How re space shuttles able toreturn to erth safely?

Answer 1

Autopilot and heat shielding.

The autopilot takes care of the tedious work of adjusting pitch and performing steep S-turns to keep the shuttle's speed down. Even with this control, the bottom of the shuttle gets heatd up due to friction with the atmosphere, so special plates protect the shuttle from burning up.

SpaceShipOne used a different approach...

Answer 2

There are 2 ways something outside the atmosphere can safely land on the ground as we know it. The key is to lose velocity. An object in orbit is moving at 17-18,000 miles per hour which menas it falls at a rate such that it "misses" hitting the Earth. Think throwing a ball and how it curves down to hit the ground. In the case of orbit, the curve of falling exactly matches the shape of the Earth, so while it is continuously falling, it never hits anything and "misses." So, for the 1st way, use an engine with thrust to support the craft as gravity pulls it to the ground. This is how a soft landing was accomplished with the manned and unmanned lunar landers. The engine method is expensive because of the fuel loading on the craft to keep the engine running to provide the counter thrust to fight gravity. Note the first manned lunal lander had only 8 seconds of fuel remaining when it touched down and they killed the engine. The other method is to use friction, air friction, to slow the craft to the point where it can fly in the same manner as an airplane (or alternatively be supported on parachutes like the Mercury, Apollo and Gemini missions), with lift provided by wings, which is what the space shuttle does. The problem is the heat generated from the friction of the fluid (air) as the craft passes through as it loses velocity to accomodate a soft landing. The problem with the air friction method is the angle of attack, too shallow and the craft skips out of the atmosphere like a stone skipping on water, only to re-enter later at an undertermined location, too steep and there is too much heat for the heat shiled and it burns up like a meteor. So, that is how the shuttle does it, skims the atmosphere at the right angle of attack to lose energy due to air friction without too much heat buildup until it is going slow enough to use the wings to glide to a safe landing.

Answer 3

Well first off - the areas of the shuttles surface that are exposed to extreme temperatures during reentry are covered in special materials that allow the shuttle to survive extreme temperatures and stresses. These consist of thermal tiles lining the underside of the shuttle, thermal blankets on the nose, and very special, highly heat resistant custom materials covering the edges of the wings.

It was one of these special wing edges that was chipped and caused the disintegration of the Columbia over Texas.

Anyway - reentry consists of a breaking maneuver which slows the shuttle so that it drops towards earth. Once this maneuver is complete, the shuttle is rotated so that it enters the Earth's atmosphere like an airplane landing.

During the reentry, the nose of the shuttle is pointed at an angle upward, somewhat like the attitude of a plane on touchdown. This keeps the thermal tiles at an attitude to absorb the heat whilst protecting the less protected areas.

After a brief period of ionization in which communication is lost, the shuttle enters a series of turns as it approaches the landing site, in order to lose speed for a safe landing.

This leads to final approach (accompanied by chase planes) and landing as a conventional airplane or glider (note that this is an unpowered landing, so more akin to a glider in many respects.

You can find more at:

http://science.howstuffworks.com/space-shuttle.htm
http://www.nasa.gov/mission_pages/shuttle/main/index.html

-dh

Answer 4

very regretfully, it doesn't safely happen alll the time.......


BUT, when it does happen, it happens with special tiles that work like this. They are made of ceramics. They blow air into a vat of ceramics and make all kinds of bubbles in the ceramic soup. The bubble pieces are then cut into square tiles, and then kiln fired. The tiles, which i have actually had the opportunity to hold many times, are VERY lightweight and fragile, which is why they shatter when struck.

The reason why the bubbles work is the air that is in them. Air is trapped inside the now kiln fired ceramic tiles. That air makes a perfect insulator. The reason why, is when air is separated by millions of little bubbles it transfers heat VERY VERY VERY SLOWLY. This means that the shuttle can pass through the atmosphere for 30 minutes of temps of up to 4000 deg Fahrenheit the inside of the tiles is cool to the touch. I've tried it my self, with a blow torch.