Ep. 127: The US Space Shuttle



You’ve heard us talk about capsules, you’ve heard us talk about space suits, well today we take a look at the only currently in use reusable space craft. It’s a not a bird, its not a plane – It’s the US Space Shuttle. And to make it interesting – we’ve sent Scott Miller, Astronomy Cast student web developer, down to watch the launch so he can bring us back us first hand story.

  • Ep. 127 The US Space Shuttle
  • Jump to Shownotes
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  • Shownotes

  • NASA’s Space Shuttle page (current missions)
  • History of the Space Shuttle — NASA History Office
  • NASA’s Space Shuttle Gallery
  • Interactive Shuttle Simulations — NASA
  • Space.com’s Interactive Shuttle
  • Rotating Service Structure
  • Orbiters
  • Facts about the Orbiters
  • External Tank
  • Spacesuits
  • ACES (orange) launch and re-entry suits — Astronautix
  • Shuttle EMU suit — Astronautix
  • Spacesuits Built to Handle Pressure — NASA
  • For Space Shuttle, Delays are Typical — CBS News
  • Transatlantic Abort Landing sites (TAL)
  • Shuttle Abort Modes –– Wiki
  • Challenger 51L Accident
  • Solar Max Satellite Mission
  • International Space Station
  • Spacelab
  • Pathfinder Space Shuttle
  • Enterprise test vehicle
  • Columbia Accident
  • Final Report on the Columbia Accident –– Universe Today
  • Spatula in Space –– The Mirror
  • Lost in Space:  8 Weird Pieces of Space Junk — Wired
  • Redesigned External Fuel Tank — Red Orbit
  • Transcript: The US Space Shuttle

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    Dr. Pamela Gay: With me this week while Fraser’s voice recovers – he’s okay, his voice is not – with me this week is Scott Miller one of the computer scientists working with our New Media astronomy projects here at Southern Illinois University Edwardsville.

    Some of you may know Scott from his work answering e-mail and streaming coverage from the American Astronomical Society meetings. Now we have him here in person to share his expertise on the space shuttle with us. Welcome Scott.

    Scott Miller: Thank you for having me.

    Pamela: You’ve heard us talk about capsules; you’ve heard us talk about spacesuits. Today we take a look at our only currently in use reusable spacecraft. It’s not a bird, it’s not a plane. It is the US space shuttle.

    To make it interesting we sent Scott down to watch the launch, not just once but twice so he can bring us back his firsthand story. Let’s start with what’s going on the days before launch.

    Scott: The days before a launch there is lots of excitement and lots of activity down at Kennedy space center. I had the fortunate opportunity to go down for 3 days during the launch of STS-124 that was the space orbiter Discovery.

    The first few days they have some press conferences discussing the mission that is coming up. There are also some press conferences covering current activities at NASA. You have to understand this is one of the few times that they have a large number of press members down there trying to get as much information out as possible.

    They also bring out a few presentations for the press to see. We got to take a look at some spacesuits. We got to see some of the new things that were coming up with the Orion project.

    What really starts happening is the night before a launch. This is when the RSS rollback occurs or the rotating service structure. After the shuttle has been taken out to the launch pad a giant structure rotates around to protect the orbiter from the weather. Sometimes it is out there for at least several weeks. The night before a launch they have to move this back so that the shuttle can actually take off.

    We had the awesome opportunity to come out and see this right at sunset. If you can imagine this afternoon where it is low 70s, a slight breeze, there’s not a cloud in the sky. There’s Discovery in all of her elegance up on the launch pad and the sun is setting in the background.

    This service structure, this giant piece of equipment starts to rotate around the actual launch pad rotates away from the shuttle as the sun is going down. It’s just this beautiful, beautiful scene. This lasts for about 30 minutes. The press is out there for about 15 minutes before it starts until about half an hour after it is finished.

    As it is rolling back, the sun is setting, the sun is down, it is all the way back, and the stars start to come out. You can see this beautiful starlit sky. The shuttle is there with the spotlights and then they turn on those really powerful Zeon lights that everyone is so familiar with. The ones you can see miles and miles away.

