ISSN:8755-1209    

DOI:10.1029/RG021i002p00004

年代:1983

数据来源: WILEY

摘要:

It is not an exaggeration to say that the past four years have brought a growth in our knowledge of the solar system unprecedented in all of history. Prior to this quadrennium, our closeup exploration of the planets had been limited to the atmosphere and a few surface sites on Venus, the surfaces of Mercury, the Moon, Mars, Phobos, and Deimos, and an intriguing but limited glimpse at Jupiter. To this list have been added the global topography of Venus, and a wide variety of data on Jupiter, Amalthea, Io, Europa, Ganymede, Callisto, Saturn, Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion, Iapetus, and Phoebe. Among the recent discoveries are continent‐sized landforms on Venus, a ring encircling Jupiter, the most volcanically active surface in the solar system on Io, hitherto unknown forms of global tectonism on icy Europa, Ganymede, and Enceladus, and intricate structure within Saturn's ring

ISSN:8755-1209    

DOI:10.1029/RG021i002p00139

年代:1983

数据来源: WILEY

摘要:

The period from 1979 to 1982 has been characterized by extensive exploration of the Solar System. Pioneer and Voyager missions to Venus, Jupiter, and Saturn combined with ongoing analysis and data collection from the Viking‐Mars mission have contributed greatly to our understanding of planetary atmospheres.The Pioneer orbiter and the Pioneer multiprobe missions that arrived at Venus in December 1978, yielded results [Donahue, 1979] which have been combined with those from Venera 11 and 12 in December 1979, and Venera 13 and 14 in March 1982, [Moroz, 1981]to provide atmospheric data of significantly higher resolution and precision that has been available previousl

ISSN:8755-1209    

DOI:10.1029/RG021i002p00143

年代:1983

数据来源: WILEY

摘要:

During the four years 1979–1982, studies of the satellites of the outer planets matured into a major branch of planetology, largely in consequence of seven spacecraft encounters with the Jovian and Saturnian systems. Previously these objects had been investigated only by a small group of planetary astronomers, and few planetologists recognized their potential contribution to the study of planetary origins and evolution. A good perspective on the accomplishments of these largely astronomical studies can be found in reviews by Morrison and Cruikshank (1974), Morrison and Burns (1976), Morrison et al. (1977), Johnson (1978), and Cruikshank (1979).The first direct studies of the outer solar system were accomplished by the Pioneer spacecraft, which flew through the Jovian system in 1973 and 1974 and achieved a first encounter with Saturn in September 1979. These appropriately‐named craft were the pathfinders for the much more sophisticated and intensive explorations of Voyager 1 and 2, which encountered the Jovian system in 1979 (March and June) and the Saturnian system in 1980 (November) and 1981 (August). More than a dozen objects, heretofore only faint points of light visible in the telescope, were revealed as complex worlds amenable to geological and geophysical investigation. As a result, a planetologist in 1982 can consider the comparative study of about triple the number of solid‐surface planets under investigation four years ago. This sudden and dramatic expansion in our data base promises to support a revolution in perspective comparable to that achieved earlier when the first geological information was returned by spacecraft from the Moon, Mars, and Me

ISSN:8755-1209    

DOI:10.1029/RG021i002p00151

年代:1983

数据来源: WILEY

摘要:

During the last four years our knowledge of the geology of the terrestrial planets has advanced rapidly. The advances are particularly noticeable for Venus and Mars. Improved understanding of Venus has come largely from the Pioneer Venus mission (Colin, 1980), which has given us our first global view of the planet, albeit at fairly low resolution. The period was also one of almost continuous data gathering for Mars as the Viking orbiters and landers, emplaced at the planet in 1976, continued to function.

