By Irene Klotz
CAPE CANAVERAL, Florida (Reuters) - NASA's $2.5 billion Mars Science Laboratory, a nuclear-powered, car-sized rover designed to assess the planet's suitability for life, reached the Kennedy Space Center for launch preparations, officials said on Thursday.
Aboard the Air Force cargo plane with the rover, named Curiosity, was the complicated landing system it will use for a pinpoint touchdown on Mars in August 2012.
Curiosity is about four times bigger and has many more science instruments than NASA's last Mars rovers, Spirit and Opportunity, which reached the Red Planet in 2004 for what were expected to be three-month missions.
Seven years later, Spirit is no longer working, but Opportunity remains operational. Those rovers were dispatched to look for signs of past water on Mars.
The new rover's bigger size and more robust science capabilities are intended to answer a thornier riddle: Does the Red Planet have, or has it ever had, the right conditions for microbial life to arise?
The rover is designed to spend at least one Martian year -- the equivalent of almost two Earth years -- surveying the selected region to assess habitability.
Problems developing the "sky crane" descent system forced NASA to miss its original launch opportunity in 2009 and added $800 million to the project.
"The design and building part of the mission is nearly behind us now," David Gruel, manager of Mars Science Lab's assembly, test and launch operations at NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement.
The agency's inspector general warned earlier this month that NASA was in danger of missing this year's launch opportunity as well, a period that opens November 25 and runs through December 18 when Earth and Mars are favorably aligned for interplanetary transport.
But NASA said it had resolved issues by the June 8 report and is in good shape for meeting the opening of the probe's launch window.
NASA is in the midst of a final assessment of four potential landing sites.
(Editing by Tom Brown and Sandra Maler)