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STS-110 International Space Station
Question and Answer Board

Liz from Davis
How are the 5 sides of the S0 truss distinguished from each other?
The truss is like a polygon. A polygon is kind of like a circle with many sides, and this truss has six sides to it, and we have five bays. So there are five sections to the truss and each section has six sides. And we label it Bay 1, Bay 2 all the way up to Bay 5. Each side has what we call a face, so they each have six faces. So we have five bays each with six different faces, and that's how we label the truss.
Cletus from Bithlo
What happens when someone gets sick up in space?
I think that's happened a few times. Well, who gets sick in space is a good question, and what can they do to prevent it? There are different types of medicine the astronauts can take, you have to get your rest, you have to eat right, you have to exercise, there are a lot of factors that contribute to preventing you from getting sick. And like I mentioned, there are some medicines the astronauts can take. Back in the old days they used to think you had to be some kind of Superman to go into space, but we're finding out is, some of these Supermen do get sick and some of the non-Supermen don't get sick. What we're finding out is that everybody is different.
Tom from Yardley
At what speed in miles per hour are the ISS and the shuttle traveling when they dock in orbit?
Great question, great question. Very, very fast! When the station and shuttle are going around the earth, they're going about 18,000 miles per hour. They are also at the same altitude, so they're going about 18,000 miles per hour when they do dock.
Liz from Davis
I have heard that it takes 2.5 people to keep the ISS running smoothly, leaving 0.5 person to work on scientific experiments - is that true?
It does take about 2.5 people to keep housekeeping chores on the space station, and that leaves about a half a person to do science. Our goal is to get maybe seven astronauts on the space station, when it is bigger and we have different and more crew return vehicles we'll have up to seven people on the space station. Right now we are still in the building process, still putting space station together, and we are performing some science. Hopefully that will grow in the future and we'll perform more science.
Taylor from Sarasota
Why is the S0 Truss so heavy? I read that it has a mass of over 30,000 pounds, which is massive! As the S0 will be weightless once on orbit, couldn't much of the mass of the truss be "shaved off" before launch, like the old LEM, which could not support itself in 1-G, but did just fine on the Moon.
Great question, Taylor. If you remember when we went to the moon, that's very very far from us, and the gravity is a lot less than we have here on Earth. The space station is only going to be about 250 nautical miles straight up so we're still in a low earth orbit. The space station itself is considered a low earth orbiting vehicle - we're very low compared with going to the Moon, we're very low compared to some of our satellites that are 18,000 miles straight up - so we're still affected by gravity. When the solar panels and radiators are extended on the space station it does produce some drag and some force. When the solar panels are extended, it does provide a force to the station, plus we are affected by gravity, so we do have to have a rigid structure. Now, there are some components on the Truss segment that can only operate in a zero-G environment, some of the small experiments and some of the small utility panels. But the main body of the space station does have to be rigid because we are a low earth orbiting vehicle.
Judy from Cape Canaveral
What is the maximum time a human could remain on the ISS? Since bone density and muscle mass may be lost in space, do the ISS crew members lose weight?
Right now the astronauts are averaging about 4-5 months on the space station. This is kind of a new arena for us and that's one purpose of the space station, among many purposes, to study how humans react in space for a long time. I think each person is different, some people have a hard time after 2-3 weeks and some have no problem after 4-5 months. So it really depends, and we're starting to find out some of the variables, some of the reasons why people react differently in space. In space the astronauts do lose a little bone mass, there's muscle deterioration, spatial disorientation, and again it's almost like osteoporosis. It just depends on the person, and the condition they're in, and how they exercise and the foods they eat. And that's one of the purposes of the space station, because we do want to travel to different planets and asteroids in the solar system, but before we do that we have to find out how people will react in space.
Tyler from Topsham
When will people like me be able to live on the space station?
I think Tyler's going to be a future astronaut! Well, hopefully not too in the distant future, we'll have people going off to space to work. I'm not quite sure when that will be, we're going to have a space station, we're going to man it, we're going to develop it, future plans are going to Mars or even going back to the Moon, it just depends. But as time goes on, I think you'll see more of the average-type person going to space, and I think it's just a matter of time. It’s really just a matter of time.
John from Lutz, FL
Why is the S0 Truss so expensive? Isn't it a relatively simple piece of hardware (e.g. no pressurized volume, no life support, etc.)?
The space station is going to have a whole bunch of trusses up there, about 12. And this truss that just launched is called the S0 truss. It is the main truss system on the space station. We're going to have trusses that begin with the letter 'S' for "starboard" and trusses that begin with the letter 'P' for "port." And we'll have six on each side. S0 is the main truss. It weighs about 24,000 pounds and is about 43 feet long, so it is a massive piece of equipment. The reason it's so big and weighs so much is it has to support the weight and the functions of all those big solar panels that extend to about 126 feet. It has to be rigid to support the forces produced by those panels and all the utility and fluid and electrical cables and all that good stuff that it takes to make the space station run, and route all that power and all the fluids into the pressurized modules.
Roxana from Saratoga, CA
What is the expected completion date for ISS, and how many people will be able to stay on ISS when construction is completed?
Right now we hope to have the space station fully complete by the year 2006. That's our goal right now, and of course we'll have to see what happens in the future, but that's our goal right now. We currently have three astronauts on the space station and I think in the next couple years, we'll probably stick with about three people, and as time goes on and space station gets bigger and better, hopefully we'll be up to our crew of seven astronauts. Now for the second part of that question, that's an option people have looked at. Well, maybe we can go to Mars or we can go to some of these other planets, by launching from the space station or maybe even launching from the moon, because it would be a lot cheaper than launching from Earth. When you launch from Earth, you have to achieve a certain speed to escape the Earth's gravitational pull. Well, on the Moon it's a lot less and of course on the space station it's a lot less too. So that's an option, people are looking at that.