ISSN:8755-1209    

DOI:10.1029/RG021i002p00160

年代:1983

数据来源: WILEY

摘要:

Planetary ring studies have evolved from observations of a single example, (Saturn), to related studies of a class of objects, in the last several years; in fact, this is the first IUGG review article on the subject. Therefore, it seems appropriate to cite at least review articles going back beyond 1979, if only as a guide to earlier literature (Alexander 1962, Bobrov 1970, Cook et al. 1973, Palluconi and Petengill (eds) 1973, Pollack 1975, Cook and Franklin 1977, and Cuzzi 1978; all of which deal only with Saturn's rings). More recent reviews have been written by Ip (1980 a,b); Cook (1980), Elliot (1982), and Goldreich and Tremaine (1982); also of interest are review articles in books to be published shortly; Saturn (Gehreis, ed.) and Planetary Rings (Brahic and Greenberg, eds.). Popular articles of interest have been written by Pollack (1978), Burns (1981) and Pollack and Cuzzi (1982).

ISSN:8755-1209    

DOI:10.1029/RG021i002p00173

年代:1983

数据来源: WILEY

摘要:

Planetary radar research reported during 1979–1982 was highlighted by radar observations of Venus by the Pioneer Venus spacecraft, Earth‐based high‐resolution imaging of Venus and the Moon, construction of accurate topographic profiles for Martian tropical regions, observational and theoretical advances in relating the radar signatures of Mars and the Moon to surface characteristics, and the initial radar detections of echoes from a comet and a mainbelt asteroid.This review begins with a brief synopsis of radar definitions and technical terminology, and then summarizes recent results for individual targets. Readers interested in radar astronomy prior to the current quadrennium are directed to excellent reviews by Jurgens (1982a), Pettengill (1978), Evans (1969), Muhleman (1966), and Pettengill and Shapiro (1965). Detailed descriptions of planetary radar techniques include Pettengill (1970) and Evans and Hagfors (

ISSN:8755-1209    

DOI:10.1029/RG021i002p00186

年代:1983

数据来源: WILEY

摘要:

Asteroids and comets are populations of countless bodies ranging downwards in size from Ceres, which is about 1000 km in diameter. Although they constitute a virtually negligible fraction of the mass of the solar system, their physical/chemical properties and locations in the system are of particular interest, since they provide most of our observational and experimental clues about the earliest epochs of solar system history. This is particularly due to the fundamental role of meteorites in planetary science; meteorites are fragments of asteroids and comets, although they are treated in this review only tangentialIy. In addition, the ongoing behavior of asteroids and comets (primarily their response to the interplanetary radiation and impact environment) provides interesting insight to unusual physical and geological processes.Both asteroids and comets have been the subject of an important international meeting during the period covered by this report. A comprehensive book and a special issue of a journal emanated from each conference (Asteroids. Gehreis, ed., 1979, and Icarus 40. 1979; Comets. Wilkening, ed., 1982, and Icarus 47. 1981). Particularly in the case of comets, for which the book was published in mid‐1982, it would be superfluous to treat the pre‐1982 literature in great detail. More has happened since the 1979 publication of the Asteroids book, so I rely more on subsequent journal publications about astero

ISSN:8755-1209    

DOI:10.1029/RG021i002p00196

年代:1983

数据来源: WILEY

摘要:

There has been considerable progress in recent years toward understanding the origin of our solar system. Beyond a broad concensus that the planets are derived from a nebular disk that formed with the sun itself, the differences between the various theories are generally more apparent than the similarities. Most of the disagreements derive from the assumed mass of the solar nebula, based on models for its formation. Estimates range from a few percent of the sun's mass, the minimum required to make the planets, up to one solar mass.

ISSN:8755-1209    

DOI:10.1029/RG021i002p00206

年代:1983

数据来源: WILEY

摘要:

Aeronomy is the study of the physics and chemistry of the upper atmosphere. The upper atmosphere is usually defined as the region of the atmosphere above the tropopause extending upward to the point where electric and magnetic fields dominate the phenomena rather than the atmospheric atoms and molecules. The lower part of this region, from about 10 to 90 kilometers altitude, has become known as the middle atmosphere. An international program called MAP (Middle Atmosphere Program) is now underway to intensively study this region.

ISSN:8755-1209    

DOI:10.1029/RG021i002p00215

年代:1983

数据来源: WILEY