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Pioneer Venus: Evolving coverage of the near‐Venus environment |
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Eos, Transactions American Geophysical Union,
Volume 65,
Issue 25,
1984,
Page 401-401
L. H. Brace,
L. Colin,
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摘要:
Since December 1978, the Pioneer Venus Orbiter (PVO) has been orbiting Venus once every 24 hours in a near polar, highly eccentric orbit with apoapsis of about 12 Venus radii and a periapsis as low as 140 km. The spacecraft carries instruments for remote measurements of the surface, the atmosphere, and the clouds of Venus, as well as instrumentation for in situ measurements of its thermosphere, ionosphere, and magnetic field environment and the incident solar wind parameters. These instruments were described in a special issue of theIEEE Transactions on Geoscience and Remote Sensing[1980]. A dedicated issue of theJournal of Geophysical Research[1980] described the mission, its goals, and many of its early scientific results. The Venus book [Hunten et al., 1983] presented many review articles that summarized the more complete results and analysis available at that time. Two of the several major goals of the mission have been to perform exploratory measurements of the upper atmosphere and ionosphere of Venus and to investigate the interaction of the solar wind with the atmosphere of such an unmagnetized planet. The purpose of this paper is to call attention to the way in which secular changes in the PVO orbit are permitting these goals to be achieved. Note that we have addressed only the effect of orbital evolution only upon the in situ measurements. Clearly, the remote measurements of cloud patterns and ultraviolet emissions from the atmosphere will benefit from both the long baseline of observing time and the changing observing altitude and angles.
ISSN:0002-8606
DOI:10.1029/EO065i025p00401-01
年代:1984
数据来源: WILEY
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2. |
IRAS: Other planetary systems |
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Eos, Transactions American Geophysical Union,
Volume 65,
Issue 25,
1984,
Page 402-402
Peter M. Bell,
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摘要:
The search is on. After IRAS (Infrared Astronomy Satellite) resolved cool (85 K), thermally emitting masses apparently in orbit around the hot (10,000 K) star Vega during the spring of 1983, considerable efforts have been made to identify other solar systems and planets. Right now observers accept any size planets, even 20 μ diameter orbiting particles as in the case of the Vega system, as a step in the direction that could conceivably lead to discovery of a solar system like our own. (SeeEos, March 13, 1984, p. 97.)In December 1983, IRAS results had been processed further. Among the many results, IRAS had found another solar system, again probably with only protoplanets. The star Formulhaut, like Vega, a well‐known navigational aid, has a similar protoplanetary syst
ISSN:0002-8606
DOI:10.1029/EO065i025p00402-01
年代:1984
数据来源: WILEY
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3. |
Underground Sound: Application of Seismic Waves |
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Eos, Transactions American Geophysical Union,
Volume 65,
Issue 25,
1984,
Page 403-403
Thomas R. Morgan,
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PDF (301KB)
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摘要:
J.E. White concerns himself, as stated in the Introduction, with naturally and artificially generated seismic waves, the properties of the rock they travel through, and the methods used to generate and detect them. He discusses these in terms of models of earth materials which can include the effects of porosity, layering, direction of travel, loss mechanisms, and a number of other phenomena. Although the emphasis is definitely on borehole methods, attention is given to surface problems, and many of the data examples cited are surface recordings.Some needed mathematical tools, such as Fourier transforms and convolution, are briefly introduced in chapter 1. For the most part, his stated aim is to avoid the use of vector operators and tensor notation, although the lack of these methods may cause some readers to have difficulty connecting specific relations with general presentations from other sources. He steadfastly sticks to this goal, but the book is still laden with imposing math. Following in chapter 2 is a general discussion of plane waves and plane boundaries. This section covers the groundwork with which most readers will be very familiar.
ISSN:0002-8606
DOI:10.1029/EO065i025p00403-01
年代:1984
数据来源: WILEY
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