The Mars Reconnaissance Orbiter (MRO) captured this image of a 50-meter wide crater on the Red Planet back on March 28th, 2012. But the impressive thing is that this same crater was not there when the MRO took pictures of the area the day before. In other words, this crater was spotted less than a day after the impact that formed it. This is a record=setting events, since it usually takes a few years before the presence of new craters have been confirmed.
In this case, though, the constant sweep of the Mars weather camera (called the Mars Color Imager, or MARCI) picked up the black smudge that is a telltale sign of a fresh impact. Because the imager is low-resolution, it sees a large area of the surface, and does so all the time. It’s also the largest crater in the solar system ever seen with before and after shots. At 50 meters or so across, it’s half the length of a football field, so the impacting object was probably up to a few meters across.
Something that small would burn up in Earth’s atmosphere, but given that Mars has a much thinner atmosphere (about 1 percent as thick of Earth’s) rocks of this size make it to the surface with ease. Once they make it to the ground, they hit hard enough to carve out a hole and blast out ejecta debris – which was how the crater was found. But the atmosphere is thick enough to cause a lot of pressure in front of the incoming meteoroid, which can break it up into smaller pieces.
As you can see from the images above – the top which was taken on March 27th and the bottom on the following day – there was one big crater, one smaller one, and quite a few even smaller ones around the main one. These may have been from pieces of the meteoroid that broke up as it came in. Not only that, but landslides were observed in the area that occurred around the same time, so they may have been caused by the seismic ground wave from the impact as well.
Events like this are not only novel, they are also very useful for scientists, since they help them to understand how impacts have shaped the Martian landscape. They also help determine the number of small impacts suffered by Mars (and by extrapolation, Earth), and in some cases reveal what’s underneath the surface of the planet (including ice). This latest impact is many ways a gift, since most craters are very old and the atmosphere have eroded them to the point that there results are no longer fresh.
Kudos to the MRO team for their fine work in spotting this new Martian surface feature. And in the meantime, be sure to enjoy this video that explains this record find, courtesy of the NASA Jet Propulsion Laboratory.