P022-05
Venus, Earth's Divergent Twin?: Testing Evolutionary Models For Venus with the DAVINCI+ Mission
Wednesday, 9 December 2020: 04:30
Virtual
Walter S. Kiefer1, James Brian Garvin2, Giada N Arney2, Sushil K Atreya3, Bruce A Campbell4, Valeria Cottini5, Justin Filiberto6, Stephanie Getty2, Martha S Gilmore7, David H Grinspoon8, Noam Izenberg9, Natasha Johnson10, Ralph D Lorenz11, Charles Malespin2, Michael A Ravine12, Christopher R Webster13, Kevin J Zahnle14 and The DAVINCI+ Science Team, (1)Lunar and Planetary Institute, Houston, TX, United States, (2)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (3)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (4)Smithsonian National Air and Space Museum, Washington, DC, United States, (5)University of Maryland College Park, College Park, United States, (6)Lunar and Planetary Institute, USRA, Houston, TX, United States, (7)Wesleyan University, Middletown, CT, United States, (8)Planetary Science Institute Washington - PSI, Washington, DC, United States, (9)Johns Hopkins Univ, Laurel, MD, United States, (10)Goddard Space Flight Center, Greenbelt, MD, United States, (11)JHU / APL, Laurel, MD, United States, (12)Malin Space Science Systems, San Diego, CA, United States, (13)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (14)NASA, Moffett Field, CA, United States
Abstract:
Understanding the divergent evolution of Venus and Earth is a fundamental problem in planetary science. Venus today has a hot, dry atmosphere and a stagnant lithosphere. However, the high D/H ratio indicates that Venus has lost a substantial mass of water. Ishtar Terra’s folded mountain belts morphologically resemble Tibet and the Himalayas, apparently requiring several thousand km of surface motion at some point in Venus’s past. Loss of liquid water increases the coefficient of friction in fault zones; thus, climate change may contribute to a change from an early mobile lithosphere to a present-day stagnant lithosphere. Recent modeling suggests that these transitions may have occurred in the last billion years. Feedback loops between the surface and interior are likely to be important: climate evolution and water loss can be driven by epochs of high volcanism; water loss can drive tectonic evolution, which can in turn cause episodes of enhanced volcanic eruption. However, these feedback loops are poorly defined at present and understanding the combined system evolution requires new data from Venus.
The DAVINCI+ Discovery mission will test evolutionary hypotheses for Venus by observing clues that were left behind in both the isotopic composition of the Venus atmosphere and in the rock record of the Venus surface. Noble gas abundances will characterize the sources of the Venus atmosphere, revealing whether Venus and Earth formed in the same way and how their climates diverged. Atmospheric D/H ratio will quantify water loss from Venus. Atmospheric 40Ar and 4He will quantify volcanic outgassing over Venus history and in the geologically recent past. Descent imaging will characterize the geomorphology and tectonics at the Alpha Regio landing site, an ancient tessera that is a possible analog of terrestrial continents. Orbital imaging of the 1 micron atmospheric transparency window will characterize the presence and distribution of felsic rock globally on Venus, testing the presence of liquid water during igneous petrogenesis. Several mission concepts are now competing for possible flights to Venus, but only DAVINCI+ can examine both the atmospheric isotopic record and the rock record of Venus. DAVINCI+ is therefore a compelling choice for selection in the current NASA Discovery Program Phase A competition.
