Meditations on Loss: Causes and Consequences of Water Loss on Mars and Venus
Dr. Michael Chaffin
Research Scientist, Laboratory for Atmospheric and Space Physics
University of Colorado, Boulder
Water is the medium of all known life: determining the conditions that support its existence on planetary surfaces is therefore of paramount importance for understanding the prevalence of life in the universe. Earth’s planetary neighbors Mars and Venus both display extremely desiccated surfaces and lower atmospheres, whose highly enriched inventory of heavy water indicates substantial water loss to space as atomic oxygen and hydrogen over solar system history. At Mars, surface-to-space measurements by multiple spacecraft have transformed understanding of hydrogen escape, finding that H loss varies seasonally as a result of lower atmosphere dust and climate cycles. At Venus, a new fleet of international spacecraft will soon arrive to probe the planet’s geology and the water content of the lower and middle atmosphere, but will leave critical thermosphere-ionosphere processes unexplored despite substantial unknowns regarding H and O energization and escape. In this talk, I will describe current knowledge of Mars and Venus water escape, with an eye toward future missions, instruments, and measurement techniques likely to enable progress in understanding the processes that dry out terrestrial planets, which are likely to limit the longevity of livable environments throughout the universe.
Learn more about Dr. Chaffin.