TechStuff Tours the Space Shuttle

by throwing back the blanket hanging down the leg. Okay, so we want to start off. This episode was something we haven't done in a while, and by that I mean some listener mail. This listener mail comes from Megan, and Megan says, Hi, guys, I love your podcasts. I rely on them as a form of continuing education as I work on my own research and writing projects that

relate to technology. As the data approaches for the launch of the final Space Shuttle, I wondered if you would consider doing one or a dozen special episodes on space technology. One episode just on the Space Shuttle itself would be nice. How does it fly? What does it do? How does it deliver its payloads? Into space without losing its air pressure. And then I snipped a big part of her email because it relates to other possible topics we may talk about the future. And then I go to thanks and

keep up the good work, Megan. Yeah. I had to keep that last little bit in, but it's good, you know. I want to be inclusive. Yes, and Megan did have several other suggestions, all of which are wonderful ones, and we will probably get to them in the future, but we want to concentrate on the Space Shuttle right now.

Talking about trying to get us to talk about space technology is doesn't require a lot of arm twisting, so we just have to say, jiminy, yeah, we've already talked about some in the past and the older space tech, but um, yeah, I think that there are several in the future. Let's just say that, yeah. Yeah. And I also add that we have a great article on how Stuff Works dot Com about the Space Shuttle and it's called Brace Yourselves How the Space Shuttle Works. And it's uh,

it's really really well done. It's a comprehensive, very long, very involved article, lots of really great animations and illustrations in there. I do highly recommend it um. It's it's I would call it one of our classic house stuff works articles because it kind of pulls out all the stops. So we're gonna kind of talk about the space Shuttle, and I thought we'd start with maybe sort of a

brief overview of the history of the program. So you've got NASA, you know, they're they've they've had their successful launches of getting astronauts into orbit, getting astronauts all the way to the Moon and back safely. They've made some

phenomenal contributions to science um. In around nineteen seventy two, President Nixon announced that what he wanted to see what what the next up in the space program was going to be, was to create a reusable space uh shuttle or Space Transportation System st s UM, so that we could actually keep using the same vehicle over and over again. Because prior to that point, the vehicles we've been using, the capsules we've been using we're all one use, used

one time, and that was all you could use them for. Well, you know that that's one of the benefits. You know, they're disposable. You can pick one up anytime you're out on the road. Right You're right, you just go to your costco and hey, you know if I buy them in bulk. No, no, that's not how that worked at all. It was incredibly expensive to develop the capsules and you

could only use them one time. So this was an idea of creating a space program that would use the same vehicle over and over, but there were some trade offs that you had to make for that. One of those trade offs was that you couldn't necessarily create a vehicle that could go into high orbits or to travel

to distant locations like the Moon or Mars. You could only kind of launch into a lower but um part of that was this idea of a space Shuttle design that could return by gliding down to the Earth's surface, as opposed to you know, plummeting and then uh launching out a parachute and then kind of drifting down into the ocean for retrieval. So the design meant that they had to reconcile the fact that we would not be using this same sort of vehicle to go to places

like the Moon or Mars. So this was a calculated decision on NASA's part to kind of change the focus of the space program. It was now no longer. Just well, it was never just about being the first to the moon, but that was a big part of it, right, The space race was in part a competition. Yeah, that that's true.

The UH USSR Soviet Union was, of course. And this won't be a surprise to probably anybody who listens to this podcast, but yeah, we we've talked about the space race before between um, the United States and the USSR, And you know, it escalated from the time of sput Nick. You know, the the evolved the beeps UM up to the point where they decided they wanted to go to the Moon and it was a competition to see who

could go and and set foot on the moon first. Um. And you know it went from you know, who can orbit the Moon or orbit the Earth first? And then you know who can have you know, set foot on the moon and then there this this presented greater challenges because the science involved. The idea of doing science and space UM is very compelling because there are things that you can do in outer space that you can't do uh and within the Earth's gravity, like lots of flippies.

