Q: The final servicing mission to the Hubble Space Telescope was on track to fly in 2008, until unforeseen events in space prompted new plans. STS-125 astronaut John Grunsfeld is here to update the plans to upgrade Hubble. John, what was it that happened on orbit back in September that postponed your planned launch?
Preflight Interview: John Grunsfeld, Mission Specialist
A: We were packing our bags ready to go to Florida when, on orbit, a random failure on Hubble occurred that caused all the managers here at the shuttle program and the scientists and the people who run the Hubble to really scratch their heads, and in very rapid order, overnight, decide that we should stay on the ground and prepare another fix for Hubble. And what happened was that, in a box that contains the circuitry that interfaces the scientific instruments with the computers and the comm[unication] system, to get all of the amazing imagery to the ground, had a failure that reduced its ability to send data down to the ground by a factor of two. Typically on Hubble there’s redundancy, so there’s an A side and a B side, and if all the data is flowing through the A side everybody’s happy; if that fails, you turn on the B side and the data comes down. We were running on the A side, the A side of this science interface failed, and for a while there was no data coming down from Hubble at all, and it was a rather complex series of events to bring up all of the other parts of Hubble to get to the B side, so we for a while had no ability to get science to the ground. We had to make a decision quickly whether we would fly off to Florida and launch, and so everyone decided unanimously we ought to stay on the ground, verify first that we have a science path to the ground for, for Hubble data, and then also to look on the ground and see if we have a spare. And all that came together, basically overnight, and we decided to stay on the ground and prepare a spare.
The equipment that, that had the failure is called the Science Instrument Command and Data Handling system. From your description it sounds like without that, no matter what Hubble sees, we never find out. Is that a way to summarize it?
Yep. The name is very descriptive. Scientific Instrument, or SI, Command and Data Handling, so all of the data, the images that Hubble produces, and all of the commands to the instruments to configure filter wheels or turn detectors on and off, all of those commands and all of the data from Hubble goes through this box, essentially—it’s a series of boxes—in order to snake its way to the communication links and down to the ground and into the hands of astronomers. So without it, no science.
And all the improvements that you were planning to make would be of no avail if there was no way to get the data down?
The worst event of all would have been for us to service Hubble successfully, put in the Cosmic Origins Spectrograph, the new Wide Field Camera, fix the Space Telescope Imaging Spectrometer, fix the Advanced Camera for Surveys, you know, land, have this big celebration, and then have it fail…all for naught.
Let’s talk about the replacement. As you mentioned, they had to scramble looking for a new Science Instrument Command and Data Handling system. What did the scientists and engineers at the Goddard Space Flight Center have to do to get this replacement ready to fly?
The amazing thing about the Hubble Space Telescope, 19 years on orbit next month, and we still have spare parts on the ground. You know, how many 19-year-old cars still have spare parts? Well, lots of them, but not exotic cars like Hubble. And so the folks on the ground scrambled and we knew we had most of the parts to build a new SIC&DH box, Scientific Instrument Command and Data Handling box. But we weren’t really sure because we didn’t need it and so all the parts were sitting on shelves, and so Goddard had to scramble and put those boxes together, verify the history of them, that they are flight-quality boxes, and in the process of doing that they discovered that really they only had half of what they needed and the other half had to be assembled and tested. It existed, but it wasn’t in flight condition. And so the reason why we’ve had a delay of all these months is to be able to put the new, fully-redundant SIC&DH together, test it, vibrate it, give it all the thermal cycles that it will see on orbit, and fully test it to make sure that when we put it on Hubble this May it’ll work just fine.
And the task of installing this new hardware has fallen to you and Drew Feustel. Talk us through what the two of you will do to install this new box.
Given that all of the science data flows through this new box, it’s been recognized with a relatively high priority on the mission, so we’re going to do this on the first EVA day. What that’s done is displaced the battery swap that we were going to do to the fifth EVA day. It’s a relatively straightforward swap; it’s very much like the battery. Drew, up at the telescope, will open the door of one of the bays, run a bunch of screws out, take the connector off, grab it, Megan [McArthur] will fly Drew down, we’ll swap the two boxes—I’ll be back in the, on what’s called the MULE [Multi-Use Lightweight Equipment Carrier], in the back of the orbiter where I’ll take off the new one, hand him the new one, take the old one, I’ll scurry down and stow the old one so we can see what actually failed once we get it on the ground. Drew will take the new one up, slide it onto the door, drive all the screws and connectors—voila, we have a new, fully-redundant box.
And it sounds, in that case, sounds like a fairly straightforward EVA task?
Yep. We think we understand it very well. As always little things can go wrong; we’ve developed the fixes for that. But from an EVA perspective it’s very equivalent to the battery we were going to do in terms of time, complexity, the shuttle arm operations. You know, we think we understand it pretty well.
So, how does the new task impact the overall plan for the spacewalks? Are, are any jobs falling off, or are you going to get to do everything that you had planned to do beforehand?
When we work the Hubble servicing missions, the one thing that’s always abundantly clear is that everybody is very success-oriented, and we had a full plate before this SIC&DH failed and now our plate is just a little fuller. Clearly, by adding a task that’s about an hour of duration, a little more an hour of duration, you know, something had to change. We moved the battery task from day 1 to day 5 so you have to ask, well, what was in that slot on day 5 that we’re not going to do now? And the answer is, Advanced Camera for Surveys, the camera repair part two, has dropped off the plate. But that doesn’t mean we’re not going to repair the camera. What it means is the time we’d allotted on EVA 3 we now, instead of just doing half of the repair, have to do the whole repair, which means Drew and I and the rest of the team have to work faster, so we’ve upped the gain on the training for the Advanced Camera for Surveys repair, and this is all the tiny screws, so I have to work a little bit faster on each tiny screw and, you know, potentially we could extend the EVA a little bit longer if we had to finish it.
How have you guys taken advantage of this extra time then, to, to get ready for the work that you have to do?
For the, me, personally, the Advanced Camera for Surveys has really been the beneficiary of this extra time. I spent a lot of time up at Goddard practicing, doing the task over and over and over again so that I can improve my efficiency and hopefully we can fit it all in. I know Mike Massimino’s been working on the Space Telescope Imaging Spectrograph repair; again this repetitive training in order to, you know, really program the muscle memory, all of the efficiencies in your brain, small techniques to make things go better, you know, the whole team has been working that. We’ve done additional Neutral Buoyancy Lab runs, the big tank, in our spacesuits, to get more and more proficient, and, you know, we, we had peaked so that we were ready for an October launch; we spent a couple of months, you know, sort of recovering from that heightened activity, and then climbed back up the ramp and now we’re at a new peak, but better trained.
And all set and eager to go?
Yep, absolutely; ready to go to Hubble.