Preflight Interview: Claude Nicollier

Claude, before we talk in detail about what you and your crewmates on STS-103 are going to do, I'd like to talk a little bit about what you have done. You have a job that a lot of people have dreamed about having. Why did you want to be an astronaut? Where is it in your life that the desire to fly in space, or to explore, where does that come from?

My first dream as a child was to become a pilot. My second dream was to become an astronomer, and I pursued in parallel efforts and studies in these two areas. I became a pilot with the Swiss Air Force, and I became an astronomer after studies in Lausanne and Geneva University in Switzerland. I became both. Of course, at the time when Gagarin flew in space in 1961, I was 17 years old. When Armstrong and Aldrin set foot on the moon in the summer of 1969, I was 25 years old. At that time, I thought that space exploration was reserved for Soviets and for Americans. I didn't think that, as a Swiss, it was possible to do that, although I was really dreaming to do that. It was an impossible dream. It was only about in the mid-70s, when the European Space Agency decided to collaborate with the United States in the human exploration of space in the frame of the Spacelab program, together with the shuttle program in development, that I saw a possibility for me to become an astronaut. Then I had a new dream, to become an astronaut. Shortly after the European Space Agency announced that they were looking for European astronauts at the end of the 70s, I signed up, but I went to visit people at the European Space Agency Headquarters in Paris. My name was on the list very early after these announcements were made through the newspapers in Europe. Then, it became my new dream, and I'm very fortunate that this dream became reality in 1978 when I was selected in the first group of European astronauts. Then, I came here in 1980 to be one of the two European Mission Specialists in training, the first non-Americans to do astronaut training here at the Johnson Space Center. And then it went on and on, and I flew for the first time in 1992, twelve years after I started training here, and I flew three missions so far. So my first dream was to become a pilot, to become an astronomer; I became both. Then, much later, my next dream was to become an astronaut, and I was fortunate to realize that dream, also.

Are there certain memorable persons or events in your life that you can look back at and credit with helping you get to where you are today?

I would say the most help I got was from my dad. My dad is a civil engineer in Switzerland; he's 90 years old now, so he's no longer active as a civil engineer, but still a very active person. He influenced me in the sense that I have the feeling that what I wanted to do is what he had wanted to do but could not because, when he was a teenager or in his mid-20s, aviation was at its beginning. It was really an era of pioneering in aviation, and very few people were becoming pilots and obviously even less, astronauts. Later when I started my first step towards becoming a pilot and an astronomer, I could feel very well that I was realizing his dream and that his dream was realized through my activities. He supported me very strongly always. He always was very keen in telling me that it is necessary to produce an effort towards reaching a goal. I remember when we were going to ski during the weekends in Switzerland, he was telling me, "You can take a cable car to go up the mountain, and then come down skiing. But sometimes you need to go up by yourself, also, and you will see the reward when you come down. You'll have a much better feeling if you have gone up yourself before coming down." This is a lesson that I always kept in myself, and it helped me a lot in all my career steps towards becoming an astronaut.

You're now assigned to a shuttle mission that's been put together on comparatively short notice for an early servicing mission to the Hubble Space Telescope. Can you, at first, summarize for me your role in this mission, and talk about what it's like for you to be a part of this particular flight?

I feel very privileged to be part of this mission, and when my nomination was announced, I was really very, very happy to be selected for this mission. Hubble is very close to my heart, and going back to Hubble, because I was there once already in 1993, is really [a] great privilege for me. This time I will be an EVA crewmember, a spacewalking crewmember, and out of the four spacewalks to do planned repairs and improvements on the Hubble Space Telescope together with Mike Foale, I will be doing two of them. So this is really my major role. I will also be assisting the robotic system operator, on one hand, in the capture of the telescope and the release of the telescope after completion of the repair and maintenance work. Also, I will help him-Jean-François Clervoy-as an RMS operator during the spacewalks of my two other colleagues Steve Smith and John Grunsfeld. So my two major roles will be, first of all, as an EVA crewmember, and another important role as support to RMS operation or robotic system operations.

