Sushil Atreya's research is highly interdisciplinary, cutting across traditional scientific disciplines. His major areas of expertise are: origin and evolution of planetary and satellite atmospheres; solar system formation, photochemistry, electrochemistry, planetary thermodynamics; astrobiology; modeling and observational studies of comparative composition and structure of planetary atmospheres; development of future planetary exploration mission concepts, especially entry probes to the giant planets; and education and public outreach. 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.
- 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
A sampling of Sushil Atreya's significant research contributions:
MAJOR PROFESSIONAL ACTIVITIES
- First high precision measurement of primordial argon isotope ratio on Mars, which shows that Mars has lost much of its atmosphere in the past four billion years, and also provides conclusive evidence that the so called martian meteorites are indeed rocks from Mars.
- Methane cycle on Titan, which explains the origin, loss, surface 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 actually detected on Titan by the Voyager spacecraft in 1980. The Cassini-Huygens measurements in 2005 provided first direct evidence in support of the hypothesis.
- Predicted H2CN+ as the major ion of the ionosphere of Titan, before an ionosphere was even measured (by Voyager in 1980). In 2005, Cassini orbiter confirmed H2CN+ as Titan's major ionospheric species.
- First model of triboelectric field induced electrochemistry in the Martian dust devils and storms, with possible implications for destruction of surface organics.
- Sources and sinks of methane on Mars, which are key to understanding the biological potential of Mars and the planet's habitability.
- Photochemical stability of the Martian atmosphere, including the role of catalytic 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 first measurements were made by the Pioneer spacecraft for Jupiter in 1974.
- Discovering with the Galileo probe team the enrichment of heavy elements in Jupiter relative to solar, which led to the icy planetesimal model of Jupiter's formation.
- First ever determination of the molecular hydrogen density height profile in the earth's atmosphere, which has important implications for evolution of atmospheres.
Solar System Exploration Missions Co-Investigator and Science Team Member
Sushil Atreya has played a key role on a number of planetary spacecraft missions of the US, Europe, Japan and the former Soviet Union, in several cases starting from concept development to their fruition. He has been a staunch advocate of entry probe missions to the giant planets. A select list of Sushil Atreya's involvement in missions is given below.
- Mars Science Laboratory: Sample Analysis at Mars (SAM Suite, with Gas Chromatograph- Mass Spectrometer and Tunable Laser Spectrometer). Also a Science Lead for the MSL-SAM Suite EPO Program, 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, 1990-Present
- Cassini-Huygens: Aerosol Collector and Pyrolyzer, 1990-Present
- Mars Express: Planetary Fourier Spectrometer, 1998-Present
- ExoMars: MOMA (Mars Organic Molecule Analyzer, Collaborator) on 2018 Lander, 2012-Present
- Galileo: Jupiter Entry Probe Mass Spectrometer, 1977-2003.
- Voyager I and II: Ultraviolet Spectrometer at Jupiter, Saturn, Uranus, Neptune Systems, 1974-1990
- Mars '96: Soviet Mars Mission, U.S. Participating Scientist, 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. Planetary Science Laboratory Homepage