Event

The Department of Earth & Environmental Science

University of Pennsylvania

Invites you to attend a EES Seminar Series

Friday, March 18th - 3:00 PM

Eva L. Scheller

Ph.D. Student in Geology

California Institute of Technology

"The fate of water on Mars: Tracing water-rock interactions through isotopic modelling, satellites, and rovers"

There is abundant geological and mineralogical evidence for large volumes of liquid water early in Martian history (~3-4 Ga). For present-day Mars, we observe that most water is stored in the polar cap or subsurface ice. Based on geological observations, liquid water availability on Mars has also decreased over geological time. However, the processes dictating the loss of water remain unresolved. Previous studies suggested that the fractionation of atmospheric D/H can be explained by significant water loss on Mars due to atmospheric escape. We hypothesize instead that the sequestration of water into the crust during the first 1-2 billion years caused the long-term drying of Mars and explains the atmospheric D/H evolution. We model Martian water history through a new integrated hydrogen isotopic model that simulates the three key processes affecting the Martian water budget and hydrogen isotopic composition including crustal hydration or the sequestration of water into the crust, volcanic outgassing of water, and atmospheric escape of water. Our model results show that sequestration of ocean-scale volumes of water in the crust played a large role in the long-term drying of Mars, simultaneously explaining the hydrogen isotopic budget and geological observations of large past water volumes. This has tremendous implications for considerations with regards to understanding climate and the habitability potential of Mars on a geological time scale. Furthermore, the recently landed Perseverance rover has been tasked with studying the ancient aqueous history and astrobiological potential of Mars. The first spectroscopic results from the rover reveal evidence of abundant aqueous alteration and organic compounds within the Jezero crater floor, landing site of the Perseverance rover. Perseverance rover analyses and returned samples will be used to test the presented models for alteration of the ancient (~3-4 Ga) crust, water loss, and habitability potential of Mars.

Information on Eva's research can be located here:

http://web.gps.caltech.edu/~eschelle/