Nasa Revising its Mars Master Plan

NASA has been engaged since last year in what the agency calls a roadmapping effort to flesh out the details of a Mars master plan that would lead to an expeditionary crew landing on that remote world.

One scenario that has been under active discussion is slipping the mission of the mobile, nuclear-powered Mars Science Laboratory, or MSL, from 2009 to 2011. Another possibility was building two MSL rovers to double the data that could be gathered during that mission and reduce program risk.

James Garvin, the chief scientist at NASA Headquarters in Washington, said the space agency’s science program is undergoing a "rebalancing." He said the status of MSL is still under review, but also said he thinks the prospect for launching two MSL rovers "is long gone."

"Right now, my aim is to ensure one, full-scope Mars Science Laboratory, at the least risky opportunity and best-suited to making revolutionary scientific discoveries," Garvin told Space.com.

Garvin also said that maintaining progress with the Phoenix Mars lander, which is being readied for a planned 2007 launch, and MSL in either 2009 or 2011 "is essential if the rapid pace of scientific progress is to be continued."