Washington

Mounting criticism of NASA's decision to cancel an upgrade of the Hubble Space Telescope will surface at a congressional hearing this week. Critics are expected to charge that the agency has not been honest about its reasons for the cancellation.

NASA administrator Sean O'Keefe has repeatedly said that astronaut safety — not money — is behind the decision. The 2006 space shuttle mission would have installed two new science instruments and replaced gyroscopes and batteries in the 14-year-old telescope to extend its life to 2010. Without this repair, one of NASA's most productive scientific missions could fail as early as 2007.

Many astronomers think that the real reason for cancelling the mission is to conserve resources to fund President George Bush's proposal to return astronauts to the Moon. The House Committee on Science, chaired by Sherwood Boehlert (Republican, New York), will hold a hearing on 12 February on the plan, with O'Keefe and White House science adviser John Marburger as the main witnesses.

Committee members are expected to raise two reports by an unnamed NASA engineer that are circulating on the Internet. These contend that O'Keefe's statement that a Hubble flight would be riskier than space station flights “cannot be supported” on technical grounds. Hubble's higher orbit actually poses less of a threat of orbital debris hitting the shuttle's fragile insulating tiles, say the reports. And NASA's plan to have another shuttle ready to rescue astronauts in case their vehicle fails could just as well be used for Hubble missions as for space station missions, the reports argue.

Many in the space community have questioned O'Keefe's decision, none more harshly than Robert Zubrin, president of the Mars Society, a group that advocates manned Mars expeditions. “The grounds given for deserting Hubble are irrational, and constitute a form of moral cowardice that if accepted as the basis of space policy, would absolutely prevent any human missions to the Moon, Mars, or anywhere else,” Zubrin said in a statement last week.

The controversy pits scientists against NASA at a time when the agency could do with their support for President Bush's widely criticized Moon initiative. It also calls into question the regime of openness that O'Keefe has said he is implementing. The New York Times reported on 7 February that the author of the reports wished to remain anonymous for fear of losing his job.