Images from NASA's Phoenix lander released late Thursday appeared to confirm the presence of buried ice on Mars, the first evidence that the spacecraft landed in the right spot last month to find water on the Red Planet.

Pictures taken of a trench dug earlier in the week by the lander's nearly 8-foot-long robotic arm showed that eight small, whitish chunks of material at the base of the trench had disappeared by Thursday.

If those chunks had been some form of salt, as some scientists believed, they would not have evaporated, said Peter Smith of the University of Arizona, the lead scientist for the $420-million mission.

Phoenix parachuted to the Martian north pole May 25 with the primary goal of finding water, which is crucial for determining whether the planet ever was, or still might be, habitable for rudimentary forms of life.

Water is also a key element of NASA's long-range dreams to send humans to the planet because it not only would be necessary to sustain the first generation of pioneers but would be a source for fuel.

Nearly two weeks ago, the lander's robotic arm began digging into the soil. On Sunday, it enlarged the trench that scientists named Dodo-Goldilocks. At one edge of the 2-inch-deep trench were eight chunks of whitish material, each less than an inch across.