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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 631 records · Page 35

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NASA NTRS1991

Ka-band MMIC microstrip array for high rate communications

In a recent technology assessment of alternative communication systems for the space exploration initiative (SEI), Ka-band (18 to 40 GHz) communication technology was identified to meet the mission requirements of telecommunication, navigation, and information management. Compared to the lower frequency bands, Ka-band antennas offer higher gain and broader bandwidths; thus, they are more suitable for high data rate communications. Over the years, NASA has played an important role in monolithic microwave integrated circuit (MMIC) phased array technology development, and currently, has an ongoing contract with Texas Instrument (TI) to develop a modular Ka-band MMIC microstrip subarray (NAS3-25718). The TI contract emphasizes MMIC integration technology development and stipulates using existing MMIC devices to minimize the array development cost. The objective of this paper is to present array component technologies and integration techniques used to construct the subarray modules.

Lee, R. Q.↗

NASA NTRS1991

Cryogenic transfer options for exploration missions

The literature of in-space cryogenic transfer is reviewed in order to propose transportation concepts to support the Space Exploration Initiative (SEI). Forty-nine references are listed and key findings are synopsized. An assessment of the current maturity of cryogenic transfer system technology is made. Although the settled transfer technique is the most mature technology, the No-Vent Fill technology is maturing rapidly. Future options for development of cryogenic transfer technology are also discussed.

Chato, David J.↗

NASA NTRS1991

Potential converter for laser-power beaming

Future space missions, such as those associated with the Space Exploration Initiative (SEI), will require large amounts of power for operation of bases, rovers, and orbit transfer vehicles. One method for supplying this power is to beam power from a spaced based or Earth based laser power station to a receiver where laser photons can be converted to electricity. Previous research has described such laser power stations orbiting the Moon and beaming power to a receiver on the surface of the Moon by using arrays of diode lasers. Photovoltaic converters that can be efficiently used with these diode lasers are described.

Walker, Gilbert H.↗

NASA NTRS1991

Space mechanisms needs for future NASA long duration space missions

Future NASA long duration missions will require high performance, reliable, long lived mechanical moving systems. In order to develop these systems, high technology components, such as bearings, gears, seals, lubricants, etc., will need to be utilized. There has been concern in the NASA community that the current technology level in these mechanical component/tribology areas may not be adequate to meet the goals of long duration NASA mission such as Space Exploration Initiative (SEI). To resolve this concern, NASA-Lewis sent a questionnaire to government and industry workers (who have been involved in space mechanism research, design, and implementation) to ask their opinion if the current space mechanisms technology (mechanical components/tribology) is adequate to meet future NASA Mission needs and goals. In addition, a working group consisting of members from each NASA Center, DoD, and DOE was established to study the technology status. The results of the survey and conclusions of the working group are summarized.

Fusaro, Robert L.↗

NASA NTRS1991

Structural Design Concepts for a Multi-Megawatt Solar Electric Propulsion (SEP) Spacecraft

As a part of the Space Exploratory Initiative (SEI), NASA-Lewis is studying Solar Electric Propulsion (SEP) spacecraft to be used as a cargo transport vehicle to Mars. Two preliminary structural design concepts are offered for SEP spacecraft: a split blanket array configuration, and a ring structure. The split blanket configuration is an expansion of the photovoltaic solar array design proposed for Space Station Freedom and consists of eight independent solar blankets stretched and supported from a central mast. The ring structural concept is a circular design with the solar blanket stretched inside a ring. This concept uses a central mast with guy wires to provide additional support to the ring. The two design concepts are presented, then compared by performing stability, normal modes, and forced response analyses for varying levels of blanket and guy wire preloads. The ring structure configuration is shown to be advantageous because it is much stiffer, more stable, and deflects less under loading than the split blanket concept.

Lawrence, Charles↗

NASA NTRS1990

Launch site integration for mixed fleet operations

Launch site impacts and integration planning issues are presented to support launch operations for a mixed vehicle fleet (manned and cargo). Proposed ground systems and launch site configurations are described. Prelaunch processing scenarios and schedules are developed for candidate launch vehicles. Earth-to-orbit (ETO) vehicle architectures are presented to meet future launch requirements, including the Space Exploration Initiative (SEI). Flight vehicle design recommendations to enhance launch processing are discussed. The significance of operational designs for future launch vehicles is shown to be a critical factor in planning for mixed fleet launch site operations.

