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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Orbit transfer vehicle engine technology program. Task B-6 high speed turbopump bearings

Bearing types were evaluated for use on the Orbit Transfer Vehicle (OTV) high pressure fuel pump. The high speed, high load, and long bearing life requirements dictated selection of hydrostatic bearings as the logical candidate for this engine. Design and fabrication of a bearing tester to evaluate these cryogenic hydrostatic bearings was then conducted. Detailed analysis, evaluation of bearing materials, and design of the hydrostatic bearings were completed resulting in fabrication of Carbon P5N and Kentanium hydrostatic bearings. Rotordynamic analyses determined the exact bearing geometry chosen. Instrumentation was evaluated and data acquisition methods were determined for monitoring shaft motion up to speeds in excess of 200,000 RPM in a cryogenic atmosphere. Fabrication of all hardware was completed, but assembly and testing was conducted outside of this contract.

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NASA NTRS2020

Low-energy Trajectories From Geosynchronous Transfer Orbits to Lunar Libration Orbits

The ability to reduce the cost of space missions beyond Earth orbit by leveraging innovative concepts is of great interest in the field of spaceflight. In this paper, the trajectory design for a mission from an inclined geosynchronous transfer orbit (GTO) to an Earth-Moon L2 Halo orbit is presented. The mission scenario for this investigation involves the use of a small satellite launched in a rideshare configuration and the use of a low-energy transfer to reach the target orbit. As a consequence of choosing a rideshare launch, the mission scenario entails critical uncertainties on the time of launch and injection parameters of the spacecraft, which could complicate the insertion into a low-energy transfer. Thus, the goal of the project is to develop a robust design methodology to deal with the launch uncertainties and assess launch readiness at any time of the year.

Wilson, Roby↗
NASA NTRS1979

Orbit Transfer Vehicle (OTV) engine, phase A study. Volume 1: Executive Summary

Design and parametric data for the hydrogen oxygen engine used in the orbiter transfer vehicle are presented. The engine design is analyzed and minimum engine performance and man rating requirements are discussed. Candidate cycle performance, weight and tradeoff analysis, and cost estimates are reported.

Mellish, J. A.↗
NASA NTRS1985

Orbital transfer vehicle concept definition and system analysis study, 1985. Volume 5: Work breakdown structure and dictionary

To establish consistency and visibility within the Orbital Transfer Vehicle (OTV) program, a preliminary work breakdown structure (WBS) and dictionary were developed. The dictionary contains definitions of terms to be used in conjunction with the WBS so that a clear understanding of the content of the hardware, function, and cost elements may be established. The OTV WBS matrix is a two-dimensional structure which shows the interrelationship of these dimensions: the hardware elements dimension and the phase and function dimension. The dimension of time cannot be shown graphically, but must be considered. Each cost entry varies with time so that it is necessary to know these cost values by year for budget planning and approval as well as for establishing cost streams for discounting purposes in the economic analysis. While a multiple dimensional approach may at first appear complex, it actually provides benefits which outweigh any concern. This structural interrelationship provides the capability to view and analyze the OTV costs from a number of different financial and management aspects. Cost may be summed by hardware groupings, phases, or functions. The WBS may be used in a number of dimensional or single listing format applications.

Nelson, James H.↗
NASA NTRS1985

Thermal Protection Requirements for Near-Earth Aeroassisted Orbital Transfer Vehicle Missions

The thermal protection required for decelerating and maneuvering spacecraft by aerodynamic forces is determined for return missions from geosynchronous to low Earth orbits. The effect of vehicle configuration on surface heating rates and selection of heat shield materials is analyzed. The effects of the current widespread estimates in the structure of atmospheric density are also evaluated. It is shown that nonequilibrium radiation can be a major source of surface heating during atmospheric entry and a significant factor for heat shielding requirements. It is also demonstrated that drag-brake concepts have application to a broad range of orbital transfer missions because of the favorable tradeoffs with aeromaneuvering vehicles in volumetric efficiency, retrothrust plane-change capability, and heat protection requirements. In addition, the results of this study indicate that the aeroassist technique produces acceptable penalties in vehicle payload capacity for drag-brake concepts, because of the system's heat protection requirements, and is highly attractive relative to all-propulsive orbital change maneuvers.

