Planetary Exploration, 1968-1975; Report of a Study by the Space Science Board, Washington, D.C., June 1968 (1968) / Chapter Skim
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Planetary Surfaces
Planetary Surfaces
Pages 27-34
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From page 27... ...
At a particular spot the last signature on the surface rock may be that of any one of dozens of different processes: the lava spewed forth from a hot interior; the accumulation of sediments and fossils on the floor of a former sea; the deposits left by a vanished glacier; the craters formed by infall of objects from outer space. Because planetary surfaces have been subjected to a great variety of modifying processes of both internal and external origin, we expect considerable local variation.
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From page 28... ...
This interpretation is challenged by other models involving inorganic changes affecting either the surface or the lower atmosphere. For example, gases seasonally generated by melting or subliming ice caps may systematically move light absorbent hazes towards
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From page 29... ...
If, indeed, the region is underlaid by sediments a single panoramic photograph may confirm and amplify this presumption by showing stratification and other large scale sedimentary features. The panoramic photography should be followed by a limited and selective program of detailed photography to a lower limit of 1 mm coupled with 0.01-mm resolution microscopic photography of the sample.
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From page 30... ...
Venus Study of the surface of Venus may be more difficult and less rewarding than that of Mars. Recent evidence indicates surface temperatures between 600 and 700°K, and atmospheric pressure as high as 100 atmospheres.
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From page 31... ...
To be specific, visual imaging of Venus to detect discontinuities in the cloud cover seems a reasonable requirement for a Venus-Mercury fly-by, though it might not be accorded highest priority in a mission devoted entirely to Venus. Similarly, chemical analysis of the Venus surface at the termination of the descent phase of an atmospheric probe would be tremendously interesting even if not preceded by adequate reconnaissance missions.
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From page 32... ...
The best way to underscore the scientific value of a limited imagery mission for Mercury is to recall the major changes in our thinking about Mars produced by the 4-km resolution Mariner 4 pictures. The short lead time, the low cost of a Pioneer mission, and the value to our national prestige of a planetary first are strong arguments supporting the basic scientific value of the mission.
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From page 33... ...
The wide range of information to be derived from orbital images has bearing on almost all other aspects of Martian exploration. The success ratio of the Lunar Orbiter missions and the extent to which their data have modified both our view of the Moon's basic processes and the detail of much of our present lunar planning speaks eloquently for the need of similar data for Mars.
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From page 34... ...
resolution photographs of a large part of the southern hemisphere. One flight to obtain black-andwhite images with maximum morphologic detail taken at low Sun angles from a high inclination orbit; the second, same resolution at several band passes that will produce color images taken at very high Sun angles from low inclination orbit.
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