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Preflight Interview: Nancy J. Currie

A couple of weeks prior to scheduled launch, STS-88 Mission Specialist Nancy Currie took some time out from training to answer questions about the mission.

Nancy, it's been two years since you and your crewmates were assigned to STS-88 and now you're closing in on the scheduled launch date; what're your feelings at this point as this flight becomes closer to being a reality?

I've been here since 1987; first as a support, flight simulation engineer on the Shuttle Training Aircraft, and then as an astronaut since 1990. And I know when I came here in 1987 there were already people working on the space station program. So to be a part of the very first flight of the space station program as an astronaut is really the culmination of all my dreams. And especially in the last few months, we're just trying as hard as we can to prepare for the mission. It is extremely complex, extremely demanding, and so we're just trying to make sure that, because we're entrusted with the goals and all the hard work of the thousands and thousands of folks across NASA and the contractor community, that we can go do this mission right.

The target launch date for your mission has been postponed twice now because of delays in getting hardware ready. You look at the delay from your point of view, you and your crewmates that is, is it simply a source of frustration, or has it been an opportunity for you to be better prepared?

It has been an opportunity for both the crews to be better prepared and the hardware and software to be better prepared. We have been going through integrated testing of the hardware and software to a much greater detail than was originally planned, so I think, that the probability of mission success and the probability of any types of problems that might come up, has changed tremendously by having that extra year. Essentially, of preparing for the flight, and we certainly learned a lot, being down at the Cape, being involved in all the hardware and software testing. So I think all around, of course, we'd like to fly whenever we can, but we understand the delays and we've tried to take advantage of those delays to better prepare for the mission.

Now over the course of the two years you've been part of a group of five people who've been getting ready to fly this mission; recently your group has grown with the addition of Sergei Krikalev to your crew. How will this change, in crew makeup, relatively late in the game for you folks, effect how you get ready?

It's gonna help tremendously because, as I said, we have an extremely complex mission. In our training for the flight we've added three additional days to the flight because we just have so many events that occur during the mission. And so to take a crewmember like Sergei who not only has, literally years of experience on Mir; is also training to be a long-duration space station crewmember; he's just going to be a tremendous asset. We can offload some of our tasks because we were getting to the point where, in an extremely complex operational environment, the one thing you don't want to have is a sole person doing a job with nobody looking over their shoulder. Nobody calling out in kind of a call out and response to procedures; adding Sergei to the flight will allow us to do that and, therefore, will give us a greater, success probability because, possibly reducing human error.

Do you see that it was Krikalev that was added as opposed to someone else who could've done what you were describing because of any particular expertise that he has in the systems of the Russian component, the Zarya control module, that he's been studying, because of his assignment to the other crew?

He's, an excellent candidate, he's flown on the shuttle before, which is a great benefit, and he's been training to be a station long-duration crewmember so he's familiar with not only the American segment systems but also certainly the Russian segment systems. And also the one thing about the systems on Zarya is they're very, very similar to a lot of the Mir systems, so certainly having all his years of experience, to carry on and to help us out in that arena, will be a tremendous asset.

As you get ready to go begin assembly of the International Space Station, does it also make sense from a point of view of symbolism to have a multinational crew on board the shuttle?

Certainly. I think everybody's aware that this is a multinational effort, and as we kick off this program to have a multinational crew also totally makes sense and serves as a symbol to the multinational effort.

Before we get to detail on what you're going to do, I want to ask you to look at the International Space Station from a big picture point of view. To you, what's the historical significance of your flight, STS-88? Why, should we be building a space station in Earth orbit in the first place?