When you were first assigned to this mission, more than a year ago, you and your spacewalking colleagues expected to have about two years to train for a mission that was going to involve six spacewalks. Earlier this year, of course, you found out that those plans had changed. Tell us about how you got that news and how the reality of the change has made a difference in how you all are preparing.

We got the news at the end of February this year and early March, when we had the failure of the third out of six gyroscopes in Hubble. Obviously, since that time, Hubble has been functioning with three gyroscopes, which is a minimum necessary to do science. We felt like there may be a possibility that we might have to go early in case another gyroscope was going to fail. In fact, it developed rather rapidly at the end of February and early March. We got the message that the decision was made to perform an earlier servicing mission number three, or better said, maybe to split servicing mission number three in two. [We would] have one early in order to-as soon as practically possible-replace all gyroscopes on board Hubble in case of a failure of another gyroscope and do some other important maintenance and repairs on Hubble that I can talk about later. Then, [we would] have the second half of the third servicing mission about a year or year and a half later to replace one of the cameras, to replace the solar arrays, and do some other work in terms of cooling of some of the existing scientific instruments. For the four spacewalkers already in training, doing evaluation and engineering runs in the Neutral Buoyancy Lab here at Johnson, and [visiting] Goddard Space Flight Center since the summer of 1998, it meant that suddenly the pace of our activity picked up quite a bit. In mid-March, we only had about six months to flight, so it's a very short time to get ready for a relatively complex space shuttle mission. So the pace picked up quite a bit, but I must say this is very exciting. I'm very happy to be part of that.

As you mentioned a moment ago, you have seen the Hubble Space Telescope up close once before, on STS-61. Has your firsthand experience with this telescope helped you and your current crewmates get prepared for the tasks on this mission?

I think it did. In fact, I had the chance, on the first Hubble Space Telescope Servicing Mission in December, 1993, to be, on one hand, the flight engineer on board and the robotic system operator, the role that Jean-François Clervoy, another ESA astronaut, will have on this mission. Of course, I didn't train for any of the EVA tasks that we performed at that time, but I was still working pretty close to my crewmates who were going to go EVA and who went EVA, in the sense that I was responsible for moving them from one place to the other above the cargo bay and toward the telescope to perform their task. I did a number of runs as a scuba diver when they were doing their practice runs in the large water basin at Marshall Space Flight Center. Right now we do this here at Johnson. So I was relatively familiar with the EVA task, but I was, of course, quite familiar, because it was my major responsibility, with the robotic system tasks. In a way, now, I'm going to be at the other end of the arm, if I can say, and maybe the contribution that I was able to bring to this mission is in that area-the cooperation between the EVA crewmember and the RMS operator to perform the job. It's really a so-called EVR activity, in the sense that there is EVA, on one hand, which is a major tool to perform the repair, but together with robotics. In fact, we will assemble the whole space station using also EVR means. The first Hubble Space Telescope Servicing Mission, mission number 61 in December '93, was, in a way, the first mission where, from the shuttle, we used a total EVR scenario to do major maintenance and repair work on a scientific satellite or instrument on orbit. So I think this experience that I had in December '93, I brought it to the team this time. I helped somewhat, mainly for EVA number 4 for our mission, which was quite poorly defined initially, to redefine it from an EVR point of view and from the point of view of the various attitudes and geometries of the arm to perform the task.

Specifically on that point, did your experience allow you to offer any particular tips or insights to Jean-François Clervoy about how to operate that large arm around that huge telescope?

Well, a little bit, but Jean-François is so talented that I didn't have to bring him a lot of information because he grasped all of this very rapidly. Still, we talked quite a lot at the beginning of the training, in March and early April, about how we're going to do it: what terminology we were going to use between the EVA crewmember and the RMS operator to have a clear indication of where he wanted to go, what attitude his body had to have, and the changes in the position of his body to perform a certain delicate task on the telescope. So we worked together, but once again Jean-François has a lot of talent. I'm very impressed with the quality of his work, and I know he will be doing a perfect job on the mission.

To help set the stage for us all to understand the job you and your crewmates are going to do, let me get you to talk for a moment about the mission of Hubble. What is it that the Hubble Space Telescope can do that telescopes on the ground, or even other telescopes in orbit, cannot do?

