Human Spaceflight

The Hubble Space Telescope is in the grip of space shuttle Columbia's robotic arm in March 2002 at the beginning of STS-109, the third Hubble servicing mission. Image: NASA

The Hubble Space Telescope is seen in March 2002 with its new solar arrays after the completion of STS-109, the third Hubble servicing mission. Image: NASA

Since then, the team has come up with a plan for the work that Ceccacci believes will be very successful. But it won’t be easy – the repair of the spectrograph, for instance, requires the spacewalkers to remove more than 100 screws to access a computer card they will pull out and replace.

Still, the mission’s commander pointed out that it’s good practice for the future.

“I think it’s a step that we need to take to make us better able to go to places like Mars,” Altman said. “You don’t want to drag a whole spare giant box along – you’d like to be able to have the one little transistor you need to plug in when that fails. Being able to demonstrate this in space is a key element of us growing as a space-faring people.”

The Hubble spacewalks won’t be the only things that differ from missions to the space station. Confined to just the shuttle, the quarters will be tighter; with five back-to-back spacewalks, the pace will be faster.

Without the station crew to give the shuttle a once over and photograph its heat shield , the customary survey of the heat shield done the day after launch will be much more intensive. The crew will use the shuttle robotic arm and its 50-foot boom extension and sensor systems to perform not only the standard nose cap and wing leading edges inspection, but also a survey of the upper crew cabin and the entire underside.

In the unlikely event that irreparable damage is found, the crew also won’t be able to get to the space station to wait for a ride home – Atlantis can't reach the station from Hubble’s orbit. Because the crew won't have access to the station and the support it could provide in an emergency, the mission to Hubble requires some changes on the ground.

For every shuttle mission since Columbia, there has been a contingency plan in place to allow another shuttle to be launched if needed to rescue a stranded shuttle crew. On station missions, that stranded crew can wait longer at the station than would be the case for Atlantis. So, for 125, another shuttle will be standing ready on Kennedy Space Center’s Launch Pad 39-B. If needed, space shuttle Endeavour, manned by the flight deck crew of mission STS-123 which flew in March, will be ready to fly to Hubble and retrieve Atlantis’ crew within days.

What puts Altman’s mind at ease, however, are the changes NASA has made to keep damage from occurring in the first place.

“I feel pretty good that we’ve made incredible improvement in the external tank,” he said. “That’s the root cause. But if something does happen, I think we have the tools to find it, see where it is, evaluate how serious it is and fix it. And then on that one-way-down-at-the-edge-of-the-probability-level chance that you could have damage such that you wouldn’t want to come home on it, we have the capability to stay up there – extend our time and have another shuttle come get us.”

The risks, he believes, are relatively small, and the payoff is huge.

“Hubble puts cutting edge science together with a visual image that grabs the public’s imagination,” Altman said. “I think that’s the first step in exploration. Because Hubble takes light that’s been traveling for billions of years, sucks it in and shows it to us. It’s like taking you on a journey 13 and a half billion light years away while you sit there at home and look out at the universe.”