Well, you can make the case that we once had a space station, some time ago, when we had Skylab, but I think it's a natural progression: we have taken the shuttle and done tremendous things with shuttle flights, and science on space shuttle flights. However, I always compare to the public that, if you walk into any laboratory in this country and tell a scientist, you have two weeks to run this experiment, get your results, and come up, with a cure for cancer, or design a new drug, or whatever the results might be-almost any scientist in the world will tell you it cannot be done. And those are the kind of limitations that we're faced with - with the space shuttle. So I think to have long-duration science on board the International Space Station is extremely important. The other thing is that as we look beyond space station, and as we look to a mission to Mars, for example, still to this day the single limiting factor is human physiology during long-duration spaceflight. So I think we need to have a greater understanding of the effects of long-duration spaceflight on the human physiology and any types of countermeasures that we might be able to impose on crewmembers that might lessen those effects when they do reach the surface of Mars.

In the course of a couple of years, as you've been preparing for this mission, you've had time to also get familiar with overall plans for the assembly of the entire space station and not just the couple of pieces that you folks will be working on, here in a couple of months. For the layman who might see assembly as simply "fly a space shuttle up, plug two things together like you would a couple of pieces of LEGOs, and then, come back down." Talk to us a bit about the complexity of planning, and then executing, a task of assembling this space station at that location, 220 miles up.

Typically, when we have a typical space shuttle payload, we will assemble it at the manufacturer. We will then take it to Kennedy Space Center and integrate it with the shuttle, completely test out all the systems, completely ensure that everything is compatible with one another, whether it is an electrical system or a mechanical system. For the very first time we are going to have elements that aren't even being built in the same country, and being built to such a tolerance that for the first time that they're mated together is going to be over 200 miles up in orbit. And so it is a great, a very detailed and complex task in order to manufacture parts that are to that strict of a tolerance, and to devise ways to test them on the ground to ensure their compatibility. So those are some of the sorts of things that we're struggling with. Also there are very, very few mechanical switches on board the space station; everything is computer controlled. So even though a light downstream in a module may still work, if the computer command to get to that light switch cannot be sent, the light won't come on. So the integration of computer, software and hardware, is extremely important in this program, and that also adds to the complexity of what we're trying to do.

Now you touched on the fact that there are pieces of this space station that are being built all over the world, might never see each other, so to speak, until they do so on orbit. There are plenty of people here on the ground who've criticized the fact that the United States is working with Russia and various other countries in doing this, in working together in order to execute the assembly of the space station. What do you say to people who would voice that criticism?

Well, there's two things. First of all I think, as we look from sort of a universal perspective, if we keep in mind Earth orbit in this universal perspective, then it only makes sense to have all the countries who are willing to participate in this program to come together and to build something like the space station. Where we can all work together in Earth orbit. So it only makes sense from a political standpoint, and a geopolitical standpoint that we can all work together orbiting the Earth that we all live in. The second point is that spaceflight has become so tremendously expensive that I think, no sole country could afford that great cost. So I think from a financial perspective also, it makes sense to bring multinational partners in and everybody brings their element or their expertise to the table, if you will, to build this space station.

The United States and Russia, the two major spacefaring nations of the Earth, have spent most of the last four years working together to get set for assembly of this station, the task that you and your crewmates are going to begin. As you look at the effort of the Shuttle/Mir program, what do you see as the most valuable lesson that has come out of that as you get ready to go do your job?

I think probably the most valuable lesson is how we've worked together in an operational sense; and I'll give you a "for instance." If anything were to occur, say after we grapple Zarya and their active control system were not to mode to off, we would have to rely on the Russian ground station to immediately send a command to command their control system to off. We feel very confident that - that will flow very smoothly and very quickly which is of great importance. I think prior to, Phase 1, maybe we would've been a little more leery of that, but now we've been working very closely, certainly in situations like docking situations. Where decisions have to be made very rapidly, and we've worked out all those sorts of operational, handoffs and, so I think that's of great importance as we head towards the Phase 2.

In the process of Phase 1, on STS-74, there's an operation that, to the layman's eye, looks similar to what you're going to do. They used the robot arm to pull the Docking Module out of the payload bay and set it up on the Orbiter Docking System so that it could be attached to the Mir space station. How important is an exercise like that in setting the stage for what you're going to do on your mission, the exercise that is going to be so similar to that?