    Everyone is out there in complete awe and reverence, even the people who’ve seen it time and time again. It is really exciting the night before a launch.

    Pamela: So you’ve given a great sense of how beautiful it was. Now what about a sense of scale? How many stories tall is this entire system roughly?

    Scott: I can’t tell you. I really don’t know how many stories tall. I can remember sitting there just being in complete awe of the size. The sheer size, these giant rockets, the external fuel tank and the shuttle sitting there and I can only imagine the six or seven astronauts that are stuck in this little cabin in the shuttle about to get launched by massive amount of human power – this giant rocket.

    Pamela: The entire system is almost 200 feet tall. It is a bunch of stories and one of the statistics that has always stayed in my brain is standard American US yellow flat-nosed school bus is the same size as the cargo bay on the space shuttle.

    Scott: Right.

    Pamela: This is the cargo bay on the orbiter. You corrected me on this one earlier so explain what are the different parts that are referred to as the shuttle system?

    Scott: What commonly happens in the news is what you hear about the shuttle Discovery or the shuttle Endeavour and that is completely wrong. A space shuttle is the entire system you see at launch. This consists of the white part we commonly refer to is actually known as the orbiter. We have Discovery, we have Endeavour, and we have Atlantis. Strapped to the shuttle is that giant red-orange fuel tank you’re familiar with is called the external tank or referred to as the ET. On the side of the ET are the solid rocket boosters or the SRBs.

    This complete system of four pieces, three components make up a shuttle. As soon as any one component of this shuttle is separated it is no longer referred to as a shuttle. In space it is just referred to as the orbiter. Everyone down at NASA, anyone that’s involved technically refers to it as the orbiter not the shuttle.

    Pamela: What’s neat is throughout the entire launch process it’s as though the orbiter is slowly shedding and shedding more and more pieces. We’ve seen what it’s like the night before when they roll away the protective outer parts. What happens as they lead towards this launch of this amazing machine?

    Scott: The day of launch is kind of exciting. During STS-124 that was it was all a daylight launch. Early in the morning we get there, it’s a little crisp out, probably the low 60s. It’s Florida, we’re on the coast, it’s [Laughter] beautiful weather. I was so excited and happy. You couldn’t have asked for better.

    We got to go to the crew walk out. We go to this building where every crew that I can ever recall, I can ever see on any TV shows has walked out into that same hallway into that famous air stream. There are people lined up everywhere, media, family, friends, and people from NASA. People that work there, the janitors are outside. It’s this really tight sense of community.

    People are there for pictures and the video but everyone is there to support this crew. They’re about to take on a massive endeavor launching themselves. They’re strapping themselves to a rocket and going into space. They bring us there long before they walk out for obvious security reasons. Security is very, very tight. I remember being stopped at multiple checkpoints. There are guards everywhere, especially on day of launch.

    We’re out there, it’s starting to get a little warm because we’re on concrete and we’re in this little cove – there’s no wind. Someone comes out and says okay the crew is about to come out. People are just going crazy. It’s like you’re in the front row of a rock concert. Everyone is screaming and cheering and clapping.

    This crew walks out and you can see at first they’re being very serious and very professional. As soon as they hear the crowd, they’re all laughing, smiling and waving to everybody. It is the last time they’ll see their family and their children even though they’re not allowed to walk up because they’re in their bright orange spacesuits.

    They walk down this little ramp to the hallway, the turn in front of the air stream and stop and wave. They load them up with their helmets into the air stream they go and they take off of course with escort – police front and back. Everyone is still just really excited.

    Pamela: One of the things that you just said is they’re wearing these bright orange spacesuits. When I was a little kid, I actually still have this and I blogged about it [Laughter] they had blue jumpsuits. Every little kid could get one of these things at the US space camp and I was one of those kids.

    Nowadays they wear orange spacesuits and the only time they get worn is during take off and re-entry. When they actually want to go out and do stuff in space they have these big white bulky things. What is the justification for these orange spacesuits?

