When a single small meteorite struck Mars a few million years ago, it didn鈥檛 just create one crater. It ultimately created billions of them. The main crater, called Corinto, is just under 14 kilometres across, but the debris from that meteorite collision formed about two billion additional craters, called secondaries.
When a meteorite slams into the ground, it can blast a huge plume of rocks into the air. When these rocks fall back down, they create their own smaller craters, often in chains and clusters around the original impact site. This process is common on rocky bodies with thin atmospheres such as Mars or the moon, but it is much harder to spot on Earth, where geological activity can destroy the evidence.
at NASA鈥檚 Jet Propulsion Laboratory in California and his colleagues used images from two spacecraft orbiting Mars to estimate the number of secondary craters created by the debris from the Corinto crater, which formed about 2.3 million years ago. They found that Corinto has between 1.3 billion and 3 billion secondaries 鈥� the most ever spotted on Mars. Each secondary was at least 10 metres across. Golombek presented this work at the in Texas on 11 March.
Advertisement
The craters cover an area of about 1.4 million square kilometres, including the area where NASA鈥檚 Mars InSight spacecraft landed in 2018. The area is volcanic, and the craters pepper the surfaces of dried lava flows from Elysium Mons, one of the tallest mountains on Mars.
鈥淨uantifying the number of secondaries is important to better understand how a relatively small crater could possibly eject that much material during the cratering process,鈥� says Golombek. The formation of secondaries depends strongly on the geology of the area struck by the meteorite, as well as the geological properties of the impactor itself, so studying them could help us understand what Mars is made of and how various materials react to space rocks slamming into them.
