Mega-tsunamis on Mars show life potential: study

Two large meteorites that hit Mars billions of years ago triggered a pair of mega-tsunamis which forever scarred the martian landscape and yielded evidence of cold, salty oceans conducive to sustaining life, a new study has found.
"About 3.4 billion years ago, a big meteorite impact triggered the first tsunami wave," said Alberto Fairen, a visiting scientist at Cornell University in the US.
"This wave was composed of liquid water. It formed widespread backwash channels to carry the water back to the ocean," said Fairen, principal investigator at the Centre of Astrobiology in Spain.
Scientists found evidence for another big meteorite impact, which triggered a second tsunami wave. In the millions of years between the two meteorite impacts and their associated mega-tsunamis, Mars went through frigid climate change, where water turned to ice, researchers said.

"The ocean level receded from its original shoreline to form a secondary shoreline, because the climate had become significantly colder," said Fairen.
The second tsunami formed rounded lobes of ice.

"These lobes froze on the land as they reached their maximum extent and the ice never went back to the ocean - which implies the ocean was at least partially frozen at that time," said Fairen.
"Our paper provides very solid evidence for the existence of very cold oceans on early Mars," he said.
According to him, these icy lobes retained their well-defined boundaries and their flow-related shapes, suggesting that the frozen ancient ocean was briny.

"Cold, salty waters may offer a refuge for life in extreme environments, as the salts could help keep the water liquid. If life existed on Mars, these icy tsunami lobes are very good candidates to search for biosignature," said Fairen.
"We have already identified some areas inundated by the tsunamis where the ponded water appears to have emplaced lacustrine sediments, including evaporites," said Alexis Rodriguez from Planetary Science Institute in the US.
The findings were published in the journal Scientific Reports.