Remember that mystery white substance that the Phoenix Lander uncovered beneath Martian soil with its robot arms? Scientists were speculating that it might be salt or it might be ice. Now, a few days later, it's looking very much like ice. Why? It's melting, as you can see in these pictures.
This represents a huge breakthrough for the mission, which had until now been unable to find much solid evidence that frozen water existed beneath the Martian pole. A release from NASA quoted lead researcher Peter Smith, who said:
It must be ice. These little clumps completely disappearing over the course of a few days, that is perfect evidence that it's ice. There had been some question whether the bright material was salt. Salt can't do that.
Early yesterday, Phoenix was digging in a trench unrelated to the icy one, and found a very hard surface that scientists might be an entire layer of ice beneath the planet's surface. This bodes well for future missions to Mars that contain humans. If the ice can be converted into something drinkable, it could become a supply of much-needed water for thirsty colonists.
Exploring the Arctic Plane of Mars [via NASA]