Well yeah that too, but yeah, I mean this is the the also from what I understand, tang tastes best if you're in if you're in a low Earth orbit. And yes, contrary to popular myth, tang was not created for the Space program. It just happens to be very handy in this in this content. But um, but yeah, I mean this was, this was we're talking about this as the early seventies, fresh on the heels of uh, you know, the Apollo program. Yes, um, so this is

really the next step exactly. And so NASA then awarded the prime contract for the Shuttle to Rockwell International, and Rockwell International had to come up with different ways of creating some reusable materials, including things like the tiles that help absorb heat upon re entry. That was a big thing, right,

you know. It wasn't just that, uh that it needed to be able to fly to the surface of the Earth safely, but it had to have something that would absorb and redistribute heat in a way that would protect the people inside and could be used over and over again, as opposed to something that could only do it the

one time. Right, if you if you go see one of the capsules from the earlier space missions and say the Smithsonian Institution, for example, and you actually look at the heat shield on the bottom of the capsule and how burned it looks from re entry. It's it creates an impression because that's a it's an awful lot of friction coming back home. You said the word friction, did, Yeah, what's we'll we'll address that when we get into re entry.

But before you guys right in about friction, just let I want to let you know I will address that. But you're kinda have to wait. Should we take that? No, No, we need to keep that in because it's important. It's important because it's it's sort of shorthand right from talking about the heat that's generated. But it's a little more complicated than that. And don't worry people, we will talk about it. We're just gonna talk about that when we

talk about the shuttle re entering the Earth. Samus here, So the the first shuttle that was ever built, you know the you know the name of the very first shuttle ever built that was not designed to go into space. It was just the first one that was built to test the flying capability, right, Yes, yes, As a matter of fact, I have some history on each of the spacecraft involved. Um and I remember this because I actually have I still have it a lunchbox with this space

particular spacecraft on it. What was from one from my younger days. Um, and that would be the Enterprise OV one oh one. Yes, this is a and And you may wonder is this in reference to the the long loved science fiction series Star Trek. Yes, it is the inner the Shuttle Enterprise, which was not designed to go into space. It was only to test the the gliding and flying capabilities of the Shuttle to UH, to see make sure that the design actually worked. Um, that's all

it did. So they launched it from a Boeing seven forty seven and it successfully flew and landed safely at the Edwards Air Force Space Yes, and it actually rolled out. If think about it, we were talking about the early seventies, they didn't waste any time. The Enterprise rolled out on September seventeenth, nineteen seventy six, So it was it didn't take years and years and years to develop. I also

want to say, is just as an aside. I know we've got a lot to cover, but it ended up being sort of a recursive thing since the Enterprise space Shuttle was mentioned in Star Trek as being the first Enterprise, So it's that I find that amusing. So uh, there were other the The actual shuttles that were used in space uh flights were the Columbia, the Discovery, the Atlantis, the Challenger, and then later the Endeavor. Now the Columbia, Discovery, Atlantis,

and Challenger were the original four shuttles. Yep. The Columbia was rolled out in seventy nine, Challenger in eighty two, Discovery in eighty three, Atlantis and eighty five, and Endeavor in ninety one. And the very first space Shuttle flight as in going into lower thorbit was in nineteen eight one, and it was the Columbia. Yes. Uh. Now, again these were all designed to go into low Earth or a bit. And I thought it might be interesting to kind of take sort of a an audio tour of the Shuttle.

In other words, we're just going to kind of talk about the different parts of the Space Shuttle. And and this is um I kind of took it from pre launch, So this is the the whole kit and caboodle. One might say, it's not just the orbiter. And now that's what most of us think about when we think about the Space Shuttle. You think of the orbiter, which is the one that looks kind of like a funky airplane. But the the if you're talking about the whole Space Shuttle,

you're talking about three major sections. Your solid rocket fuel boosters, which do the lion share of the work when you're talking about launch, they do. They provide seventy of the thrust that's needed to lift off the launch pad. So you're thinking, like, well, if the solid rocket fuel boosters are doing sev of the work, where's the other coming from. That's actually coming from the orbiter's engines. But we'll get into that. So the solid rocket fuel boosters are using

a They use a solid rocket motor. It has a propellant that's uh uh. It's also got an igniter and a nozzle, so the nozzle courses where it directs the gases out so that it creates thrust. The fuel it uses is it consists of. While the fuel part is the atomized aluminum has oxidizers in the form of ammonium percolate. It's got a catalyst the form of iron oxide powder.