    Scott: The orange spacesuits are technically referred to as an escape suit. I had the unique pleasure to talk with a gentleman that just simply goes by Casey – he has a very long detailed name. He is in charge of the spacesuit program down at NASA.

    One of the neat things they brought to the press two days before launch was one of these spacesuits with the helmet to show us and explain what it is for. You cannot imagine the number of scenarios and possibilities they thought out. So if at any point in time during a launch there is trouble this suit is designed to help protect the astronauts.

    There is everything from what happens if they have to escape while they are at the launch pad. What happens if they have to get out of the shuttle during launch or at high altitude or low altitude over land, over water? They have shark repellent and survival kits and radios and two GPS systems, flashlights and food. They have food for days and water for days.

    They have health kits, medical kits and another back-up radio. It is so amazing. There is a pressurized oxygen system in case they are in a low place in the atmosphere. Just the number of things they thought of when they developed this suit is amazing.

    After he was done presenting to about 6 or 7 press members who were sitting there I stopped and just asked some personal questions. I’m an engineer; I just have a generic interest. We chit chatted for about half an hour. It was so neat, he said go ahead and play with it. It has been in space. Just tinker with it.

    I asked him detailed questions about the way they had the valves set up and the way things were designed. It’s really crazy because every piece of this suit is designed to be usable by an astronaut, every single piece.

    The way the oxygen feeds are set up in the helmet, the way the microphones sit. The way the visors are designed, everything is so amazing. He gave us this really interesting statistics because someone asked how much does one cost. He said I really can’t put a price on it.

    There is so much R & D that went into this, so much development you can’t just buy one. I said well if you had to put a price on it. He goes, if you could buy just one it is about $275,000. At which point I put the spacesuit back down. [Laughter] It was very nice.

    Pamela: What’s neat about these is they have to actually be flexible enough to both enable astronauts to ride zip lines should something happen on the launch pad and also strong enough to withstand if the astronaut has to abort during take-off.

    We’re going to get to aborts in a few minutes. We’ve now loaded the astronauts onto the shuttle.

    Scott: We’re getting there.

    Pamela: So take us through with less detail on the weather perhaps, to what is going on during the rest of the countdown.

    Scott: It takes several, several hours to get the shuttle prepped. It takes a long time to get the astronauts into the shuttle. We’ve all seen movies and television where you see people kind of crawling into the space shuttle and there’s plenty of room. It’s not so. It’s a little cracker box in there. There is barely enough room. You can remember that the shuttle is on its back, it is loading vertical.

    So trying to load these astronauts that have these somewhat bulky spacesuits on in a vertical position takes a long time. And a foot in any direction they have boards of switches and gauges and screens and buttons and it is very difficult. It is a very detailed process of where you put your arm when and how you move your leg this way or that way to get in. They get everyone strapped in.

    As soon as someone is in they’re doing com checks. They’re going through the checklist. They have checklist after checklist of everything. It is so detailed. There is not a single detail that gets skipped in any part of the launch process.

    It’s really hard to follow along if you’re not involved technically with the program because the acronyms that are used. They have eight nine word acronyms that they all use. We get to hear this over the loud speaker, over the television system they have, both press members and just audience that are the visitors.

    Pamela: And anyone who is watching on NASA TV which I encourage everyone out there to do. There’s going to be one later this month.

    Scott: Yes, hopefully if it doesn’t get delayed, cross our fingers. It’s real exciting and there are a few kind of pivotal moments that happen. One is when they shut that orbiter door and you can see the astronauts’ faces.

    It is this combination of excitement and nervousness. I’m sure they’re a little bit afraid too, a little scary. But they’re excited and you can see they’re happy and the closeout crew is what is referred to as the people who assist them into the shuttle – the closeout crew in the white suits with the big numbers on the back. They lock them in and just kind of wave good by and good luck.

    There are still a few hours until launch. There are several points in the countdown where they have pauses. They actually stop the countdown clock and these are built in in case they run behind on the checklist they have time to get caught back up. The biggest one of these happens at T minus 9 minutes. There is about a 45-minute pause – I shouldn’t say about I should say exactly there is a 45-minute pause.