If you have an astronomical instrument on orbit outside of the atmosphere, the radiation that you are studying, whether it comes from a star, from interstellar matter, from a planet, from a galaxy, or some kind of exotic object far away in the universe, doesn't go through the atmosphere. The atmosphere, on one hand, blocks a lot of the radiation. It blocks all of the gamma rays, the x-rays, the ultraviolet. It blocks a good part of the infrared, also. So you have available the whole spectrum of radiation, and finally, we learn about these objects in the universe mainly through the radiation they send us. So it's much more information that you get when you do observations of celestial objects from space compared to observations from the ground. On the other hand, the atmosphere is an inhomogeneous [medium]. It has always turbulence, and this turbulence and lack of homogeneity of this medium, which is transparent in the visible part of the spectrum, is such that the resolution or the accuracy of the picture that you get at the focus of a telescope on the ground, even from a mountaintop observatory, is limited by the atmosphere itself. So these are the two advantages of having a telescope in space: on one hand, you get much better resolution, or accuracy, of the pictures, which means you can see further away for a given size of a telescope, and you have accessible the whole spectrum. In the case of Hubble, beyond the visible part of the [spectrum], which is accessible from the ground, you can go quite far in the ultraviolet and somewhat in the infrared, also. So you get more information about the object you study because you have a wider spectrum available. Of course, one of the great benefits of Hubble (and this has brought us incredible results over the last nine years of operation, especially after the first servicing mission that restored the optical quality of the telescope that was [caused] by the somewhat flawed shape of the primary mirror), is it has brought us incredible results about the faraway universe, about planetary surfaces, about birth and death of stars. It has been [an] incredible instrument.

Can you further characterize the value of the data - the pictures - that Hubble has brought to us so far and presumably would continue to do?

The spectrum of the studies made with Hubble is very wide. We look at relatively close-by objects like planetary surfaces, and the pictures we get of the surface of Mars, for instance, are really incredible. Since we had visits [to] Mars by planetary probes that got very far, landed on the surface and, of course, that gave us extremely detailed pictures of Mars, we have not had any picture with the level of detail that we have with Hubble. So we have a constant monitoring of planetary surfaces-in particular, Mars-and other planetary surfaces-for instance, the giant planets Jupiter, Saturn, Uranus, and Neptune-with the Hubble Space Telescope. This is a great benefit for regular follow-up of what's going on in the atmosphere of these large planets like beyond planet Mars. This is the close part of the studies of the Hubble Space Telescope. If I go to the other extreme, the studies of the early universe and of objects that are very far away and objects that we see as they were a very long time ago, we have been able, especially with the Hubble Deep Field (an exposure that was taken during ten days at the end of 1995 which is the deepest picture of the universe that has ever been taken by any telescope in the history of humankind) we see objects that are about 10,000,000,000 light-years away. That means that, not only [do] we see very deep in the universe, but [that] we see very deep in the past of our universe. We see these objects as they were 10,000,000,000 years ago which is not too many billion years after the Big Bang so we've been going down, or going back in time further away than we have ever been able to do before. I think these are incredibly valuable results, and we look forward to the continuation of incredible science with Hubble over the next few years, and of course a continuation with the Next Generation Space Telescope beyond 2008, when Hubble will be slowly replaced with an even more capable instrument. This is very, very exciting.

The Hubble program is a cooperative effort between NASA and the European Space Agency. Talk about the involvement of ESA in the Hubble effort and the part ESA has played and continues to play in the development and operation of this telescope.