Scott, L. P.↗

NASA NTRS1990

Long duration mission support operations concepts

It is suggested that the system operations will be one of the most expensive parts of the Mars mission, and that, in order to reduce their cost, they should be considered during the conceptual phase of the Space Exploration Initiative (SEI) program. System operations of Space Station Freedom, Lunar outpost, and Mars Rover Sample Return are examined in order to develop a similar concept for the manned Mars mission. Factors that have to be taken into account include: (1) psychological stresses caused by long periods of isolation; (2) the effects of boredom; (3) the necessity of onboard training to maintain a high level of crew skills; and (4) the 40-min time delays between issuing and receiving a command, which make real-time flight control inoperative and require long-term decisions to be made by the ground support.

Eggleston, T. W.↗

NASA NTRS1990

Propulsion for the lunar mission

The paper describes the selection process utilized by NASA during the conduct of the 90-day study of the mission set that is known as the Space Exploration Initiative (SEI). It is directed specifically toward propulsion system definition and selection, with emphasis on the proposed Lunar Transfer Vehicle and the Lunar Exploration Vehicle. Results of trade studies show that selection cannot be readily made on the basis of engine performance alone, because the cost of launching hardware elements and the required propellant are very high. A decision must be made to use either life-cycle costs or annual program costs as the economic figure of merit, because they drive the selection in opposite directions.

Jones, Lee W.↗

NASA NTRS1990

Cryogenic propellant management architectures to support the Space Exploration Initiative

The initial results of a current study to develop fuel system architectures to support the lunar requirements of the Space Exploration Initiative (SEI) are reported. The study includes the development and assessment of propellant management facility concepts, supporting infrastructure, operations analysis, and identification of impact on current programs, including Space Station Freedom, Earth-to-Orbit vehicles, and the Space Transfer Vehicle. The cryogenic propellant management architectures are evaluated using criteria that have been defined to provide for minimum subjective assessment and effective data reliability.

Cady, E. C.↗

NASA NTRS1990

Space Station Freedom flight operations in support of exploration missions

The operational requirements on Space Station Freedom (SSF) for supporting the Lunar Phase of the Space Exploration Initiative (SEI) are examined, and a concept is developed for carrying out these operations. Attention is given to the types of events and tasks that must be performed on the SSF to process the lunar vehicles, as well as to resources required for the SSF and the methods of meeting the operational requirements of the lunar missions. Critical technology areas and needs that must be addressed to enable lunar missions are also discussed.

Brender, Karen D.↗

NASA NTRS1990

A Personnel Launch System for safe and efficient manned operations

Several Conceptual designs for a simple, rugged Personnel Launch System (PLS) are presented. This system could transport people to and from Low Earth Orbit (LEO) starting in the late 1990's using a new modular Advanced Launch System (ALS) developed for the Space Exploration Initiative (SEI). The PLS is designed to be one element of a new space transportation architecture including heavy-lift cargo vehicles, lunar transfer vehicles, and multiple-role spcecraft such as the current Space Shuttle. The primary role of the PLS would be to deliver crews embarking on lunar or planetary missions to the Space Station, but it would also be used for earth-orbit sortie missions, space rescue missions, and some satellite servicing missions. The PLS design takes advantage of emerging electronic and structures technologies to offer a robust vehicle with autonomous operating and quick turnaround capabilities. Key features include an intact abort capability anywhere in the operating envelope, and elimination of all toxic propellants to streamline ground operations.

Petro, Andrew J.↗

NASA NTRS1990

Lunar orbiting microwave beam power system

A microwave-beam power system using lunar orbiting solar-powered satellite(s) and surface rectenna(s) is investigated as a possible energy source for the moon's surface. The concept has the potential of achieving reduced system mass by placing the power source in orbit. This can greatly reduce and/or eliminate the 14-d energy storage requirement of a lunar surface solar system. Also, propellants required to de-orbit to the surface are greatly reduced. To determine the practicality of the concept and the most important factors, a zeroth-order feasibility analysis is performed. Three different operation scenarios employing state of the art technology and forecasts for two different sets of advanced technologies are investigated. To reduce the complexity of the problem, satellite(s) are assumed to be in circular equatorial orbits around the moon, supplying continuous power to a single equatorial base through a fixed horizontal rectenna on the surface. State of the art technology yields specific masses greater than 2500 kg/kw, well above projections for surface systems. The specific masses are on the order of 100 kg/kW using advanced technologies, which is within the range of projections for surface nuclear (20 kg/kW) and solar systems (500 kg/kW). Further studies examining optimization of the scenarios, other technologies, such as laser transmitters and nuclear sources, and operational issues, such as logistics, maintenance, and support, are being carried out to support the Space Exploration Initiative (SEI) to the moon and Mars.