It's got a binder agent which I don't even think I could even pronounce, and then there's a curing agent which is an epoxy resin, and this material altogether makes a solid rocket fuel. And this stuff weighs a lot, and you know that it's one of the one of the big challenges with space flight is the fact that your fuel weighs so much. Um. In order to to launch something of a particular mass into space, you need

a lot of fuel to get there. Well, the more fuel you add, the more weight you add, so you you have this problem where you've got to get the right ratio of fuel to counteract not just the weight of the vehicle, but the weight of the fuel as well. According to NASA, the Space Shuttle, if you wanted to put it on a scale, you need a pretty big scale. It weighs more than two point zero four million kilograms or four and a half million pounds at launch, and uh it uses in in eight and a half minutes

after launch. It uses more than one point five nine million kilograms or three point five million pounds of propellant. Yeah, it's slightly less fuel efficient than a hummer. Yes, but hummer doesn't use solid fuel. No, no, no, But I wanted to mention something else that this this solid rocket fuel booster, it's actually jointed it's not it's not one solid piece. And if you were to ever actually take a look at one of these and just see the scale of it, how huge it is, you would understand

there's no building in of one piece. Would not be it would not be a practical Well, they use O rings, rubber O rings seals to seal the two sections or the multiple sections together. Right, Basically, they're they're sort of like gaskets. Yes, so these are meant to create uh an airtight seal around the solid rocket boosters. Well, it was it was one of these O rings that caused the problem that led to the Challenger disasters. We wanted to talk a little bit about the disasters that have

happened in the Space Shuttle program. Well, the Challenger disaster was a very famous one. And what happened was that when the day of that launch it was unusually cold. The cold weather had made the the rubber O rings shrink a little bit, so they were no longer properly

sealing the joints. But in the solid rocket booster upon launch, some of the hot gases, I mean we're talking incredibly hot gases from the that were being emitted by the solid rocket booster were escaping through the joints because the O rings were no longer sealing them properly. Some of these cut through like a blowtorch. They cut through the exterior of the external fuel tank, which is the next

section we'll be talking about in a second. And the external fuel tank has two different kinds of fuel in it, as liquid oxygen and liquid hydrogen. Well, the hot gases from the solid rocket booster ended up igniting the liquid hydrogen inside the external fuel tank, which then promptly exploded. That was what caused the explosion on the Challenger flight.

So it was after that the spatial program actually stopped for a few years after the Challenger disaster while NASA was investigating the disaster and trying to determine what was the cause and how would the organization prevents such a thing from happening in the future. So ultimately you could say that the rubber O rings in the the solid rocket fuel booster was they were to blame for at least that part of the Challenger to that disaster, the

whole initial um emergency that then lead to the tragedy. Yeah, and it it those engines do get hot. They according again according to NASA. The temperatures inside the engines themselves reach more than six thousand degrees fahrenheit around three three thousand, three fifteen point six degrees celsius. Yeah, so that's you know, any any leak, it can be very catastrophic in a very very short span of time, as we have seen. Right. So that's our first section that we wanted to talk about. Next,

we have the external fuel tank. Now, this is the big kind of rocket looking thing that sticks to the

shuttle even after they they jettison the rocket boosters. By the way, in order to jettison these things, they have these explosive charges between the sections that that when they explode, they break the the the links between one element in the next, which, of course that means that you have to also be very careful with that because I mean, anytime you're using explosives near a whole lot of fuel,

clearly you've got to take a lot of precautions. Well, external fuel tank stores liquid hydrogen liquid oxygen, as I said, and that's what provides fuel to the orbiters three main engines. Uh, and it's uh, there's there's a six to one ratio for liquid hydrogen to liquid oxygen so there's far more

liquid hydrogen on than the than oxygen. The external fuel tank is a hundred fifty eight feet long, which about forty eight ms, and it's got a diameter of twenty seven point six ft or about eight point four meters, And when it's empty, it weighs a feather light seventy eight thousand pounds or thirty five thousand four UM, and it holds one point six million pounds of propellant, which again seven nineteen thous so it's got a total volume of around five and twenty six thousand gallons or two

million liters. So yeah, it holds. It holds a lot of fuel UM and it's it's made out of aluminium and aluminium composite materials. It's got the two tanks. The forward tank is the one for the oxygen, the aft tank is for hydrogen, and then there's an inner tank region that separates the two from each other. So this this UH propellant, it flows, It flows through a um

seventeen in diameter feed linet cimeters. I always have to try and do that because I keep forgetting that we have so many people from around the world who listen to our podcast and we're used to using these outmoded methods of measurement, and everyone else is much more forward thinking than we are. Then we uh So the fuel flows through this this diameter or the diameter this feed line and goes to the shuttle's main engines and then

the oxygen. By the way, if you if you want to know how fast the the the fuel flows through this line. The auction flows through at a rate of around seventeen thousand, six hundred gallons per minute, which is sixty six thousand, six hundred liters per minute. Strangely enough, we still use minutes in both systems of measurement. Uh. Then hydrogen, though, flows at forty seven thousand, four hundred gallons per minute, or a hundred seventy nine thousand liters

per minute, so quite fast indeed. Yeah, well, I mean seriously, you could if you were using water instead of fuel, the shuttles engines could drain a regular size swimming pool uh in about seconds. Yeah, which, and if you were using water instead of fuel, that would be the most awesome water park ever, although you could probably only go once.

