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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

The acceleration and propagation of solar flare energetic particles

Observations and theories of particle acceleration in solar flares are reviewed. The most direct signatures of particle acceleration in flares are gamma rays, X-rays and radio emissions produced by the energetic particles in the solar atmosphere and energetic particles detected in interplanetary space and in the Earth's atmosphere. The implication of these observations are discussed. Stochastic and shock acceleration as well as acceleration in direct electric fields are considered. Interplanetary particle propagation is discussed and an overview of the highlights of both current and promising future research is presented.

Forman, M. A.↗
NASA NTRS1990

Applications of different design methodologies in navigation systems and development at JPL

The NASA/JPL deep space navigation system consists of a complex array of measurement systems, data processing systems, and support facilities, with components located both on the ground and on-board interplanetary spacecraft. From its beginings nearly 30 years ago, this system has steadily evolved and grown to meet the demands for ever-increasing navigation accuracy placed on it by a succession of unmanned planetary missions. Principal characteristics of this system are its capabilities and great complexity. Three examples in the design and development of interplanetary space navigation systems are examined in order to make a brief assessment of the usefulness of three basic design theories, known as normative, rational, and heuristic. Evaluation of the examples indicates that a heuristic approach, coupled with rational-based mathematical and computational analysis methods, is used most often in problems such as orbit determination strategy development and mission navigation system design, while normative methods have seen only limited use is such applications as the development of large software systems and in the design of certain operational navigation subsystems.

Thurman, S. W.↗
NASA NTRS1990

Use of magnetic sails for advanced exploration missions

The magnetic sail, or magsail, is a field effect device which interacts with the ambient solar wind or interstellar medium over a considerable volume of space to generate drag and lift forces. Two theories describing the method of thrust generation are analyzed and data results are presented. The techniques for maintaining superconductor temperatures in interplanetary space are analyzed and low risk options presented. Comparisons are presented showing mission performance differences between currently proposed spacecraft using chemical and electric propulsion systems, and a Magsail propelled spacecraft capable of generating an average thrust of 250 Newtons at a radius of one A.U. The magsail also provides unique capabilities for interstellar missions, in that at relativistic speeds the magnetic field would ionize and deflect the interstellar medium producing a large drag force. This would make it an ideal brake for decelerating a spacecraft from relativistic speeds and then maneuvering within the target star system.

Andrews, Dana G.↗
NASA NTRS2003

A New Time-dependent Model for the Martian Radiation Environment

Manned space activities have been until present time limited to the near-Earth environment, most of them to low Earth orbit (LEO) scenarios, with only some of the Apollo missions targeted to the Moon. In current times most human exploration and development of space (HEDS) activities are related to the development of the International Space Station (ISS), and therefore take place in the LEO environment. A natural extension of HEDS activities will be going beyond LEO, and reach asteroids, Mars, Jupiter, Saturn, the Kuiper belt and the outskirts of the Solar System. Such long journeys onboard spacecraft outside the protective umbrella of the geomagnetic field will require higher levels of protection from the radiation environment found in the deep space for both astronauts and equipment. So, it is important to have available a tool for radiation shielding which takes into account the radiation environments found all along the interplanetary space and at the different bodies encountered in the Solar System. Moreover, the radiation protection is one of the two NASA highest concerns and priorities. A tool integrating different radiation environments with shielding computation techniques especially tailored for deep space mission scenario is instrumental in view of this exigency. In view of manned missions targeted to Mars, for which radiation exposure is one of the greatest problems and challenges to be tackled, it is of fundamental importance to have available a tool which allows to know which are the particle flux and spectra at any time at any point of the Martian surface. With this goal in mind, a new model for the radiation environment to be found on the planet Mars due to Galactic Cosmic Rays (GCR) has been developed. Solar modulated primary particles rescaled for Mars conditions are transported within the Martian atmosphere, with temporal properties modeled with variable timescales, down to the surface, with altitude and backscattering patterns taken into account. The tool allows analysis for manned Mars landing missions, as well as planetary science studies, e.g. subsurface water and volatile inventory studies. This Mars environmental model is available through the SIREST website, a project of NASA Langley Research Center.

