Formation of Martian Gullies by the Flow of Simultaneously Freezing and Boiling Liquid Water,

Jennifer Heldmann

NASA Ames Research Center

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Abstract: Geomorphic evidence from the Mars Orbiter Camera (MOC) aboard the Mars Global Surveyor (MGS) spacecraft suggests that recent gullies on Mars were formed by fluvial activity. The Martian gully features are significant because their existence implies the presence of liquid water near the surface on Mars in geologically recent times. The young geologic age of these gullies is paradoxical because liquid water is generally unstable with respect to boiling and freezing on the Martian surface due to the low atmospheric pressures and sub-freezing ambient temperatures. Irrespective of the ultimate source of the fluid carving the gullies, we seek to understand the behaviour of this fluid after it reaches the Martian surface. We have thus developed a numerical model to simulate the flow of liquid water in polar desert environments. This model is first tested and validated for observed liquid water activity in the Canadian High Arctic and is then applied to the case of the Martian gullies. We find that, contrary to popular belief, the fluvially-carved Martian gullies require formation conditions such as now occur on Mars, outside of the temperature-pressure stability regime of liquid water. Mars Global Surveyor observations of gully length and our modelling of water stability are consistent with gully formation from the action of pure liquid water that is simultaneously boiling and freezing.

PROFILE: Dr Jennifer Heldmann is a National Research Council postdoctoral researcher working at NASA Ames Research Center in the Space Science Division. She has a BA in Astrogeophysics from Colgate University, a MS in Space Studies with a minor in Geology from the University. of North Dakota and a PhD in planetary science from University of Colorado, Boulder. Jennifer has a keen interest in sending humans to Mars and has taken part in previous Mars analogue field work in the High Arctic (Canada), Spitsbergen (Norway), the Atacama Desert (Chile), and the Mojave Desert (California). Her research focuses on an analysis of spacecraft data, numerical modeling, and terrestrial analogue studies to understand the nature and origin of the recent gully features on Mars, with a particular interest in the recent liquid water activity on the Red Planet. Jennifer served on Crew 1 at the Mars Desert Research Station (MDRS) in Utah. She is a member of the Mars Society, Planetary Society, Association of Mars Explorers, American Geophysical Union, and the American Astronomical Society Division of Planetary Sciences.