Why can't space shuttle enter without using heat shield?

Question

Why can't space shuttle enter without using heat shield?

Answer 1

The shuttle cannot enter slowly because it has no power to slow itself down. The shuttle itself does not carry fuel (except small amounts for maneuvering is space). Only the rocket that launches it into orbit carries fuel, and that fuel is totally used up during the launch. Since the shuttle cannot reenter slowly, the friction creates heat, just as others have explained above. Now in case you’re wondering why the shuttle doesn’t carry fuel, the answer is that fuel is too heavy, so they don’t send any more into space than absolutely necessary. In fact, most of the fuel burned during the early phase of the launch is needed just to lift the rest of the fuel for the final phase. The goal is to burn up all of the launch fuel, then discard the rocket so that just the shuttle itself actually goes into orbit. (The rocket parts fall back to earth.)

Answer 2

if they added solid rockets it might help

Answer 3

It would require more fuel to slow the orbiter down than the tanks can hold!



Plain and simple...

Answer 4

the space shuttle can't slow down or it will bounce off the atmosphere like a skipping stone because of the magnetic field around the Earth. This field protects us from radiation and lessens the impact of asteriod collisions.



Also when they leave Earth they are expending a lot of energy and weight needs to be taken account of. more weight more fuel needed to get them off the ground. THey don't have the fuel to have more than 1 attempt at landing so why would they have the fuel to slow down their hit to the atmosphere? To make sure they get in they need to hit hard and at the right angle or they burn up on impact or boune off

Answer 5

because it might be inposoble for the spoace shuttle to exit the atmosphere. that atmosphere is mostly there to protect us in a way.

Answer 6

because it's really hot because its close to the sun

Answer 7

I could not carry enough fuel to slow it down, with that amount of fuel it could not get off the ground..

Answer 8

I believe it needs the heat shield due to the friction from gravity

Answer 9

Space shuttle is traveling in excess of 28000km/hr in orbit so it wouldn't fall to earth. It goes through three stages of re-entry to reduce it's speed to glide back down on earth. The energy created by the orbiter's mass and speed must be released during re-entry. This is done by using friction between the orbiter and the atmosphere and a series of s-shaped turns as speed brakes to slow it down. The friction creates tremendous amounts of heat, some of which must be absorbed by the orbiter and some of which must be deflected away from the vehicle. The re-entry is an excellent example of using a law of physics that states (energy can be changed from one form to another) to bring the orbiter from a speed nearly 30 times that of sound to a complete stop on the runway. The whole process takes a little more than an hour to complete and begins about 8,000 kilometres (5000 miles), or about halfway around the world from the landing site.



To appreciate how difficult this is, you may want to purchase a space shutter flight simulator and try to land it yourself.

Answer 10

Basically, the shuttle travels at orbital speed to stay aloft. Slowing from that kind of velocity requires incredible force that can harm the crew. The slowing is accomplished safely by turning the shuttle bottom forward so that the force of the atmosphere pushes against the bottom of the shuttle. This creates a tremendous amount of heat, which is why the heat shield is required.



The shuttle can't enter the atmosphere more slowly because there is no way to exert the forces necessary to do so without harming the crew.



A similar question was asked on a NASA Q&A site:



"Shuttle re-entry from space-

How come when the space shuttle re-enters the atmosphere it does not enter more gradually to avoid heating up a lot? I have wondered about that for a while. Hope you can clear that up for me. Thanks."



Reply

"The answer is, such gradual re-entry will not work.



Generally, a craft suspended above the ground (excluding balloons) stays up in one of two ways. Either it has enough velocity (looking at it one way) for the curvature of its fall to match the curvature of the round Earth. Or else, it gets lift from the air its motion encounters, the way airplanes do.



