After years of uncertainty, cancellations, reinstatements, and delays, the shuttle mission to repair the Hubble Telescope for the last time is finally next on the list.
On Saturday, the space shuttle Discovery landed after another successful mission to the International Space Station. It will be another four months until the next space shuttle launch, when Atlantis is sent on her last (scheduled) mission, to repair the Hubble!
Hubble is showing signs of age right now. It's a healthy telescope, and still capable of outstanding science, but its health is on the decline. Its rechargeable batteries are wearing out, two of its cameras are broken, and its running on only two gyroscopes (three are preferred, but it is saving one in case one of the working gyroscopes fails). Atlantis will return Hubble to almost-new condition (think factory-refurbished), if all goes well.
The plans are ambitious. First, one old camera will be removed and replaced with a new one. When the new camera goes in, one other instrument, the "glasses" that the first Hubble repair mission put to correct for Hubble's mis-shapen mirror, will also be taken out. All the remaining instruments have their own internal glasses. This will allow another brand new science instrument to be put on. Hubble will get new batteries, new gyroscopes, and one malfunctioning navigation camera will be replaced. And, if all of that goes well, the two broken cameras will also be fixed.
It is quite possible that not all of the repairs will be done. The two broken cameras were never meant to be fixed in space, so we don't know if the repairs will work. We think the repairs should work, but there may be problems. The batteries were also not meant to be replaced. They should be able to be repaired, but if that repair fails, the telescope won't work at all.
We astronomers are very grateful to the astronauts who will be repairing our telescope. They are risking their lives for science. They have trained years for this one mission. They helped us fight for this mission when NASA wanted to cancel it after the Columbia disaster. We owe these men and women a huge debt of gratitude, no matter how successful the repair is.
Next stop, Hubble!