So the the fuel, they burn the fuel in the prechamber to create high pressure and then the heat and the pressure from the gases drive turbopump, and then the fuels burned in the main combustion chamber. They direct the gases out of the nozzle at around six thousand miles per hour ten thousand kilometers per hour, and that means that each of the three engines can generate around three

thousand to four seventy thousand pounds of thrust. Uh. And so that's you know, that's what's providing that other of thrust when the Shuttle is going to launch. Um. Now, the the external tank is covered with a spray on foam installation, which leads us to a discussion, a brief discussion about the second Space Shuttle disaster, and uh, this

is the Columbia disaster. Now, you may remember when the Columbia was coming in in two thousand three, when it was coming up for the descent towards Earth, it broke apart on re entry. Well, the investigation led to the discovery that that the likely cause of that was that a piece of this foam installation broke off of the external tank during launch and struck the orbiter and that's what weakened the orbiter and caused it to break apart

upon re entry. And one of the most controversial things about the the orbiter itself has been the heat resistant tiles. I mean even from the very beginning. I remember those discussions when I was a kid, and um, you know those they're they're made of a type of foam, uh basically, and and they're they're delicate. I mean, even on the very first missions they would notice that some of them

would fall out. Um. And they've done a lot of you know, made made a lot of changes to the tiles over the years, but um, they are still all things considered, even though they are very heat resistant, I mean we're talking thousands and thousands of degrees and um, because they do on re entry hit about three thousand degrees fahrenheit actually comes back into the atmosphere forty eight

degrees celsius. So I mean, even though they are amazingly heat resistant, they are remarkably fragile for all of that. So they have to be very careful, um with that. And now they on on flights subsequent to Columbia's um accident, they have been very careful to check the outside of the spacecraft before re entry. Yeah, and there have been spatial launch delays when they've discovered even the smallest of of flaws which you know, as far as we know,

could have potentially have saved the lives of other astronauts. Yes, it's of course it's impossible to know, you know which ones would have successfully landed and which ones wouldn't. But it's much better to know that they've they've gone through these sort of procedures in order to maintain astronauts safety. I mean, these these accidents were tragic and multiple ways. Uh. First of all, and in my opinion, most importantly meant the loss of lives, and and that is truly a

tragic thing. Uh. It also in a more superficial way, really, when you look at the big picture, men a setback in the space program um, which you know that's a problem as well, and we've had a lot of advances in technology due to the Space program. So I admire the fact that NASA has taken these incredible precautions, which when you're excited about a launch and you've planned a trip down to Florida to watch a launch, UH, can be frustrating, you know, you go down there and then

the launch is delayed because of this. But it's that's much better than the alternative obviously. So now we're moving on to the orbiter. We talked about the solid fuel rocket boosters and the external tank. The orbiter is next. So the orbiters, of course what we think of when we when we talk about the space Shuttle. That's the very iconic shuttle. UM it has a like I said, three main engines, it's got an orbital maneuvering system. It is.

Each of the orbiter engines, by the way, as fourteen ft long or four point three meters and seven and a half feet in diameter or two point three meters, and each engine weighs six thousand, seven hundred pounds or around three thousand and they are it's hard to get a a vision on how big that is just when I start saying numbers. If you ever visit one of the the centers that has a Space Shuttle or has one of the engines there, to see it in person

is pretty phenomenal. I mean, it's it's a really you start to grasp how big the entire vehicle is just by looking at one engine. Now, the orbiter consists of there's a forward fuselage which has the crew compartment inside of it. Um. And it also has the the reaction control system module. It's got a movable airlock which can be used to put inside the crew compartment or inside the cargo bay. Uh. Then you've got the mid fuselage.