    Both shuttle launches I’ve been to they were on time so there was a lot of dead wait time, nerves building. It gets really exciting a few minutes before launch when you see the final countdown – like the Apollo 13 movie. It is so exciting at about T minus one minute everybody is standing up. Everybody is cheering. They’re excited. At about T minus 30 seconds again the crowd is just going crazy.

    Then the most exciting thing you can ever possibly imagine happens. At T minus 6 seconds, they light the main engines on the orbiter. These are the engines that are attached to the actual white orbiter. They are fueled by that big red external fuel tank. When this happens the shuttle actually starts to lean backwards. This is what is referred to as the twang.

    It leans backwards I think about 6 degrees if I recall properly and the launch pad is still strapped to the shuttle and holding it in place. It pulls it back square right at T minus zero and that’s when those giant white solid rocket boosters – the SRBs on the side ignite.

    I cannot describe the amount of power being put out by this system. They claim and I completely believe it, near shock wave of these rockets igniting can kill you instantly up to 800 feet away just from the concussion.

    Pamela: What is amazing is this is happening at T minus 6.6 seconds.

    Scott: 6.6.

    Pamela: When this happens, everything goes nuts; everything goes wild but they can still turn the sucker off.

    Scott: Yes.

    Pamela: That’s just cool. [Laughter]

    Scott: Once the SRBs are lit, that’s the no going back time. The solid rocket boosters are very similar to the toy rockets you see in the back yard. Once you light them, they are lit and continue to go. That’s the no going back. They can still have multiple options for aborting but those rockets will go until they’re burnt out.

    It was really exciting the first launch I witnessed was STS-123 the space orbiter Endeavour in March of last year. It was a night launch, 2:28 a.m. I believe. I was 6.5 miles away – 6.5 miles away at the visitor’s center. There’s a tree line I can’t see the shuttle until it is several hundred feet in the air.

    When those engines lit, night turned into day. There was cloud cover so there were no stars or moon. And 6.5 miles away it was so bright. It was brighter than the sun coming up. I could see every blade of grass like someone had a bright flashlight shining on it. It was so amazing and this shuttle just pierces the night sky with a power and speed you can’t imagine.

    We’ve all seen videos of a shuttle launch and you it elegantly gliding through the air. That’s a total lie. Those are probably shot from tens of miles away. When that shuttle takes off, it is going. It just cuts right through the air.

    At STS-124 I was a member of the press. I actually watched the shuttle take off from right in front of the big giant clock. It was really neat; my little brother called me and said he could see me on TV. He was watching like so cool so I’m waving like a little kid “Hi” you know and I had to get out of the way. They didn’t like that. [Laughter]

    When the shuttle takes off from that close, we’re about 2 miles away; the closest anyone is except for rescue crews in reinforced bunkers the sound concussion vibrates your chest. I had my laptop sitting on the ground – it was vibrating. The sound of a shuttle taking off is so powerful.

    You see the videos and you can hear it crackling and ripping like someone just blowing on a microphone. You think oh, it’s just too loud it doesn’t really sound like that. It does. It is actually tearing through the atmosphere. It is so powerful and so amazing.

    There are a few important things that happen afterwards during the launch process. One of those is Max Q. At a certain point while they are accelerating to get into space the pressures and the strains on the shuttle are at their maximum and much more and it might actually damage the shuttle. They actually have to throttle back the main engines, the engines that are on the orbiter, because remember the SRBs are lit. We can’t slow those down.

    They throttle back to release some of the pressure. As soon as they cut through some of the lighter layers of the atmosphere they can fire back up to full throttle and try to get into orbit.

    One of the neatest things I got to experience afterwards, I didn’t realize it while it was happening was as we’re going you may be aware the SRBs come off the side once they’re burned up. It’s just the external tank and the shuttle is finishing up getting into orbit.

