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Exploration of the solar system during the next decade will concentrate on the Earth, Sun, Moon, and the near planets, Mars and Venus. In the previous paper, the exploration of the Earth and Sun by means of sounding rockets and satellites was discussed. In this paper, our most active projects to explore the Moon, Mars, and Venus will be reviewed briefly.
Quantitative degradation rates of power subsystems of nineteen initial defense satellite communication system spacecraft and their solar array activity
Nearly three years of Ames magnetometer data from Explorer 35 are used to establish plasma-sheet configurations in the geomagnetic tail at the lunar orbit. The plasma sheet is defined either as a region with different field orientations from normal magnetic-field directions in the tail, or as a region where the magnetic field variance is greater than elsewhere in the tail. The plasma-sheet configuration at the lunar orbit derived in this manner is found to be similar to the distribution at 18 earth radii observed by Vela satellites. The seasonal dependence and variations with geomagnetic activity are also presented.
During the last half of 1972, the Haystack antenna was utilized 88% of the time. Of this useful time, 81% was devoted to radio astronomy investigations, 8% was spent on radar-related research and 11% was scheduled for maintenance and system improvements. Thirteen programs were completed of which 10 were spectral-line studies involving primarily recombination lines and H2O vapor investigations. The others involved 2 cm and 1.3 cm continuum observations. Fifteen new programs were accepted and the currently active radio observing programs totalled 24 as of 31 December 1973. The last radar measurements in the lunar topography program have now been completed. Radar activity, including measurements on Mercury, Venus and synchronous satellites has continued.
Two examples of regional interpretation of imagery acquired from satellite photographic and television systems are discussed. The imagery was taken aboard the Zond 7 and Kosmos satellites, and depicted; (1) sand and dust storm activity in the eastern Mediterranean Sea area; and (2) landscape and structural properties of territory of southwestern United States and northwestern Mexico.
Planetary exploration is examined in terms of the interaction of technological growth with scientific progress and the intangibles associated with exploring the unknown. The field is limited to unmanned exploration of the planets and their satellites. A descriptive model of the endeavor, its activities and achievements in the past decade, a characterization of the current state of the art, and a look at some of the planetary mission opportunities for the next decade are presented. A case is made for the value to civilization of ongoing planetary exploration. The pioneering U.S. planetary explorers, Mars, Venus, and Jupiter, are discussed in the second part of the work. Launch velocity, navigation, the remote system, the earth base, and management technology are considered in the third part. Authorized near-term U.S. planetary projects and opportunities of the next decade are described in the last section.
Tests have been conducted concerning the active control of the potentials of the geosynchronous satellites ATS-5 and ATS-6. The ATS-5 tests show that a simple electron emitter can be used to reduce the magnitude of the potential of a spacecraft which has been charged negatively by the environment. The ATS-6 ion thruster had also a pronounced effect on the potential barrier. In this case, the flux of high-energy primary ions and of low-charge exchange ions produces a space-charge neutralization effect which the electron gun alone cannot achieve.
In situ measurements of the neutral constituent densities and temperature were made at 200 km by the open source mass spectrometer on the AE-D satellite during a rapid onset of the magnetic activity that occurred in January 1976. At high latitudes a 340 K temperature increase was accompanied by an increase in N2 and O2 concentrations, a decrease in He concentration, and a variable response in O concentration. At low latitudes, the rise in temperature was smaller, however; all constituent densities increased. It is concluded that the observed variations are consistent with heating and upward winds at high latitudes, meridional flow towards lower latitudes and subsidence near the equator.
For the first time, high-resolution Ly-alpha observations of the Saturn vicinity were completed with the Princeton spectrometer on board the Copernicus satellite. They showed that near a minimum solar activity the emissions related to several sources are 250 + or - 50 rayleighs for the interplanetary medium in a near-downwind direction, less than 100 rayleighs for the rings, 200 + or - 100 rayleighs for a torus linked to the Titan orbit, and 1400 + or - 450 rayleighs for the disk of Saturn. These results induce some constraints through the corresponding theoretical evaluations: the B ring as the primary source of the atoms for the ring emissions; an efficient production mechanism for hydrogen atoms in the Titan torus; and a slightly larger eddy diffusion coefficient in the Saturn atmosphere than in the Jupiter atmosphere near solar minimum.
The paper describes the attitude control flight performance of SEASAT-A, (launched in June 1978), until failure of the power subsystem terminated the mission in Oct. 1978. Information provided by the satellite pertained to surface winds and coastal storm activity, currents and wave heights, ocean topography and temperature. The ACS used three-axis momentum exchange and magnetic momentum containment and was set in a nose-down configuration. Attitude control sensing was via horizon sensors and attitude anomalies, resulting from solar interference with the sensors, is covered in detail. Remedial action was taken by reconfiguring the IR scanners, but failure resulted nevertheless. Recommendations for similar future missions include consideration of the effect of light sources and circuit time constants and scan rates. A block diagram of the ACS is included.