Menees, Gene P.↗
NASA NTRS1984

Problems of rate chemistry in the flight regimes of aeroassisted orbital transfer vehicles

The dissociating and ionizing nonequilibrium flows behind a normal shock wave are calculated for the density and vehicle regimes appropriate for aeroassisted orbital transfer vehicles; the departure of vibrational and electron temperatures from the gas temperature as well as viscous transport phenomena are accounted for. From the thermodynamic properties so determined, radiative power emission is calculated using an existing code. The resulting radiation characteristics are compared with the available experimental data. Chemical parameters are varied to investigate their effect on the radiation characteristics. It is concluded that the current knowledge of rate chemistry leads to a factor-of-4 uncertainty in nonequilibrium radiation intensities. The chemical parameters that must be studied to improve the accuracy are identified.

Park, C.↗
NASA NTRS1985

Laser propulsion for the orbital transfer mission

America's space activities in the 1990s and beyond will partly consist of missions involving the transportation of cargo from low earth orbit (LEO) to higher orbits or to an escape trajectory. Such missions are to be performed with the aid of an orbit transfer vehicle (OTV). The operation of the OTV can be based on different propulsion concepts. A chemical OTV is characterized by a high thrust and low specific impulse. The result is a short trip time at the cost of large quantities of propellant. On the other hand, low-thrust systems such as electric propulsion units, consume very little propellant, but would have a long trip time. The present paper is concerned with a compromise between these two extremes. The employed propulsion system utilizes laser thermal propulsion, in which a ground or space-based laser is used to beam energy to a thruster on the OTV. The laser light is absorbed by a propellant. The resulting heating of the propellant causes an expansion of the propellant through a nozzle to produce thrust. Details regarding this propulsion concept are discussed, taking into account operational questions and missions.

Frisbee, R. H.↗
NASA NTRS1988

Orbital transfer vehicle concept definition and systems analysis study. Volume 11: Study extension 2 results

Work conducted in the second extension of the Phase A Orbit Transfer Vehicle Concept Definition and Systems Analysis Study is summarized. Four major tasks were identified: (1) define an initial OTV program consistent with near term Civil Space Leadership Initiative missions; (2) develop program evolution to long term advanced missions; (3) investigate the implications of current STS safety policy on an Aft Cargo Carrier based OTV; and (4) expand the analysis of high entry velocity aeroassist. An increased emphasis on the breath of OTV applications was undertaken to show the need for the program on the basis of the expansion of the nation's capabilities in space.

Willcockson, W. H.↗
NASA NTRS1985

Problems of Rate Chemistry in the Flight Regimes of Aeroassisted Orbital Transfer Vehicles

The dissociating and ionizing nonequilibrium flows behind a normal shock wave are calculated for the density and vehicle regimes appropriate for aeroassisted orbital transfer vehicles; the departure of vibrational and electron temperatures from the gas temperature as well as viscous transport phenomena are accounted for. From the thermodynamic properties so determined, radiative power emission is calculated using an existing code. The resulting radiation characteristics are compared with the available experimental data. Chemical parameters are varied to Investigate their effect on the radiation characteristics. It is concluded that the current knowledge of rate chemistry leads to a factor-of-4 uncertainty In nonequilibrium radiation intensities. The chemical parameters that must be studied to Improve the accuracy are identified.

Park, Chul↗
NASA NTRS1992

Titan III Mars Explorer Transfer Orbital Stage Delivery to the PHSF

This NASA Kennedy Space Center video presents live footage of the delivery of the Titan III Mars Explorer Transfer Orbital Stage (TOS) to the Payload Hazardous Servicing Facility (PHSF). The TOS is a single-stage, solid propellant upper stage vehicle used to propel a spacecraft from low Earth orbit toward it's ultimate destination. The TOS is delivered to the PHSF where it is designed to accommodate a variety of NASA and NASA customer payloads and can be used as a payload processing facility (PPF) or a hazardous processing facility (HPF).

Source record↗
NASA NTRS1986

Orbital transfer vehicle concept definition and system analysis study. Volume 1A: Executive summary. Phase 2

The objectives of the Phase 2 study were to improve the orbit transfer vehicle (OTV) concept definition by focusing on the following issues: the impact of mission requirements on OTV system design; OTV basing concepts on the Space Shuttle, separate platforms, and/or remote locations; cost reduction of an OTV program to improve its economic benefits and support its acquisition. The OTV mission scenario includes a wide range of missions the main drivers of which are manned GEO servicing, mid-inclination/polar DOD, and lunar/planetary projects. A mission model is presented which includes the type and number of missions per year and the estimated propellant requirements. To accomplish the missions, many OTV concepts were defined including ground-based OTVs launched either in the STS orbiter, the aft cargo carrier, or a heavy lift launch vehicle, and a space-based OTV. System and program trade studies were conducted using performance, cost, safety/risk, and operations/growth criteria. The study shows that mission requirements and substantial economic benefits justify a reusable, cryogenic (H2/O2) space-based OTV. Such a system would not be subjected to Earth-to-orbit launch loads and would not be constained in size or weight. Safety is enhanced by the fact that the system components are launched unfueled. Its inherent reusability and ability to be refueled in space make the space-based OTV very economical to operate.

