a caulk gun and a putty knife to repair the sample tiles. The video contains several Earth views, including one of Baja California.

Source record↗
NASA NTRS2005

Lightning Often Strikes Twice

Contrary to popular misconception, lightning often strikes the same place twice. Certain conditions are just ripe for a bolt of electricity to come zapping down; and a lightning strike is powerful enough to do a lot of damage wherever it hits. NASA created the Accurate Location of Lightning Strikes technology to determine the ground strike point of lightning and prevent electrical damage in the immediate vicinity of the Space Shuttle launch pads at Kennedy Space Center. The area surrounding the launch pads is enmeshed in a network of electrical wires and components, and electronic equipment is highly susceptible to lightning strike damage. The accurate knowledge of the striking point is important so that crews can determine which equipment or system needs to be retested following a strike. Accurate to within a few yards, this technology can locate a lightning strike in the perimeter of the launch pad. As an added bonus, the engineers, then knowing where the lightning struck, can adjust the variables that may be attracting the lightning, to create a zone that will be less susceptible to future strikes.

Source record↗
NASA NTRS2004

Space Shuttle Upgrades: Long Life Alkaline Fuel Cell

NASA has utilized the alkaline fuel cell technology to provide electrical power for manned launch vehicles such as Gemini, Apollo, and the Space Shuttle. The current Shuttle alkaline fuel cells are procured from UTC Fuel Cells, a United Technologies Company. The alkaline fuel cells are very reliable but the operating life is limited to 2600 hours due to voltage degradation of the individual cells. The main limiting factor in the life of the cells is corrosion of the cell's fiberglass/epoxy frame by the aqueous potassium hydroxide electrolyte. To reduce operating costs, the orbiter program office approved the Long Life Alkaline Fuel Cell (LLAFC) program as a shuttle upgrade in 1999 to increase the operating life of the fuel cell powerplant to 5000 hours. The LLAFC program incorporates improving the cell by extending the length of the corrosion path, which reduces the cell frame corrosion. UTCFC performed analysis to understand the fundamental mechanisms that drive the cell frame corrosion. The analysis indicated that the corrosion path started along the bond line between the cathode and the cell frame. Analysis also showed that the oxygen available at the cathode, the catalyst on the electrode, and the electrode substrate all supported or intensified the corrosion. The new cell design essentially doubled the corrosion path to mitigate the problem. A 10-cell stack was tested for 5000 hours during the development phase of this program to verify improved cell performance. A complete 96-cell stack was then tested for 5000 hours during the full manned-space qualification phase of this program. Additional upgrades to the powerplant under this program are: replacing the aluminum body in the pressure regulator with stainless steel to reduce corrosion, improving stack insulator plate with improved resistance to stress failure and improved temperature capability, and replacing separator plate elastomer seals with a more durable material and improved seal retention.

Kerri McCurdy↗
NASA NTRS1984

Kennedy Space Center polygeneration facility

This is a report on the status of the polygeneration feasibility study conducted by the Kennedy Space Center (KSC). Polygeneration is an innovative approach to reducing cost per flight for the Shuttle by reducing propellant and other costs. Cost of LH2 is expected to be adversely affected by sharp increases in natural gas pricing as well as other costs such as electricity and transportation. The polygeneration concept is to produce liquid hydrogen (LH2) for the Shuttle and gaseous nitrogen (GN2), electricity and thermal energy to meet KSC requirements by means of an integrated coal gasification plant. Conclusions of the initial feasibility study will be presented as well as the status of on-going activities.

Gutkowski, G. P.↗