NASA rover closes in on Mars to search for life clues

This artist's concept features NASA's Mars Science Laboratory Curiosity rover as seen in this handout NASA image. Credit: Reuters

NASA's Mars rover is heading to the red planet, towards a mountain that may hold clues about whether life has ever existed on Mars. The rover, also called Curiosity, has been travelling to Mars since its launch in November.

The nuclear-powered rover, the size of a small car, is due to end its 352-million-mile journey on August 6 at 1:31 am EDT (0531 GMT). The landing zone is a 12-mile-by-4-mile area inside an ancient impact basin known as Gale Crater, which is near the planet's equator.

Three of six 20 inch aluminum wheels are seen on an engineering model of NASA's Curiosity Mars rover. Credit: Reuters

The crater, one of the lowest places on Mars, has a 3-mile-high mountain of what appears to be layers of sediment. Scientists suspect the crater may have once been the floor of a lake. If so, they believe that sediments likely filled the crater, but were carried away over time, leaving only the central mound. Getting ready to travel the last stretch to its landing site, Curiosity fired its steering thrusters for six seconds, tweaking its flight path by 0.4 inches per second.

The area where NASA's Curiosity rover will land on Mars on August 6, 2012 is seen in this NASA handout. Credit: Reuters

Curiosity is expected to hit the top of the Martian atmosphere at 1:24 a.m. EDT on August 6. If all goes as planned, seven minutes later the rover will be standing on its six wheels on the dry, dusty surface of Mars.

Landing is by no means guaranteed. To transport the one-ton rover and position it near the mound, engineers devised a complicated system that includes a 52-foot diameter supersonic parachute, a rocket-powered aerial platform and a so-called "sky crane" designed to lower the rover on a tether to the ground.

NASA last week successfully repositioned its Mars-orbiting Odyssey spacecraft so that it would be able to monitor Curiosity's descent and landing and radio the information back to ground controllers in as close to real time as possible.

Earth and Mars are so far apart that radio signals, which travel at the speed of light, take 13.8 minutes for a one-way journey.