    I had a really nice video camera compliments of Pamela. I didn’t realize how nice it was. You can see the launch and it is just arcing and this thing is taking off and it gets to the point where it is just a little dot in the sky. You can barely see it. In the video you couldn’t see with the human eye but in the video you could see these two little dots come off of it. I realized this is SRB separation and after the launch, after I couldn’t see it anymore, I went back into the press center and they were showing the videos from the shuttle.

    Some of the TVs were looping old information, some where showing the current information. One of the old loops was SRB separation. From the shuttle’s point of view when it is this high, at this altitude you can actually see the entire state of Florida. [Laughter] I have that one too and it is so amazing.

    I could see that, I could see something in space coming apart. Those SRBs are recovered. They fall into the water where they’re parachuted down and there are Navy ships that go out and recover these. They get reused. The external tank separates some time later and it does burn up in the atmosphere or most all of hopefully, burns up in the atmosphere.

    Pamela: One hopes, yes. [Laughter]

    Scott: I think there has only been a few times where it hasn’t?

    Pamela: Right.

    Scott: And that doesn’t get reused. Those are a one-time expendable piece. Then the shuttle finishes its rolls, gets into orbit and then starts going into safety and security checks. It’s really neat because it only lasts a few minutes.

    All these amazing things happen, it seems like it is a year but it is just a few minutes. The next thing you know the astronauts are getting out of their seats and they’re trying to float out of this little tiny cabin to check on the shuttle. It’s so crazy.

    Pamela: What’s neat is how purposeful everything in all of these different steps is. For instance you said that just as it hits orbit it rolls.

    Scott: Yes.

    Pamela: It rolls and it opens the space shuttle doors. This is to help radiate away all of the heat. So even little things like basically throwing open the pickup bed – it’s basically a pickup.

    Scott: Right. [Laughter]

    Pamela: They’re just dumping heat into space and reorienting themselves to have the bottom of the space shuttle exposed to space and protecting everything else beneath and it also gives the astronauts a prettier view of the planet Earth. What has always amazed me is all the different abort procedures they have. Just like airplanes taking off, they have contingencies for all sorts of different things.

    For instance return to launch site is one of their abort programs where if they realize something is going wrong during take-off they can abort their solid rocket boosters, let them go fly off in their own directions and actually come around using the space shuttle’s main engines that steer for awhile, drop them and then basically 25 minutes after liftoff come back into a normal gliding landing.

    Scott: One of the really neat things about some of these aborts, there are a lot of things that into whether a shuttle launch happens or not. The biggest one of these is weather obviously and the condition of the shuttle. That’s what causes a lot of the delays. They want to be very, very sure. A valve was sort of sticky, they want to take it out, take it apart and clean it. But the weather is the biggest one.

    There are constant weather updates. But not just in Florida. Weather updates in New Mexico, California, in Spain. They have emergency landing strips all the way in Spain. Which strips they are concerned about have to do with what orbit they are trying to achieve, but they are well aware of these at all times.

    They’ve never had to land outside the United States but they’re prepared. If they get to a certain altitude during launch and they have to land, Spain is an option. There is a strip there that is prepared for it.

    Pamela: Up till 2 minutes and 30 seconds after launch they’re ready for basically transoceanic abort landing. Spain, Nigeria, Casa Blanca, that would just be cool I think. [Laughter]

    Scott: Free vacation.

    Pamela: I don’t know, I just think landing the space shuttle in Casa Blanca is cool. They have all these contingencies for okay forget making it into orbit; we’re just going to land.

    They also have, well let’s kind of make it into orbit but not quite and abort once around landing back here in the United States which makes it much easier to use the space shuttle later.

    When these things land, they move them around using 747s when they land in the wrong place.

    Scott: Very expensive, they don’t like to do that.

    Pamela: It is very expensive, it is very scary. The safety aspects and the idea of trying to bring the space shuttle back from Spain or Morocco. I don’t think that’s something we would want to do necessarily.

    Scott: I don’t know what they would do in that case. I know they use 747s from California. One of the neat things they show us down at Kennedy is they have what they call a mater-de-mater. They don’t have very complicated names for things.