Jacqueline from San Diego
I have read that the truss has over 200 thousand parts. How many man hours does it take to completely assemble the unit in space?
Oh, boy. Well, it has taken us about a year and a half, almost two years at Kennedy Space Center to do the integration and testing of this unit, and about three to four years before that just to put the main frame together. So it took awhile to get there. But in space, they're going to have four spacewalks over a couple of days to remove this truss from the space shuttle, attach it to the top portion of the lab which is currently attached to the node, and of course the astronauts have a bunch of fluid and electrical connections they have to make. So it took us about six or seven years to build and they're going to put it up in a few days with four spacewalks.
ronnie from myrtle beach
What is the life expectancy of the ISS? Since MIR outlived all expectations, has NASA reevaluated its original life span for the ISS?
V Well, on paper the life expectancy of the space station is 15 years, but we have a factor safety of two built into it. Fifteen times two is 30. But I can pretty much guarantee you it's going to be around for a long time. This is a fantastic piece of equipment that we're putting into space, it's very rigid, it's very solid, and I think our kids - and maybe even their kids - will see the space station.
Matthew from Oviedo, Florida
Since the ISS is only about 245 miles up, can gravity pull it down? Also, why is the SO an important truss?
Good question. I think we kind of answered that in the last few questions. The ISS or International Space Station is going to be only about 245 to about 250 nautical miles straight up. So yes, it can be pulled down by Earth's gravity. Over time, it's going to want to come down, for a little further and a little further, just like the Russian Mir space station or our Skylab that we had. But we do have thrusters up on the station, Matthew, so as things start to degrade, or it starts to come back to Earth, we can put on the thrusters and push the station back to its proper orbit. Now the second part of that question, why is the S0 Truss so important, again, just like a mentioned a couple questions ago, it is the main center truss segment of all the trusses. Its main purpose is to gather the electricity from the solar panels, gather the cooling fluids from the radiators, and route these to the pressurized modules where the astronauts live. So it has a very important function.
David from Boca Raton, FL
Why hasn't there been any tests for artificial gravity on the ISS or the shuttle? Why can't you spin the spacecrafts a little, similar to the Moon's rotation and gravity?
I think it's a good question and that David has been watching James Bond movies. That can happen. Well, we are going to have a thing on the space station called the CAM, or Centrifuge Module. And the CAM is going to be a circular disk about four feet in diameter and maybe about three feet in height. The purpose of the CAM is to artificially produce gravity. This will be rotated and I think it will be positioned on top of the Japanese module. And the CAM will be rotating because the main purpose of the space station is to perform all sorts of research experiments. There are things that we can do in space better than we can do on Earth, and there are things we can do on the space station that we just can't do on Earth. And medical, life science, computer, the list is really endless of the different types of research we can do in space. But there are certain experiments that we want to do in space in a microgravity environment, or what people call zero-G, but at the same time we want to perform these experiments in a gravity environment to compare the results. And this CAM, or the Centrifuge Module, that will be rotating on the space station, will allow us to do that. And that's going to go up on the UF-7 flight in the year 2006.
Bryant from Avon, Indiana
Why not rotate the space station while in orbit if it would make artificial gravity? After all, isn't bone and muscle loss due to zero-g one of the biggest problems for people in space?
Good question, it is a problem in space. One of the main purposes of the International Space Station is to perform all sorts of experiments in space, and I mentioned this in the last question. There are things we can do in space that we can't do on Earth, and there are things we can do in space better than we do on Earth. So the main purposes of the International Space Station are to perform medical, life science, computer, biology - the list is endless of things that we can do in space that eventually will have spinoffs for us on Earth. So we don't want to make it like a James Bond space station where it's rotating. Maybe in the future, as we're traveling through space for long distances, we may have spacecraft that can do that. But right now the purpose of the Space Station is a big research and development facility where we really need and want that microgravity, or zero-G, environment to perform all these experiments.
Ross from Wilkes-Barre
About how many benefits will the ISS produce that will be available to the general public within its lifespan?
Well, if I had about three hours, I would go through the spinoffs that have come from the space program, going all the way back to the late 1950s. It is just amazing what has come from the space program. Again, if I had three hours, I would list a thousand spinoffs that have come from the program. But like any program, whether it's NASA or a big military project or any type of huge civilian project, when a company or organization is given what I call an impossible goal, we achieve it. But by working towards that impossible goal and making it possible, this allows us to achieve it, and there are always benefits that come from it. Just like the tiles on the shuttle, back in the Apollo days we didn't have material that could resist 3,000 degrees Fahrenheit for reentering the Earth's atmosphere. We actually had a heat shield that burnt a little bit. Now we have material that can resist that heat. And there may be spinoffs from that in the future. Nomex material is the flame-retardant material that firemen wear in their suits. That's a spinoff from the NASA program. So there are just thousands of spinoffs that have come from the program, and I guarantee you one thing, Ross. Once the space station is built and is fully operational, you're going to see a big increase in the spinoffs that benefit humans on Earth from the space station.
6th Grade Class from West End Elementary School
What is the SO truss used for on this mission?
Let me start by saying again that this truss is the center truss of all the trusses that are on the space station. When I use the word truss, basically, if you were to go into your house and up into your attic, you have bunch of pieces of wood that hold your roof up. Think of the truss segments as a bunch of different pieces made out of aluminum that hold the space station together. And this is the center of the truss segments. It weighs about 24,000 pounds and it's about 43 feet long, so it's a very important truss segment. And like I mentioned earlier, this is going to take all the electricity and all the cooling from the radiators and solar panels and route them into the modules where the astronauts are going to be living. So it plays an important function for all the trusses up in space.
NASA's John F. Kennedy Space Center