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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 127 records · Page 7
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NASA NTRS1976

Planetary missions in the Shuttle era

A conservative fifteen-year plan for planetary exploration is presented in which the Space Shuttle is considered as just a basic transportation system that should be quite economical and have excellent reliability. It is noted that these planned missions are limited by the out-of-orbit escape capability of the Shuttle's Interim Upper Stage (IUS), rather than by the orbital payload capability of the Shuttle itself. A mission model is provided in which a rather even balance is maintained among missions to the inner planets, the outer planets, the comets and asteroids, and interplanetary missions out of the ecliptic plane; the cost estimate for this model is plotted. Launch requirements for the various missions are compared with the performance available from various IUS candidates under evaluation, and it is shown that even the lower-performance candidates can be brought up to the capability of the current Titan IIIE/Centaur/TE-364 expendable launch vehicle, which is adequate for most of the missions in the program. Missions which require higher-performance IUS options are noted, including the Mariner Jupiter and Saturn Orbiters.

Kraemer, R. S.↗
NASA NTRS1976

Performance of a recoverable Tug for planetary missions including use of perigee propulsion and corrections for nodal regression

Mathematical equations are derived by using the Maximum Principle to obtain the maximum payload capability of a reusable Tug for planetary missions. The mathematical formulation includes correction for nodal precession of the Space Shuttle orbit. The Tug performs this nodal correction in returning to this precessed orbit. The sample case analyzed represents an inner planet mission as defined by the declination (fixed) and right ascension of the outgoing asymptote and the mission energy. Payload capability is derived for a typical cryogenic Tug and the sample case with and without perigee propulsion. Optimal trajectory profiles and some important orbital elements are also discussed.

Borsody, J.↗
NASA NTRS1976

Solar sail mission applications

The paper discusses the concept and the current baseline configuration of a reusable solar sail vehicle using light pressure for propulsion. The range of characteristic accelerations which solar sail vehicles might achieve during early years of operation is estimated to be from 0.2 to 1.3 mm/sq sec, with overall sail efficiency about 80 to 90%. Operating without the expenditure of propellant, the vehicle has the potential of delivering large payloads throughout the solar system. Detailed attention is given to various possible missions of the solar sail vehicle operating as an Interplanetary Shuttle. The vehicle may deliver payloads to the inner planets, asteroids, short period comets, or sun polar orbits and then return to earth, possibly with samples. It may also be used for outer planet missions or solar system escape. An 800-m sail may return samples totaling 200 kg from Mars and deliver them to an earth orbital laboratory. The first mission for the solar sail may be rendezvous with Halley's comet in 1982.

Wright, J. L.↗
NASA NTRS1974

Geologic guide to the island of Hawaii: A field guide for comparative planetary geology

With geological data available for all inner planets except Venus, we are entering an era of true comparative planetary geology, when knowledge of the differences and similarities for classes of structures (e.g., shield volcanoes) will lead to a better understanding of general geological processes, regardless of planet. Thus, it is imperative that planetologists, particularly those involved in geological mapping and surface feature analysis for terrestrial planets, be familiar with volcanic terrain in terms of its origin, structure, and morphology. One means of gaining this experience is through field trips in volcanic terrains - hence, the Planetology Conference in Hawaii. In addition, discussions with volcanologists at the conference provide an important basis for establishing communications between the two fields that will facilitate comparative studies as more data become available.

Greeley, R.↗
NASA NTRS1977

SUNSPOT: A computer program for producing optimal solar sail planetocentric trajectories

The input, output and subroutines, including listings, for the SUNSPOT code are described. SUNSPOT can calculate time optimal planetocentric trajectories including orbit-to-orbit transfer and orbit to a subescape point. Trajectories about the the four inner planets can be calculated, and shadowing, oblateness, and solar motion may be included. A penalty function may be included to prevent trajectories which intersect the planet's surface.

Sackett, L. L.↗
NASA NTRS1977

Optimal solar sail planetocentric trajectories

The analysis of solar sail planetocentric optimal trajectory problem is described. A computer program was produced to calculate optimal trajectories for a limited performance analysis. A square sail model is included and some consideration is given to a heliogyro sail model. Orbit to a subescape point and orbit to orbit transfer are considered. Trajectories about the four inner planets can be calculated and shadowing, oblateness, and solar motion may be included. Equinoctial orbital elements are used to avoid the classical singularities, and the method of averaging is applied to increase computational speed. Solution of the two-point boundary value problem which arises from the application of optimization theory is accomplished with a Newton procedure. Time optimal trajectories are emphasized, but a penalty function has been considered to prevent trajectories which intersect a planet's surface.