G De Angelis↗
NASA NTRS1985

Diagnostic of electromagnetic conditions in space using cosmic rays

The method of spectrographic global survey was used to study the time variations in parameters of cosmic ray (CR) pitch angle anisotropy and their relationship with the variations of some solar wind characteristics under different electromagnetic conditions in interplanetary space. A classification is made of the conditions that are accompanied by the increase in CR anisotropy.

Dvornikov, V. M.↗
NASA NTRS1981

Potentials of surfaces in space

The subject of surface potentials on natural and artificial bodies in space is reviewed with particular emphasis on recent developments. Following a brief survey of work done up to the early 1970s on the charging of astrophysical objects in interstellar and interplanetary space and spacecraft charging, the various charging mechanisms in space are examined, including the collection of plasma particles, photoemission, and secondary electron emission by electron impact and ion impact, and the effects on charging of nonisotropic plasmas, wakes, and environmental magnetic and electric fields are considered. The concept of equilibrium potential is discussed, along with differential charging, potential barriers and discharge processes. The measurement of spacecraft potentials is then considered, and recent work on spacecraft potential modification and control by active and passive means is presented. Finally, astrophysical applications where charging effects may be important are discussed, and areas for further work are indicated.

Whipple, E. C.↗
NASA NTRS1971

Space and planetary environment criteria guidelines for use in space vehicle development, 1971 revision

A consolidation of natural environment data is presented for use as design criteria guidelines in space and planetary exploration vehicle development programs. In addition to information in the disciplinary areas of aeronomy, radiation, geomagnetism, astrodynamic constants, and meteoroids for the earth's environment above 90 kilometers, interplanetary space, and the planetary environments, the upper atmosphere model currently recommended for use at MSFC is discussed in detail.

Smith, R. E.↗
NASA NTRS1973

Energy losses of galactic cosmic rays in the interplanetary medium.

Using realistic models of cosmic-ray propagation in interplanetary space we present, for electrons, protons and helium nuclei of a given energy near earth, calculations of their distribution in energy before entering the solar cavity and their mean energy loss. Interplanetary conditions appropriate for the epochs 1965 and 1969 have been used. Cosmic-ray energies in the range of 20 to 1000 MeV/nucleon have been considered.

Urch, I. H.↗
NASA NTRS1991

Earth observations during Space Shuttle flight STS-41 - Discovery's mission to planet earth

An overview of space flight STS-41 is presented, including personal observations and comments by the mission astronauts. The crew deployed the Ulysses spacecraft to study the polar regions of the sun and the interplanetary space above the poles. Environmental observations, including those of Lake Turkana, Lake Chad, biomass burning in Madagascar and Argentina, and circular features in Yucatan are described. Observations that include landforms and geology, continental sedimentation, desert landscapes, and river morphology are discussed.

Lulla, Kamlesh P.↗
NASA NTRS1983

Space and planetary environment criteria guidelines for use in space vehicle development. Volume 1: 1982 revision

Guidelines on space and planetary environment criteria for use in space vehicle development are provided. Information is incorporated in the disciplinary areas of atmospheric and ionospheric properties, radiation, geomagnetic field, astrodynamic constants, and meteoroids for the Earth's atmosphere above 90 km, interplanetary space, and the atmosphere and surfaces (when available) of the Moon and the planets (other than Earth) of this solar system. The Sun, Terrestrial Space, the Moon, Mercury, Venus, and Mars are covered.

Smith, R. E.↗
NASA NTRS1989

Impulsive acceleration and scatter-free transport of about 1 MeV per nucleon ions in (He-3)-rich solar particle events

Impulsive solar energetic particle (SEP) events are studied to: (1) describe a distinct class of SEP ion events observed in interplanetary space, and (2) test models of focused transport through detailed comparisons of numerical model prediction with the data. An attempt will also be made to describe the transport and scattering properties of the interplanetary medium during the times these events are observed and to derive source injection profiles in these events. ISEE 3 and Helios 1 magnetic field and plasma data are used to locate the approximate coronal connection points of the spacecraft to organize the particle anisotropy data and to constrain some free parameters in the modeling of flare events.