From the beginning on the European Space Agency was part of that program; in fact it's a joint program of NASA and the European Space Agency with about 15% contribution of the European Space Agency to this project. Initially, the European Space Agency provided the solar arrays, which are responsible for transforming the solar radiation into electrical power [for] the on-board systems of Hubble. Also, ESA provided one of the focal instruments, the so-called Faint Object Camera, which is still on board the telescope at this time and will be replaced on the fourth servicing mission, which is the second part of the third servicing mission, by an Advanced Camera for Surveys. So ESA contributed from the beginning in the systems of the Hubble Space Telescope, and of course, in return, the European astronomers receive a similar fraction of observing time on the telescope. In fact, the European astronomers have received a little more than 15% of the observation time. It's about 20%. All this activity of the European astronomers is coordinated through a facility in Garching, near Munchen in Germany. It's called Space Telescope European Coordinating Facility, which, by the way, is located at the headquarters of the European Southern Observatory. The European Southern Observatory [is] responsible for the manufacture and management and utilization of several large telescopes in the southern hemisphere, in Chile. I must say, it's very good that we have these two organizations co-located because there's a lot of exchange of information and joint programs between the team utilizing the Hubble Space Telescope in Europe and the people using these large telescopes in Chile, in particular the Very Large Telescope, a set of four eight-meter-diameter mirror telescopes located in Mount Paranal in northern Chile. There's been a lot-and there will be even more so in the future-of cooperative studies between ground-based telescopes which, of course, suffer from what I was talking about. They look through the atmosphere, so they suffer from these problems. But they are very large telescopes, and they collect more light than Hubble can collect. They are eight-meter-diameter telescopes, so they collect much more light. So there's a very interesting synergy between these two approaches to astronomy, and we are fortunate that in Europe these two are co-located and work together very closely.

Another question from a broader outlook: Hubble is the first of four components of NASA's Great Observatories program, already followed to orbit by the Compton Gamma Ray Observatory and just recently the Chandra X-ray Observatory, with an infrared telescope still to come. Can you give us a sense of the value, if not the necessity, of having several telescopes to investigate different parts of the spectrum of light in order for astronomers to really learn about the nature of the cosmos?

Again, if you can study a wide part of the spectrum, you can get more information about the objects that populate the universe, and, technically speaking, we cannot have a telescope that can study objects in the gamma ray part of the spectrum and at the same time the infrared because these are completely different technologies. Not only the detectors at the focus of the telescope, but all the imaging system is of a different nature. So we cannot have a telescope that observes the total spectrum of radiation. So we need to have different instruments to study different parts of the spectrum. And the benefit of having all the spectrum available, I mentioned already before, is that you get the information from celestial objects through radiation so if you can have access to the full spectrum you get more information. In general, the objects in the universe that are very high-energy objects, or the processes that are high-energy processes, will radiate more in the short wavelength range towards the gamma rays or the x-rays. The objects that are of moderate energy, like our sun or most of the stars that we see in the night sky with the naked eye, are objects in which relatively moderate energy processes are taking place. And they radiate in the visible part of the spectrum or somewhat toward the ultraviolet or the infrared. Objects that are very cool and objects where low-energy physical processes take place radiate more in the long wavelength part of the spectrum; they radiate in the far infrared or in the millimeter radiation, or even the radio waves. So, in general, with this ability to observe the whole spectrum of radiation, we can observe the whole range of physical processes from the high-energy processes, covered with the x-ray and gamma ray observatories, through the medium range energy processes, covered with Hubble Space Telescope and later with the "next generation" Hubble Space Telescope. Of course, in the low-energy processes, we have Hubble to a certain degree because it can see some in the infrared but not very far. The future infrared space telescope will cover that area in a much more efficient manner. And also the Next Generation Space Telescope, which will be located much further away from the Earth than the Hubble Space Telescope presently is, will also explore the infrared part of the spectrum. As far as the radio waves part of the spectrum, we can do these adequately from the ground because the atmosphere is basically transparent to our radio waves.

For Hubble to continue to make its contribution in this effort there is a servicing mission going now, a little earlier than was originally planned due to the failure of gyroscopes on board the telescope. You mentioned it earlier, but let me ask you to do it again. What is it that the gyroscopes on Hubble do, and why has the failure of these pieces of equipment prompted NASA to take the unusual step of flying this mission so much earlier than planned?

