[PLS] Aditya Khuller (Applied Physics Lab)

“The Evolution of Dusty Ice on Mars:  Present-day Liquid Water and the Search for Life on Mars”

The presence and stability of water ice and liquid water are central to the evolution of Martian geology and climate, the potential for past or extant life, and future robotic and human exploration on Mars. Recent observations reveal that much of the Martian mid-latitudes are covered by deposits containing ~99% water ice mixed with ~1% dust, overlain by desiccated material. When the overlying desiccated material is removed via impact processes or slumping on steep slopes, the ice becomes exposed, and seems to disappear within a few Mars years.

Pure ice cannot melt under present-day conditions because sublimation losses exceed absorbed solar energy. But dust increases radiative absorption and can tip the energy balance in favor of melting. I will present new modeling showing that dust-laden firn and ice can melt centimeters below the surface within favorable topographic microclimates, even while the surface remains frozen. Dusty ice remains frozen on horizontal terrain, but reduced wind-driven sublimation and enhanced thermal infrared radiation within gullies enable melting at 213 of 7,846 mapped sites between 28.6°S and 65.2°S. Melting occurs for a median of 67 days each Martian year, producing up to 3.2 mm day−1 of liquid water and 7.8 × 10⁶ liters globally. The recurring presence of liquid water on Mars could provide favorable conditions for life just below the ice surface, where sunlight is available for photosynthesis and overlying ice attenuates ultraviolet radiation.

Planetary Lunch Seminar —

Colloquia topics span the range of research interests of the department’s planetary sciences research program, and the talks are intended to appeal to any graduate students, postdocs, research scientists, and faculty with a background in planetary science. Speakers include members of the MIT community and visitors.

Contact: planetary-org@mit.edu