Google+ Mars Travel: May 2013

Counting Impact Craters on Mars

NASA has recently finished a study in which they determined the approximate number of asteroid and comet impacts on Mars every year. Using data collected by Mars Reconnaisance Orbiter (MRO) scientists have estimated there are 200 small craters formed every year on Mars as a result of asteroid and comet impacts. These craters measure at least 3.9 meters (12.8 feet) across.

MRO was able to image craters previously detected by itself and other Mars orbiters. Images of the same spots on Mars are taken at different times, thus if an older image does not show a crater, but a more recent one does, we know the impact occured before the most recent image, but after the one previous. This technique allows scientists to more accurately determine the age of craters on the surface.

Understanding the frequency of impacts is important to our understanding of Mars' past and allows scientists to more accurately determine the age of features on the planet. A feature or region with less impact craters is much younger than one with more craters because we know that overtime a feature on Mars will accumulate more impacts. The science will never be perfect, but can at least give us a better understanding of Mars and its development.

For example, scientists will be better able to determine the age of Hadley Crater based on the number of small craters within it. Just look at the image below and you will see that even within Hadley Crater there are multiple smaller craters.

Click to see the original high resolution image from Mars Express [See ESA article]

Previous estimates placed the number of yearly impacts on the Martian surface at 3 to 10 times the amount recently calculated. Those previous studies were done in the 1960s and 1970s and based off studies of lunar craters. MRO's HiRISE Principal Investigator Alfred McEwen says that this new study means "Mars now has the best-known current rate of cratering in the solar system," meaning that of all the bodies in the solar system, Mars is the one we are best able to determine the frequency of asteroid and comet impacts on.

Dwayne Brown, Guy Webster, Daniel Stolte. NASA Probe Counts Space Rock Impacts on Mars. 15 May 2013.NASA (accessed 15 May 2013) 

Mars Travel's Mars Photo of the Day - 15 Sept 2012