The NASA scientists are ready to uncover Mars’ secrets as a new probe destined to dig into the arctic northern plains of the planet is on track for its planned Saturday launch.

To find out more, the Phoenix will use instruments to analyze the samples for elements that could help support life. The cost of the mission is close to 420-million-dollar.

The space craft is scheduled for takeoff on Saturday, toward the beginning of a window through August 24 that positions Earth for a clear shot at Mars. Because the planets are only properly aligned every 26 months, another launch window won't be open until 2009.

A Delta II launch vehicle will carry the Phoenix Mars Lander into Earth orbit and, about 90 minutes later, give it the push needed to send it to Mars.

Phoenix was scheduled to be launched on August 3, but it was delayed due to the bad weather.

"Mars is a great opportunity. We always have exciting missions, but missions to Mars just seem to capture the imagination," NASA's launch director Chuck Dovale said.

The launch will take place before dawn dawn to maximize the chances of clear weather in a season that often brings afternoon thunderstorms to NASA's Kennedy Space Centre in Florida.

"We have worked for four years to get to this point, so we are all very excited," said Barry Goldstein, Phoenix project manager at NASA's Jet Propulsion Laboratory, Pasadena. "Our attention after launch will be focused on flying the spacecraft to our selected landing site, preparing for surface operations, and continuing our relentless examination and testing for the all-important descent and landing on May 25 of next year." 

Phoenix, which is due to reach Mars on May 25 , will travel 679 million kilometers (422 million miles) in an outward arc from Earth to Mars. It will determine whether icy soil on far northern Mars has conditions that have ever been suitable for life. Phoenix's robotic arm will use a scoop shovel to dig as far as 1 metre into a mixture of ice, rock and dust at its landing place.

"Phoenix investigates the recent Odyssey discovery of near-surface ice in the northern plains on Mars," scientist Peter Smith of the University of Arizona said. "Our instruments are specially designed to find evidence for periodic melting of the ice and to assess whether this large region represents a habitable environment for Martian microbes."