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Science 6 July 1979:
Vol. 205. no. 4401, pp. 49 - 52
DOI: 10.1126/science.205.4401.49
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Articles

Composition and Structure of the Venus Atmosphere: Results from Pioneer Venus

J. H. HOFFMAN 1, R. R. HODGES JR. 1, M. B. MCELROY 2, T. M. DONAHUE 3, and M. KOLPIN 4

1 Center for Space Sciences, University of Texas at Dallas, Richardson 75080
2 Center for Earth and Planetary Physics, Harvard University, Cambridge, Massachusetts 02138
3 Department of Atmospheric and Oceanic Sciences, University of Michigan, Ann Arbor 48105
4 Physics International, San Leandro, California 94577

Results from the Pioneer Venus sounder probe neutral mass spectrometer indicate that there is no difference in the isotopic ratios of carbon and oxygen between Venus and Earth to within ± 5 percent. The mixing ratio of nitrogen is 3.5+3-2 percent with an isotopic ratio within 20 percent of that of Earth. The ratio of argon-36 to argon-40 is 85 percent, and the ratio of argon-38 to argon-36 is 20 percent. The mixing ratios of argon-36 and argon-40 are approximately 40 and 50 parts per million, respectively, with an error of about a factor of 2 (mainly toward a lesser amount) resulting from uncertainty in the response of the ion pump to rare gases. Hydrogen chloride cannot account for more than a few percent of the 36 mass peak, and therefore the large excess of primordial argon is a reasonable conclusion. The ratio of neon-20 to argon-36 of 0.5 ± 0.3 is definitely terrestrial in character rather than solar. These results indicate that there is a large excess of all primordial noble gases on Venus relative to Earth. There appears to be a considerably higher abundance of sulfur compounds below 20 kilometers than in or above the main cloud layer. The 32 and 60 mass peaks show a sharp increase below 22 kilometers, indicating the possible production of sulfur and carbon oxysulfide (COS) at the expense of sulfur dioxide.

Submitted on May 15, 1979


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
The Color of the Surface of Venus.
C. M. PIETERS, J. W. HEAD, S. PRATT, W. PATTERSON, J. GARVIN, V. L. BARSUKOV, A. T. BASILEVSKY, I. L. KHODAKOVSKY, A. S. SELIVANOV, A. S. PANFILOV, et al. (1986)
Science 234, 1379-1383
   Abstract »    PDF »
Venus: Halide Cloud Condensation and Volatile Element Inventories.
J. S. LEWIS and B. FEGLEY JR. (1982)
Science 216, 1223-1225
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Corrections in the Pioneer Venus Sounder Probe Gas Chromatographic Analysis of the Lower Venus Atmosphere.
V. I. Oyama, V. I. OYAMA, G. C. CARLE, and F. WOELLER (1980)
Science 208, 399-401
   Abstract »    PDF »
Implications of the Gas Compositional Measurements of Pioneer Venus for the Origin of Planetary Atmospheres.
J. B. POLLACK and D. C. BLACK (1979)
Science 205, 56-59
   Abstract »    PDF »


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