Fay, Edgar H.↗

NASA NTRS1991

A review of candidate multilayer insulation systems for potential use on wet-launched LH2 tankage for the Space Exploration Initiative lunar missions

The storage of cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) for the future Space Exploration Initiative (SEI) will require lightweight, high performance thermal protection systems (TPSs). For the near-term lunar missions, the major weight element for most of the TPSs will be multilayer insulation (MLI) and/or the special structures/systems required to accommodate the MLI. Methods of applying MLI to LH2 tankage to avoid condensation or freezing of condensible gases such as nitrogen or oxygen while in the atmosphere are discussed. Because relatively thick layers of MLI will be required for storage times of a month or more, the transient performance from ground-hold to space-hold of the systems will become important in optimizing the TPSs for many of the missions. The ground-hold performance of several candidate systems are given as well as a qualitative assessment of the transient performance effects.

Knoll, Richard H.↗

NASA NTRS1991

Ka-band MMIC microstrip array for high rate communications

Lee, R. Q.↗

NASA NTRS1991

An historical perspective of the NERVA nuclear rocket engine technology program

Nuclear rocket research and development was initiated in the United States in 1955 and is still being pursued to a limited extent. The major technology emphasis occurred in the decade of the 1960s and was primarily associated with the Rover/NERVA Program where the technology for a nuclear rocket engine system for space application was developed and demonstrated. The NERVA (Nuclear Engine for Rocket Vehicle Application) technology developed twenty years ago provides a comprehensive and viable propulsion technology base that can be applied and will prove to be valuable for application to the NASA Space Exploration Initiative (SEI). This paper, which is historical in scope, provides an overview of the conduct of the NERVA Engine Program, its organization and management, development philosophy, the engine configuration, and significant accomplishments.

Robbins, W. H.↗

NASA NTRS1991

CFM technology needs for future space transportation systems

Several technological capabilities must be developed to realize the vision of the Space Exploration Initiative (SEI). Cryogenic fluid management (CFM) is one technology area common to virtually every space transportation propulsion concept envisioned. The physics of storage, supply, transfer, and handling of subcritical cryogenic fluids in the reduced gravity environment of space present fundamental challenges. The CFM state of the art relative to future mission requirements is reviewed and associated technology challenges are outlined.

Hastings, L. J.↗

NASA NTRS1991

An overview of the LeRC CSTI thermal management program

This report presents an integrated multielement project effort, currently being carried out at NASA LeRC, for the development of space heat rejection subsystems, with special emphasis on lightweight radiators, in support of SEI power system technology, and in particular the SP-100 program. Principal project elements include both contracted and in-house efforts. Included in the first category are two contracts aimed at the development of advanced radiator concepts, and demonstration of a flexible fabric heat pipe radiator concept. In-house work is designed to guide and support the overall program by system integration studies, heat pipe testing and analytical code development, radiator surface morphology alteration for emissivity enhancement, and composite materials research focused on the development of lightweight high conductivity fins.

Juhasz, Albert J.↗

NASA NTRS1991

Alkali metal propellants for MPD thrusters

Experiments performed in the United States in the 1960s and early 1970s and in the Soviet Union with alkali metal-fuelled MPD thrusters indicate performance levels substantially better than those achieved with gaseous propellants. Cathode wear appears to be less in engines with alkali metal propellants also. A critical review of the available data indicates that the data are consistent and reliable. An analysis of testing and systems-level considerations shows that pumping requirements for testing are substantially decreased and reductions in tankage fraction can be expected. In addition, while care must be exercised in handling the alkali metals, it is not prohibitively difficult or hazardous. The greatest disadvantage seems to be the potential for spacecraft contamination, but there appear to be viable strategies for minimizing the impact of propellant deposition on spacecraft surfaces. Renewed examination of alkali metal-fuelled MPD thrusters for ambitious SEI missions is recommended.

Polk, J. E.↗