That's where the cargo bay is. That's you know, the when we think of the doors opening out to space. That's the mid fuselage area. That's where the payload for the Space Shuttle will be in. Uh. Payloads could be anything from a satellite that needs to be launched into orbit, two pieces of equipment or material for the International Space Station,

including of supplies for the International Space Station. Uh. Then you've got it also has the remote manipulator arm, the robotic arm that we've seen that helps position satellites and the right uh orientation and that kind of thing. Then you've got the aft fuselage. So that's the back end of the the orbiter. That's that's where the engines are, the main engines, so the orbital maneuvering system is there. Um And then uh, that's so you can think of

the orbiter and those three big sections. The one that the astronauts stay in the most is, of course, the the forward fuselage. That's where the crew quarters are in the control systems are for for the orbiter itself. Yeah, I mean the crew module is UH, isn't three sections where where the astronauts will work, live and and stow their their gear. UM, And it's got UM. I was looking something up. Did you get into the where the

flight deck and mid deck are? Okay? Yeah? The flight deck UH and the mid deck, equipment bay and an airlock are the three parts of the crew module. UM. Basically, the flight deck is the you know, what you might see in an airplane if you think about it in those terms, you see where the pilot and the co pilot are, right and if if the shuttle we're sitting on the ground, you know, horizontal flat on the ground like exc. The flight deck would be the uppermost section

of that of the crew compartment. That's where you'll find the flight controls. UM has all the hand controllers, the rudder pedals. UM. There are four people. There's for four people on the flight deck UM, and you know it's got all the everything they need to basically fly or you know, I guess what do you call it in space? I guess you call it flying? It navigating and space UM.

And if you're looking on the if you were in the cockpit, you would see the displays and the controls for operating the orbiter itself, and there are a lot of them. Yeah. Um. On the right you would see the controls for handling payloads. Um. And it according to NASA, again more than two thousand, twenty separate displays and controls.

That's what you will find in the flight. And in case you're worried about right versus left starboard, on the starboard side, because it all depends on which way you're facing. If you're facing the towards the front of the shuttle, it's on the right. Yeah, yeah, that's true. Starboard side. Yeah. Well, you know it's funny that NASA didn't actually use port and starboard in here. But uh, and mid deck is

where you'll find uh four cruise sleep stations. Um. And uh you also find other types of gear, the waste management system, toilet, the head yeah, um, a personal hygiene station, and where you work and and eat there. Um. They do fit seven people up to seven people in a shuttle. Um. The upcoming actually, as we're recording this, the the last, the very last in a thirty year program Space Shuttle mission is about to uh launch on July eight, which

is kind of why we are um. We actually recorded several episodes before this, but we wanted to get this in before that. Yes we did, and the last crew is actually going to be four people from what I understand, so they can hold up to seven, but uh, you know, uh,

this last mission will have four. And the mid deck also includes exercise equipment because one of the things we learned in these these um missions is that if you are in space for any significant amount of now granted, Space Shuttle missions last between about seven and fourteen days, depending on the mission, but you can so uh, you can experience muscle loss and bone bone density loss. So

the exercise equipment is there to help counteract that. It's because you know, you're in a witless environment, so you're no longer needing to support your own weight whenever you move around, and everything is much easier. But that means that once you get back down on the ground where we do have gravity, um, it becomes a little bit you know, you may suffer some some problems because of

muscle loss or bone density loss. So then in the lower deck that's pretty much where equipment that's where it quote unquote lives so life support equipment, electrical systems, that kind of thing. And there are five on board computers that handle the data processing and the flight systems aboard the shuttle. So those five systems are are distributed throughout this this area as well. And uh, you've got the two orbital maneuvering systems engines that are located in the

aft of the the orbiter. These burn UM monomethyl hydrazine fuel and nitrogen tech tetro oxide oxidizer. I thought you could get through then I definitely bungled it at any rate. Uh. This is a different kind of fuel mixture than the external fuel tank obviously UM and also from the solid fuel rocket boosters. Uh. And the reason why they're using this subs these two substances together is that when you combine them, they ignite even if there is no oxygen present.