The gyroscopes are part of the guidance control system of the Hubble Space Telescope. There are many elements in this control loop for the guidance of Hubble. On one hand, to be able to go from one direction in the sky to study such an object to another direction to study another object, and on the other hand to be able to maintain accurately the position in space. In fact, Hubble is able to maintain its position in space, or its attitude in space, with an accuracy of seven-thousandths of an arc second, which is a very remarkable achievement. We need several elements in order to be able to control the attitude of Hubble. We need gyroscopes, on one hand, which keep constant position in space once they are spinning fast. We have several types of gyroscopes on board Hubble, including these Rate Sensor Units that we have to exchange. We have also gyroscopes that are massive gyroscopes that are used as reaction wheels, against which a telescope reacts in order to change its attitude from one direction to another one. We have the Fine Guidance Sensors, one of which we will exchange out of three. Another one we changed on the last servicing mission, and on the fourth servicing mission in 2003 or 2004, the third one will be exchanged. So, the gyroscopes that we'll exchange are part of a control system that is responsible for maintaining an accurate attitude of Hubble in space to perform its scientific duty-it's a very important element, obviously…absolutely indispensable to do science.

Yet the telescope was launched with backups for these systems. Why have the failures up to this point necessitated the early response?

It has backups in the sense that we have six of these gyroscopes, and we need three to properly do science. It happens that we had failures. The telescope has been in orbit [for] nine years, and we had failures of these. In fact, there are failures in very thin electrical wires or leads that provide power to these gyros. It happens that in the gyroscopes that we will replace, all the replacement gyroscopes have some modification that will make it much less likely for these leads to be damaged and break after a while. So the redundancy of the system will be certainly improved. Although we only have three gyros that failed, we will replace all six with gyroscopes that are designed in such a way that the future failure likelihood will certainly go down. I'm pretty sure, I hope at least, that these gyroscopes that we will exchange will take Hubble to the completion of its useful lifetime in about ten years from now.

To begin to do this job, you and your crewmates, after a successful launch, are going to approach this satellite and snatch it out of orbit and put it down in the payload bay. Talk us through the procedures of that day, the rendezvous and grapple and berthing and talk about what you will be doing as part of the team.

I will be assisting Jean-François Clervoy…I'm the so-called R2, or the assistant to the prime robotic system operator, who is Jean-François Clervoy. I don't have, during this phase, any role as far as the orbiter systems are concerned but I have a responsibility as an assistant to Jean-François Clervoy. In fact, the task of grappling the Hubble Space Telescope, or any free-flying object in space, and then installing that massive object inside the capture envelope of small latches in the back of the cargo bay is a pretty difficult task. Once again, Jean-François Clervoy has a lot of talent. He could do it all himself, but I will certainly assist him to provide redundancy and backup to his operation. It's going to be basically a two-person task to do this jointly. This is going to be my duty during the capture of the Hubble Space Telescope. I will have a similar role during the release of the telescope a few days later.

With the telescope in place in the payload bay, the next day Steve Smith and John Grunsfeld will exit the airlock to start the series of spacewalks to keep Hubble in shape, and on that first spacewalk they're to replace the failed and the ailing gyroscopes. Talk us through the timeline for that first spacewalk and, in the process, also explain what you and Mike Foale will be doing inside the orbiter while Steve and John are outside.

The main purpose of the first EVA, obviously, is to replace those gyroscopes because that's the primary task. [If], for some reason or another, we need to come back early and we can only do one EVA, at least we will have done that, which is the primary reason why we go early on this mission. So Steve Smith and John Grunsfeld will have as a first task the [replacement of] these three Rate Sensor Units, each of which contains two gyroscopes. And their second task is to work on circuitry for the loading of the battery's so-called Voltage Improvement Kit they will install, for each of the batteries Voltage Improvement Kits to improve the efficiency of loading of the batteries. So that's going to be the first EVA, which should last about six hours. Mike Foale is going to be the so-called IV crewmember, the intravehicular crewmember, and, in a way, like a conductor of a two-person band. He will be directing the operation from inside the cabin. He has total knowledge of what has to be done on this EVA, and he has the procedures and all the cameras in his direct view of what's going on. He will be directing the operation. I will be assisting Mike Foale during this IV task. We may have unforeseen events. We may have some bolts that we try to undo, and the torque will be higher than we anticipate. We have a full list of so-called "contingency operations" that we'll be ready to jump in. We'll give guidance to the crew about what to do in case things happen that were not foreseen. I'm sure that it will require two persons to do that, especially if we have problems. We have large sections of our Flight Data File, of our documents on board, that list all that can be done in case we have unforeseen problems. So I will be assisting Mike as an IV crewmember. Of course I will also assist the EVA crewmembers when they get ready to go out, when they suit on preparation of the EVA, and when they come back I will assist in reconfiguring the suits, loading the batteries, recharging the water, and so on.

