In The Field

AAS: Return to Hubble

Shuttle schedules willing, astronauts will be going back to the orbiting Hubble Space Telescope this summer. The next and final servicing mission to the telescope (right) is slated for early August, and top NASA brass were out at the astronomy meeting today to tout it.


It’s a far cry from a couple of years ago, when in the wake of the disintegration of the shuttle Columbia NASA’s chief at the time, Sean O’Keefe, cited safety reasons in canceling the final trip to Hubble. That decision prompted an outcry from astronomers and others (Nature story, subscription required) and NASA eventually reversed its decision – after first looking into options to send robots instead of astronauts, and then getting a new administrator in the form of Mike Griffin.

Now the trip is hostage only to delays in shuttle launches; right now, the shuttle is backed up on delivering the European Columbus science module to the international space station, a trip that was supposed to go in December but now looks more likely for February. If other launches continue to slip, an August date for the Hubble mission doesn’t look likely.

No matter – astronomers don’t seem to mind waiting. The next servicing mission will bring two new scientific instruments up to Hubble, plus fix two other ones already up there.

If all goes to plan, here are the new tools that researchers will have to play with once the astronauts undock from Hubble:

– A new wide-field camera, the most powerful ever flown in space. The Wide Field Camera 3 will span the wavelengths of light most coveted by astronomers: ultraviolet, visible, and infrared. It covers more of the sky, with better resolution, than ever before. “This just really shows what we’ve been missing,” says astronomer Mark Dickinson, talking about a gap in near-infrared wavelengths where there really isn’t just much good data … yet.

– A new ultraviolet spectrograph, the most sensitive ever flown in space. The Cosmic Origins Spectrograph is designed to study point sources such as stars and quasars, revealing more about both the near and far universe.

– Repairs to the ACS camera and STIS spectrograph, two instruments already on Hubble that have suffered electronics failures. Astronauts will have to do some tricky work to extract the malfunctioning components from the instruments – involving hundreds of tiny screws that have to be extracted in space, as astronaut John Grunsfeld – the man who has to do the work – points out.

– New gyroscopes to help the telescope point itself, and new batteries to keep it alive. These are the ‘consumables’ that otherwise would eventually limit the physical life of Hubble itself.

– A new thermal blanket to insulate it from the cold of space.

– Some docking hardware that will, sometime around 2020, allow a robotic spacecraft to hook onto the telescope and then guide it into a safe burnup and crash into an ocean somewhere.

If it sounds like a lot of work, it is. Astronauts are budgeting five full days of 6.5-hour spacewalks to get it all done. Grunsfeld and the other crew members have been spending a lot of time in the giant swimming pool training area in Houston, in which astronauts practice spacewalks underwater. But if they manage to pull it all off, Hubble will be in the best scientific shape of its life. “We will have more scientific capability on this mission than ever before,” Grunsfeld said excitedly this morning. Sandra Faber, an astronomer at the University of California at Santa Cruz who uses Hubble, notes that, roughly speaking, the telescope will be *90 times* more powerful after the servicing mission than it was when it was launched back in 1990.

Hubble is expected to last another 5 to 10 years after this final mission. Now it’s up to astronomers to see what they can dream up to do with it before Hubble goes dark for good.


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