So clearly, if you're going to go into an environment where there is a distinct lack of oxygen, that is important mm hmm. So uh that and they use uh nitrogen to help pump that fuel through, and and also helium, the helium pressurized helium is actually used to move the fuel through the system. Nitrogen is used to help clear it out once you're done maneuver doing your maneuvers, because you don't want any fuel sitting in those fuel lines, um, because that could be a problem the next time you

need to use them. So then there's a whole section about the what the orbital maneuvering system can do. It's actually can produce up to six thousand pounds of thrust, and um, you can accelerate the shuttle by two ft per second per second. Remember acceleration is a change in velocity. Yes. Yeah, as a matter of fact, I did find this one interesting fact. Um, the h the shuttle can go from zero to seventeen thousand, four or miles per hour in eight and a half minutes, just slightly faster than a

hummer and nine times the speed of a rifle bullet. Yeah, so don't never mind. Uh yes, yes, why don't we? Uh well, I have an interesting uh kind of breakdown of what a launch sequence is like for leading up to well half a minute before the shuttle actually launches. So half a minute before the shuttle launch is actually T minus thirty one seconds, meaning that in thirty one seconds you're gonna have launch, assuming that everything is is coathetic. Yes,

that there go, Yeah, that there go for launch. So at thirty one seconds to launch, the onboard computers take over the launch sequence, so the astronauts really are sitting back and waiting to make sure that they are going to launch. Uh. Six point six seconds from launch, the shuttle's main engines ignite one at a time, and they ignite point twelve seconds apart from each other. I always love that part watching launch. Yeah, and they build up to about oh a little bit over nine of their

maximum thrust at that point. Now, three seconds from launch, the shuttle main engines are in liftoff position, so they have been They're all mounted on gimbals right, so they can actually be directed. They're not they're not stuck in a single direction, so they've been positioned and they are at the correct amount of thrust for launch. That part two team mine is zero seconds. This is the actual

launch part. That's when the solid rocket boosters are ignited, and of course they produce the of the thrust needed to get the orbiter or actually the entire shuttle off the launch pad. So that's the point where you've got enough thrust to counteract the weight of this vehicle and launch it into the air. It looks like there's a ton of smoke, but actually what comes out of then

the engines is mostly water vapor. Uh So, twenty seconds after the launch you've got the first maneuver where the shuttle will roll right about a hundred eighty degree roll in adjustment of seventy eight degrees and pitch. A minute after launch, the shuttle engines are at their maximum throttle. And then two minutes after launch, your solid rocket boosters will separate from the orbiter and fuel tank at about they're about twenty eight miles up orty kilometers up in

the atmosphere at that point. Now, the main engines on the the orbiter continue to fire at that time. Now, once the solid rocket boosters separate from the rest of the shuttle, uh, they will deploy parachutes and will land in the ocean about room around a d forty miles off the coast of Florida. That's about two kilometers and then UH those will be recovered by ships and actually be reused after being processed. Obviously, you can't just slap

them back on the launchpad. Clearly, seven and seven point seven minutes after launch, the main engines are thralled down to keep acceleration below three g's because otherwise you may harm the integrity of the space shuttle itself. And a half minutes after launch you shut the main engines down.

Nine minutes after launched, the external tank separates from the orbiter, and the external tank actually will burn up upon re entry the Ten and a half minutes after launched, the orbital maneuvering system engins fire to get the shuttle of the orbiter into a low orbit, and forty five minutes after launch, the UH Orbital Maneuvering System eensions will fire again to place in a slightly higher circular orbiter orbit, which is about two fifty miles above the surface of

the Earth or or four kilometers there you go. That's that's the whole process of just getting the orbiter into that that orbit around the Earth. Now. Of course, um, once they're up there, they will deploy satellites, they will do science experiments. Sometimes they'll go for an extra vehicular activity. Yeah, it's a space walk. Yes, the NASA terms UM E V A is what then and yes, and then they'll try to uh, you know, get everything ready, pack up, uh you know, and it's time to head home. You know,

you wanted to to talk about that. They have to, Uh, they have to. There are a lot of people in the Mission Control Center that help the shuttle astronauts as they're going through their mission. Um they will help them position the shuttle in the correct direction to come home, the right attitude exactly, and they also will make they also monitor all the different systems aboard the shuttle, because

there are tons of different systems on there, right. I mean when I say tons, of course, I mean there are lots of them. So things like everything from what we would call life support systems, so stuff that not just distributes oxygen through the system, but oxygen at the right mixture. You know, it's not going to be pure oxygen.

