Some will say that scientists overreacted to last week's threatened termination of NASA grants for outer-planets research (see page 447). It was much ado about nothing — the money will be awarded after all. But it shows how jumpy space scientists are these days at any hint that their budget might be raided.

They're right to worry. NASA is heading for deep financial trouble, and no one in Washington appears willing to say so.

NASA scored a victory of sorts in the autumn when the White House and Texas Republican Tom DeLay, the most powerful figure in the House of Representatives, made sure the agency got nearly its full budget request of $16 billion. Congress also removed the barriers that prevented NASA managers from using space-science funds to solve other problems within the agency.

But these moves can only temporarily hide the truth — that NASA simply can't afford a vigorous space-science programme, a space station, the space shuttle and a new Moon–Mars astronaut programme, all on $16 billion a year. The shuttle costs $4 billion a year when things are going smoothly. NASA plans to fly 28 shuttles to the space station between now and 2010 — more than the average of 4.7 launches a year, even though the ageing shuttle is down from four vehicles to three and launch directors will be more cautious than ever. Expect delays and cost overruns: the cost of fixing a few systems after the Columbia accident is $1.5 billion and counting. The White House promised that its new “vision” would be paid for by phasing out the shuttle and space station, but that already seems like a pipe-dream.

If NASA is committed to finishing the space station, and the Moon–Mars plan remains a White House priority, that leaves only science to cut. But agency managers won't admit this. The battle over servicing the Hubble telescope is a case in point. Outgoing administrator Sean O'Keefe claimed that his decision last year to ban astronaut repair missions to Hubble was based solely on safety. But a National Academy of Sciences panel and the head of the Columbia accident investigation both say a Hubble mission is not significantly more dangerous than a trip to the space station.

No wonder scientists suspect it's really about money. NASA says that any Hubble servicing option — using astronauts or robots — will cost about $2 billion. What do they get for this? A November report by the Government Accountability Office revealed that nearly half the estimated price of an astronaut servicing mission is for extending the shuttle's life by three months beyond the planned phase-out in 2010. In other words, NASA would charge its space-science office for the repair flight, something it never used to do, and had not planned to do before the Moon–Mars plan was announced.

Congress will take up the subject of Hubble servicing in a hearing this week. Politicians in Maryland, the home state of the Space Telescope Science Institute, have already promised to come to the telescope's rescue, and some astronomers hope Congress will simply restore the funds for Hubble servicing if the White House cuts them from the NASA budget as expected.

But that would be no substitute for honesty and realism. If NASA maintains its present course, the shuttle and space station will be a drain on its finances for years, leaving little money for the Moon and Mars. And it will be an even greater tragedy if science, NASA's most forward-looking enterprise, suffers to make up the shortfall.