Mercury A to Z: Prokofiev Crater

Hello, friends!  My theme for this year’s A to Z Challenge is the planet Mercury, a planet that just never seems to get the same love and attention as all the other planets of the Solar System.  In today’s A to Z post, P is for:

PROKOFIEV CRATER

We haven’t talked about this as much as I expected to, but there is ice on Mercury.  The frozen water kind of ice.  Craters near Mercury’s north and south poles are shielded from direct sunlight throughout the Mercurian year.  As a result, despite the proximity of the Sun, the bottoms of these craters are dark enough and cold enough to allow ice to remain frozen.  One of the largest and, perhaps, most well studied of Mercury’s icy craters is Prokofiev Crater, near Mercury’s north pole.

Prokofiev Crater is named after Russian classical composer Sergei Prokofiev.  The crater is slightly removed from the north pole, and so part of the crater floor does get exposed to direct sunlight during part of the Mercurian year.  However, there is still a large region inside the crater that remains in permanent shadow.  That same region also happens to be a radar bright spot, meaning that radar beams directed at Mercury reflect off that region in an especially bright and brilliant way.

These super bright radar reflections could be caused by water, but they could also be caused by large deposits of metal.  In the early 2010’s, NASA’s MESSENGER space probe took a much closer look, using multiple scientific instruments, and confirmed that the radar reflections in Prokofiev (and other neighboring craters) are indeed caused by frozen water.

Now ever since I first heard about ice on Mercury, there was one thing I wanted to know: is it possible to go iceskating on Mercury?  I’ve done research on this in the past, and I couldn’t find a clear answer.  Is the ice exposed on the surface, or is it covered by a layer of dust and rock?  Most sources I looked at were vague about that.  I got the impression that nobody really knew for certain.  But it seems there’s been some new research since the last time I looked into this.

In most cases, Mercury’s ice is covered by some sort of insulating layer.  But in the largest, deepest, and coldest craters on Mercury—craters like Prokofiev Crater, as well as nearby Kandinsky Crater, Tolkien Crater, and Chesterton Crater—the ice is most likely out in the open, exposed or partially exposed, just waiting for somebody with a spacesuit and a pair of ice skates to show up.

Someday, if humans decide (for some reason) to settle on Mercury, places like Prokofiev Crater will be prime real estate.  Not just for iceskating but for basic survival reasons. Humans need water, after all.

Personally, I wouldn’t mind living in nearby Tolkien Crater, because that’s the kind of nerd that I am.  However, I’d strongly advise that nobody should live in Lovecraft Crater, a large, icy crater near Mercury’s south pole.  If you’re familiar with H.P. Lovecraft’s work, you’ll know why.

WANT TO LEARN MORE?

Here are maps of Mercury’s north and south poles, showing the locations of radar bright spots, regions in permanent shadow, and where the two overlap.

Here’s an article from NASA explaining the different experiments MESSENGER used to confirm the presence of water in Mercury’s polar craters.

And here is a 2022 paper published in The Planetary Science Journal confirming that water ice lies exposed on the surface inside Prokofiev Crater.