At orbital speed, at least 8 km/sec, the shuttle keeps its height the first way. However, once it enters the atmosphere and slows down, its fall no longer matches the curvature of the Earth, and instead it gets lower and lower. It could have entered more gradually if it could have used the atmosphere to keep its height, the way an airplane does. But at 15-20 times the speed of sound, wings create more resistance than lift, and anyway, presenting a wing edge-forward as an airplane does would concentrate too much heating and pressure on its front.



The shuttle starts re-entry with appreciable altitude and a lot of forward speed, so its fall will take some minutes. The trick is now to lose speed and kinetic energy safely in the time allowed by this fall, and it turns out possible to do so--just barely--without deceleration forces getting too high for the crew. To lose its energy, the shuttle turns its bottom (covered with heat resisting tiles) to face forward, creating a wide shock front in which most of the heating occurs, sparing the shuttle itself. Only at the last stage of its descend does the shuttle actually "fly." By that time, only a small fraction of its energy remains."



Search the NASA website to learn more.

Answer 11

Apparently you are too young to remember the Apollo and gemini Missions but speed had little to do with the heat at reentry.



You can slow it down to a crawl and it won't make it unnecessary to have a heat shield. Basically that is what the old space capsules use to do. They still lit up from the effects of gravity pulling them down at an accelerated rate of speed.



Your question is can you diminish speed to the point that the heat generated by gravity is disipated. Answer No. The slower you go the hotter you will become. If you wanted to lose heat you would have to go faster not slower. However, in going faster the effects of gravity and centripetal force will make stearing the ship nearly impossible and perhaps creat a new heat signature on the top of the shuttle from the added g force due to the added cetripedal force. You are also talking about needing more fuel, and fuel is a combustable. It would be like riding a stick of dynamite.



I also believe you would burn out the hydralics on the flaps, brakes and stearing when you tried to navigate the ship.



Now if you can come up with some sort of anti-gravitational force field which doesn't exist right now then you could slow down the shuttle to where it can make a gradual landing without heat. Otherwise the current landing procedures are the best possible solution. It limits heat primarily to the heat shield. It diminishes speed. And, it allows the pilot to go immediately to manual after reentry.



Sorry but that is just the way it is. It is a relative mass and speed thing.

Answer 12

I don't think that the changing the speed of the object can stop or remove aerodynamic friction. Even if the object entering the atmosphere didn't move, the Earth still is. As long as the Earth (and the atmosphere with it) is moving, I imagine that friction will be present regardless of what speed the object is moving at. After all, it the shuttle wants to reenter the atmosphere it has to move at a different pace then the Earth moves or it would just stay in orbit. Also, at the speed the Earth is moving and the speed the shuttle is moving for entry the atmosphere is like a solid. I don't remember the whole theory, but it has to do with the behavior of molecules and atoms with they hit an object moving at a different speed. It's like a giant car crash between the atoms in the shuttle and those in the atmosphere. When they collide, heat is released.

Answer 13

Well, here's what I'm thinking: The air is really really thin in the upper atmosphere; therefore, if the shuttle slows down too much with reverse thrusters or whatever, it will lose lift and stall. It's the forward speed of the shuttle that keeps it from stalling! In order for the shuttle to slow down enough that it doesn't need the heat shield, it would probably have to use lots of fuel to thrust it upwards like it was hovering. As you know, the space shuttle does slow down eventually before it lands, but not until it's in thicker air. The "bounce off" thing might also be true, and it is definitely true that the air resistance offers a fuel-free way to slow down.

