Monday, September 26, 2016

Ancient Tsunamis Supported Life on Mars

Ancient Tsunamis Supported Life on Mars

www.nasa.gov

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Massive tsunamis on Mars billions of years ago could have altered the Martian landscape and paved the way for icy cold salty oceans needed to sustain life on the Red Planet. According to the study published on May 19 in the journal Scientific Reports, these mega-tsunamis were caused by two large meteorites that hit the planet millions of years apart.

“About 3.4 billion years ago, a big meteorite impact triggered the first tsunami wave. This wave was composed of liquid water,” says principal investigator Alberto Fairén from the Centre of Astrobiology in Madrid. “It formed widespread backwash channels to carry the water back to the ocean.”

The second tsunami was caused by another massive meteorite impact. During the freezing climate change that occurred for millions of years between the two impacts, the water on Mars turned into ice, with the ocean level moving away from its original shoreline and forming another shoreline.

massive tsunamis
Upslope direction of flow indicated by white arrow. The lobe is about 250 km in length or the distance between Baltimore and New York City. Credit: Cornell University

The second tsunami created lobes that froze on land and never returned into the ocean, implying that the ocean on Mars was partially frozen at the time. Lobes are massive projections on the surface that measure up to hundreds of kilometres long and wide. The same lobes, though smaller, can be observed after devastating waves occur on Earth.

massive tsunamis
The lobes on Mars were caused by tsunamis. Credit: Alexis Rodriguez

However, the cold, salty waters helped keep the waters from turning into solid ice, which provided shelter for life during the extreme climate change. This suggests that the tsunami lobes are good samples to investigate signs of life.

“We have already identified some areas inundated by the tsunamis where the ponded water appears to have emplaced lacustrine sediments, including evaporites,” points out the study’s lead author Alexis Rodriguez, from the Planetary Science Institute in Arizona. “As a follow-up investigation, we plan to characterise these terrains and assess their potential for future robotic or human in-situ exploration.”