• Close-up of a 12-metre diameter impact crater formed between 25 October 2012 and 21 April 2013 (NASA/GSFC/Arizona State University)Source: NASA/GSFC/Arizona State University
No atmosphere means our satellite is being constantly bombarded.
By
Signe Dean

13 Oct 2016 - 2:28 PM  UPDATED 13 Oct 2016 - 2:32 PM

A new study has revealed that the Moon’s already pockmarked face acquires new craters at a much faster rate than previously thought.

This news is important for potential future Moon settlement missions - not only is it good to know your risk of being hit by a space rock over there, but it also gives us an idea of the churn of hazardous surface dust.

Unlike our planet, the Moon has no protective atmosphere in which to burn up meteorites, so the surface gets bombarded at a steady rate. Now a team of researchers, led by Emerson Speyerer from Arizona State University, have determined how often our rocky satellite gets a new crater.

To do this, they compared more than 14,000 pairs of before-and-after photos of the lunar surface, analysing data collected by NASA’s Lunar Reconnaissance Orbiter. The study was published yesterday in Nature.

The research revealed 222 new craters in the time period studied, which is 33 per cent more than the usual impact frequency models predict. According to the researchers, that works out to an annual count of about 180 new craters of at least 10 metres in diameter.

This doesn’t mean that standing on the surface of the Moon puts you at high risk of being hit - but these impacts do kick up a lot of smaller rocks, showering them across the surface in lots of small “secondary impacts.”

"Future lunar bases and surface assets will have to be designed to withstand up to 500 metre per second impacts of small particles," Speyerer tells Space.com news.

In fact, the researchers counted some 47,000 splatter-like changes on the Moon’s surface caused by these secondary impacts, and some of these were up to 30 kilometres away from the initial space rock crash site.

“If you are an astronaut sitting on the surface, you don’t necessarily have to worry about being directly hit by a meteorite, but you would have to worry about all these secondaries, that are coming from kilometres and kilometres away,” Speyerer tells New Scientist.

There’s more to the study than just safety of future lunar astronauts, however - knowledge gleaned from analysing impact craters and their aftermath will prove valuable in our efforts to learn more about other such bodies in the Solar System and beyond. 

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