Answer 14

think about it, it's not rocket science (ok, it is!). The shuttle would have to expend a great deal of fuel to resist the acceleration attributable to gravity. engineers do not consider this a serious possibility, and the shuttle is therefore treated as a ballistic body for purposes of re-entry. it is using no fuel at all, except sometimes (usually before actual re-entry) to adjust attitude (pitch, yaw, roll). this does not require large quantities of fuel.



once the orbiter is on proper trajectory for re-entry, it is not using any fuel, and is travelling much the same way as a bullet travels. the atmospheric friction forces on re-entry have been the single greatest design problem for the space program. the tile system which the orbiter uses for a heat shield has been a laughing stock since the '70's. (i'm letting you in on a little secret, here). No credible engineer ever said tiles would work well, and they don't. Why? Because everyone knew they would constantly fall off, endangering the craft and crew. Why was it done anyway? Because NASA is principally a public relations enterprise. The politics were such that many powerful, toupe wearing white guys who drove Chrysler LeBarons with vinyl seats, and cheated on their wives, and were generally not nice people, would have been "embarassed" by a dismantling of the shuttle program. but that's America.

Answer 15

OK folks here ya go. You are correct that the space shuttle comes into the atmosphere at a high rate of speed however the burning effect comes into play once the shuttle hits the atmosphere or air.,gravity comes into play since the shuttle is coming from space with no gravitational pull at all. So the earth pulls the shuttle down as it breaks the atmosphere causing the heat & burn the shuttle comes in at an extreme angle which is actually acting like a break rather than coming in head first & immediately crashing into the Earth. Hope this helps with your question.

Answer 16

The Earth has a protection system in the atmospheree that will burn up any object entering the atmosphere like for example meteorites , that's why you see them going across the night sky , because they are hot and glowing from being burned by the atmosphere to stop it from hitting the earth. although these objects small and big still penetrate the earths atmosphere but they are burned . the space shuttle needs the heat tiles to reenter the earths atmosphere to keep from being burned up. the shuttle must travel at certain speeds to enter earth because of the earths speed and gravitational pull. also the shuttle will enter the atmospher at a angle allowing the heat to hit the bottom of the shuttle where the tiles are at. but most important is the shuttle must enter the earth at certain times so the shuttle can glide to the destination it needs to land. because it is not using any power to fly like a plane to go just anywhere and land. maybe this will make some sense to you.with out the heat tiles the shuttle would burn killing whoever is in it.

Answer 17

Maybe it's more of a precautionary measure? In case the shuttle HAS to enter the atmosphere faster than normal.



Here's another idea: the space shuttle would have to have rocket thrusters pointing all over the place in order to slow itself down enough to enter the atmosphere without the heatshield, and that might be more expensive to do (because of cost of the fuel) than just using a heatshield.



Once you get going in space, you don't stop until you hit something or gravity catches you, hence the need of my expensive directional thrusters for deceleration without a heat shield.



I hope you find a good answer, this one is on my Watch list.

Answer 18

The only reason that I know that the space shuttle has a heat shield is because of the earth's atmosphere. I believe that when the space shuttle is coming back done to earth it has to break through the area between the earth's sky and the area of actual outer space and this causes a friction and if the space shuttle does not have a heat shield, everyone in the space shuttle would burn up like in a very massive house fire.

Answer 19

When the Space Shuttle goes through the process of returning from space to the Earth's atmosphere it encounters severe friction.



It is the friction that creates the massive heat.



As for "bouncing" off the atmosphere, the space shuttle must re-enter the atmosphere at the right angle, neither too steep nor too shallow.

Answer 20

The Friction between the air molecules causes it to become hot as it enters the atmosphere. In order to slow down, one would have to use rockets, just like how they got off the planet, but would not have to put as much force. This would indeed slow it down but most of their major fuel supplies has been used up. This friction between the air and the shuttle is what causes the extreme heat and the need for a heat shield.

Answer 21

1. The atmosphere is layers of gases covering the earth.

2. You need to enter at high speed do the ship doesn't crush under the high pressure, also the pressure is so great your blood will boil.

3. actually the first space shuttle The Orbiter Columbia(the one that disinagrated in 2003 on it's 28th mission) actually didn't use a heat shield and landed safely.

