Space Travel 101: Fundamentals of Space Travel

Overview A spacecraft must re-enter Earth's atmosphere from a very high orbital speed and not burn up like a meteor. It must give up a lot of energy to slow down so that it can land safely.

Analysis After a ship finishes its mission, it prepares for the bumpy ride down to Earth. It needs to slow down, so it turns around to fire its engines in order to have a low enough speed to fall down from orbit. The Space Shuttle lowers its speed by 200 miles per hour before re-entering the Earth's atmosphere. Then it turns around and faces down into the atmosphere at an agle of 30 degrees. In the upper reaches of the atmosphere, the Space Shuttle travels at around Mach 15 and still uses its thrusters for controlling. As the atmosphere thickens, the Space Shuttle can use its aerodynamical capabilities to move like an airplane. The Shuttle has a delta-wing configuration that is optimized for traveling at high velocities while maitaining control over the spacecraft. It has an elevator/aileron on each wing that help it with rolling motion and moving up and down. On its tail it has a rudder that controls left and right motion. The underside of the Shuttle is coated with heat-resistant carbon-carbon tiles that can sustain the heat of friction with the atmosphere without burning up. The underside of the Shuttle can get as hot as 1650 degrees Celsius during descent. As the Shuttle nears its landing point, it travels in a series of S-shaped turns that reduce its speed to about Mach 1. It is flown by computer until it is about 40 km from landing. At this point, the commander takes control and flies the Shuttle in a wide arc, lowering its speed to about 360 miles per hour. About 20 seconds before touchdown, the pilot pulls up the nose of the Shuttle before touching down on the runway at about 215 miles per hour. The Shuttle takes several kilometers to stop, using the rudder and a drag parachute as a brake. Other spacecraft do not necessarily land on a runway. The Russian Soyuz capsule and the American Apollo module often land in the middle of the ocean, and sometimes on land. They use airbags and parachutes to slow the spacecraft before impact. There are rescue teams standing by to take the astronauts to safety.