NASA launched the first of two robotic rovers to Mars on Tuesday in an international quest to determine if life ever existed on the red planet.
After two days of weather delays, the Mars Exploration Rover, nicknamed "Spirit," lifted off from Cape Canaveral as part of a global fleet of probes sent to Mars.
If the rover Spirit and its twin, Opportunity, which is scheduled to be launched later this month, succeed, scientists will know if ancient, now-vanished, water sources on Mars were there long enough for life to emerge.
Mars is a perilous destination for spacecraft. Of 30 missions launched by various nations over the years, only 12 have succeeded. Landing on the surface is even harder, with just three of nine attempts ending in success.
"We celebrate in just small steps, one at a time. The launch is just the beginning of the journey," Orlando Figueroa, the NASA Mars program manager, told reporters after the launch.
The rovers will join Japanese and European satellites on their way to Mars and two NASA satellites already orbiting there. The launches take advantage of a rare proximity between the planets that has cut the normal travel time to seven months from the usual nine to 10 months for missions launched this year.
The two Mars explorers, worth a combined $800 million and each about the size of a golf cart, are wrapped inside a landing craft that will descend by parachute to Mars after a seven-month, 311-million-mile (498-million-km) voyage.
After nine balloons have deployed, completely enveloping the landing craft, it will bounce along like a toy on the Martian surface as much as a mile (1.6 km) before coming to rest.
{{/usCountry}}After nine balloons have deployed, completely enveloping the landing craft, it will bounce along like a toy on the Martian surface as much as a mile (1.6 km) before coming to rest.
{{/usCountry}}Large petals on the landing craft will then open like a flower, allowing the six-wheeled rover to roll off and begin its exploration.
"It'll take us about four days in all to get completely off the lander and get what we call six wheels on the ground," said Peter Theisinger, the mission manager.
The solar-powered rovers will land where scientists think large bodies of water once formed, before some cataclysmic event or epoch stripped Mars of most of its atmosphere, causing much of its surface water to boil away.
The rovers can travel about 100 metres an hour on a flat surface with no obstacles. Small cameras facing to the front help it identify rocks or holes too large to cross.
"If it finds itself in a situation it cannot work out of, it will actually call home for help," said Theisinger.
The rovers have the ability to scoop up soil and drill into rocks, then examine the samples under a microscope. Raw data will be sent back to Earth for analysis by scientists at the Jet Propulsion Laboratory in Pasadena, California, where mission control will be located.