Nasa and space shuttle’s do-or-die Hubble mission

It's a mission so dangerous that it seems fitting for Tom Cruise's Top Gun pilot stunt double to be at the controls. On May 11, space shuttle Atlantis is scheduled to lift off, bound for a rendezvous with the orbiting Hubble telescope.

Captain Scott Altman - who performed aerial stunts for Tom Cruise's character in the 1985 film, ten years before joining Nasa's astronaut corps - will lead the mission which aims to perform a spacewalk to repair four broken functions and upgrade Hubble so that it boasts 14 "instrumentations".

"It will never have been better, and it's at the apex of its operations," said David Lectrone, the Hubble project manager. The mission will be the 19-year-old space observatory's final service before it is decommissioned and allowed to burn up on re-entry some time around 2020.

But casting a shadow over the excitement of returning the Hubble telescope back to full working order is the very real prospect of failure and what that would mean for the future not just of Nasa, but of the whole concept of manned spaceflight.

Confidence in the 30-year-old space shuttle is so low following the disaster of 2003 when the Columbia disintegrated during re-entry that on a nearby launchpad, the space shuttle Endeavour is waiting, ready to launch a rescue mission within seven days of a Mayday call.

The Hubble upgrade is one of nine final missions due to be undertaken before the planned retirement of the space shuttle program in 2010. The trouble is there is no definite successor planned for the Nasa workhorse.

Nasa could even use commercial enterprises to send astronauts into space

The shuttles' supposed replacement, a combination of the Orion crew module and Ares rocket dubbed 'Project Constellation' which is supposed to return man to the moon by 2020 and possibly form the basis of a mission to Mars, won't enter service until 2015 at the earliest. It's looking likely that Nasa astronauts will be forced to hitch a ride with Russian spacecraft during the intervening five years.

The agency could even use commercial enterprises to send its astronauts into space. Nasa is already planning to use a company called SpaceX to carry cargo to the International Space Station from 2010 on its unpiloted Dragon capsule and Falcon 9 rocket – subject to successful test flights later this year.

Neither option is ideal, which is why there is a movement in Washington - led by Florida congressmen scared stiff of the consequences of up to 6,400 shuttle-related job cuts from the Kennedy Space Center - to delay the retirement of the space shuttle program. They are working on a resolution that would provide $2.5bn to fund shuttle missions up to the end of 2011. The problem is, Nasa needs almost that much per year just to keep Project Constellation on track.

The expected budget squeeze is so severe that the agency may be forced to pull out of the International Space Station early to save money. A congressional mandate to delay action on the shuttle’s future expires tomorrow. At that point NASA officials will be free to start the phase-out of the fleet if they so choose.

But nothing is likely to be decided until President Obama, who many space-enthusiasts suspect of being lukewarm on manned spaceflight, finally chooses a new administrator for Nasa, which has been rudderless since the departure of Mike Griffin in January - and presents a detailed plan for Nasa’s proposed $18.7bn budget to Congress in May. On the eve of the Hubble mission, never before has Nasa been in such need of a successful maintenance job. ·