Venus : Geochemical conclusions from the Magellan data
- Wood, J. A.
- JAN 1, 1992.
- Physical Description:
- 1 electronic document
- Restrictions on Access:
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- Though the Magellan mission was not designed to collect geochemical or petrological information, it has done so nonetheless. Since the time of the Pioneer Venus mission it has been known that high-altitude (greater than 2.5-5 km) mountainous areas on Venus exhibit anomalously low radiothermal emissivity (e less than 0.6). Magellan has greatly refined and extended these observations. The low emissivity requires surface material in the uplands to have a mineralogical composition that gives it a high bulk dielectric constant, greater than 20. The dielectric constant of dry terrestrial volcanic rocks seldom exceeds 7. The high-dielectric character of high-altitude surface material cannot be a primary property of the local volcanic rock, because there is no reason why rock having the required special mineralogy would erupt only at high altitudes. Therefore it is a secondary property; the primary Venus rock has reacted with the atmosphere to form a mineralogically different surface layer, and the secondary minerals formed are controlled by the ambient temperature, which decreases with altitude on Venus. A further investigation of venusian mineralogy is presented.
- Other Subject(s):
- NASA Technical Reports Server (NTRS) Collection.
- Document ID: 19930005206.
Accession ID: 93N14394.
Lunar and Planetary Inst., Papers Presented to the International Colloquium on Venus; p 132-133.
- No Copyright.
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