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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 847 records · Page 47

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NASA NTRS1972

Study to adapt solar electric propulsion to the Pioneer F and G spacecraft

The addition of an electric thrust subsystem to the spin-stabilized Pioneer F and G spacecraft to improve performance capability for certain missions is discussed. The evaluation was performed for the Atlas and Titan launch vehicles with Centaur and TE-364-4 stages and for electric thrust stages of 8- and 5-kw with three 30- and five 15-cm thrusters respectively. The combination of a spinning spacecraft with electric propulsion is a concept only recently evaluated and the penalty from spinning over three-axis stabilized is not as significant as might initally be thought. There are major gains in weight, cost, and reliability, the disadvantages being lower data rate during the thrust phase and less efficient pointing. A variety of missions were evaluated from a solar approach mission into 0.14 AU to a flyby mission of Neptune at approximately 30 AU. Performance improvements were present for all missions evaluated.

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NASA NTRS1972

Some scientific criteria for a cometary mission

Scientific data necessary for a successful flyby or rendezvous cometary mission are outlined. Specific material cover photometric profiles of the different molecular bands of various comets and instruments by which such measurements can be made.

Delsemme, A. H.↗

NASA NTRS1972

Directions of strong winds on Mars inferred

Asymmetrical crater shadings and diffuse light and dark streaks visible on the photography returned by the 1969 Mars flyby of Mariners 6 and 7 are probably eolian in origin. Wind directions inferred from mapping of these features parallel motions of observed global dust storms or relate to expected patterns of topographic funneling of winds.

Howard, A. D.↗

NASA NTRS1972

Planetary missions handbook, first edition

A consistent source of payload performance data for missions to the outer planets is provided. The payload data for both flybys and orbiters is presented graphically as a function of flight time for various launch years, launch vehicles, and orbit sizes. All the relevant parameters have been combined to produce useful data on a single graph to make advanced mission planning much easier. The limitation of this mode of presentation is that only a reasonable number of payload vs. flight time curves can be drawn. Thus it is necessary to select parameters carefully to reflect frequently used values.

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NASA NTRS1972

Trajectory correction propulsion for TOPS

A blowdown-pressurized hydrazine propulsion system was selected to provide trajectory correction impulse for outer planet flyby spacecraft as the result of cost/mass/reliability tradeoff analyses. Present hydrazine component and system technology and component designs were evaluated for application to the Thermoelectric Outer Planet Spacecraft (TOPS); while general hydrazine technology was adequate, component design changes were deemed necessary for TOPS-type missions. A prototype hydrazine propulsion system was fabricated and fired nine times for a total of 1600 s to demonstrate the operation and performance of the TOPS propulsion configuration. A flight-weight trajectory correction propulsion subsystem (TCPS) was designed for the TOPS based on actual and estimated advanced components.

Long, H. R.↗

NASA NTRS1972

The outer planets - Fly-by prospects

The projected benefits of flyby missions to the outer planets are discussed. Possible changes in existing theories of planetary composition as a result of such missions are also discussed.

Demarcus, W. D.↗

NASA NTRS1973

Single thrust period missions to Uranus for unmanned nuclear-electric propulsion systems

The effects of trip time, propulsion time, and specific powerplant mass are studied for optimized unmanned probe spacecraft on missions to Uranus with nuclear-electric propulsion systems. Electric propulsion is confined to a single thrust period at the beginning of each mission. Mission profiles include both high-thrust and electric-propulsion Earth-departure modes for planet flyby and orbital capture. Effects of propulsion time and propulsion system parameters are evaluated, and typical design features of the nuclear-electric spacecraft are outlined. Payload capability comparisons are made with systems employing ballistic transfer and solar-electric propulsion.