Take us through the timeline and from the point of view of somebody who's inside the spacesuit this time; tell me what you'll be doing during this, your first spacewalk.

We'll be doing the next activities as far as maintenance and repair on Hubble in the order of priority, and the next activity will be replacement of the brain of the Hubble Space Telescope, which is the on-board computer. The computer that is presently on board, although it was somewhat improved on the first servicing mission with the addition of a so-called co-processor, is a relatively old computer that has limited capability in terms of its speed and its memory capacity. So we'll exchange that computer to a much more up-to-date computer. That will take an hour and a half to two hours, and [on] the second part of the EVA number 2, Mike Foale and myself will replace one of the Fine Guidance Sensors, which is located in a radial position on board Hubble. Some of the scientific instruments are axial instruments, but the Fine Guidance Sensors are in radial position. And these Fine Guidance Sensors are, in a way, star trackers-they give you an image of the periphery of the field of view that is being studied by the Hubble Space Telescope. Now there are a certain number of stars in that field of view, and the operator on the ground picks up one of these stars. This is a guide star. We do this for all three Fine Guidance Sensors, and the telescope always keeps these stars in the same position within these fields at the periphery of the science field, at the center of the instrument. This is the way that Hubble can be maintained through these gyroscopes that I was talking about before, can maintain a precise attitude in space to do the science. So, as a summary, EVA number 2 is going to be computer and Fine Guidance Sensor number 2 exchange.

I'd like you to take EVA number 2 as an example and give us a sense of the steps that you have to go through and a sense of the kind of coordination between the spacewalker and the arm operator to get these things done. At least for a portion of this spacewalk will you be on the end of the arm?

That's correct, yes. In fact, we try to share this position at the end of the arm because there are certain challenges about free-floating: always being linked with a tether to the space shuttle and being at the end of the arm. For EVA number 2 Mike Foale will be at the end of the arm for the first part, for the replacement of the computer, and then, I will [be] on the arm for the second part, for the replacement of the Find Guidance Sensor. Now, it happened that what we have to exchange on the telescope is normally located in thermostabilized containers inside the cargo bay. You can see these boxes which are covered with metal foils for thermal reasons, and they are also, most of the time, thermally controlled inside to keep reasonable temperature inside each of these containers. A typical operation for an exchange of a component on board Hubble is to remove the component from Hubble after opening the doors. This is normally done by the EVA crewmember at the end of the arm. Then, [we] put that component in a temporary location and go to the thermostabilized container, open the door-and these doors always have latches, either screw latches or other kind of latches- take the new component [and] go and install it on Hubble. Then [we] take the old component that was in a temporary location and bring it inside the thermostabilized container and close the door. This is [a] typical operation; for instance that's what we'll do for the Fine Guidance Sensor, which is a very large instrument. When we have smaller components like a data transmitter that will be exchanged on the third extravehicular activity day, then we can do that swap more easily. We don't need to have a temporary location for the old components. We can do the swap directly at the thermostabilized container in the cargo bay. For a large object like the Fine Guidance Sensor, we need to find a temporary location for the old instrument. Of course, this is all done as a well-coordinated ballet between the free-floater and the EVA crewmember at the end of the robotic arm, and we practice that a lot in the water. We practice it up to about ten times the duration that we will have on the EVA. A typical EVA is six hours, and we practice about sixty or sixty-plus hours in the water to do that task.

Given your own experience as an arm operator, now as a spacewalker in training, do you have a new sense of appreciation for the coordination between the people inside and the people outside?