Passive and active microwave measurements from surface based, airborne, and satellite instruments were obtained together with surface observations northwest of Svalbard. Emissivities of different ice patches in the ice edge region over the spectral range from 4.9 to 94 GHz are presented. The combination of a 6.6 GHz microwave radiometer with a 14.6 GHz scatterometer demonstrates the usefulness of an active/passive system in ice classification. A variety of mesoscale features under different meteorological conditions is revealed by a 1.36 GHz synthetic aperture radar. Ice edge location by Nimbus 7 scanning multifrequency microwave radiometer is shown accurate to 10 km when the 37 GHz horizontal polarized channel is used.
The Lightning Mapper Sensor is proposed as an instrument for use on a geosynchronous satellite in the late 1980s to monitor lightning activity continuously over broad areas of the earth. The system was suggested in response to a variety of needs and the resulting data will provide important research information for such fields of geoscience as magnetospheric and ionospheric physics, atmospheric electricity, atmospheric chemistry, and storm physics. The research applications of Lightning Mapper Sensor data and related research programs are explored and sensor requirements are discussed.
Prospects for the mastery of space and the basic problems which must be solved in developing systems for both manned and cargo spacecraft are examined. The achievements and flaws of rocket boosters are discussed as well as the use of reusable spacecraft. The need for orbiting satellite solar power plants and related astrionics for active control of large space structures for space stations and colonies in an age of space industrialization is demonstrated. Various forms of spacecraft propulsion are described including liquid propellant rocket engines, nuclear reactors, thermonuclear rocket engines, electrorocket engines, electromagnetic engines, magnetic gas dynamic generators, electromagnetic mass accelerators (rail guns), laser rocket engines, pulse nuclear rocket engines, ramjet thermonuclear rocket engines, and photon rockets. The possibilities of interstellar flight are assessed.
The Galilean satellites are locked in the Laplace resonance, which is responsible for forcing their significant orbital eccentricites. The eccentricites in turn result in tidal energy dissipation within the satellites that is responsible for the great thermal activity on Io, including both volcanism observed by Voyager and heat flux measured from Earth. The resonance results from the nearly 2:1 commensurability of orbital periods (or equivalently of mean motions) taken by pairs. These geometrical relations enhance the mutual gravitational effects. Yoder pointed out that tides raised on Io tend to drive the system out of resonance (toward greater nu and correspondingly smaller eccentricities) while tides raised on Jupiter tend to drive the system towards deeper resonance (smaller nu and larger forced eccentricities). The possible behavior of the system in deep resonance is investigated.
Contents include the detailed index for 1985; data for June 1985 (solar flares, solar radio bursts at fixed frequencies, solar X-ray radiation from GOES satellite graphs, mass ejections from the sun, and active prominences and filaments); data for January to May 1985 (solar flares January 1985, solar flares February 1985, solar flares March 1985, solar flares April 1985, solar flares May 1985, and number of flares August 1966 to June 1985); and the international geophysical calendar 1986.
The present conference discusses the effect of target signatures on active tracking, the high resolution obtainable with a two-degrees-of-freedom angle sensor having a high update rate, solar object tracking for the Hubble Space Telescope, scaled experiments for the assessment of precise active tracking, and large aperture high-accuracy satellite laser tracking. Also discussed are laboratory test results for the Spaceborne Geodynamic Ranging System's high speed optical tracking system, jitter stabilization for precise optical pointing, scan stabilization and jitter control for an airborne telescope, a simulation of the Solar Optical Telescope's pointing performance, a microprocessor-based dual-speed angle converter, and image localization for alignment by means of adaptive preprocessing.
The equatorially orbiting Active Magnetospheric Particle Tracer Explorers CCE and IRM satellites have made numerous observations of Pc 3-4 magnetic field pulsations (10-s to 100-s period) simultaneously at locations upstream of the earth's bow shock and inside the magnetosphere. These observations show solar wind/IMF control of two categories of dayside magnetospheric pulsations. Harmonically structured, azimuthally polarized pulsations are commonly observed from L = 4 to 9 in association with upstream waves. More monochromatic compressional pulsations are clearly evident on occasion, with periods identical to those observed simultaneously in the solar wind. The observations reported here are consistent with a high-latitude (cusp) entry mechanism for wave energy related to harmonically structured pulsations.
Teleoperation (remote manipulation) will someday supplement/minimize astronaut extravehicular activity in space to perform such tasks as satellite servicing and repair, and space station construction and servicing. This technology is being investigated by NASA with teleoperation of two space-related tasks having been demonstrated at the Oak Ridge National Lab. The teleoperator experiments are discussed and the results of these experiments are summarized. The related equipment design recommendations are also presented. In addition, a general discussion of equipment design for teleoperation is also presented.