Why do things burn up in the atmosphere upon re-entry?

Question

Such as.. The space shuttle has to re-enter the atmosphere at a certain angle so that they won't burn-up.

Would some dude wearing a space suit burn-up if he was trying to go through the atmosphere?

Answer 1

The reason why objects without a heat shield or entering the atmosphere uncontrolled incinerate is simply due to the fact air can't get out of their way fast enough. The Space Shuttle strikes the atmosphere at 25 times the speed of sound, and objects coming in from deep space can be moving three or four times faster. As an object encounters the atmosphere, air cannot move out of the way due to the hypersonic velocity, and instead it piles up ahead of the object and compresses into a shock wave. The gases there are compressed rapidly enough to heat up to 20,000 degrees or more, and because of that the radiant heat from the shock wave starts to heat up the incoming object. The heat will either melt or vaporize any material exposed to the shock wave, and since aluminum is used heavily in the construction of spacecraft, the spacecraft tears apart and the pieces melt or vaporize. The shock wave also creates drag upon the object, which slows it down as well and created immense pressures on it as well. If the object has a heat shield, it either melts and burns away, taking the heat with it, or like the Space Shuttle's simply insulates the skin from the heat. This is possible because instead of just diving in like a nuclear bomb or skipping along the atmosphere like a rock off a pond as the Apollo lunar missions did, the Shuttle rides the upper atmosphere like a surfer. That keeps the temperatures low enough for thermal tiles to protect the spacecraft during re-entry. Other spacecraft make a ballistic re-entry, which not only creates hull temperatures of 6,000 degrees and higher, it also treats the crew to severe and sometimes near bone crushing deceleration too. The spacecraft require a very heavy heat shield that cannot be reused, and it burns away to save the spacecraft. The re-entry must be made at a precise angle, or the spacecraft will burn up like a meteorite, or even skip off the atmosphere to careen off into space again. A spacecraft must make a controlled entry no only to avoid breaking apart and burning up, it's also to keep the gee forces from killing the crew. As for a man in a space suit, he couldn't hope to survive a re-entry in one. Even if he didn't burn up, he would hit the ground at several hundred miles an hour without a parachute to bring him to a safe landing. The idea of making a re-entry in this way has been considered, but shelved in the 1960's.

Answer 2

cause of all the speed and pressure

Answer 3

this one didn't...

http://www.dropzone.com/news/SpaceParach...

but then, he ''ONLY" broke the sound barrier in his fall... much slower at 600 mph than the 17,000 mph of an orbiting shuttle....

so speed has a great deal to do with it....

Answer 4

Well, it's a matter of the speed they are going, for example...

The title of world's fastest human actually goes to three humans, Thomas Patten Stafford, John Watts Young and Eugene Andrew Cernan.

These three men reached a speed of 24,790 MPH or 39,897 km/h on board Apollo 10 during their return from the Moon.

That translates to 6.88 miles per second or 11.08 kilometers per second.

Most objects entering from space go much slower...say 17,000 MPH.

At those speeds two things happen. One is the air literally can not get out of the way fast enough as you move in you get a compression wave in front of the spacecraft.  The second is that as the air gets denser, the spacecrafts looses energy...but energy can neither be created nor destroyed...just transfered. In this case it is transfered in the form of heat.

There is a lot of energy to be transfered...so you get a lot of heat.

Answer 5

because they are going 17,000-35,000 mph

Answer 6

Simple answer: Friction.  As the orbiter enters the atmosphere, friction causes the heat build up, which could (and has ) cause disintergration disasters.  By entering at an angle, the increased area of the fuselage and wings allows for a greater dissapation of the heat. If someone in a space suit only were to enter the atmosphere, at first he would be safe, but due to gravity, he would fall faster and faster, thereby increasing the friction.  Without a means to dissapate the heat, he would eventually burn up.

Answer 7

It's friction between the atmosphere and whatever is falling through the atmosphere.  Stick your hand out the window while riding in the car.  Feel that resistance?  Now imagine it multiplied by thousands.  

In space, there's virtually no resistance (no atmosphere), so when things are hurtling towards earth, they're moving pretty fast.  They hit the atmosphere at such high speed, and go through such a thick (relative to space) resistance, that they heat up (like rubbing courdoroy pants).  Most objects get so hot that they burn.

A dude in a space suit would burn to dust.

Answer 8

A space ship could slow down prior to re-entering the atmosphere, but that would use a lot of fuel.  Typically most of a spacecraft's fuel is used up just getting into space, at which point it is now travelling at incredible speed just to maintain orbit.  Most of that speed was attained while still in space, so friction of the atmosphere is not a problem then.  It does become a factor when re-entering, however, because now the atmosphere is used to slow the ship down from 17,500 mph, or 5 miles per second.  The process is called aerobraking, and it saves fuel at the expense of subjecting the spacecraft to high friction and heat.

Answer 9

cuz it gets hot