Sackett, L. L.↗
NASA NTRS1978

Icy craters on the Galilean satellites

The high degree of echo depolarization observed for linearly polarized incident waves in the case of radar observations of Europa, Ganymede, and Callisto is consistent with a rough, icy surface. Measurements with circularly polarized waves, however, conducted in 1976 suggest that the types of surface irregularities found on the Galilean satellites must be very different from those on the moon and the inner planets. A description is presented of an investigation in which geometrical optics and the Stokes-vector formalism are employed to examine several possible configurations which could cause the circular polarization transmitted to exceed unity. On the basis of the obtained results it appears that a model which postulates that significant parts of the surfaces of the three satellites are covered with an icy layer at least several kilometers thick and saturated with hemispherical craters can explain nearly all the observed radar behavior.

Ostro, S. J.↗
NASA NTRS1978

Planetary benchmarks

Design criteria and technology requirements for a system of radar reference devices to be fixed to the surfaces of the inner planets are discussed. Offshoot applications include the use of radar corner reflectors as landing beacons on the planetary surfaces and some deep space applications that may yield a greatly enhanced knowledge of the gravitational and electromagnetic structure of the solar system. Passive retroreflectors with dimensions of about 4 meters and weighing about 10 kg are feasible for use with orbiting radar at Venus and Mars. Earth-based observation of passive reflectors, however, would require very large and complex structures to be delivered to the surfaces. For Earth-based measurements, surface transponders offer a distinct advantage in accuracy over passive reflectors. A conceptual design for a high temperature transponder is presented. The design appears feasible for the Venus surface using existing electronics and power components.

Uphoff, C.↗
NASA NTRS1979

The NASA space program

Current and planned NASA space programs are outlined. The major current activity is the development and installation of the Space Transportation System consisting of the Space Shuttle, Spacelab and upper stages for payload launching from the Shuttle. NASA's space sciences program includes spaceborne astronomy by means of the future Space Telescope and Spacelab instruments as well as the current HEAO and IUE satellites. In the area of solar-terrestrial physics, the Solar Maximum Mission and the Solar Polar Mission are scheduled for 1980 and 1983, respectively. Planetary programs generally include ground-based and flyby observations to specify planetary environments, exploration missions to acquire knowledge of planetary processes, history and evolution, and study missions to investigate specific problems. Missions underway include the Voyager mission to Jupiter and Saturn and the Pioneer Venus mission. Research involving the inner planets, the outer planets and asteroids and comets is being planned.

Naugle, J. E.↗
NASA NTRS1979

Radar observations of asteroid 1 Ceres

Radar observations of asteroid 1 Ceres were made at a 12.6-cm wavelength from the Arecibo Observatory in March/April 1977. The measurements, made with a received circular polarization orthogonal to that transmitted, yield a radar cross section of (0.04 + or- 0.01) piR-squared, for R = 510 km. The corresponding radar reflectivity is less than that measured for any other celestial body. Within the accuracy of measurement, no significant variation of cross section with rotational phase is apparent. The shape of the power spectrum suggests that Ceres is rougher at the scale of the observing wavelength than the moon and inner planets, but smoother than the outer three Galilean satellites.

Ostro, S. J.↗
NASA NTRS1980

Astrodynamics 1979; Proceedings of the Conference, Provincetown, Mass., June 25-27, 1979. Parts 1 & 2

Topics are presented on navigation systems, inner planets, comets and asteroids, outer planets, earth orbital applications, and computational methods. Individual subjects include an overview of the Navstar Global Positioning System and the Navy Navigation Satellite System, the solar probe mission, Uranus mission options, as well as a study of lifetimes of geosynchronous transfer orbits, and the price of oil in the year 2000.

Penzo, P.↗
NASA NTRS1980

Stability of planetary orbits in binary systems

The possible existence of stable orbits is investigated in binary systems using Hill's method. Analytical stability conditions are established for satellites, for inner planets and for outer planets, allowing arbitrary values for the mass-ratio of the binary.

Szebehely, V.↗
NASA NTRS1983

A program for planetary exploration

A series of recommendations constituting a core program for planetary exploration, to last from the present to the year 2000, is the outcome of a two-year study undertaken by the NASA Solar System Exploration Committee. The missions envisioned by the core program must be insulated from costly changes and delays once they are approved. The present Committee has therefore restricted its recommendations to missions which do not require novel technologies, but rather continue the techniques of the flybys, orbiters and atmospheric entry probes that have been successful in the past. Recommendations are made for exploration of the inner planets, cometary and asteroid bodies, and the outer planets. Attention is given to the identification of key elements driving mission costs. It is noted that the Space Shuttle/Centaur upper stage combination brings within reach comet and asteroid rendezvous missions that were once thought to require costly new technology.

