The European Space Agency has shared an incredible composite image showing a 50-mile wide crater on Mars that is filled with water ice all year long. Budding future colonists hoping for a white Christmas on Mars will be somewhat disappointed as the ESA has confirmed that sitting in the Korolev crater is, in fact, a thick block of water ice, not snow. The enormous, 82-kilometer-wide, 2-kilometer-deep "ice trap" could still be good for ice skating though. Even better, the 2,200 cubic kilometers of water ice – same as the volume of Canada's Great Bear Lake – could be important for the survival of future colonists, and may even enable them to return back home, as water could be split into hydrogen and oxygen for rocket fuel. The crater is found in the northern lowlands of Mars near the planet's north pole which is known as Olympia Undae for its wavy, dune-filled terrain. The crater's ice