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Updated: Jul 11, 2026
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Non-equilibrium Microwave Plasma for Efficient High Temperature Chemistry
Published on: August 1, 2017
Venus Thermosphere: In situ Composition Measurements, the Temperature Profile, and the Homopause Altitude.
Science (New York, N.Y.)
|February 23, 1979
Summary
Pioneer Venus data revealed Venus
Area of Science:
- Planetary Science
- Atmospheric Science
- Space Physics
Background:
- The upper atmosphere of Venus is a complex region influenced by solar radiation and interactions with the solar wind.
- Understanding its composition and structure is crucial for comprehending planetary atmospheric evolution and space weather.
- Previous missions have provided limited data on the neutral composition of Venus's dayside upper atmosphere.
Purpose of the Study:
- To measure the composition and structural parameters of the dayside Venus upper atmosphere.
- To determine the number densities of key atmospheric constituents like carbon dioxide and helium.
- To investigate the distribution of noble gases and the location of the helium homopause.
Main Methods:
- In-situ measurements using a neutral mass spectrometer aboard the Pioneer Venus multiprobe bus.
- Data collection occurred on December 9, 1978, during the probe's descent through the Venusian atmosphere.
- Analysis of mass spectral data to derive molecular and atomic abundances and isotopic ratios.
Main Results:
- Carbon dioxide and helium number densities were measured at approximately 6 x 10^6 and 5 x 10^6 cm^-3 at 150 km altitude, respectively.
- Mixing ratios for argon-36 and argon-40 were found to be around 80 parts per million at 135 km altitude.
- The exospheric temperature was determined to be 285 +/- 10 K between 160 and 170 km, with the helium homopause located at approximately 137 km.
Conclusions:
- The study provides valuable in-situ data on the composition and structure of Venus's upper atmosphere.
- The measurements offer insights into the atmospheric dynamics and thermal structure of Venus.
- The findings contribute to our understanding of atmospheric escape processes and the evolution of planetary atmospheres.
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