Scientists have confirmed that a huge asteroid crashed into Mars about 3.4 billion years ago, at a time when the planet had a huge ocean in which microbes could live.
The researchers, led by Alexis Rodriguez, a senior scientist at the Institute of Planetary Sciences, identified a likely location, called Pohl Crater, where the asteroid could have collided with the Martian ocean at a speed of about 38,000 kilometers per hour.
This key discovery suggests that the 110-kilometer-diameter Pohl Crater and its surrounding regions could be important targets in the search for extraterrestrial life, as they could hold information about how the habitability of the ocean evolved, according to the study, published in the Scientific Reports journal. The team was also able to reconstruct some of the stunning effects of this ancient collision and the subsequent megatsunami, which could have produced waves as high as 240 meters.
The new research also reopens a fascinating mystery about Martian life that dates back to NASA’s Viking 1 lander, which was the first mission to operate on the surface of Mars in 1976. The lander found strange compounds at the landing site that some scientists believe may indicate life, but the evidence has remained controversial for decades. Now, Rodriguez and his colleagues have demonstrated that Viking 1 did sit on the remains of an ancient megatsunami, a promising area for the search for life.
In 2019, scientists, including Rodriguez, were able to detect another impact crater, named Lomonosov, which caused another megatsunami in the same region about three billion years ago. Although the remnants of an older megatsunami were clearly visible, Rodriguez and his colleagues had to carefully examine the Martian landscape to find a crater that matched the age of this flood.
“There is a possibility that this mud volcanism was driven by the release of seawater trapped in the sediments, or gasses connected to the evaporation of seawater, and obviously, that has very interesting astrobiological implications,” concludes Rodriguez. “So, there are lots of targets to understand the evolution of the ocean of Mars, its potential biochemistry, and the way that the environment changed within the ocean over time.”