Zola, C. L.↗

NASA NTRS1972

Determination of parameters related to the interior of Mercury

Bounds on (C-A)/C for Mercury as a function of the uncertainty in the value of the obliquity are determined. The high precision of 1 min of arc which is required for reasonable bounds on (C-A)/C cannot be obtained by either earth based observations or the television imagery of the Mariner 73 flyby. Among other methods discussed, one involving both landers and orbiters could determine unambiguously not only (C-A)/C but also (B-A)/C and C/sq MR.

Peale, S. J.↗

NASA NTRS1972

Photopolarimetry team outer planets mission definition phase

The work is reported of the Photopolarimetry Team in identifying scientific objectives for photometer/polarimeter experiments for outer planet flyby missions. A discussion of the scientific objectives which can be attained with a photometer/polarimeter experiment, and summaries of the special studies which were performed for the Photopolarimetry Team are presented along with a description of the photometer/polarimeter design which was developed for the Meteoroid Detection Team.

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NASA NTRS1973

Tracking and data system support for the Pioneer project. Volume 1: Pioneer 10-prelaunch planning through second trajectory correction, 4 December 1969 - 1 April 1972

The tracking and data system support of the launch, near-earth, and deep space phases of the Pioneer 10 mission, which sent a Pioneer spacecraft into a flyby of Jupiter that would eventually allow the spacecraft to escape the solar system is discussed. The support through the spacecraft's second trajectory correction is reported. During this period, scientific instruments aboard the spacecraft registered information relative to interplanetary particles and fields, and radiometric data generated by the network continued to improve knowledge of the celestial mechanics of the solar system. In addition to network support activity detail, network performance and special support activities are covered.

Siegmeth, A. J.↗

NASA NTRS1973

Saturn orbiter mission study

A preliminary analysis of the important aspects of missions orbiting the planet Saturn is provided. Orbital missions to Saturn is given serious consideration for the 1980's, or after flybys by Pioneer 10/G and Mariner Jupiter-Saturn 1977. An attempt is made to characterize Saturn orbiters in detail so that comparisons with Jupiter missions can be made. The scientific objectives of Saturn exploration are grouped under four topics: (1) the atmosphere, (2) the magnetosphere, (3) the rings, and (4) the satellites.

Wells, W. C.↗

NASA NTRS1971

Optimum solar electric interplanetary mission opportunities from 1975 to 1990

A collection of optimum trajectory and spacecraft data is presented for unmanned interplanetary missions from 1975 to 1990 using solar electric propulsion. Data are presented for one-way flyby and orbiter missions from Earth to Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. The solar system model assumes planetary ephemerides which very closely approximate the true motion of the planets. Direct and indirect flight profiles are investigated. Data are presented for two representative flight times for each mission. The launch vehicle is the Titan 3 B (core)/Centaur, and a constant jet exhaust speed solar electric propulsion system having a specific mass of 30 kg/kw is completely optimized in terms of power level and jet exhaust speed to yield maximum net spacecraft mass. The hyperbolic excess speeds at departure and arrival and the launch date are optimized for each mission. For orbiter missions, a chemical retro stage is used to brake the spacecraft into a highly eccentric capture orbit about the target planet.

Mann, F. I.↗

NASA NTRS1973

Mission Planning for Pioneer Saturn/Uranus Atmospheric Probe Missions

Mission planning for a series of atmospheric probe missions to Saturn and Uranus using a modified Pioneer spacecraft launched in 1979 and 1980 was examined. The operational options and the associated systems requirements consistent with the major scientific goals and spacecraft constraints of the missions is summarized. It is feasible to obtain in-situ atmospheric measurements in the atmosphere of Saturn and Uranus down to a pressure level of 10 bars using a common probe and spacecraft design. Spacecraft can be launched to both objectives with an adequate launch window in 1979 and 1980 using a Titan/Centaur launch vehicle with a TE-364-4 upper stage. Other scientific objectives can be accomplished by the flyby spacecraft. Encounters with the satellite Titan and RF occultations of Saturn, the ring system of Saturn, and Uranus can be obtained.