It has to be atmosphere that's comparable to the Earth's atmosphere. Also, there have to be scrubbers that will scrub carbon dioxide from the atmosphere so it doesn't get too stuffy or uh, eventually it would get to a point where you could not breathe um of the carbon dioxide. Scrubbers use a chemical reaction where it takes carbon dioxide from the system, combines it with another another compound and then you end up getting a kind of a nert material and sometimes

water as a result. And that way you don't have carbon dioxide build up in the cabin and also you have to worry about maintaining heat. The heat inside the space shuttle would continue to get warmer and warmer. The electrical systems actually provide more than enough heat to keep the shuttle warm, despite the fact that you would think, oh, well,

you know what, space is probably pretty cold. Well, that's true, but the electrical systems on the shuttle generate enough heat where they actually have to figure out ways to manage that heat so it doesn't overheat. So they've got a lot of different systems for that and uh, both passive and active systems for managing heat. There are lots and lots of other ones that we could talk about, but really, if we want to talk about the re entry system or the reentry process, um that gets uh, that's also

a very delicate procedure. Obviously, launching is going to be a pretty delicate thing as well. You're talking about lots and lots of of of very um reactive agents in the launch process. Well, coming back down is also pretty tricky, so here's the process that goes through a re entry.

They closed the cargo bay doors. That's clearly very important. UH. And most of the time when the or the orbiter is flying around the or in orbit around the Earth, UH, in relation to us, it would look like they are upside down, like the top of the Space Shuttle would be facing the surface of the plant. So they will actually use their thrusters to turn the orbiter, and they don't turn it so it faces directly like it's gonna

come down nose first. Actually they face it tail first. UM. In order to start firing the the the oms, the orbital neuvering system engines to slow the orbiter down, so they're actually, you know, they're using it to to fire in the opposite direction of their orbit to slow down the the orbiter. And it takes about twenty five minutes from the first time they start firing those engines to

the point where they reach the upper atmosphere. And at that during that that twenty five minutes, they use their thrusters in order to turn the orbiter over again so that the bottom of the orbiter will face the atmosphere, and UH, they're moving again where it's nose first as opposed to tail first at that point, and then they will burn all the leftover fuel from their forward thruster system as a safety precaution because of course it's going to heat up quite a bit, so they don't want

any fuel in that area of the orbiter before they start to really gain lots of heat. Now, this is where we talked about the idea of friction generating the heat. That's not exactly true. What's happening is pressure there. When the orator comes in at the into the atmosphere, it's compressing the air below it, and that compression is what's generating that heat. So you may have heard that the friction is what causes the heat. Of everyone's heard it.

I mean the Smithsonian reports it as friction. It's not friction. It's actually compression that's generating the heat. Now, there is friction playing a role. It is not that there's no friction, because if there were no friction, then the shuttle would just slide through the atmosphere like it was nothing. Uh,

it's not, you know, not a non factor. It's just that the major contributor to heat is the compression of the atmosphere as the shuttle re enters the atmosphere, so then um, it's it starts to come into the atmosphere. It's generating tons of heat through this compression again literally tons. I always get mail whenever I use the word tons to just say a lot um and it tries to distribute,

it doesn't try that. There's heat distribution methods that are mostly used through things like the reinforced carbon carbon which is r c C, which is on the wing surfaces, the underside of the shuttle. UM, there's some high temperature insulation tiles on the uppard forward fuselage and around the windows, things like that. That's what's used to absorb that heat UM once it encounters once it's re entered the our atmosphere. Now is the time where we talk about the the

whole flying element here. So the shuttle has um we swept back delta wings. That's the name of the design for the shuttles wings, and it can generate generate a lot of lift with a small surface area of wingspace because of that design. So it's essentially flying under comput to control. At this point, the astronauts are not guiding the shuttle, the orbiter as it's coming in at at this moment, and it starts to have to make these long S shaped flight patterns, And the reason for that

is to continually decelerate the the orbiter. You know, you have to slow it down. You can't just come in for a landing straight away or else. You you know, you need a much further You have to go a much further distance in order to do it. So the S shape kind of helps the shuttle slow down. So it's banking back and forth and um around though about

a forty miles away from the landing site. Uh, you've got the radio beacon from the runway, which is called the tactical Air navigation system that gets picked up by the shuttle. And about twenty five miles out from the the landing site, that's when the computers handover control to the shuttles commander. So at that point the shuttle does come under human control, and the commander actually flies the shuttle down and has to make a long curved entry

toward the landing strip and sets down the shuttle. Now, this whole time when the shuttle is coming down, it's coming down in a much steeper approach than what you would experience on your typical commercial air flight. So uh yeah, this would really freak me out if I were on a on a normal flight and and arrived at a