It is extremely similar. We will have the same sort of target system, the same sort of centerline camera to look at that target, we will also, eventually, not on the Node installation but on the FGB installation, we'll be using the Space Vision System that the Canadian Space Agency has developed. Many elements of those tasks are very, very similar, and we certainly learned a lot from their experience.

Let me ask you to expand a bit for us then, because one of the first highlights of this mission is going to be when you, as the operator of the RMS, are going to get the Node, called Unity, that you're bringing, ready for its mating with the Zarya. Talk us through what is going to happen and what you're going to be doing as you, go through that task.

OK. Well, first of all, in the shuttle's payload bay, in the aft portion of the shuttle payload bay, will be the Node, and at either end of the Node is attached a Pressurized Mating Adapter. Now one of those Pressurized Mating Adapters, what we call PMA, PMA-1, will be the interface between the U.S. element and the Russian element, between Unity and Zarya. That is a fixed segment that will never be moved in follow-on construction missions. And so with the two Pressurized Mating Adapters, and the Node in the middle, we will pick it up through the robotic arm with a grapple fixture located on the Pressurized Mating Adapter number two. We will go ahead and lift it up out of the payload bay, maneuver it around, and then place it on top of the Orbiter Docking System. Now with the Orbiter Docking System, because it's aft of the windows, it's very, very difficult to tell things like pitch and yaw and roll of the element. So we have a centerline camera that looks straight up through the Orbiter Docking System that we actually put on orbit, on the first day we go ahead and install this camera. Then on the end of the Pressurized Mating Adapter is a target, and that target is so accurate that if you're, say, .2 degrees off in pitch, you can tell by looking at this target. It is the same target they have used to dock with the Mir, so we have a lot of experience with this and, feel pretty confident that this is a very good way to get within a very tight tolerance. About two inches and two degrees is the tolerance of how close we have to be, between the two elements in order to have a successful mating. We actually won't take it all the way down to the Orbiter Docking System. We will take it four inches apart, separation between hardware to hardware, so the petals will actually overlap, but the rings themselves will not be touching. And then our Commander, Bob Cabana, will fire the jets on board the orbiter to provide some thrust to close the gap between the two segments.

Why is the mating of those two elements to be done by forcing the shuttle up into it rather than you, at the control of the arm, placing it down?

This is the same element that is used to dock the shuttle with the Mir; interestingly enough it's the same designer who designed the Apollo-Soyuz docking mechanism-it's basically an Apollo-Soyuz docking mechanism kind of turned inside out. And it's a very robust structure but it does require some closure rate, some force, to activate the latches and so forth, in the docking system.

A force that you don't want the arm to try to have to create?

That's right.

Let's, move ahead from that point: you've successfully grappled Unity and it's now in place on the Orbiter Docking System. The next highlight comes as Bob Cabana flies Endeavour to a rendezvous with the Zarya control module while you, standing by prepared to grab it out of the sky as you go by; tell us, tell the story of how that is going to transpire?

Well, the first thing is because the day prior we did put the Node and the two Pressurized Mating Adapters on top of the Orbiter Docking System, we now have no aft view into the payload bay; that's all we see out the window is these elements. So that's one of the first problems we have to overcome is that almost for the first time, when we're trying to grapple a free-flying payload or dock with a free-flying payload, we don't have visual contact with it out the window. So we're going to be greatly relying on the cameras in the shuttle payload bay. We have two what we call keel cameras, which are located in the bay looking straight up. We also have, of course, the four normal orbiter payload bay cameras; we have a camera on the end of the arm, the end effector, and we will also use that to look at the FGB as it comes down. My role during the rendezvous is to assist the Pilot and Commander with all the rendezvous burns: they're also very complex, it's not like, any rendezvous we've ever done before because we have this 25,000 pound mass mated way down at the Orbiter Docking System we are greatly constrained on the way we fire the jets and the way we fire the Orbital Maneuvering System engines on the shuttle, otherwise it puts too much stress at that interface, and so it's a very, very complex rendezvous. So I'm backing up the Pilot and Commander, I'm timing between the thruster firings; we're constantly monitoring the data coming in to the rendezvous radar and so forth. About seventy feet out my role changes, and I go to the back and Bob and I talk back and forth and decide when in fact it is stable in the end of the end effector view, stable enough to go ahead and move the arm over and to grapple the, grapple fixture on the Zarya.

