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NASA NTRS1978

The solar terrestrial observatory

The larger system of the earth environment is controlled externally by electromagnetic and particle energy from the sun. Recent studies have shown that the sun is a variable star with changes in its radiation which produce significant effects in the earth's climate and weather. The study of the solar-terrestrial system requires simultaneous, long-duration observations of the different elements or 'links' in the solar-terrestrial chain. Many investigations must be conducted in space from a vantage point above the earth's atmosphere where all of the sun's emissions can be observed free from atmospheric distortion, where the magnetospheric particles and fields can be measured directly, and where the atmosphere can be observed on a global scale. The extension of the Shuttle on-orbit capability in connection with the development of the power module will offer an important near-term step in an evolutionary process leading toward a permanent manned Solar Terrestrial Observatory capability in low-earth orbit. Attention is given to the required solar-terrestrial measurements, the operation of the Solar Terrestrial Observatory, and an evolutionary approach to the Solar Terrestrial Observatory.

Chappell, C. R.↗

NASA NTRS1978

High beta plasma in the dynamic Jovian current sheet

The equatorial current sheet, which Pioneer 10 repeatedly encountered on its outbound pass through the Jovian magnetosphere, frequently was associated with intense fluxes of energetic protons. Simultaneous observations of the changes in the energetic proton flux and in the magnetic-field magnitude demonstrate that the current sheet is embedded in a high-beta plasma in which high-energy (above 60 keV) ions frequently are the dominant constituents. Large differences in the plasma temperature and the thickness of this plasma sheet between encounters only 10 hours apart indicate that the Jovian plasma sheet is very dynamic on a time scale of hours. Occasional observations of significant temporal variations in the magnetic field and particle populations during periods within the plasma sheet may represent in situ observations of Jovian magnetic disturbances. Comparison with previous observations suggests that low-energy (not more than 5 keV) plasma contributes less than 3% to the current-sheet energy density.

Walker, R. J.↗

NASA NTRS1978

Report on active and planned spacecraft and experiments

Information is presented, concerning active and planned spacecraft and experiments known to the National Space Science Data Center. The information included a wide range of disciplines: astronomy, earth sciences, meteorology, planetary sciences, aeronomy, particles and fields, solar physics, life sciences, and material sciences. These spacecraft projects represented the efforts and funding of individual countries as well as cooperative arrangements among different countries.

Vette, J. I.↗

NASA NTRS1979

Report on Active and Planned Spacecraft and Experiments

Information concerning concerning active and planned spacecraft and experiments known to the National Space Science Data Center are included. The information contains a wide range of disciplines: astronomy, earth sciences, meteorology, planetary sciences, aeronomy, particles and fields, solar physics, life sciences, and material sciences. These spacecraft projects represent the efforts and funding of individual countries as well as cooperative arrangements among different countries. Approximately 850 articles are included.

Vostreys, R. W.↗

NASA NTRS1978

The Pioneer Venus spacecraft program

The Pioneer Venus program consists of two spacecraft: an orbiter and a multiprobe. Both will arrive at Venus in early December 1978. The orbiter will collect data on the upper atmosphere and fields and particles and will sense the clouds and surface remotely from a 75 deg inclined orbit. The multiprobe consists of a bus, three small probes, and a large probe. All five objects will enter the Venus atmosphere and will transmit data on its characteristics directly to earth while descending to the surface. The development of these spacecraft required the solution of many difficult and unique technical problems.

Dorfman, S. D.↗

NASA NTRS1979

The interaction of the solar wind with Mars, Venus and Mercury

The history of investigation of the solar wind interaction with Mars, Venus, and Mercury is reviewed, and our knowledge on this interaction for each of the three planets is compared. The primary objective is to gain insight into the basic physical mechanisms operative in the earth's magnetosphere from a study of (the somewhat different) magnetospheres of the planets under consideration. Mercury and Venus have significant dipole moments which play an important part in solar wind interaction. The Martian magnetic moment appears to be too weak to influence solar wind interaction. As expected, the bow shock of Mercury and the earth are quite similar since the magnetic moment of each is sufficient to stand off the solar wind. The shocks of Venus and Mars are also similar, but the Venusian shock lies much closer to the planet than the Martian shock. Both Mercury and Venus show evidence of substorm-like field and particle behavior, but with clear differences in the time scale.

