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 Drew Feustel is here to update the plans to upgrade Hubble. Drew, what was it that happened on orbit back in September that postponed your planned launch?
Preflight Interview: Andrew Feustel, Mission Specialist
A: Well, so a few weeks before launch as the news media has reported, of course, the SIC&DH, which is the Scientific Instrument Command and Data Handling, redundant paths failed on Hubble, and, what that means is that for Hubble we lost one of its backup channels for, basically, command and data handling for the scientific instruments on the telescope. I believe Goddard [Space Flight Center], at that time, and NASA, made a decision that, if we’re going to go and do the servicing mission it was important to have both of those, command and data handling paths available, so the decision was made to hold off on our launch, look at options and opportunities to provide additional hardware to, you know, repair those problems during our servicing mission so that we can give, you know, provide new components to not only the instruments themselves but also this, command and data handling box.
To clarify, the telescope is still telescoping. It’s still…
It’s working fine.
…but can’t get the results, or couldn’t get the results to the ground.
It couldn’t. I mean, there’s two channels there, an A side and a B side, and it essentially was operating on the A side and that failed and, and Goddard folks successfully brought up this backup B channel, but, and so the telescope was working fine just as it was previously, but the challenge is that now there’s no backup, redundant path for that data to, command the instruments and get the data back from them. So, the decision was made to try to repair that, you know, as part of the servicing mission that we’re performing.
So, clearly an important piece of hardware; what did the scientists and engineers and Goddard have to do to come up with a new one?
Well, we initially heard that there was, you know, a backup box available on the ground, and what it turned out to, what they really meant was that there were backup parts available on the ground, to assemble another box and basically put one, bring one back up to speed, and this was a box that’s been in existence, for as long as the telescope has been in orbit, even, you know, even before that when they were first making these boxes, so, but it was a component that wasn’t fully assembled, wasn’t fully tested out and made spaceflight ready, so since that time and since the decision was made to repair that box and provide that as new hardware, the folks at Goddard and, you know, within NASA have spent a considerable amount of time getting that box up to speed and making it ready for spaceflight.
The job of installing this new Science Instrument Command and Data Handling system has fallen to you and John Grunsfeld in the first spacewalk of the mission. Tell us what you have to do in order, in order to put this new piece in place.
Well, I mean, I want to start by saying I feel, you know, fortunate and honored to be able to have the opportunity to install the box. I think that’s a neat thing and, of course, you know, having cancelled the mission, or delayed the mission for that box, was a big deal, so, in a sense, you know, I feel kind of lucky to be able to have a chance to actually be the one who puts the new box back in the, in the telescope. That said, the task itself is very similar to what we were doing to replace batteries on, on the, you know, as part of the servicing mission, and are still doing, so in terms of learning new, you know, techniques and, and, parts of our EVA or additions to the EVA, it really wasn’t necessary. We’re, I guess you could say we were already in a sense trained to install this box because its shape, its, its mass, its—well, its mass is different than the batteries—but its, its general size and installation features are almost identical to what we do for the batteries that we’re installing, very similar in terms of the techniques we use, so in that sense, I think, we’re well prepared for it. The real challenge was fitting it into the EVA, and that, and that’s what’s taken a little bit of time to work through.
All right, the first step what is, what’s the choreography like? How do you go about getting it in there, and what’s involved?
Well, you know, that really wasn’t, something that the crew, let, you know, was the leader on the decisions. It was really something that we looked to our EVA team, our support team, our task leads to, to figure out, you know, what, where it was going to fit best in the, in the scenario and the choreography so, what we had to look at was the overall picture, you know, how much time we had within the five EVAs, was there any margin to make it fit, and then where to place it. Now, it’s extremely high on the priority list so it, they wanted to place it towards the front of the EVA. So it ended up on day 1 and what we did was we moved day 1 around and instead of doing a battery now on day 1, we’re actually doing the, the SIC&DH on day 1. And we moved the battery task that we’re doing on that first day to the last day, where we found some room, and that’s contingent on success on day 3 with our ACS [Advanced Camera for Surveys] repair. We originally had that slated for two days, you know, part one and part two, days 3 and day 5, and we’ve reduced that now to [one day] with the understanding and risk that if we don’t complete ACS completely on part one, on day 3, we’re not going to probably go after it again on day 5. We’ve filled that space now in with the battery that we were doing on day 1 and some additional tasks, some new outer blanket, you know, NOBLs, to put on the telescope, so it fits and we believe it fits with some margin because we’ve gotten proficient enough on the rest of our tasks to, to understand, you know, what the requirements are going to be to have time for it.
So you’re able to do this and still do everything that…
We’ve basically essentially just added it on, yeah, that’s what we’ve done.
Would you talk us through the steps for the task itself, what you and John will do to install the new box?
It happens on day 1 which means I’m riding the robotic arm and John is the person we call the free floater, and essentially we approach, the instrument is in bay 10, and, which is one, is one of the bays around, you know, above the scientific instruments, actually above the radial instruments on the telescope, near the top half of the, of the telescope. And, essentially, I approach the door on the robotic arm, release the, well, I’m sorry, before we get there, John installs a radiator cover, or a blanket, over the radiator that’s on the back of the door to help with some thermal control issues, or not really issues but basically thermal control properties of the door and the instrument itself, because once we open up that, that bay door and remove the instrument off the door, the door goes through some heating and cooling that, that can change some of the geometry and cause some challenges for us to reinstall. So, John approaches the door, installs a blanket, heads back to the aft of the, the vehicle, the aft of the payload bay, down to where the replacement instrument is, which is on the starboard side of the vehicle, or the right side of the vehicle, in the back, down low. So he goes to that worksite area. I take the robotic arm up to bay 10 and start removing the bolts on the doors, open the door, and then basically begin removing the bolts that, that hold this instrument on to the door, and, lastly once the four outer bolts and six inner bolts are removed, I drive a screw on the bottom that releases the electrical connector and I pull the instrument off and, you know, have it in my hands. The robotic arm then flies me down to the position where John is where he’s removed the replacement box. We sort of do a, you know, I’ve-got-the-new-one-you’ve-got-the-old-one trade off. I fly back up to the top, he goes back down to the bottom and, and I reinstall. And in a nutshell, that’s, that’s all we do. It’s very similar to what we do for a battery task, just a slightly different handoff location.
I would imagine that all of that is part of the answer to the other question, which is, what have you guys been doing with the extra preparation time since you haven’t flown?
Yeah, we’ve been doing that and since I believe we did, we added some additional runs in the Neutral Buoyancy Lab, some additional EVA runs, to practice this, and so, you know, each month we spend some time in the pool and, you know, go through a series of runs so, you know, having the delay from October, I believe we did a set of runs in November, and then February, and we just finished our runs here in March and we’ll do one more set in April, so we’ve added four additional, you know, pool runs to train this. The advantage, as I stated, it’s very similar to a battery task, so in a sense it was just really about working out some of the details and understanding what the contingencies are, more so than it was, you know, learning a whole new installation of something that we’ve never seen before.
So now you’re all set, eager to go?
I think we’re all set and eager to go with the installation, yeah, it looks pretty good in the pool and we feel very confident with the techniques and the contingencies that we have, would maybe have to deal with and how we work out those.