Was Mars once green?

Many scientists believe that Mars once boasted running water and even oceans. Now, a new study published in JGR Planets presents evidence that an impact event may have taken place in water and caused a mega-tsunami, as The New York Times reports.

Planetary scientists still debate whether the red planet ever had a liquid ocean. Many climate models suggest that Mars was too chilly. Others contend that signs of ancient river deltas suggest that Mars did have flowing water early in its existence. But one thing is for sure: A mountain-sized meteorite punched a hole in Mars’ northern lowlands, creating a 75-mile wide impact crater.

A Compelling Crater

Lomonosov crater, as its called, might represent the smoking gun proponents of a maritime Mars have searched for. The crater has a large hole in its southern area. One of the proposed reasons for the hole is that the impact displaced the ocean and the water rushed back in violently, causing a rift in the rim of the crater.


The rim is also around the same height as the estimated depth of the ocean. But perhaps the most compelling evidence is that Lomonosov looks like marine craters on Earth, most notably, the Chicxulub crater which struck off the coast of the Yucatán Peninsula. But planetary scientists don’t believe that the Lomonosov impact and tsunami were isolated incidents.

Related: Mars may have had life before Earth, according to a new study

Orbital photos of the Martian northern lowlands feature what look like ragged, buried coastlines. These features suggest that more than one mega-tsunami may have mangled Mars’ ancient shores.

What geologists call thumbprint terrains also snake around the area. The wavy lines resembling a human thumbprint could have resulted from the wild waters of a massive wave. The red planet experiences Marsquakes. But it lacks the truly dynamic inner-workings that could cause a big enough quake to initiate a mega-tsunami. Therefore, the thumbprint terrain-causing inundation was likely the result of an impact on water.

But researchers have long wondered just which craters are connected with these tsunamis. Over 30 years ago, photos of thumbprint terrains on Mars’ surface intrigued François Costard, study lead author and planetary geomorphologist at the French National Center for Scientific Research. Costard theorized that mega-tsunamis etched the shoreline. The new findings in the Lomonosov crater are exciting for maritime Mars proponents and seem to prove Costard right.

Is There Life on Mars?

Also exciting is the study’s implications for life on the red planet. If Mars did have an ocean, where it once sloshed is a great place to look for ancient signs of life. Moreover, some planetary scientists have posited that massive flooding from underground water sources fed Mars’ oceans.

If geochemical signs of biological activity come to light, it could mean that life currently exists in these aquifers. With new robots on Mars that have capabilities to go below the surface, it may only be a matter of time before humanity discovers if there’s life on Mars.

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