PASADENA, CA - MAY 25:  Phoenix principal investigator, University of Arizona, Peter Smith (L) and Phoenix project manager, JPL, Barry Goldstein address a final press conference before an illustrative video of the Phoenix Mars Lander approaching Mars at Jet Propulsion Laboratory (JPL) prior to today's expected landing of NASA's Phoenix Mars Lander on a northern polar region of Mars May 25, 2008 in Pasadena, California. The Phoenix Mars Lander is the newest hope in the search for signs of life on Mars. Fewer than half of the Mars missions have made successful landings. At a cost of $420 million, the Phoenix Mars Lander has flown 422 million miles since leaving Earth in August 2007. Getty Images logo Getty Images 18 months ago

PASADENA, CA - MAY 25: Phoenix principal investigator, University of Arizona, Peter Smith (L) and Phoenix project manager, JPL, Barry Goldstein address a final press conference before an illustrative video of the Phoenix Mars Lander approaching Mars at Jet Propulsion Laboratory (JPL) prior to today's expected landing of NASA's Phoenix Mars Lander on a northern polar region of Mars May 25, 2008 in Pasadena, California. The Phoenix Mars Lander is the newest hope in the search for signs of life on Mars. Fewer than half of the Mars missions have made successful landings. At a cost of $420 million, the Phoenix Mars Lander has flown 422 million miles since leaving Earth in August 2007.