Russell, C. T.↗

NASA NTRS1980

Report on active and planned spacecraft and experiments

Information on current and planned spacecraft activity for a broad range of scientific disciplines is presented. The information covers a wide range of disciplines: astronomy, Earth sciences, meteorology, planetary sciences, aeronomy, particles and fields, solar physics, life sciences, and material sciences. These spacecraft projects represent the efforts and funding of individual countries as well as cooperative arrangements among different countries.

Horowitz, R.↗

NASA NTRS1979

Correlation of lunar far-side magnetized regions with ringed impact basins

By the method of electron reflection, we have identified seven well-defined magnetized regions in the equatorial belt of the lunar far side sampled by the Apollo 16 Particles and Fields subsatellite. Most of these surface magnetic fields lie within one basin radius from the rim of a ringed impact basin, where thick deposits of basin ejecta are observed or inferred. The strongest of the seven magnetic features is linear, at least 250 km long, and radial to the Freundlich-Sharonov basin. The apparent correlation with basin ejecta suggests some form of impact origin for the observed permanently magnetized regions.

Anderson, K. A.↗

NASA NTRS1980

A macroscopic profile of the typical quasi-perpendicular bow shock - Isee 1 and 2

A macroscopic examination of field and particle properties of the bow shock recorded on November 5, 1977, identified earlier as stable features by comparison of Isee 1 and 2 data, is presented. Attention is given to the extent to which the shock was in a typical state, and multidiagnostic observations are combined to define the shock profile. It is found that the shock profile offered several unanticipated structural features, which include a variable directional profile of the reflected proton group passing through the front, an electrostatic boundary effect associated with the reflected protons upstream, and an oscillatory buildup of proton thermalization behind the overshoot portion of the shock signature.

Greenstadt, E. W.↗

NASA NTRS1981

Sounding rocket research Aries/Firewheel, series 22, issue 15

Rocket experiments in ionospheric particle and field research flow in seven programs during the last decade are summarized. Experimental techniques were developed and are discussed including the double-probe field technique. The auroral zone, polar cap, and equatorial spread F were studied.

Mozer, F. S.↗

NASA NTRS1981

Voyager backgrounder

The Voyager spacecraft and experiments are described. The spacecraft description includes the structure and configuration, communications systems, power supplies, computer command subsystems, and the science platform. The experiments discussed are investigations of cosmic rays, low-energy charged particles, magnetic fields, and plasma waves, along with studies in radio astronomy photopolarimetry. The tracking and data acquisition procedures for the missions are presented.

Source record↗

NASA NTRS1980

A solar encounter mission - Starprobe

Accurate measurements of the internal mass distribution and dynamics of the sun as well as in situ observations of its environs are proposed through a JPL-designed satellite, STARPROBE. Scheduled for launch in 1988 under NASA's five-year plan, the probe will conduct radiometric experiments to determine the solar quadrupole moment (J2), fields-and-particles experiments (evaluating such phenomena as heating, acceleration, and peak random velocity of solar wind), and optical experiments potentially superior to those of the Earth-orbiting Solar Optical Telescope (SOT). With flight times ranging from 2.7 to 5.9 years, present delivery options comprise planetary gravity-assist trajectories that will give the spacecraft a perihelion of four solar radii at a 90 deg-inclination. Owing to science- and mission requirements, the thermal shield of the craft should tolerate a solar flux 3000 times greater than that at earth, radioisotope thermoelectric generators supplying 700 watts of power, and a three-axis stabilization system with reaction wheels providing control torque. Implementation concepts now under study may change some of the details of the design.

Randolph, J. E.↗

NASA NTRS1981

On the conservation of the first adiabatic invariant in perpendicular shocks

The conservation of the first adiabatic invariant of particle motion, the particle magnetic moment, at the front of perpendicular magnetosonic fast-mode shock waves is considered. Results of numerical simulations are presented which show that preshock and postshock values of the magnetic moment are on the average equal for particles transmitted by infinitesimally thin perpendicular magnetosonic fast-mode shocks, in contrast to extrapolations from adiabatic theory, which suggest that the first invariant is least likely to be conserved in this situation. The observed conservation is thus attributed to the continuity of the flux of total particle and field angular momentum across the shock front as a result of angular momentum conservation.

