Saturday, May 9, 2009

New Lease On Life For The Hubble

The fairy of the Eagle Nebula, one of the many pictures taken by the Hubble Space Telescope over the last eighteen years.

In a few days, the space shuttle Atlantis will launch to upgrade the Hubble Space Telescope (HST) one more time. Besides its objective, this mission is interesting for another reason - the manner in which NASA intends to rescue the shuttle's crew should something go wrong:

If the Hubble repair crew due for liftoff on Monday got into the deepest sort of orbital trouble, yet another shuttle would have to be launched into orbit as little as a week later. NASA hasn’t launched two piloted spacecraft so close together in more than 40 years. But that's just the first act of the drama.

The rescue shuttle, Endeavour, would have to pull within about two dozen yards of the stranded shuttle Atlantis, and then help Atlantis' crew members make their way across a lifeline to refuge. Then Endeavour, full to capacity, would have to leave Hubble as well as Atlantis behind and return home — but not before Atlantis' controls are set for a self-destruct sequence.

NASA Set For Dramatic Shuttle Rescue

It all sounds a bit like something out of science fiction,, but this is actually a very difficult thing to do. Shuttle launches are, despite the prosaic implications of the word "shuttle", complicated processes involving thousands of people directly and indirectly. As James Oberg explains:

In a perfect world, the STS-400 team would just mark time until Atlantis heads back to Earth, after which Endeavour would be put back into preparation for a flight to the space station in mid-June. But if STS-400 is needed — and the need might not be discovered until the final few days of the STS-125 mission — the countdown would resume, and Endeavour would launch three days later. A day after that, using an abbreviated rendezvous path, it would be hovering back to back, 75 feet (23 meters) from Atlantis.

NASA Set For Dramatic Shuttle Rescue

The "repair" Oberg mentions really sounds more like an upgrade to me. This image, from shuttle mission STS-109, is similar to what will we will probably see out of this mission. STS-109 replaced the old solar panels with the new ones, and also upgraded the power system.

The BBC describes one of the reasons for this upgrade:

If all goes completely to plan on Hubble Servicing Mission 4, the orbiting observatory will be reborn as the most productive telescope in history, with even greater powers to probe the Universe's deep history and help cosmologists make sense of one of their biggest problems - "dark energy".

Peering Into Hubble's Future

Interestingly, this mission might not have happened at all if it hadn't been for public support for the HST. The Columbia disaster was thought to have doomed the HST at one time:

The mission, scheduled for May 2008, should see the space shuttle Discovery take a team of astronauts to the orbiting space telescope. Once there, the crew will boost the satellite into a higher orbit, replace its ageing batteries and gyroscopes, and install some new instruments.

Taken together, the repairs should leave the telescope in fine form until its replacement, the James Webb Space Telescope, can be launched in 2013.

Ups and downs

The decision is the latest turn of fortune for Hubble, which, in recent years, has seen its repair plan approved, replaced, cancelled and reconsidered. The mission, the fifth to the telescope, was originally scheduled for 2006, but was cancelled in the wake of the 2003 Columbia disaster.

NASA approves Hubble repair

The Mice, two colliding galaxies photographed by the HST

But all those wonderful pictures convinced the public to ask for more:

"I'm very excited about it!" said Fernando Ribeiro, a Brazilian educator and artist who runs the Web site "It's what we've been fighting for all these years. I think this is going to mean a lot both to science and to the public."

Telescope rally cry

Ribeiro founded his site in 2004 after the shuttle servicing mission, originally scheduled to launch in 2004, was cancelled over safety concerns in the wake of the 2003 Columbia disaster. Ribeiro collected some 5,500 signatures on a petition to reverse the decision, which would have left Hubble without new instruments and repairs needed to keep it alive.

Other Hubble fans (often called "Hubble Huggers") founded similar sites such as [(Flashmedia support required)], which sells Hubble T-shirts.

NASA credits this outpouring of public support for the mission as part of the reason it was resuscitated.

Hubble Huggers Ecstatic for Telescope's Facelift

Dark energy is one of those ideas that may help explain the origins of the universe. In essence, it's an idea to explain why the universe is expanding at an accelerated pace. Observing distant supernovae has made it possible to calculate how long dark energy has existed. The HST upgrade should allow that to be done with greater precision.

Far from being a trivial concern, public pressure has helped scientists continue to research some of the most important questions in physics.

Its new solar panels installed, the Hubble once again orbits Earth on its own at the end of STS-109.

In a way, this mission marks the ends of two eras. One is the era of the space shuttle, which will be phased out in a couple of years. The other is the age of the Hubble Space Telescope. Without continued visits from a vehicle like the shuttle, the HST will eventually break down.

The HST has given us both wonderful pictures of the universe we live in, and a far greater understanding of it. Many of us will miss it when it goes.

1 comment:

Dana Hunter said...

I'm glad they're repairing Hubble. It's been an incredible asset to science - and art. Thanks for teaching me things about it I never knew!