U.S. Sen. Barbara Mikulski (D-Md.) may be onto something with her proposal for emergency legislation to help NASA recoup the roughly $2 billion she says the agency has paid to return the space shuttle fleet to flight following the Columbia disaster.

The emergency designation would exempt the funding from limits Congress sets when it divvies up the annual federal budget pie among its various appropriations committees. Critics might dismiss Sen. Mikulski’s proposal as a cap-skirting gimmick that would only add to the ballooning federal deficit, but a strong case can be made that NASA is facing an emergency.

The emergency stems less from the cost of returning the orbiter fleet to flight — most of that bill has been paid already — than from the fact that the White House has failed to fund NASA at the levels promised back in 2004, when it charted a new course for the U.S. space agency in the wake of the Columbia tragedy. That course entails retiring the space shuttle fleet by 2010 and completing the international space station, and building a new vehicle to transport astronauts to and from the station and lunar orbit, all while maintaining a healthy space science program.

The science community went along with U.S. President George W. Bush’s Vision for Space Exploration with the understanding that it would come with sufficient funding increases to allow NASA to continue studying the heavens with unmanned probes. But the White House has not lived up to its end of the bargain: NASA’s 2007 budget request is some $1 billion short of what it would have been had the president followed through on his promise three years ago to boost the space agency’s spending by an annual average of about 4 percent. Compounding this is the fact that the White House underestimated space shuttle program costs through 2010, while the return-to-flight bill has grown far larger than anyone anticipated.

In an effort to stay on track with retiring and replacing the space shuttle, NASA Administrator Mike Griffin was forced to renege on a promise not to make science the bill payer for these activities. NASA’s 2007 budget request calls for an increase of 1.5 percent in this area, which amounts to a decline when inflation is factored in. This has led to an open rebellion by the space science community that threatens to tear apart the fragile coalition upon which the Vision for Space Exploration rests.

The precedent for Sen. Mikulski’s proposal is the emergency bill that helped get NASA’s shuttle fleet up and flying again after the 1986 Challenger disaster. One could argue that NASA faces an even more dire set of circumstances today: a four-year gap — and possibly much longer — in its human spaceflight capability precipitated by the decisions that were forced by the Columbia tragedy and its aftermath. The fact that the bills directly attributable to NASA’s return-to-flight efforts have been mostly paid by now is beside the point.