Morrison, D.↗
NASA NTRS1985

Martian Terrain Ages

The cratering record in the inner Solar System shows two crater populations based on their size/frequency distributions. The heavily cratered surfaces of the Moon, Mercury and Mars all show a similar multisloped crater size distribution which represents the period of heavy bombardment. On the younger plains units of the Moon and Mars the crater size/frequency distribution has about a -3 slope over the same diameter range. The different crater population represents the accumulation of craters since the end of heavy bombardment. The high flux of the early impacting objects dominated the cratering record prior to 3.8 BY. If heavy bombardment was primarily the result of comets (1) or a disrupted planetesimal (2), then heavy bombardment ended simultaneously on all of the inner planets. If, on the other, heavy bombardment was caused by accretional remnants, then it may have extended as much as 1 BY later on Mars than on the Moon and other terrestrial planets (3). Martian surfaces can be dated relative to the end of heavy bombardment by the type of crater population superposed on them. The relative ages of surfaces within these two time divisions can be determined by crater densities.

Strom, R. G.↗
NASA NTRS1985

Large arcuate scars: A geological legacy of the Earth's accretionary past

Immediately following accretion, the surface of the Earth was densely patterned with circular scars which were the surface expressions of 3-D craterform structures. In the course of geological time these structures would have become less and less visible due to the workings of the Earth's atmosphere, surface waters, and plate tectonics regime but there is no compelling reason to assume that they have been entirely eradicated. Furthermore, a very imperfect analogy with the other inner planets suggests that geological processes may not in fact be capable of totally erasing such deep features. Some illustrative examples of arcuate scars are discussed.

Saul, J. M.↗
NASA NTRS1984

Interplanetary navigation through the year 2005 - The inner solar system

A diverse collection of unmanned missions to explore the inner planets, outer planets, and small bodies of the solar system is being considered by the National Aeronautics and Space Administration for the remainder of this century and beyond. This paper describes the key navigational problems which are anticipated for some of these missions and the techniques which are likely to be used to solve these problems. Emphasis in this paper is placed on those missions which take place entirely within about 2 Astronomical Units of the sun. The missions studied include Orbiters of Venus, Mars, the moon, and an earth-approaching asteroid, probes of the atmosphere of Venus and the surface of Mars, fast flybys of comets, and sample return missions from Mars and a short-period comet.

Wood, L. J.↗
NASA NTRS1985

The Mars Observer Mission

The Mars Observer Mission is to be the first in a series of modest-cost inner-planet missions. Launch is planned for the August/September 1990 Mars opportunity with arrival at Mars one year later. The geoscience/climatology objectives are to be met during a mapping mission over the course of one Mars year (687 days). The mapping orbit will be near-polar (93 degree orbital inclination), sun-synchronous (2 PM sunward equator crossing), and near-circular (350 km orbit altitude, 116 minute period). The spacecraft, to be selected in late 1985, will be a modified version of an existing commercial design which, in the mapping orbit, will maintain a nadir orientation. Experiments and instruments will be selected through an Announcement of Opportunity (AO) process with release of the AO in April 1985, and selection in early 1986. A description of current planning for this mission, with emphasis on climatology, is presented here.

Palluconi, F. D.↗
NASA NTRS1985

Communicating through deep space

NASA's Deep Space Network (DSN) consists of a worldwide set of communication stations and a central control facility in California, enabling communication with spacecraft thousands of millions of miles from earth. The stations have gone from 26 m diameter antennas operating at 960 MHz to 70 m diameter (by 1988) at 8400 MHz. The DSN provides exceptional performance in high gain steerable antennas, ultra-low noise receivers, high power transmitters, frequency and time standards, and precise radio metric data. Spacecraft missions envisaged in the 1990's for the continuing exploration of the Solar System include an array of increasingly complex visits to the inner planets, asteroids and comets and the outer planets. The Deep Space Network planned for the mid-1980s may not meet all the needs of these missions without substantial change. Deep space stations may require conversion to operation with beam waveguides, higher frequency and relative frequency stability of 10 to the -16th. A deep space relay station in earth orbit could permit operation at higher frequencies, with attendant higher performance. Long range planning to select the appropriate future network configurations and develop the technologies essential to their implementation is underway.

Smith, J. G.↗