Pesses, M. E.↗

NASA NTRS1980

Transient phenomena originating at the sun - An interplanetary view

Analyses of several transient phenomena which occurred in 1978 and 1979 are presented using data from the Pioneer Venus, ISEE, and Pioneer 10 and 11 spacecraft. The interplanetary phenomena studied are associated with solar flares and coronal holes. The observations show that phenomena originating at the sun affect the structure of the particle and field regimes throughout the explored solar system, extending out to at least 17-20 AU in the vicinity of the elliptic plane over a range of azimuthal angles greater than 90 deg. High frequency fluctuations in the interplanetary medium appear beyond 1 AU, indicating that transient phenomena are significantly modified by their passage through this medium.

Intriligator, D. S.↗

NASA NTRS1981

Voyager at Saturn

The spacecraft design and operations and mission results of the Voyager Project are reviewed with particular emphasis on the results of the Saturn encounters. The mission was undertaken by two spacecraft: Voyager 2, launched first on August 20, 1977 on a lower energy trajectory to Jupiter, Saturn, Uranus and Neptune; and Voyager 1, launched on September 5, 1977 on a higher energy trajectory to closer flybys of Jupiter and Saturn. The Voyager spacecraft make use of earlier Mariner and Viking Orbiter design concepts, with additional capabilities for solar independent power, long-range communications and autonomy as well as equipment for the 11 science investigations. The Voyager operations system consists of a ground data system, missions operations system, and support by the Mission Control and Computer Center and Deep Space Network. Among the results of the Jupiter encounter are data concerning the magnetospheric structure and atmospheric dynamics of the planet and the surface features of the Galilean satellites. The encounters with Saturn produced scientific data concerning wind speeds, auroral emissions, and radio emissions from the planet, the fine structure of the previously known and newly discovered rings, the surface features of the satellites and the atmospheric composition and conditions of Titan. Voyager 1 is presently making field and particle measurements on its flight into interstellar space, while Voyager 2 is headed for an encounter with Uranus in January 1986 and Neptune in August 1989.

Heacock, R. L.↗

NASA NTRS1981

Report on Active and Planned Spacecraft and Experiments

Active and planned spacecraft activity and experiments between June 1, 1980 and May 31, 1981 known to the National Space Science Data Center are described. The information covers a wide range of disciplines: astronomy, Earth sciences, meteorology, planetary sciences, aeronomy, particles and fields, solar physics, life sciences, and material sciences. Each spacecraft and experiment is described and its current status presented. Descriptions of navigational and communications satellites and of spacecraft that contain only continuous radio beacons used for ionospheric studies are specifically excluded.

Vostreys, R. W.↗

NASA NTRS1981

Impact cratering - The effect of crustal strength and planetary gravity

The effect of varying planetary crustal strength and surface gravity on the depth of impact craters is investigated, by coupling the results of compressible flow, finite difference calculations carried out to stress levels below the compressional dynamic yield point, in keeping with the incompressible fluid flow model of Maxwell (1973). The fundamental assumption in this description is that the amplitude of the particle velocity field decreases with time as kinetic energy is converted into heat and gravitational potential energy. By using a Mohr-Coulomb yield criterion, the effect of varying strength on transient crater depth and on crater formation time in the gravity field of the moon is investigated for the case of 5 km/sec impactors having radii in the 10 to 10 to the 7th cm range.

Okeefe, J. D.↗

NASA NTRS1982

Starprobe thermal shield system design concepts

The mission goals, flight trajectory, and material durability requirements for the NASA Starprobe spacecraft are reviewed. The spacecraft will use a Jovian gravity assist to pass within four solar radii of the sun to study fields and particles near the sun, perform experiments dealing with relativity and gravity, and observe the structure of the solar atmosphere from the photosphere to the corona. Constraints on the system size and mass design are given, and the system is noted to be required to withstand 2500 K at perihelion, thermally insulate the instrument payload, have a tube for optical measurements, and provide protection from meteorite damage. A secondary shield is also required to dispense thermal radiation that passes the primary shield and could endanger the payload. Design options are discussed, along with temperature control requirements and a conical carbon-carbon primary shield with mass-loss rate characteristics sufficient to meet a 2.5 mg/sec criterion.

Maag, C. R.↗