    It’s this giant apparatus that actually drives the 747 with the shuttle attached on top underneath. Just like a crane it just it’s got these special arms and just picks it right up.

    They move the 747 out from underneath it, lock the orbiter right back down. [Laughter] It’s really simple looking but I’m sure there are a lot of intricacies and a lot of engineering detail that went into designing it.

    Pamela: And I’m pretty sure we don’t have one of those in Morocco.

    Scott: No, we don’t, I don’t think so. It is possible there is I’m not sure but I’ve only seen the one.

    Pamela: We also have an abort to orbit. This is really the only abort that has so far occurred. Abort to orbit is where everything goes well enough to make it most of the way to orbit, most of the way to where you want to be, but you don’t quite make it all the way there.

    You either end up in a lower orbit, or you end up in a different type of orbit than what you had planned. Something goes wrong. This actually occurred on a couple of different missions. The first one it occurred on was STS-51F. This is a mission that is strangely enough most famous for testing carbonated beverages. They had Coke on the space shuttle. [Laughter]

    They also had Spacelab II onboard. It was a scientific mission filled with mission scientists. They did a lot of good work, they’re famous for soda. During this mission, they first had to halt at T minus 3 seconds.

    Then during takeoff after they thought they got everything fixed, got everything working, they actually had main engine failure. They made it to orbit but it wasn’t where they meant to be. It was fine, it worked. Luckily they weren’t going to service the Hubble space telescope or anything like that which required a specific orbit.

    There were also problems later on the second mission as well. The other mission was on STS-93. This is the mission where they launched the Chandra X-ray Observatory. Again, things didn’t quite go as planned but they accomplished their mission. Of all the failures you can have ending up in slightly the wrong place isn’t all that bad of one to have.

    It’s still frustrating when you don’t make it to the correct place. The Chandra itself didn’t actually end up in entirely the indented orbit but the space telescope works fine, everyone was safe, everything was fine on these missions. Not every mission has been completely fine.

    Scott: No unfortunately not.

    Pamela: During launch is probably one of the most difficult places.

    Scott: Absolutely, there are a few contingencies that happen on the launch pad that we haven’t talked about yet. I don’t want to call it the fun one. They actually have zip lines that go from the launch tower all the way down to the ground. If something was to happen and the astronauts’ lives were in danger during a launch for any number of reasons, they actually get out of the orbiter. They can release themselves from inside the orbiter.

    This is sort of remnant of the Apollo I accident. They can get onto the launch pad, get into a giant basket and slide down these zip lines. They actually get to practice this which is really fun. At the bottom, at the ground there are armored personnel carriers that everybody is trained to drive. First one in, gets in the driver’s seat; last one in locks the door and they drive to safety. You can also have a lot worse things happen during launch.

    Pamela: They have some contingencies for abort mechanisms where they don’t plan to recover the orbiter. They have holes where they can actually open the side hatch and go out and zip underneath the wing of the, in the process of reentering vaguely under control space shuttle, and try to parachute to safety.

    All of these abort using the orbiter mechanisms though. They all come as the result as well as the spacesuits they’re wearing of one mission that was actually right before you were born.

    Scott: Yes, this is the unfortunate incident that happened with the orbiter Challenger that we’re all so familiar with. They talked about it a little bit when they talked about the spacesuits. You mentioned earlier, you saw the blue jumpsuits. After the blue jumpsuits came the orange spacesuits technically referred to as the escape suits.

    A lot of these innovations that occurred happened as a result of the Challenger accident. A lot of things have been taken into consideration. A lot of accidents they try to avoid now. There are certain situations where the probability of survival is low, they’ve erased that. They’ve done an excellent job. They tried to develop ways to get out of the shuttle while it is launching if they have to.

    Pamela: And that one mission had a very simple fatal flaw and that was plastic doesn’t respond well to being frozen. The O-rings that prevent firing solid rocket fumes from escaping out the sides of the rockets instead of strictly through the thrusters at the end didn’t expand as they were supposed to. Fuel was able to burn, exhaust was able to go out through the sides and it led to cataclysmic failure.