The next step, maybe one of the more interesting things that is going to happen, is to try to put the Zarya together with the Unity, and as you've mentioned this is going to be an exercise where you don't have an eyeball view of where you're working. What's the plan? How do you overcome that situation?

Well, one of the first problems is, again, we have this Node and the two Pressurized Mating Adapters and we have to put Zarya on top of that, so it's already stretching about forty feet out of the payload bay. Because of the limitations of the robotic arm we can't just drive the robotic arm all the way up and move it forward, so as we come forward we kinda have to move it up. And so one of the first things we're going to do is we're going to retract that ring for the adapter between the Pressurized Mating Adapter and Zarya; we're going to retract it, otherwise it sticks up another thirteen inches. That's just one more thing to kind of overcome as we kind of stair-step up. Once we do that and we're looking, at that interface with the aft cameras and we're watching it with the elbow. But because the elbow camera's located on the elbow as the arm moves that camera moves so it's kind of some strange camera views that we have had to get used to. Once we think it's in place, and again we have somewhat very tight tolerances. We can be about three inches and three degrees offset between surface to surface, in order for a successful capture. Again we're not going to take it all the way down, we're going to take it this time to about six inches apart before we fire the thrusters on board the orbiter. Once we think it's in place, and we think we're there, we're going to use the Space Vision System before we really start moving it down to that six-inch gap, and we're going to use the Space Vision System to acquire targets, which are dots. It's kind of a joke in the space station program that all the elements look like dominos because they either have targets that are black on white or white on black. By using the techniques of photogrammetry, you have what's called an array, and the array may be four targets or dots, or maybe five. Then we have targets on the other element; in this case we have targets on the Node and we have targets on the FGB, and so the camera angle has to be far enough away that we can acquire both of those. So as soon as we give the Space Vision System a camera view that they like in order to acquire both sets of targets, for me as the arm operator that really is not very useful to me because the camera zooms so far away that I really can't tell down to three inches and three degrees. So it's going to be very complex to switch back and forth between the camera views that the Space Vision System wants to acquire their data, and then the data that we would like to see. Visual data, through the cameras, on board the orbiter, a much tighter zoom-in angle, so we'll be trading back and forth. Now each time we take and move that camera, they have to go and realign that camera for the SVS data to occur, and so it's not just a matter of zooming the camera in and out; it's a reconfiguration each time we do that. So we're going to stair-step it down and check it again, and check it again. We're going to check it several times as we come down.

How many steps of that do you, in your simulations, do you suppose you've got to go through in order to get within that three-inch tolerance that you talked about?

We think maybe up to three times that we'll have to do that. One at approximately forty inches away, one at about a foot away, and then one at the six-inch, level away. Where we'll be doing this hand off, back and forth- SVS, the Space Vision System, says that we're within the tolerances. Now we want to take the cameras and verify what we're seeing. Of course the third level is the digital accuracy of what the robotic arm is telling us because it does provide digital data in terms of the "x," "y," and "z" position and the pitch, yaw and roll. But sort of the, the advertised engineering accuracy of those numbers is plus or minus two inches and two degrees, so that's already putting us quite a bit into our tolerance for a successful mating, so we want to be very, very cautious and use all the available cues.

This past June, the STS-91 crew conducted tasks of some upgrades to the shuttle's robot arm which you're going to be using on this mission; can you explain what those improvements are and the impact that you expect they might have on the job you've got to do?