Mason, G. M.↗
NASA NTRS1973

Propellant isolation shutoff valve program

An analysis and design effort directed to advancing the state-of-the-art of space storable isolation valves for control of flow of the propellants liquid fluorine/hydrazine and Flox/monomethylhydrazine is discussed. Emphasis is on achieving zero liquid leakage and capability of withstanding missions up to 10 years in interplanetary space. Included is a study of all-metal poppet sealing theory, an evaluation of candidate seal configurations, a valve actuator trade-off study and design description of a pneumo-thermally actuated soft metal poppet seal valve. The concepts and analysis leading to the soft seal approach are documented. A theoretical evaluation of seal leakage versus seal loading, related finishes and yield strengths of various materials is provided. Application of a confined soft aluminum seal loaded to 2 to 3 times yield strength is recommended. Use of either an electro-mechanical or pneumatic actuator appears to be feasible for the application.

Merritt, F. L.↗
NASA NTRS1976

Interplanetary acceleration of relativistic electrons observed with IMP 7

The intensities of 0.22- to 0.5-MeV and 0.5- to 0.8-MeV electrons in interplanetary space following the Oct. 29, 1972, solar particle event have been observed by the IMP 7 satellite. Intensity variations associated with the SSC disturbance of 1655 UT on October 31 are interpreted as suggesting interplanetary acceleration. The results are consistent with an energy-dependent acceleration process which is most effective for electrons of about 0.4 MeV. This is the first reported interplanetary-shock-wave acceleration of relativistic electrons of which the authors are aware.

Armstrong, T. P.↗
NASA NTRS1977

Space and planetary environment criteria guidelines for use in space vehicle development 1977 revision

Space and planetary natural environment data were presented for use as design criteria guidelines in space vehicle development programs. Specifically, information is provided in the disciplinary areas of atmospheric and ionospheric properties, radiation, solar cycle predictions, geomagnetic field, astrodynamic constants, and meteoroids for the Earth's atmosphere above 90 km, interplanetary space, and the atmospheres and surfaces (when available) of the moon and the planets (other than earth) of the solar system. The current upper atmosphere model and solar cycle prediction routines were described in detail.

West, G. S., Jr.↗
NASA NTRS1977

Noncompressive density enhancements in the solar wind

When the bulk flow speed is nearly constant or falling, high densities are sometimes observed in the solar wind. These densities do not appear to be generated in interplanetary space. It is noted that the magnetic field is not enhanced within these events, and that the proton and/or electron temperatures are low, varying in opposition to the density. About 1/3 of these density events contains interplanetary magnetic field reversals, some of which are noisy and do not qualify as sector boundaries. It is estimated that the average event contains approximately 10 to the 16th g of material and 2.6 x 10 to the 31st ergs, so that aggregated events, when they are common, make a negligible contribution to the total mass and energy budget of the solar wind at 1 AU. It is suggested that there may be an association between density enhancements and solar coronal mass ejection events.

Gosling, J. T.↗
NASA NTRS1988

Mars Mission profile options and opportunities

Mars Mission profile options and mission requirements data are presented for Earth-Mars opposition and conjunction class round-trip flyby and stopover mission opportunities. The opposition class flyby and sprint mission uses direct transfer trajectories to and on return from Mars. The opposition class stopover mission employs the gravitational field of Venus to accelerate the space vehicle on either the outbound or inbound leg in order to reduce the propulsion requirement associated with the opposition class mission. The conjunction class mission minimizes propulsion requirements by optimizing the stopover time at Mars. Representative interplanetary space vehicle systems are sized to compare and show sensitivity of the initial mass required in low Earth orbit to one mission profile option and mission opportunity to another.

Young, Archie C.↗
NASA NTRS1990

Mechanical joints and large components for pathfinder in-space assembly and construction

This paper summarizes the background of the Pathfinder Project, In-Space Assembly, and Construction activity for fiscal year 1989. Work is presented on high strength mechanical truss joints and the definition of typical large components that might be required for assembly on-orbit and use on interplanetary space missions. Several mechanical joints were designed, and the most promising early design is presented in detail. The primary design drivers were the ability for robot assembly, the correction of up to a + or - 0.020 inch axial misalignment, and an axial load in the vicinity of + or - 100,000 lb. The most promising joint uses axisymmetric grooves to correct the misalignment and to transfer the load in a smooth path.

Finckenor, Jeff↗