I certainly do. We developed already, before the first servicing mission, this has been further developed on the second servicing mission and we refined it this time, all the terminology. And the words to be used between the EVA crewmember at the end of the arm and the RMS operator, we want to be very precise. Sometimes you want to have certain motions, either linear or rotational motions, with respect to the shuttle's cargo bay, but sometimes you want to have these changes made, either in position or rotation, with respect to your own body. When you are very close to the work site and you want to have access to a certain connector on the left-hand side, then it doesn't matter what the reference is with respect to the orbiter as a whole, but you want a reference with respect to your body or with respect to the work site itself. So we had to develop all this terminology, so it has been fun and I think it's working quite well. In fact, I have the feeling that what we develop here may be useful not only for Hubble, because that's the main purpose, but useful also for space station assembly. In a way, what we do is not totally different from some of the tasks that will be performed for the assembly of the International Space Station.

You and Mike Foale are now scheduled to make a second spacewalk on this mission; again, talk us through the timeline of that excursion and what your tasks are on this fourth and final planned spacewalk on this mission.

The main purpose of this fourth spacewalk is going to be to install some passive thermal insulation on the outside skin of the telescope. There is one part of the telescope that is constantly exposed to the sun, and this part has been more damaged by the space environment than the part that is in the shadow. There's been more peeling off and damage of the passive thermal insulation than on the shadow side. I will install, pretty much like you install wallpaper from rolls, a new thermal insulation against the surface of the telescope. We have wires and clips that we'll use in order to affix these thermal insulation panes into the telescope. That's going to be the main purpose of the fourth EVA: we have a large surface to cover so it will take quite a lot of time to do that. We will also, at the end of that EVA, work on some of the latches. Some latches are not working properly, door latches on the lower part of the telescope, the aft shroud of the telescope, and we'll replace two of the latches [with] new latches that will make it easier in a future mission to open and close the doors. At the end of that last EVA, we have to complete a certain number of tasks because that's going to be the very last EVA of the mission. We have a certain cleanup task to perform in the cargo bay, which will take about an hour, before we go back in the airlock.

You go back in the airlock. The next day, the telescope is to be returned to its mission and Discovery heads home to the Kennedy Space Center, having completed another important upgrade to the Hubble. When you are asked about it, how do you explain how the mission that you and your crewmates are preparing to fly, in conjunction and coordination with a lot of engineers and scientists who don't get to fly as you do, is going to help further the objectives of space exploration?

I think it does this first of all, because it gives a new life to Hubble. As we know, we have no more redundancy as far as the gyroscopes are concerned, and if we are not doing this mission sooner or later-we don't know exactly when- a fourth gyroscope would probably fail. Then, the telescope could not be used any longer to do science. So in order to preserve our ability to do this first class science with Hubble we feel it very important to do this mission, to do it early. So that's going to be, for us, very gratifying to feel that we serve the scientific objective of the Hubble Space Telescope through, of course, the replacement of the gyroscopes, [and] also through the other improvements that we will bring on that mission. So this is going to be the very first and fundamental benefit of this mission. It's going to be a new life for Hubble for several years to come. I think-and I mentioned that already before-that, to a certain degree, we start to refine the EVR activities from the shuttle, the combined robotics and spacewalking activities. Such activities will be typical for space station assembly and space station maintenance. I remember on the first Hubble Space Telescope servicing mission in December '93, this was the first time that we were doing this at a grand scale. It had been done previously but only for a relatively simple operation. But the whole first servicing mission of Hubble was devoted to a combination of robotics and EV activities to do major repairs and maintenance on a free-flying object in space. I think, from a Hubble Space Telescope maintenance mission to the next one, we make improvements, and I think this serves, not only Hubble, but it serves also the whole human spaceflight community, mainly in the area of maintenance and repairs of anything in space, including the space station. And I think a third benefit is that we try to put it up in a short time. From the decision to do this mission until we fly, it's six months and one week or so, so it's [a] very short time. It is going to be an experiment of how it works, and I see I have all reasons to believe that it will work fine. But it's a short time. And we also have [pushed] the envelope here a little beyond what has been done in the past. So, three benefits, to summarize: the benefit to Hubble, the benefits to EVR activities, or extravehicular and robotic activity, joint activities in general, and an experiment about preparing for a mission in [a] relatively short time. It's not only us, it's the whole team getting ready for this mission: the whole training team, the flight control team, the support team for the Goddard Space Flight Center, the management team. This is a challenge, but we'll make it.