4. Using a Shield is faster and safer for the passengers.

Answer 22

The atmospheric gases mix with the shuttles components and cause a combustion-like result. There is no way to slow down and calm the heat because the extreme difference from no gravity to gravity is pulling them in too quickly. You can't just hit the brakes like in a vehicle that is on a solid or liquid surface. The heat shields simply protect the passengers and the equipment and burn off once they've done their job.

Answer 23

the air is made of particles. when reentering the atmosphere those particles rub up against the bottom of the shuttle and create friction, which produces high temperatures and wears away at the shield on the shuttle.



the shuttle is pulled in by the gravitational pull of the Earth and the pull is so strong that it causes the shuttle to fall rapidly. if the shuttle wanted to slow down it would need jets or rockets on its underside and plenty of fuel. but that couldn't happen. remember Columbia, when it disintegrated during reentry because of a hole in its shielding? rockets on the underside of a shuttle would be the same thing: the air would still rub up against the internal parts of the engine and wear them down and that would cause them to fail. if they have 4 rockets, 2 on each wing, and an engine fails that can cause the shuttle to roll in the direction of the failed engine. the top of the shuttle isn't as well protected and that would be catastrophic for the crew inside.

Answer 24

The space shuttle without a heat sheild will burn on reentry much like meteors burn as these enter the earth's atmosphere. Why is that? A meteor approaches the earth at a "falling" speed. At that speed the surface of a meteor encounters resistance in the earth's atmosphere as it enters the planet. This resistance is what's commonly referred to as friction. This friction causes flammable gases in the air (oxygen, hydrogen, etc...) around the meteor to burn increasing the surface temperature of the meteor. Eventually, the heat overcomes the surface of the meteor and the meteor itself starts to burn.



A heat shield is a super heat resistant material lined underneath the shuttle. It is designed to withstand tremendous surface temperature, effectively protecting the space shuttle. Any crack in the heat shield causes the heat to breach and endanger the space shuttle's internal structure.



The space shuttle needs to "fall" from space in order for it to enter the planet. By "falling" means that it needs to submit itself to the earth's gravitational pull. It might be possible to slow down the fall using retro-rockets, but that just requires more energy. Managing free-fall is the best option for reentry. The way the space shuttle does this is to glide on a zig-zag pattern until it reaches the lower atmosphere. The patterns helps in dissipating the friction during reentry.

Answer 25

They could slow way down, but you have to remember that the shuttle is essentially a very inefficient glider once it re-enters the atmosphere -- it's jets are meant for maneuvering in space, not propelling it great distances through air. The easiest way for it to slow down from orbital speeds is to scrub off speed in the atmosphere; if you burned a whole lot more fuel to slow down to, say 2000-3000 mph, then you'd simply drop straight down in a more-or-less ballistic trajectory, rather than gliding in more gracefully. This is why a design like Burt Rutan's Spaceship One is so revolutionary -- it doesn't glide all the way, and it doesn't fall and depend on parachutes, either, but "feathers," goes vertical with its aerilons and dangles the fuselage in a sort of cradle which allows the craft to sort of drift down into the upper atmosphere, at which point there is enough wind resistance for the plane to straighten out and fly like a regular glider. The shuttle can't do that, so it actually requires the high speeds to get it to where it needs to go in the manner it was designed to fly.

Answer 26

Assuming sufficient fuel resources, they could indeed enter the atmosphere at whatever leisurely pace they wanted to. The problem is, they don't have sufficient fuel resources. Just attaining the velocity needed to orbit the Earth requires fuel and staging equipment in excess of 15 times the shuttle's mass. To slow down to a reasonable entry velocity under power would require nearly as much fuel - meaning that 15 times the shuttle's mass in fuel would have to be resent with it IN ORBIT. Lifting all this fuel into orbit along with the shuttle would take 225 times the shuttle's mass in fuel (15 times the mass of what you're lifting, and what you're lifting is 15 times the mass of the shuttle). It is beyond impractial to design a spacecraft capable of carrying that much fuel - as such, NASA engineers use the "trick" of using the Earth's atmosphere to slow down instead. It's dangerous, and that heat shield is expensive, but it's nowhere near as expensive as providing the shuttle with the fuel to enter the atmosphere at a reasonable speed.

