Planetary scientists, usually an affable lot, are plenty riled up at the moment.

The field is bristling at cutbacks, proposed last month by the Obama administration, to planetary science and especially to NASA’s program of robotic Mars explorers. Researchers gathered here for the annual Lunar and Planetary Science Conference have taken turns railing against the cuts, in scientific lectures, in conference center hallways and in open meetings with NASA management. One NASA official, having briefed a group of scientists on one facet of the budgetary outlook, joked about needing a Kevlar flak jacket for his talk.

In the budget proposed by Obama for the 2013 fiscal year (pdf), NASA’s planetary science division would lose more than $300 million compared with the previous year. The bulk of that would come from Mars exploration. If Congress agrees to the Obama plan for NASA, the Mars exploration program would lose roughly $225 million, a cut of more than 38 percent. (Some members of Congress have already protested the cuts; NASA Administrator Charles Bolden will appear before a House subcommittee this week to discuss the budget.)

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