Debris could hamper shuttle’s Hubble missionby Todd Halvorson on Sep. 09, 2008, under Nation/World
HOUSTON – NASA’s Hubble Space Telescope repair crew faces a serious chance of a catastrophic space debris strike during a mission next month – a risk so high the agency’s top executives will have to OK the flight.
But senior managers say the astronauts, in a worst case scenario, would be able to inspect their ship, make repairs or shelter in place until another shuttle on standby could be launched on a rescue mission.
“We have done everything you can do to mitigate this,” NASA shuttle program manager John Shannon said Monday. “However, it’s understood that this is the environment, so this is the risk, and it will be up to the agency to accept that risk.”
Atlantis and seven astronauts are scheduled to blast off Oct. 10 from Kennedy Space Center on NASA’s fifth and final mission to service the Hubble Space Telescope.
Top-level NASA executives will meet with shuttle managers later this month in a review that will include an analysis of an increased chance – 1 in 185 – that Atlantis could be destroyed by a micrometeoroid or orbital debris strike.
The Hubble telescope is flying in an orbit 350 miles above Earth, one littered with thousands of tiny meteorites and pieces of space junk that travel at speeds up to six miles per second. A collision with the shuttle could cause catastrophic damage.
Holes could be punched in the hull of the spaceship, triggering a rapid and deadly decompression. A fiery atmospheric reentry would be too dangerous if a small space rock or a wayward piece from an exploded rocket stage breached the shuttle’s fragile heat shield.
The danger from micrometeoroid and orbital debris is so great that NASA in 2003 raised it to the No. 1 risk faced by astronauts during shuttle missions – higher than the chance of main engine or solid rocket booster failures.
“I’ll tell you this, too: It’s not theoretical,” Shannon said.
Shuttles return with damage from orbital debris on every flight. Spacewalking assembly workers at the International Space Station note bullet-like holes in solar wings and other damage on every construction mission.
And the problem is growing.
A Russian spy satellite and the fourth stage of a rocket from India exploded in 2001, creating clouds of deadly shrapnel.
China blew up a weather spacecraft as part of an anti-satellite missile test in 2007. The U.S. shot down a malfunctioning American spy satellite in February.
Said Shannon: “The environment has gotten worse.”
A shuttle visiting the space station – which circles in a less littered orbit 220 miles above Earth – faces a 1-in-300 chance of a catastrophic hit.
NASA safety guidelines call for a top-level examination if chances exceed 1 in 200. The topic will be taken up at an executive flight readiness review to be held Sept. 22. Senior shuttle managers will lay out actions taken to mitigate the risk. They include:
- Inspection. Atlantis is equipped with a sensor-laden boom that will be used to examine the spaceship once it reaches orbit and again before it returns to Earth.
- Repairs. The astronauts will be outfitted with tools and techniques to repair heat shield damage – means developed in the wake of the 2003 Columbia accident.
- Altered orbit. Once Hubble is serviced, Atlantis will fly to a lower, safer orbit.
- Rescue. Endeavour and a rescue crew will be on standby to fly within a week if Atlantis sustains serious damage. But Shannon doesn’t expect a rescue will be required.
“It’s just nice extra insurance to have since we’re in a position that we can have a vehicle on the pad ready to go launch. So we’re treating it very seriously,” he said. “We don’t expect to use it, but if we do, we feel very confident we could.”