Answer 27

All things fall at the same rate. That is why it gets so hot is because of friction with the atmosphere as it falls ti Earth. The bounce would come from the fact that the earth is spinning really really fast. Drop a toothpick on a spinning top and it bounces off. Now if you increase the velocity of the toothpick so its inertia is higher, it would penetrate the top, or at least slow the top.



It is not that the atmosphere is "hard", it is that the earth spins so damn fast and the speed of the spin with the friction of the shuttle causes the "bounce".

Answer 28

The heat shield would still be needed. In practice, the shuttle is orbiting about 300 km above the earth surface. Assuming it had the needed fuel, As it slowed down in would immediately "fall" and enter a lower orbit and heating from air friction would commence. The falling would continue and increase as the orbital speed was reduced. It would take a finite amount of time to reduce the velocity to zero - with respect to a point on the earth's surface. By that time the shuttle would have a vertical speed of about 300 km per hour (and a date with destiny when it "landed". (ouch) In practice it would have to maintain a forward velocity in order to make a landing. And its descent point would need to be very near an airport.

Answer 29

The average speed of the shuttle in Earth orbit is about 186k a SECOND!!



And when it enters Earth's atomsphere, that speed causes friction with ozone and our oxygen rich atomsphere, causing it to heat up fast because the shuttle is going IN at about 8 times the speed faster than it travelled going OUT our atomsphere.



The Shutttle's onboard computers precisely fire off retro-rockets and steers the vehicle in a complex series of "S" turns which effectively slow the ship down to safe landing speeds. Even then, a parachute is needed to slow the shuttle down once it's landing gear hits the tarmac.

Answer 30

The Space Shuttle HAS a heat shield. On the bottom of the Shuttle, there are black tiles which repel the heat. Also before launch, NASA does a Sound Suppression System where it puts tons of water below the ET (External Tank) and the Shuttle to protect sound and heat.

Answer 31

This are some Problems that seem possible.

1) It would increase the weight considerably and require bigger rockets.

2) The rocket cannot deaccelerate very fast and this is very inappropriate for negative acceleration.

3) Some heat is surely produced even at slower pace. This would blast the shuttle. So heat shield is again necessary. This proves the futility again.

(I don't know about bounce off)

Answer 32

Well, it is going while in orbit approx 17,000 mph or a little faster I think. Anyway, the shuttle has no air or jet engines, just rocket engines. It comes in as a glider. Or, like one astronaut says, flight ability of a nose heavy brick and handling characteristics that make a Mack truck seem like a sports car. So, if it were to slow enough to not need a heat shield, by say firing off its last bit of chemical propellant to slow it down before starting to fall, it would be one helluva ride DOWN. It would have to wait to bite into enough air for any lift to happen and give it ability to maneuver, by that time it would be too low to come out of the dive with time to turn and get lined up with a runway.

Answer 33

Friction is friction.



Even if the shuttle is moving at nearly no speed when it enters the atmosphere, gravity takes over and pulls it down, generating the heat.



You need a certain amount of speed to crack the layers

Answer 34

1. The shuttle carries almost no fuel, except the small amounts needed for retro rockets to maneuver itself in orbit.

2. The shuttle is traveling at a very high speed (it is essentially in free fall)



Your question is the answer to your question. Why can't it slow down? It can slow down. If it couldn't slow down then it could never return to Earth. It stays in orbit precisely because of its speed. So to return to Earth it needs to slow down. It does so by entering at very high angles of attack and performing the maneuvers someone else earlier has described quite well. This process slows it down to speed where it can actually glide like a paper plane.

