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Project Progress

During the past year we have been very active in proposing new mechanisms to form the river valleys on Mars. These had been attributed to an early greenhouse on Mars. However, we were able to show that such a greenhouse cannot be created with the known materials on Mars (mainly carbon dioxide and water). As part of the Astrobiology project at CU, we have shown instead that impacts of asteroids and comets on Mars may have distributed great sheets of hot melted rock over the planet. Such layers of rock are observed on Mars. This hot material may have then released water from the soil. In this scenario, the planet would only have brief periods of warm temperatures in which to arise, and near surface life would have been killed by the hot rock. (Segura, O. B. Toon, A. Colaprete, and K. Zahnle, 2002, Environmental effects of large impacts on Mars, submitted to Science).

We have also worked on the origins of small streams on Mars. Gullies on steep slopes on Mars seem to be relatively young. We have been exploring terrestrial analogs in order to understand how ground water might make such streams and to calculate what their properties might be on Mars ("Cold Springs in Permafrost on Earth and Mars"— D. Andersen, W. Pollard, C. McKay, J. Heldmann, Journal of Geophysical Research-Planets, Vol 107, No E3, March 2002).

Finally with a new NAI post-doctoral fellow, Dr. Alex Pavlov, we have begun a series of studies of the early atmosphere of Earth. We are investigating the nature of methane rich atmospheres, the effects of collisions of the solar system with dust clouds in the galaxy, and the nature of terrestrial clouds in an atmosphere without the oxygenated aerosols that are critical to cloud formation today.