Installing the Near Infrared Camera and Multi-Object Spectrometer (NICMOS)

EVA 1 February 14, 1997 Daily Updates from NASA Space Walkers: Mark Lee and     Steve Smith     EVA One Overview Getting Ready Opening the Telescope Inside the Telescope Remove GHRS, put in STIS Reconnecting STIS Remove FOS, put in NICMOS Close doors of HST Testing the Instruments

In His Own Words
The mission as seen by
NASA Astronaut Steve Smith
STS-82 Mission Specialist

Overview		We're doing 4 space walks, and the first one is probably the one with the most pressure because it has 2, it has the highest priority task in it and probably the 3rd or 4th highest priority tasks according to the customer. So the first day, we're going to take, we'll go out to the payload, into the payload bay, Mark Lee and I will. And, of course, this will be my first space walk. Our major goal that day is to take out 2 scientific instruments that are in the Hubble space telescope that are working fine and to put brand new instruments in. Both of these instruments that we're swapping out and replacing are about the size of a phone booth, if you'll think about that, about 7 or 8 feet tall. Most of them weigh. Excuse me. They both weigh about 6-, 7-, 800 pounds. So, of course, they're heavy on earth. In space, they won't weigh much. The primary purpose for replacing them, again, is to upgrade the scientific capability of Hubble. And I'll talk a little bit more about that.
Getting Ready		Physically, what we'll be doing is using the robotic arm to help access Hubble. So I will be on the arm most of the first day, and Mark will be crawling around, floating around the payload bay, helping open doors and undoing the connectors, and things like that. As the person on the arm, I'm much more anchored or steady, so I will be the one that will be handling the boxes. So I will be on the arm and Mark will be free-floating. The first thing we do when we go out the door for the 6-hour EVA, each space walk, or Extra-Vehicular Activity, is scheduled for 6 hours. The first thing we'll do is basically set up the payload bay. And there's several little things that we do just to make our work later in the space walk easier. So that's about a half-hour task.
Opening the Telescope		Opening the Telescope Specifically, the way it works is we'll go up to Hubble and open up a couple doors. We'll go in and release the cables that are attached to GHRS, release bolts that are attached to GHRS. We'll pull it out, again, very carefully because the connections are low. We'll park it on this fixture that's in the payload bay, just so it stays there for a while.
Inside the Telescope		Then we move on to the big task, and that's to take these 2 boxes out and to put 2 new boxes in. The boxes we're going to take out are 2 spectrographs. I'll explain a little bit later what spectrographs are. One is called the GHRS or Goddard High-Resolution Spectrograph. It will come out first and be replaced by another phone-booth-sized box called STIS, and that stands for Space Telescope Imaging Spectrograph. That'll be a one-for-one swap. The new STIS, or the new box, is, of course, launched in the payload bay in a special container, where it's bolted down. STIS We'll be using power tools to release the bolts that have the old instrument and, of course, the new one. Mark will have his own power tool, and I'll have a separate one. And we have several of each in case those break. On the end of the arm, you also notice during the flight, I have a whole slew of tools on this little tool board behind my back. That's in case we need, in case the power tools break or some unplanned contingency occurs where we have to use one of these other tools.
Remove GHRS, put in STIS		So we'll take out GHRS and put STIS in. That will take about 2 hours. Each box that we're putting in is valued at tens of millions of dollars, about $60 million a piece, so we have to be very careful. The clearances around these massive boxes is just a couple inches on the top and bottom. And I cannot see around the boxes as I'm holding them. So I'm very dependent on Mark to tell me to go left, right, up, and down, etc. So we've had a real good practice of that coordination.
Reconnecting STIS		For me, that's the most critical point of the day, is when I take the new boxes into Hubble because, again, they're very valuable, they're very sensitive astronomical instruments, so we can't bump them at all. And we'll put STIS in, tighten the bolts down, and reconnect the connectors.
Remove FOS, put in NICMOS		We take out the faint object spectrograph, or FOS, and same size box and everything. Park it on its little fixture in the payload bay, then go get the new box or NICMOS, which I discussed before, and Near Infrared Camera and Multi-Object Spectrograph, and put it into Hubble. And, again, tighten the bolts, tighten the cables up.