    Scott: That happened right after that Max Q point we discussed earlier. They throttled the engines back up and increased the pressure. That allowed the release which ignited and caused the Challenger to break up.

    Pamela: That was the only mission of all of the launches we’ve had since I was 5 years old, since before you were born, we’ve managed to other than that have a whole series of very successful missions that have accomplished an amazing range of tasks.

    The space shuttle is essentially a giant pickup truck that you throw construction workers in and Scott is giving me a terrible look [Laughter] as I say this but it is true. One of the things that astronauts are truly sensational at doing is repairing things, building things and creating things in space that robots just can’t do. I know you’re a robot builder.

    Scott: But I’m also aware there are some things that a human is just best for.

    Pamela: So we’ve had over the course of the space shuttle history we’ve had it repair solar max. We’ve had it go out and catch satellites and release. Catch and release of satellites is just a cool concept. Hubble space telescope

    Scott: Hubble repair, such an amazing project. I’m so happy that they succeeded. What they did was just astronomical.

    Pamela: The Hubble is one of these great examples of astronauts figuring out how to do something that really wasn’t meant to happen. The Hubble was originally intended to go into space, get packed back into the space shuttle, carry it back down to Earth, have stuff done to it and then take it back up into space again.

    After the Challenger accident it was decided it probably wasn’t really safe to try and land carrying basically a school bus. So since then, we’ve repaired everything on orbit. They’re doing repairs that we’ve all tried to make random car repairs when it’s not (not all of us) many of us have foolishly tried to do things like change tires during snow storms. It’s miserable.

    They’re doing something even worse. They’re trying to change out batteries in the cold dark space in astronaut spacesuits that are hard to use, aren’t very flexible and they’re doing it consistently successfully.

    Scott: Let alone they’re doing this and some of these extra vehicular activities last hours upon hours. You think an 8-hour shift is hard, my Lord some of these last so long. The stress load is amazing that these astronauts have to deal with is just almost incomprehensible at some levels.

    Pamela: Over the past well 29 years basically at this point, the astronauts have repaired spacecraft, they’ve built the International Space Station. They’ve carried Space Lab up for the Europeans to do experiments on orbit. They’ve caught and released I don’t know how many satellites at this point.

    The shuttle has got one more year left in it. At the end of 2010, it looks like the United States is going to retire these different missions and they are actually trying to find homes for all the shuttles.

    Scott: Right there is actually quite a fight going on if I understand correctly?

    Pamela: Yes.

    Scott: Can you give us some details on that?

    Pamela: Well it’s a please tell us why you deserve to have an orbiter.

    Scott: I want one by the way.

    Pamela: Currently there is the space shuttle Pathfinder and it is mounted on SRBs and an external tank like the space shuttle.

    The Pathfinder is down at the Huntsville Space and Rocket Center, home of the US Space Camp which I attended as a small geeky child.

    Scott: Very nice place, I’ve been there once.

    Pamela: So it’s out there sort of as an inspiration to all the kids who are there. It’s not a fully functional shuttle. It’s not quite full to scale but it was used in different aerodynamic tests.

    There’s also the space shuttle Enterprise which was again used in drop tests – how does this thing behave in the atmosphere? It’s currently property of the Smithsonian. It also never flew into outer space.

    Other ones have been randomly claimed by other places throughout the entire United States, but there’s one still left to be claimed.

    I know that there’s a variety of universities, NASA centers, planetariums that are all hoping maybe they will be the one to get their hands on that orbiter.

    Scott: We’ll see what happens. I still want to put my bid in though. [Laughter]

    Pamela: When the space shuttle comes back in for a landing, it is far less exciting. It basically lands a lot like a big old airplane. It comes down through the atmosphere at an angle that allows the majority of the heat to get absorbed by the black tiles on its belly.

