ESA Discovers Triplet Overlapping Craters on Mars

Finding and studying craters on Mars' surface helps shed light on the planet's past. 

The European Space Agency's (ESA) Mars Express discovered an old impact triplet with three overlapping craters — a clear sign of Mars' past. The crater was found in the red planet's southern hemisphere in a region called Noachis Terra, named after the Noachian era some 4.1 - 3.7 billion years ago.

The triplet crater is most likey residual of the time when comets and asteroids came crashing down on Mars, leaving their long-lasting marks. 

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Small but significant discovery

The triplet crater is fairly smaller than its neighboring Le Verrier Crater. The latter spans almost 87 miles (140 km) across, whereas the three overlapping craters measure at most 28 miles (45 km), and at their smallest location, 17 miles (28 km), per ESA.

It's still unsure how such a triplet crater could be formed. The most plausible explanation is that its impactor broke off into three pieces before smashing into Mars' surface. 

Another explanation could be as simple as three separate impacts in time hit spots near each other. Pure coincidence, but not altogether unlikely. 

If the first explanation of a broken impactor is the correct one, this would shed light on Mars' Noachian era. It would have meant that the planet's atmosphere was much denser than was previously believed. So perhaps Mars was warmer and wetter than today's conditions of the red planet, and that larger pools of water flowed on its surface. 

The three crater formation has "flattened rims, shallow floors, and have been filled with sediment in the four billion years since its formation," per ESA's report. Signs of ice are also present.

Mars Express' mission is to help understand the history of Mars in more detail by mapping out the planet's surface in strong detail. The spacecraft has been exploring Mars since 2003. Not only are new discoveries crucial to understanding our neighboring planet's past, but they also shed a lot of light on the history and nature of our universe.