Mercury is the closest planet to the Sun, and as a result is a dry, barren planet scorched by solar heat. Parts of Mercury’s surface often exceed 450 °C (840 °F) when the planet is closest to the Sun. However, at night, temperatures can drop by over 600 °C (1,100 °F) and some scientists believe that there is actually ice in deep craters that never see the Sun. Radar imaging of the planet has revealed areas of high reflectivity near the planet’s poles. This may be frozen water carried to Mercury by meteorites.
This orthographic projection view provides a look at Mercury’s North Polar Region. The yellow regions in many of the craters mark locations that show evidence for water ice, as detected by Earth-based radar observations from Arecibo Observatory in Puerto Rico. MESSENGER has collected compelling new evidence that the deposits are indeed water ice, including imaging within the permanently shaded interiors of some of the craters, such as Prokofiev and Fuller. The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft’s seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System’s innermost planet. In the mission’s more than four years of orbital operations, messenger has acquired over 250,000 images and extensive other data sets. messenger’s highly successful orbital mission is about to come to an end, as the spacecraft runs out of propellant and the force of solar gravity causes it to impact the surface of Mercury in April 2015.