Close Doors of HST		We'll then close the doors of Hubble. We expect the NICMOS test also to take 2 hours and close the doors on Hubble, grab FOS off that parking fixture and put it away in the payload bay. That's the major tasks for that day. NICMOS is the single most important thing we can do for Hubble. That scientific instrument, and I'll tell you why in a second.
NICMOS: A New Eye on the Galaxy NICMOS		NICMOS is the single most important reason for going to Hubble. And it is going to allow us to look at new things because it can help us look at infrared items. Let me explain that. I'll just pretend you don't know anything about this. When we see things, light, we think of visible colors, the colors of the rainbow. And that's because our eyes are designed to see those colors. But those colors, as wave lengths of light, are only a small portion of what is actually out there. And there are wave lengths that are actually shorter than what we see and longer. The ones that are shorter are called ultraviolet rays. And the ones that are longer are called infrared. And this is as if you were looking at something and not seeing everything. So when we look at these beautiful pictures that Hubble is returning, it only sees the things in this very small band of light that we can see with our eyes. So right now, we can look at a star and not see everything. Well, the technology has been developed to be able to detect infrared light. So we will take out instruments of Hubble that cannot see this light and put in an instrument that will see infrared light. Kind of the way I think about it is: In the old days, doctors could look at a person who was sick and collect certain information. It was very limited in the 1930s and 40s. As technology developed, you could look at the same body but get much more information, going into X-rays and blood tests and CAT scans and ultrasounds. So as technology developed, you could look at the same thing and get much more information than you used to. Well, that's the situation here. Hubble right now cannot see in the infrared region of light even though we know that there's lots of information coming from stars and planets in the infrared wave lengths. So Hubble will basically open up a new eye on the galaxy, or the universe. That's kind of the main thought there.
STIS: Getting Fingerprints of the Stars STIS		STIS is the spectrograph. Spectrographs don't really provide pretty pictures, but they provide a lot of information about celestial bodies, like stars. Spectrographs take the light that is received from an object and break it out into its different components, much like a prism does that you'll hold up to the light. The light coming from the sun looks like one color to all of us; it looks yellow. But we know that it's actually made up of a bunch of different colors. When we see a rainbow in the sky, for example, that's the sun's light being diffracted and made into a spectrum. So that's what a spectrograph does. And it's important to have a spectrum analysis of something because you can tell much more about a celestial body if you have its spectrum. We know, for example, that the sun is made up of certain elements. We know its size. We know the mass of the sun. We know its rotation rate, etc., etc. A spectrum from a body in space is like a fingerprint, like an X-ray, and like a CAT scan. It gives you all of this information about a particular body. So, for example, when we take a spectrum analysis of a star, we can tell its rotation rate, its composition, its mass, its density, etc., etc. So if you take a picture of it, a physical picture of a body and take its spectrum, you have so much information that it's both together are very important. Well, the spectrographs on board Hubble are very limited. They're not very efficient. Each image that these spectrographs take right now is made up of about 512 pieces of data, in simple terms. Well we have detectors now that will provide over a million bits of information in each view. So we go from a 512 bit image, one-dimensional image, to a 2-dimensional over 1-million-bit image, basically a thousand bits by a thousand bits. So the increase in the amount of information that you get is incredible. Thirty times more efficient is the number I've heard. So these spectrographs that take fingerprints of celestial bodies can be much more advanced now. And that's the whole objective of taking out old spectrographs and putting the new one in. That's about as basic as you can get. Haha.
Testing the instruments out		And each time we put a box in, the customer, at his control center in Maryland, at the Goddard Space Flight Center, after we put a box in, will test it using domestic satellites to send signals to Hubble to make sure that we put in a box that works. Because we don't want to leave until we're sure they all work.

RETURN TO MAIN PAGE