    Wherever you see black on the space shuttle, these are the surfaces that get extraordinarily hot due to frictional heating from going through the atmosphere. This is the second most dangerous point – coming in. This is where NASA has become amazingly OCD

    Scott: Very detail oriented.

    Pamela: Yes, about checking the surface. They’ve developed entirely new sets of checklists to check over the outside of the space shuttle. Originally the space shuttle was all tile.

    Now it is a mixture of tile and special basically quilted material. It’s a squishy orbiter now. [Laughter] That’s because there was always fear that the tiles were either going to zip themselves off or the squishy material is just more resilient to things like well wood peckers which they have a problem with when they land in California.

    Scott: Sometimes, yeah.

    Pamela: With the Columbia back in 2003 they had a chunk of foam come off of the external tank and hit one of the leading wing edges along the black tile and damage it.

    Scott: So that’s where the damage actually occurs at a more regular interval than most people know. The tiles do chip; they do fall off from time to time. It’s something they always keep an eye on, they always did but unfortunately I don’t think they took it seriously enough until the Columbia tragedy.

    Since then they’ve made changes. We have new repair methods for how to fix tiles in space. They tested these before they returned to launch. There have been 2 return to launches after Challenger and Columbia obviously.

    They tested these methods and in one launch I forget which one, one mission actually had to use them and it worked flawlessly. They have some really neat methods of essentially stitching tiles in and they have some glues and some putty that the use to slap tiles in – not quite slapping them in.

    Actually a funny story, one of the pieces of space debris is a spatula that was used. [Laughter] The gentleman, the astronaut that lost it said “Oh there goes my favorite spatula, don’t tell the others at home,” while he was trying to put some thermal putty on.

    One of the biggest things they’ve done is they’ve made changes to the external tank or the ET. They have their own numbering system. It’s not really relevant; people don’t pay attention to it. After the accident they changed what they refer to as the ice shelves on the tank it is just one big round structure full of fuel. It is separated into two sections; one for the oxygen and one for the hydrogen and up the side of the tank on the outside are two lines that they fill these with.

    That needs to be insulated, it is exposed to the atmosphere and what happens is these are mounted. There are mounting brackets that mount these lines to the tank and then there are these foam chunks of structure around them to keep them from freezing and icing up. They changed the shape and the make-up of these foam structures as well as the hinges.

    The hinges are now made out of titanium instead of aluminum for its superior thermodynamic properties. It’s also got some Teflon in the touching surfaces so friction is reduced so actual ice doesn’t get between the surfaces of the foam.

    The foam is shaped with a new leading edge that cuts through a little better. When ice breaks off at launch it doesn’t hit at as steep an angle. It’s a lot nicer on the ice shelves. STS-124, that launch was actually the first tank where these were implemented as part of the construction process instead of just added on later.

    So far they’ve had an amazing amount of success with the amount of foam coming off has been greatly reduced. It has been very successful and they’re very excited about it.

    Pamela: So NASA has effectively been able to over the course of my entire lifetime have managed to build, retrofit, reengineer and keep these vehicles going like the Energizer Bunny.

    Scott: Absolutely.

    Pamela: They’ve proved themselves to be solid work horses for the United States fleet. We are leaving them behind. They’re extremely expensive to operate which wasn’t quite why we decided to use the space shuttle design.

    Scott: No, it’s way over budget unfortunately, as everything else does.

    Pamela: Right and they just can’t get into high orbit.

    Scott: No.

    Pamela: We need heavy lift capacity, higher orbits if we want to go to the moon. So we have to leave our old friend behind and park it out in the pasture like you do with a good pickup truck. [Laughter]

    Scott: Right.

    Pamela: So now we’re going to move on to the future and in the next episode of AstronomyCast and hopefully I’m not lying to you this time, hopefully next time Fraser will be me, we’re going to move on to talk about the future of the US space fleet and the new Orion program.

    Scott: Great, very exciting stuff.

    Pamela: Scott’s still going to be hanging around AstronomyCast; he’s just probably not going to be behind the microphone. Thank you for joining me.

    Scott: Thank you for having me. It’s been a pleasure.

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