Actually, the upgrade was originally designed, to upgrade the capability of the arm, to grab a mass about nine times greater than it can currently; right now it's constrained to about 65,000 pounds. Certainly, with Zarya being around 45,000 pounds, we didn't necessarily need those upgrades because now we have changed, in our assembly concept, to not use the shuttle's arm to grab on to the space station. However, what it's done is it's provided us kind of a greater control accuracy because it was designed to handle much, much greater masses. Now as we control the arm, with heavy masses in the old arm, and certainly the Zarya falls into that category of one of the heaviest things we've ever, grappled and moved with the robotic arm, it'll give you a finer control. You won't have as many start-up and stopping transients. We used to have something, when you took the brakes off the arm, the arm might move a little bit; that's gone away. So, when we're talking about tolerances on the order of plus or minus two inches and two degrees, like for the Unity installation, we really need that, that tighter controls band. Most of the changes have been, in hardware and firmware, which, controls the software on the arm.

You were the arm operator on your first spaceflight, the retrieval of the EURECA satellite back in 1993…different than what you're going to do now but, again, to the layman's eye, there seem to be some similarities. Talk about the operations of grasping two satellites like that, and how some experience in your own past has helped you prepare for this.

I learned from a great one and that was G. David Low, and, G. David Low, was the primary arm operator on a flight for the retrieval of EURECA. I was the primary arm operator for the EVA operations, where we moved the EVA crewmembers because it was G. David himself on the end of the arm. One of the things I learned from him was to question everything, to be prepared for any possibility, even though you may train in scenarios where the end effector camera's non-operational. The arm is broken down to what we call direct mode where you're applying a direct electrical impulse to each of the individual joints and it's a very painstakingly long process to move the arm joint by joint by joint. He taught me to question everything and to make sure that we're fully prepared so I would say that's one of the things in having flown previously, particularly as the arm operator, is to constantly be looking ahead: what other cues can I gain from other camera positions? Are there any things that we can look at in the labs here at the Johnson Space Center to better prepare us for the mission? Perhaps there's a different camera view that we can look at something as simple as a handrail on Zarya, and we can use that as sort of a boresighted cue to determine our pitch and our yaw and our roll. So I think, certainly having that experience has helped a little bit.

After the successful mating of these two pieces of hardware, there are three spacewalks on your mission and you're to be the arm operator standing by for all three of those. What tasks might you be called upon to do with the RMS during these three spacewalks?

We are going to use the arm from start to finish of all three of the EVAs. We have trained to have one crewmember on the end of the arm at all times during the EVA. Basically what that does is provide a very stable work platform for them to perform the multitude of tasks. All the electrical connections of which there are over forty that they're going to make between the modules; handrail installations…, sometimes people say, "Well, why are you going to install a handrail in orbit? Why don't you just put it on on the ground?" Well, the Node, or Unity, is so large and so wide that it couldn't fit in the payload bay of the shuttle had we put all these appendages on, so we literally have to wait 'til we're up in space to add some additional handrails so that the EVA crewmembers have a translation path along their elements.

After these two pieces are mated and in the midst of the spacewalks that we've talked about, you and your crewmates will be among the first group of people who will go on board the International Space Station; what are your thoughts about occupying that spot in history?

As just a tremendous, pleasure to be afforded the opportunity to do that. Never in my wildest dreams did I think I would be on this particular mission. Actually when the mission, started we weren't even supposed to go inside the elements. So that came along a little bit later that "Hey, we really need you to go inside and install the Early Communications systems" and some things that came along later, and so it's just a tremendous, pleasure to be afforded that opportunity.

Have you folks decided which one of you will get to be the first to go inside?

Well, the ingress crewmembers are Bob Cabana, the Commander, and Jerry Ross MS1, and so, Bob, being the Commander, will probably be the first one through the hatch, and as well he should be.

Presumably, entering the International Space Station-entering Unity and then Zarya-is not as simple as opening a hatch and floating inside; describe for us what it is that you do to prepare to enter these different pieces of the space station.

One of the first things that makes it so complex is that all the modules are at different pressures, and so we have to, step by step, equalize the pressure between the modules before we open up the hatches. Each of the pressures is completely different and so, at any given phase of the flight, one module may be a completely different pressure than another module so, that's part of the pre-ingress activities, is to perform all the environmental control system, operations to equalize the pressure. One of the other things we have to do is is simply accumulate all those pieces of equipment and tools that we're going to take from the shuttle into the space station. One of our tasks will be to make sure that we don't start mixing up the pieces: we don't want to take any tools into the space station and leave them behind and shut the door and then not be able to fix an orbiter problem. Nor do we want to come back with anything that the station launched with, and so, the transfer operations and tool control become very important as we go through these exercises.

