Messenger finally captures images of ice first detected on Mercury in 2012.
The images were captured by NASA's MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft. The images, some seen here, show definitively that ice exists in the 70-mile-wide Prokofiev crater near Mercury's north pole. Furthermore, NASA says this photographic evidence confirms that the ice is relatively new -- it hasn't been around since the planet formed billions of years ago.
NASA has had evidence of ice on Mercury for years, thanks to radar and other instrumentation, but this is the first time images have been captured with enough sunlight to show off the ice. Enough sunlight? Yes, Mercury is next to the Sun, but the crater's shape and location leave its inside in near-perpetual darkness.
NASA believes ice is located in other craters on the hottest planet, too, but these deposits are covered by "frozen, organic-rich material."
The MESSENGER craft was launched in 2004, entered service in 2011, and its primary objectives are to study Mercury's geology, and geography.
Geology Journal has a full breakdown of the discovery, and the PDF can be found here.