NASA just released its presidential budget request for 2013 and, as expected, the space agency's planetary science program takes a big hit. The budget document (summary pdf) is merely the first volley in an often drawn-out exchange between the White House and Congress, but still sets the general direction for the space program. Although the Obama administration's proposal would slice less than 1 percent from NASA’s current budget, it proposes some major shifts of funds within the agency.

The planetary science program, which received $1.5 billion for 2012, would take a 20 percent cut. NASA would still fly the Mars MAVEN atmospheric mission in 2013 but would back away from two joint missions with the European Space Agency:

NASA is terminating further activity on the formulation activity for the NASA/ ESA ExoMars Trace Gas Orbiter 2016 (EMTGO) mission and planning for the previous NASA/ESA Mars 2018 mission concept.

The latter mission would have included the first direct search for life on Mars since the Viking landers of the 1970s. With NASA bailing out, ESA is now casting around for another partner.

The planetary science community has seen this coming for some time now. In September, a group of 18 prominent planetary scientists signed an open letter warning that the James Webb Space Telescope (NASA's costly, complex planned successor to the Hubble Space Telescope) was eating up funds previously earmarked for planetary missions. Ed Weiler, who had been NASA's associate administrator for the Science Mission Directorate, resigned in September, partly in protest over the impending cuts. "The Mars program is one of the crown jewels of NASA," Weiler told Science. "In what irrational, Homer Simpson world would we single it out for disproportionate cuts?"

The Webb telescope is indeed taking an ever larger slice of a slowly shrinking pie. Under the proposal, it would get $627.6 million for 2013, up from $518.6 million in 2012 and $476.8 million in 2011. An even more dramatic boost, albeit one outside the NASA sector that includes planetary science and the Webb telescope, would go to programs that stimulate the commercial spaceflight industry. The Obama administration wants private firms such as SpaceX and Boeing to launch future U.S. astronauts to orbit, a job that has traditionally been NASA's. With the retirement of the space shuttle, the next time NASA astronauts lift off from U.S. soil they will likely do so as paying customers on commercially operated rockets. The president asked for $829.7 million for commercial spaceflight for 2013, more than double what those programs received in 2012.

The details of NASA's final budget will take months to work out, but it looks as if the agency's next stab at looking for life on Mars will hit the NASA scrapheap, joining other once-promising missions such as the Laser Interferometer Space Antenna and the Space Interferometry Mission as victims of the current budget morass.