It's a whole day's worth of activity that's timelined for you folks inside the station. Can you help us understand also the setup of some Early Communications equipment that is going to be put there for the first Expedition crew to use. Talk about what you have to do with that and your plans for that first day inside the station.

Well, the first day comes after the second EVA, and one of the things that they're going to do on the second EVA is to install communications antennas on the outside of Unity and then hook up the electrical connections on the outside of the module. Then when we ingress, and again it will be Bob Cabana and Jerry Ross, will be installing the Early Communications equipment. Actually what they'll be doing is using the electrical interfaces that would normally be used for the control systems to the Common Berthing Mechanisms to dock other pieces to the station eventually. So this is kind of an interim fix to communications, particularly for the early long-duration crewmembers. One of the other things we're going to be doing is, in order to withstand launch loads, they have to really snug-down all the bolts inside. Rick Sturckow, the Pilot, and I are going to be tasked with, currently, removing 774 bolts, out of the Node, many of which are non-captive. Of course as you might imagine that's kind of a problem on orbit. So we're really hoping that our electrical drills are operating properly. So most of that time we're going to be doing, some early maintenance procedures-removing bolts, taking a look at the filters, preparing some filters, installing some things in the rack, the one rack that's already in the Node.

We've talked about what you folks are going to do in terms of preparing the Unity node and grappling and mating it, the Zarya, to it, all the tasks that are required in three spacewalks. That's just the first assembly mission for the International Space Station. How critical is any one step in this whole process? Does the whole assembly sequence get thrown out of whack if STS-88 doesn't do each and every thing that's on the list?

No, not at all. And, in fact, many of our tasks that we're doing we sort of call "get-ahead" tasks for follow-on flights, like the 2A.1 mission that follows us and so I wouldn't say that any one task, in and of itself, would cause a grinding halt, to the program. Certainly if you had problems installing one module to another, we probably would have to realign the mission priorities on the next mission. Certainly it is a "building block," effort- we are counting on each of the preceding missions to do their task in order for the follow-on missions to pick up their assembly task and follow on. But certainly I think there's enough cross-training within the office that if something did not occur, that we would just change the mission priorities on the next mission.

If then as Endeavour undocks from the International Space Station, for the first time, and recedes, as you start your trip home, what will have had to have happened for you to consider the mission a success?

Well, hopefully we are leaving it with Unity mated to Zarya, and all the electrical connections mated, the Early Communications system checked out and operational, and the computer systems checked out and operational.

Let's go away from 780 nuts and bolts that you've got to remove, …more of a philosophical approach. You've undoubtedly had time to be philosophical about the part that you're going to play in this and the International Space Station itself: what in your mind is the meaning of this contraption to the future of space exploration?

I think it's the next natural progression in spaceflight. As I said, we have taken the shuttle to great places, we have done great thing, things with the space shuttle; certainly, the space shuttle will be the workhorse of building the International Space Station. But the International Space Station will truly give us this international platform to learn to work together in space, to give us a platform, a orbiting platform, for long-duration scientific investigations, and I just don't think that there's any replacement, I think it's the next natural progression. I think if we fully intend on going to Mars in the future we have to better understand physiology, and we really need long-duration spaceflight in order to do that.

Well, with that said then, with that in mind…the International Space Station is that important; STS-88 is the first mission to begin assembling that critical piece to the future; how would you like history to view STS-88?

Hopefully as a success. We would like to consider that when we undock, as I said, we look back and we're looking back at Zarya attached to Unity, that all the systems are up and operational, and that we're ready for the next mission to come up and do their task.

Image: Nancy Currie
Click on the image to hear Mission Specialist Currie's greeting.
Crew Interviews


Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 04/07/2002
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