Sushil Atreya's research is highly interdisciplinary, cutting across traditional disciplines. For over three decades, he has studied the workings of the solar system, particularly its formation and the origin and evolution of planetary and satellite atmospheres. His approach combines numerical modeling, observations, data interpretation, and mission development. Specifics are listed under
Research Expertise,
Major Professional Activities, and
Publications. Please visit the
Planetary Science Laboratory (PSL) homepage for highlights of current research projects.
RESEARCH EXPERTISE
- Solar system formation, origin and evolution of planetary and satellite atmospheres, extrasolar planets
- Photochemistry, Electrochemistry, Cloud Physics, Astrobiology
- Modelling and observational studies of comparative composition and structure of planetary and satellite atmospheres
- Development of future planetary exploration mission concepts
- Education and public affairs
RESEARCH HIGHLIGHTS
| Amongst Sushil Atreya's major research highlights are: |
- Methalogical cycle on Titan, which explains the origin, source, loss, evaporation, and rain of methane on Titan. The cycle of methane on Titan is similar to the hydrological cycle on Earth. Methane is also critical to the maintenance of a stable atmosphere of nitrogen on Titan.
- Origin of Titan's atmosphere. Showed ammonia as the source of a thick atmosphere of nitrogen, before nitrogen was detected on Titan by the Voyager spacecraft in 1980. The Cassini-Huygens measurements in 2005 provided evidence in support of the hypothesis.
- Predicted H2CN+ as the major ion of the ionosphere of Titan, before electron concentration was measured by Voyager in 1980. In 2005, Cassini orbiter confirmed H2CN+ as Titan's major ionospheric species.
- Oxidant (such as hydrogen peroxide) enhancement in the Martian dust devils, storms and saltation by electrostatic field induced chemistry. This may explain why organics have not yet been detected on the Martian surface.
- Sources and sinks of methane on Mars, which have important geological and biological implications.
- Stability of the atmosphere of Mars against photochemical loss, including role of heterogeneous processes.
- Composition and structure of the atmospheres of all giant planets, including some of the first determinations of vertical mixing, trace constituents, chemical, and cloud processes.
- Composition and structure of the giant planet ionospheres, including prediction of metallic ion layers, before the first measurements were made at Jupiter by the Pioneer spacecraft.
- Discovering with the Galileo probe team the enrichment of heavy elements in Jupiter relative to solar, which led to the icy planetesimal model of the planet's formation.
- First ever determination of the molecular hydrogen density height profile in the earth's atmosphere, which has important implications for the planetary escape of light gases.
MAJOR PROFESSIONAL ACTIVITIES
| Science and Experiment Investigation Team Member and Co-Investigator on |
- Mars Science Laboratory: Sample Analysis at Mars (SAM Suite: Gas Chromatograph Mass Spectrometer and Tunable Laser Spectrometer). Also a Science Lead in the EPO Program of MSL/SAM Suite, 2004-Present
- Juno - Jupiter Polar Orbiter, 2004-Present
- Venus Express: Deputy USA Lead Scientist, and ESA CoI, 2004-Present.
- Cassini-Huygens: Gas Chromatograph-Mass Spectrometer on Huygens Probe, 1990-Present
- Cassini-Huygens: Aerosol Collector and Pyrolyzer on Huygens Probe, 1990-Present
- Mars Express: Planetary Fourier Spectrometer, 1998-Present
- Galileo: Probe Mass Spectrometer and Orbiter, 1977-2003
- Voyager: Ultraviolet Spectrometer, 1974-1990
- Mars '96: U.S. Participating Scientist on Soviet Mars Mission, 1990-1996
- Phobos Soviet Mars Mission: UV-IR Spectrophotometer "Auguste", 1985-1989
- Nozomi: Japanese Mars Mission Neutral Mass Spectrometer, 1995-2004
Guest Observer/Investigator on ISO, HST, Spitzer, IRTF, CFHT, IUE, VLA, and OAO/Copernicus: various years since 1975.
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