Ketchum, W. J.↗
NASA NTRS1983

Thermal-protection requirements for near-earth aero-assisted orbital-transfer vehicle missions

The thermal protection required for decelerating and maneuvering spacecraft by aerodynamic forces is determined for return missions from geosynchronous to low-earth orbits. The effect of vehicle configuration on surface heating rates and selection of heat-shield materials is analyzed. Effects of the current widespread estimates in the structure of atmospheric density are also evaluated. It is shown that nonequilibrium radiation can be a major source of surface heating during atmospheric entry and a significant factor to heat-shielding requirements. It is also demonstrated that drag-brake concepts have application to a broad range of orbital-transfer missions, because of the favorable trade-offs with aeromaneuvering vehicles in volumetric efficiency, retrothrust plane-change capability, and heat-protection requirements. In addition, the results of this study indicate that the aero-assist technique produces small penalties in vehicle payload capacity for drag-brake concepts, because of the system's heat protection requirements, and is highly attractive relative to all-propulsive orbital-change maneuvers.

Menees, G. P.↗
NASA NTRS1975

Optimal orbit transfer for out-of-ecliptic mission using a solar electric spacecraft

This paper analyzes the performance capability of a Titan IIIE/Centaur/SEP (15 kw) for out-of-ecliptic missions. Two classes of orbital transfer modes are considered; circular-to-circular and circular-to-elliptic. The results presented compare the achievable heliographic inclination using these different transfer modes and also show the degradations in performance due to constrained launch azimuth and thruster life. It is observed that the latter transfer mode could deliver a spacecraft to a much higher inclination than the former, but the final orbit is very eccentric and could come very close to the sun. In view of the existence of many trajectories by which this mission can be performed, it is suggested that a trajectory other than IAU circular out-of-ecliptic type be used to explore more scientifically rewarding missions.

Yen, C.-W. L.↗
NASA NTRS1985

Orbital transfer vehicle concept definition and system analysis study, 1985. Volume 2: OTV concept definition and evaluation. Book 2: OTV concept definition

This portion of the Orbit Transfer Vehicle (OTV) Concept Definition and System Analysis Study, Volume 2, Book 2, summarizes the flight vehicle concept selection process and results. It presents an overview of OTV mission and system design requirements and describes the family of OTV recommended, the reasons for this recommendation, and the associated Phase C/D Program.

Dickman, Glen J.↗
NASA NTRS1988

Aeroassisted orbital transfer vehicle control technology

The focus of this control has been to develop the control technology required to identify the sophistication required for the Aeroassisted Orbital Transfer Vehicle (AOTV) control system. An angle of attack, bank angle command control technique has been developed which uses either on-off thruster or proportional thruster. An angle of attack adaptive controller was included to minimize the reactor control system (RCS) usage due to payload center of gravity uncertainties. The guidance and control techniques were verified using a detail six degrees-of-freedom simulation. Mission sensitivity was developed for uncertainties in the entry state, mass properties, atmosphere, aerodynamic, and sensor.

Langehough, M. A.↗
NASA NTRS1980

A study of the lifetimes of geosynchronous transfer orbits

The study concerns the orbit lifetimes of spent upper stages that are used to boost NASA Space Transportation System payloads into geosynchronous transfer orbits. A semi-analytical method of trajectory computation was developed and applied to these particular orbits. It was found that gravitational perturbations of the sun, moon and oblate earth cause large changes in the perigee altitude. The following parameters have a strong influence on orbit lifetimes: Time of year of launch; Inertial orientation of orbital plane; Inclination of orbital plane.

Graf, O. F., Jr.↗
NASA NTRS2014

Spacecraft Charging in Geostationary Transfer Orbit

The 700 km x 5.8 Re orbit of the two Van Allen Probes spacecraft provide a unique opportunity to investigate spacecraft charging in geostationary transfer orbits. We use records from the Helium Oxygen Proton Electron (HOPE) plasma spectrometer to identify candidate surface charging events based on the "ion line" charging signature in the ion records. We summarize the energetic particle environment and the conditions necessary for charging to occur in this environment. We discuss the altitude, duration, and magnitude of events observed in the Van Allen Probes from the beginning of the mission to present time. In addition, we explore what information the dual satellites provide on the spatial and temporal variations in the charging environments.

Parker, Linda Neergaard↗