So you are asking WHY can't it slow down so that there would be no heat? The answer is, it is the process of slowing down that causes the heat (friction, air compression, shockwave etc.) Yes if it could another method of slowing down like firing up a retro but the shuttle does not carry large amounts of fuel to slow it down to subsonic speeds.



This article might help:

http://en.wikipedia.org/wiki/Retrorocket

Answer 35

If you had enough fuel, yes, it's theoretically possible to slow down and re-enter without a heatshield. However, that would take just as much fuel as it does to launch, including the solid rocket boosters. The shuttle alone could never carry that much fuel...nor does it have engines capable of the required thrust.

Answer 36

The space shuttle is used mainly as a transport vehicle for unpopped corn,it takes fresh unpopped corn to the space station & returns with "old" unpopped corn.

If the space shuttle didn't have a heat shield the "old" unpopped corn would pop & u can imagine the mess that the astronauts would have to clean up b4 they landed.

Answer 37

They can if they build a spacecraft with the "Feathering" capability that Bert Rattan invented for the Space Ship One. Special wings rotate 45 degrees and the space ship slows and reenters the atmosphere. Heat shields are not required. Go here for links to several sites about Space Ship One.



http://search.yahoo.com/bin/search?fr=ybr_sbc&p=Space%20Ship%20One

Answer 38

I think basicallu if you had huge fuel reserves this might be theoretically possible, but you'd need huge amounts of fuel, which it's just not possible for the shuttle to have. It would have had to either carry the fuel up from earth in the first place, or else 'made it' in space. Neither is possible.

Answer 39

the shuttle jettisons its fuel in space so that it doesn't explode on board. this is why the shuttle re-enters the way they do. this is also why it is crucial that they hit the runway on the first try, because they have no fuel left to take off and circle around, as an airplane would do, if the first landing is off target.

Answer 40

Wow. Good question. My guess is this (becuase I think I heard this before):



You know how you skip a stone across water? Well, this works the same way. Going really fast, the air will repel the shuttle if it's going at the proper angle.

Answer 41

ok, well, the space shuttle can't enter slowly because of gravity.It needs the heat sheid because it is going so fast that it heats up. kinda like when a meteor enters the Earth's atmoshpere, by the time it gets to be really close to the ground, it is on fire.

Answer 42

It would take too much fuel to slow down that much. It's much easier to use a heat shield. It's a good question. I can't give you a very technical answer, which somebody else could.

Answer 43

It has to have the speed to enter the atmosphere.

Therefore it will burn up so the reason for the heat shield.

Answer 44

1. Earth's atmosphere

2. Gravity

3. Speed (velocity)

4. Heat and friction

5. Safety measure for astronauts

Answer 45

The same reason the Death Star needed a deflector shield and the Marty and Doc used the Flex Capacitor!

Answer 46

The slower you go, the more you are exposed to the atmosphere and heat. The idea is to enter this area as fast as you can, your descent will slow you.

Answer 47

I would assume that being similar to an airplane if it tried to enter slowly it would stall just like an airplane . So it needs to maintain a certain velocity or it would not fly

Answer 48

Gravity

Answer 49

Takes just as much fuel to slow it down as it did to speed it up

Answer 50

It could, given sufficient fuel. Unfortunately, it can't carry enough fuel to do the job that slowly. OTOH, an electrogravitic craft could easily do as you suggest.

Answer 51

It just needs to enter fast. So it needs heat shields. It doesn't matter, because it just needs it. It's like asking why does rain fall, it just does.

Answer 52

Without the heat shields, there'd be no protection from the heat and they would burn up.

Answer 53

Because the gravity pull of the earth won't let it.

Answer 54

You men think to much. It's all about the gravity dude!

Answer 55

It is being pulled in by gravity

Answer 56

I think Bren at RIT has a good point.

Answer 57

it will burn up and kill the ppl inside from the heat it ommits

Answer 58

Because they just can't! Good answer?

Answer 59

they need to put anal lube on the tip

Answer 60

it'll burn it to pieces