Swenson, B. L.↗

NASA NTRS1973

Study of ballistic mode Mercury Orbiter missions. Volume 1: Summary report

A summary is given of the scope, approach, and major results of the study of ballistic mode Mercury orbit missions (the Mariner Venus-Mercury spacecraft). The performance potential of ballistic flight mode is presented along with a study of alternate flight techniques. Orbit selection considerations are discussed in terms of the thermal environment of Mercury. Orbiter science experiments are summarized. Technology assessments were conducted for major subsystems appropriate to spin-stabilized and three-axis-stabilized spacecraft designs. Conclusions from this study are: ballistic mode Mercury orbiter missions offer adequate performance for effective follow-up of the MVM'73 science findings; the existing and programmed technology base is adequate for implementation of Mercury orbit spacecraft design; and when pending MVM flyby has been accomplished and the results analyzed, the data base will be adequate to support detailed orbiter spacecraft design efforts.

Hollenbeck, G. R.↗

NASA NTRS1972

Thermionic reactor ion propulsion system /TRIPS/ - Its multi-mission capability.

The unmanned planetary exploration to be conducted in the last two decades of this century includes many higher energy missions which tax all presently available propulsion systems beyond their limit. One candidate with the versatility and performance to meet these mission objectives is nuclear electric propulsion (NEP). Additionally, the NEP System is feasible in orbit raising operations with the Shuttle or Shuttle/Tug combination. A representative planetary mission is described (Uranus-Neptune flyby with probe), and geocentric performance and tradeoffs are discussed. The NEP System is described in more detail with particular emphasis on the power subsystem consisting of the thermionic reactor, heat rejection subsystem, and neutron shield.

Peelgren, M. L.↗

NASA NTRS1972

Microwave dual frequency propagation experiment using the Mariner Venus Mercury probe.

The Mariner Venus Mercury spacecraft (MVM) will be launched in a multiple planet flyby orbit. A coherent dual frequency down link operating at 2.3 and 8.4 GHz will be used to measure the dispersive nature of the transmission medium. Radio tracking will produce Doppler and range information at both 2.3 and 8.4 GHz so that the dispersive group and phase velocity perturbations of the medium can be measured. Interpretation of the dispersive results will yield information about the neutral and ionized atmospheres of Venus and Mercury, the interplanetary media, the solar wind, and corona.

Levy, G. S.↗

NASA NTRS1972

Nonlinear estimation theory applied to the interplanetary orbit determination problem.

Martingale theory and appropriate smoothing properties of Loeve (1953) have been used to develop a modified Gaussian second-order filter. The performance of the filter is evaluated through numerical simulation of a Jupiter flyby mission. The observations used in the simulation are on-board measurements of the angle between Jupiter and a fixed star taken at discrete time intervals. In the numerical study, the influence of each of the second-order terms is evaluated. Five filter algorithms are used in the simulations. Four of the filters are the modified Gaussian second-order filter and three approximations derived by neglecting one or more of the second-order terms in the equations. The fifth filter is the extended Kalman-Bucy filter which is obtained by neglecting all of the second-order terms.

Tapley, B. D.↗

NASA NTRS1972

Estimating trajectory correction requirements for multiple outer planet missions.

General approach to the problem of estimating trajectory correction requirements for multiple outer planet flyby missions when the navigation system uses onboard optical measurements made during approach to each target planet to complement the ground-based radio measurements. The accuracy and reliability of the onboard measurement system plays a critical role in sizing the trajectory correction capability required. An illustration of the combined use of radio and optical measurements is provided for the particular case of a Jupiter-Uranus-Neptune mission. Use of the statistical technique developed for computing the trajectory correction margin required to account for uncertainties in subsystem performance, permits trajectory correction savings of 100 to 20 m/sec over 'worst case' designs. This represents weight savings of about 50% of the science payload. For the example case trajectory correction requirements are estimated for two candidate optical systems and the radio alone case. The use of onboard measurements allows a trajectory correction savings of approximately 140 m/sec.

Friedman, L. D.↗