NASA announced today that it will delay the launch of the Mars Science Laboratory (MSL) until late 2011, postponing the rover's sweeping mission by more than two years.

In a news briefing, NASA Administrator Michael Griffin said that the agency was "not going to gamble on launch" in fall 2009. The agency says it needs more time to ready and test the equipment to ensure a successful mission, and the launch window to reach Mars requires a 26-month delay.

"The vast majority of the hardware has been built and completed," Charles Elachi, director of NASA's Jet Propulsion Laboratory, said at the press conference held at NASA headquarters in Washington, D.C. But there was no guarantee the MSL would be ready by next fall to land safely and carry out science experiments on Mars. This project, Elachi said, is much more complex than its predecessors. Doug McCuistion, director of the Mars Exploration Program at NASA HQ, added that MSL "literally dwarfs anything we've done before," with the rover weighing in at nearly a ton compared with about 400 pounds apiece for the Spirit and Opportunity rovers.

"Failure is not an option," McCuistion said, noting that the only way to avoid it is "to test [the rover] to within an inch of its life." He estimated that delaying the mission until 2011 would add $400 million to the project's price tag as staff and facilities are kept on hold and further tests are carried out, bringing the total tab to around $2.3 billion—a number that may still rise.

The mission is designed to determine whether Mars ever sustained life, to examine in greater detail the Martian surface and climate, and to help prepare for a future human presence on the Red Planet.

Artist's conception of Mars Science Laboratory courtesy of NASA/JPL-Caltech