It's only when the first radar observations to the surface of Mercury were obtained back in the 90s that it was discovered that Mercury in fact, had what appeared to be polar caps in these first radar images.

 

Some corners of Mercury’s polar craters are in permanent shadow. Here, on the most sun-baked planet of all, water seems to survive frozen in / eternal darkness.

 

The ice is contained in places where literally the sun never shines, and so the ice is quested in these dark, interiors of craters of the high latitude regions.

 

We found the same thing on our moon. In late 2009, the LCROSS mission crashed a probe into a deeply shadowed crater confirming ice hidden near the lunar South Pole. Where did it come from? A comet? 

 

It's very interesting. Because we believe that the water in the earth, in its atmosphere, in the oceans, and even below the surface, probably came from the similar source, and so part of the mystery of Mercury is to try to find out where the water came from, and maybe that might help us find out where the water of earth came from. 

 

It may never be possible to send a human to Mercury, but how about a robot? In 2011, when Messenger arrives in orbit, imagine this tough little spacecraft circling a lonely planet a very long way from home.