Today the journal Science weighed in on the MSL slip. Hightlights:
"The extra money, says NASA science chief Edward Weiler, will come from other projects involving Mars and possibly other planets. The queue contains three spacecraft to be launched in 2011--a small atmospheric probe to Mars, a robot to survey Jupiter, and a mission to chart the moon's interior. A 2016 Mars mission that has not been fleshed out will cost $800 million to $1.4 billion. And next month, NASA is expected to select a $3 billion spacecraft to study a moon of either Jupiter or Saturn that would be launched by 2020. "There will be impacts," says Weiler. "We probably will have to delay a major planetary mission.""
On possible cooperation between NASA and ESA on a 2016 Mars rover: "David Southwood, ESA's director of science, is reluctant to discuss NASA's possible contributions to ESA's ExoMars mission, proposed for 2016, before joint technical discussions are held early next year. He says that "some things are at the heart of the European investment," noting that ESA wants to test its mettle at landing on Mars and roving across its surface. But providing an orbiter to aid communication with Earth or instruments for the lander are areas in which NASA might be able to help, he adds. Cooperation would also be vital for any sample-return mission. This collaboration "is lifting a curtain on the future," Southwood says."