at this kind of steep grade. But at that point the the orbiter, once it's around two thousand feet above the ground, that's when the commander will lift the nose to slow the rate of descent, and uh, the pilot will deploy the landing gear and that's when the orbiter touches down. The they throw on the brakes, the vertical tail opens up, parachutes deployed, and best all helps too slow and eventually stop the orbiter. Uh. At that point,

you still have to wait a while. You can't have people just run up to the orbiter at that point. For one thing, it's still quite warm. Yeah. Yeah, you know. Actually I wanted to clarify because I had always been told again this is sort of a misnomer about the

foam tiles. They're not really made of foam. I wanted to do a little bit of clarification that they're actually made of a silica fiber, basically sand mixed with some ceramic um and you know, there is some air in there, which is why I think, uh, people describe it as being foam. Their their pockets of air based on the way they're made, but they're not It's not actually foam like you would see, uh you know, a styrofoam or

some kind of plastic foam. So just to clear that up before anybody writes in, I do know the difference in that. But they're actually a couple different kinds. But they do store heat and uh you know they I mean you can anytime you've put something down on a ceramic tile, like you know, the hot plate. When you have one of those tiled tables and you lift it up, you know that the the uh tiles are still holding heat in. And that's what's going on with the shuttle.

You can't just uh you know, wheel it up to the gate. Besides, usually when I get in, there's not a gate ready and you have to sit there. Yeah, and there's also some you know, the whole the fuels that that the shell burns also can generate some pretty nasty gases that need to redistribute. Chris is giving me a funny look because he's he's thinking, I'm going to make a a fart joke. I am not. Um No, there are noxious gases that are generated by the burning

of this fuel. Stop laughing a little two year old and then the uh, but you have to give it time for those two to dissipate, and also for the shuttle to cool down the orbiter to cool down. Um. Once that happens, it takes probably about twenty to thirty minutes, they'll start powering down the systems and then that's when the crew will exit the shuttle. To great acclaim. Yes, and so that's kind of a beginning to end. Look

at the basic overview of a Space Shuttle mission. Now, there are there are so many more elements we could go into. I mean, this is this episode is are a gone forty five minutes and we barely touched on on on even half of what we could have talked about.

In fact, we probably could have done an entire episode just about a launch, but we wanted to give you more of an overview of the Space Shuttle itself if you want to learn more, Like I said, the how Stuff Works article is fantastic, but also NASA has more I'm not going to use tons again, lots of resources. There's a lot of information about the Space Shuttle on their site. Uh yeah, there there there are some interesting facts, and I mean just as in factoids and little things

that are just interesting to people who are curious. Also some extremely technical documents too, So it's no matter how interested you are, assuming you're interested somewhat, there will be something. Just a couple of notes. UM. The launch date is planned for July eight, two thousand eleven UM for Space Shuttle Atlantis on STS one thirty five, which is the

last plan space Shuttle mission. They are supposed to be launching at eleven twenty six am Eastern daylight time as at the time of recording this UH from Kennedy Space Center Pad thirty nine A. They're scheduled to land on July twenty at seven oh six am Eastern daylight time UM at Kennedy Space Center UM, and their primary payload is UH the raphael OH Multipurpose Logistics Module whatever that is UM. So UH, godspeed to the Shuttle costronauts on this final mission. There may be very sad to see

the program end, but I'll be something else. I'll be watching the launch live, I'm sure, UM always on the computer. I actually had a chance to maybe get a stand by position for the tweet up, but sadly I am not able to take advantage of it because I used up all my vacation recently. Well, hopefully Megan and some of the others who are going to the tweet up will keep us up to date on what's going on. Certainly,

I sure hope so. Well. Enjoy that. That's gonna wrap up this discussion of the Space Shuttle, and we will be tackling other space related topics in the near future. Actually for Chris and I will be tackling it in about thirty seconds, but you'll be hearing it later on. Anyway, we're gonna talk about more elements about the space program. If you have anything specific you would like us to talk about, whether it's the Space program or anything else, let us know. You can let us know on Facebook

and Twitter are handled. There is text stuff h s W or you can send us an email. That address is tech stuff at how stuff Works dot com and Chris and I will talk to you again really soon. Be sure to check out our new video podcast, Stuff from the Future. Join how Stuffwork staff as we explore the most promising and perplexing possibilities as tomorrow. The house efforks iPhone app has arrived. Download it today. On iTunes, brought to you by the reinvented two thousand twelve camera.

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