Originally this mission was scheduled for October 2008, but with the problems in September with Hubble's data formatter, it was pushed back. How has that glitch changed the mission?
That was a scientific instrument command and data handling system (SI C&DH) and its subunit, known as a science data formatter, which is absolutely essential for doing observations and getting the data back home. Luckily we had two redundant electronic sides in what is essentially a computer system. It was one side that failed, so we were able to switch over to the other side. We had never done that before, but it worked fine.
The only problem is that we no longer have redundancy. And if we risk the lives of seven astronauts and go to all this trouble to get Hubble fully up to snuff for five to 10 more years, we don't want to have a single-point failure possibility, where if side B failed, suddenly all science would be over on Hubble. We didn't want to do that, and Mike Griffin, who was the NASA administrator at the time, didn't want to do that. So he called a halt to preparations for launching in October and we got our spare SI C&DH system ready to fly.
So you will replace the A side that failed?
We'll replace both the A side and the B side. We're going to replace the entire unit.
In terms of technical upgrades or longevity boosts, what do you hope to get out of this mission?
We're putting on two brand-new scientific instruments, and then the astronauts are going to attempt to repair two, including the Advanced Camera for Surveys and the spectrograph, which are quite modern instruments but had electronic failures.
One of the new instruments is called Wide Field Camera 3, and it's going to replace Wide Field Planetary Camera 2 (WFPC2)—the jargon is a little strange. We're taking out WFPC2, which has been in the observatory since 1993, and replacing it with a really golly-gee-whiz new camera that has two channels in it. One channel is optimized to observe light in the ultraviolet wavelengths, and the other channel is optimized for the near-infrared. We have a near-infrared instrument on board Hubble already, but its technology is very primitive, whereas the new infrared channel is superb. This thing is going to just clean up.
The most important program it's going to be doing in the year following the mission is another ultra-deep field. There was a Hubble Deep Field in 1995 and an Ultra-Deep Field in 2004 or so, and those were at visible wavelengths. Now we're going to another ultra-deep field in near-infrared wavelengths. Because the universe is expanding, the light emitted by very, very distant, far-back-in-time objects is shifted to red wavelengths. It may have been emitted in the visible or ultraviolet, but by the time the light gets to us, it's been shifted by the expansion of the universe to red and near-infrared wavelengths. So if you want to look really far back in time, as far back as you can, you really need to look in near-infrared or infrared wavelengths.
This near-infrared channel will probe further back in time than any image that humans have ever taken—with the exception of the microwave background explorers, which went all the way back to the big bang.
So this an ultra-ultra-ultra–deep field, essentially. Is there a name for it yet?
That's as good as any.
The same team that's going to be doing this "ultra-ultra-ultra–deep field" worked hard on the original Ultra-Deep Field to find the faintest protogalaxies or clumps of star formation that they could. And they now have identified seven or eight objects that emitted the light we see when the universe was about 700 million to 800 million years old. We think we will push back another 200 million years or so with this new camera.