A newly discovered crater on Mars, complete with a surrounding blast zone, formed sometime between January 2012 and August 2014, scientists from the High Resolution Imaging Science Experiment (HiRISE) have reported. The formation of fresh craters on Mars while we have had space probes circling the Red Planet is actually fairly common, but few have been seen in such detail, and the slightly larger-than-average crater represents a remarkable opportunity to learn about the effects of medium-sized meteorites on the planet.
HiRISE is a NASA project that photographs targeted parts of Mars in extraordinary detail from the Mars Reconnaissance Orbiter. The camera can pick out objects less than a meter (3.3 feet) across from a height of 200-400 kilometers (125-250 miles) above the Martian surface.
Images of the crater and its surroundings were taken on November 27 last year, and released to the public yesterday. It was made some time between January 2014 and August 2016, but so far HiRISE have not been able to date the collision more precisely.
According to the HiRISE twitter account, the crater itself is just 4 meters (13 feet) across. However, the dark area around it, made of material thrown up in the impact, is hundreds of meters across.
Since Mars is closer to the asteroid belt, it is exposed to more incoming objects than Earth, but a much more important difference is that it has a much thinner atmosphere. Many objects that would burn up far above the Earth make it to the Martian surface, causing a regular peppering of the planet with new craters. With only dust storms to erode them, rather than rain, plants, or flowing water, basins also last much longer than they would on Earth.
By comparing different images taken at the same location at different times, HiRISE sometimes picks up something new, providing a time period in which the impact occurred.
The largest fresh crater detected on Mars, or indeed anywhere in the Solar System, was made in 2012 and reported in 2014. At almost 50 meters (164 feet) across, the impact site dwarfed this one. On the other hand, the image quality on the latest find is exceptional, giving us a great view of what has occurred.
The crater is located less than three degrees north of the Martian equator, at a longitude of 266º, putting it in the highlands east of the giant Tharsis Montes extinct volcanoes.
This maximum resolution image shows the dark crater at the center of the blast zone. NASA/JPL/University of Arizona