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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 271 records · Page 15
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NASA NTRS1970

Guidance and Navigation Requirements for Unmanned Flyby and Swingby Missions to the Outer Planets: Low Thrust Missions, Phase B - Volume 3

The guidance and navigation requirements for unmanned missions to the outer planets, assuming constant, low thrust, ion propulsion are discussed. The navigational capability of the ground based Deep Space Network is compared to the improvements in navigational capability brought about by the addition of guidance and navigation related onboard sensors. Relevant onboard sensors include: (1) the optical onboard navigation sensor, (2) the attitude reference sensors, and (3) highly sensitive accelerometers. The totally ground based, and the combination ground based and onboard sensor systems are compared by means of the estimated errors in target planet ephemeris, and the spacecraft position with respect to the planet.

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NASA NTRS1971

Guidance and navigation requirements for unmanned flyby and swingby missions to the outer planets. Volume 4: High thrust mission, part 2, phase C

The guidance and navigation requirements for a set of impulsive thrust missions involving one or more outer planets or comets. Specific missions considered include two Jupiter entry missions of 800 and 1200 day duration, two multiple swingby missions with the sequences Jupiter-Uranus-Neptune and Jupiter-Saturn-Pluto, and two comets rendezvous missions involving the short period comets P/Tempel 2 and P/Tuttle-Giacobini-Kresak. Results show the relative utility of onboard and Earth-based DSN navigation. The effects of parametric variations in navigation accuracy, measurement rate, and miscellaneous constraints are determined. The utility of a TV type onboard navigation sensor - sighting on planetary satellites and comets - is examined. Velocity corrections required for the nominal and parametrically varied cases are tabulated.

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NASA NTRS1971

Noncoplanar minimum delta V two-impulse and three-impulse orbital transfer from a regressing oblate earth assembly parking ellipse onto a flyby trans-Mars asymptotic velocity vector.

Comparison of two-impulse and three-impulse orbital transfer, using data from a 63-case numerical study. For each case investigated for which coplanarity of the regressing assembly parking ellipse was attained with the target asymptotic velocity vector, a two-impulse maneuver (or a one-impulse equivalent) was found for which the velocity expenditure was within 1% of a reference absolute minimum lower bound. Therefore, for the coplanar cases, use of a minimum delta-V three-impulse maneuver afforded scant improvement in velocity penalty. However, as the noncoplanarity of the parking ellipse and the target asymptotic velocity vector increased, there was a significant increase in the superiority of minimum delta-V three-impulse maneuvers for slowing the growth of velocity expenditure. It is concluded that a multiple-impulse maneuver should be contemplated if nonnominal launch conditions could occur.

Bean, W. C.↗
NASA NTRS1973

Planetary flybys resulting in heliocentric orbits normal to the ecliptic with fixed perihelia.

An iterative procedure is applied to a patched conic trajectory sequence in which a spacecraft is launched from the earth, flys by the planet Jupiter, and leaves Jupiter along a heliocentric trajectory whose plane is normal to the ecliptic, and whose perihelion is fixed at 0.1 AU. Six launch opportunities, spaced apart in time at approximately the mean synodic period of earth and Jupiter (roughly 400 days), are examined.

Buglia, J. J.↗
NASA NTRS1974

Description of the meteoroid detection experiment flown on the Pioneer 10 and 11 Jupiter flyby missions

The meteoroid detection experiment has the objective of measuring the population of 10 to the minus 9th power and 10 to the minus 8th power grams mass particles in interplanetary space with emphasis on making these measurements in the Asteroid Belt. The instrument design, which uses the pressurized-cell-penetration detection technique, and the tests involved in obtaining a flight-qualified instrument are described. The successful demonstration of flight-quality penetration detectors to function properly under long-term simulated space environments is also described.

Oneal, R. L.↗
NASA NTRS1973

Encke flyby science package

Cometary exploration objectives are considered, giving attention to reasons for the selection of Encke as a target for early exploration missions. An Encke environmental model is discussed together with the scientific requirements of an exploratory mission, instrument selection criteria, and the science payload. The instruments to be used include a television camera, an IR radiometer, a UV spectrometer, a mass spectrometer, a Sisyphus dust detector, devices for the measurement of the EM field, and instruments for the determination of plasma characteristics. It is pointed out that solar electric propulsion affords the only practical, currently available means of reaching Encke with the desired encounter velocity below 7.5 km/sec.

Newburn, R. L.↗
NASA NTRS1975

Ground noise measurements during static and flyby operations of the Cessna 02-T turbine powered airplane

The field noise measurements on the Cessna 02-T turbine powered propeller aircraft are presented. The objective of the study was to obtain the basic noise characteristics of the aircraft during static ground runs and flyover tests, to identify the sources of the noise, and to correlate the noises with the aircraft operating conditions. The results are presented in the form of a overall noise levels, radiation patterns, and frequency spectra. The noise characteristics of the turbine powered aircraft are compared with those of the reciprocating engine powered aircraft.

Hilton, D. A.↗
NASA NTRS1972

Study of multiple asteroid flyby missions

The feasibility, scientific objectives, mission profile characteristics, and implementation of an asteroid belt exploration mission by a spacecraft guided to intercept three or more asteroids at close range are discussed. A principal consideration in planning a multiasteroid mission is to cut cost by adapting an available and flight-proven spacecraft design such as Pioneer F and G, augmenting its propulsion and guidance capabilities and revising the scientific payload complement in accordance with required mission characteristics. Spacecraft modification necessary to meet the objectives and requirements of the mission were studied. A ground rule of the study was to hold design changes to a minimum and to utilize available technology as much as possible. However, with mission dates not projected before the end of this decade, a reasonable technology growth in payload instrument design and some subsystem components is anticipated that can be incorporated in the spacecraft adaptation.

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NASA NTRS1974

Initial observations of plasma electrons from the Pioneer 10 flyby of Jupiter

Initial results are presented from the electron measurements made by the Ames Research Center Plasma Analyzer during the inbound passage of Pioneer 10 in the vicinity of Jupiter. The observations indicate that as in the case of the earth's magnetosheath, there is an increase in electron temperature across the Jovian bow shock. During the second extended magnetosheath traversal (approximately 54 to 46.5 Jupiter radii) the electron temperatures were generally higher than those observed during the first magnetosheath traversal (109 to 96 Jupiter radii). These higher electron temperatures are in agreement with the measured higher magnitude of the magnetic field and ion density during this traversal. These observations are consistent with the contraction of the Jovian magnetosphere due to an increase in the solar wind dynamic pressure.

Intriligator, D. S.↗
NASA NTRS1976

Atmospheric entry into Jupiter's atmosphere in view of recent flyby results

The paper examines the heating levels experienced by a probe entering Kliore's (1974) model of Jupiter's atmosphere and compares the results with those of the Jupiter model atmospheres given elsewhere (NASA SP-8069, 1971), with the heating levels of Tauber (1969) and Tauber and Wakefield (1971). The computations are made using a point-mass atmospheric entry trajectory program, i.e., the Allen-Eggers (1958) analysis and simple correlations of heating. Results of heating calculations are compared and discussed. It is found that the warm temperature bulge exists at a level too low in the atmosphere to affect any heating and that the nominal atmosphere fits Kliore's model atmosphere best insofar as heating is concerned. Previous estimates of the heating levels to be expected for a probe entering Jupiter's atmosphere are therefore unaffected by Kliore's postulated atmospheres.

Nachtsheim, P. R.↗