On the morning of Feburary 1st, 2003, the space shuttle Columbia broke up during re-entry, more than 200,000 feet above Texas. While this was the first such incident, the risk of this kind of catastrophe has always been present. For a successful landing, dozens of things have to go just right.
First, the orbiter must be maneuvered into the proper position. This is crucial to a safe landing.
Maneuvering of the orbiter for re-entry
When a mission is finished and the shuttle is halfway around the world from the landing site (Kennedy Space Center, Edwards Air Force Base), mission control gives the command to come home, which prompts the crew to:
- Close the cargo bay doors. In most cases, they have been flying nose-first and upside down, so they then fire the RCS thrusters to turn the orbiter tail first.
- Once the orbiter is tail first, the crew fires the OMS engines to slow the orbiter down and fall back to Earth; it will take about 25 minutes before the shuttle reaches the upper atmosphere.
- During that time, the crew fires the RCS thrusters to pitch the orbiter over so that the bottom of the orbiter faces the atmosphere (about 40 degrees) and they are moving nose first again.
- Finally, they burn leftover fuel from the forward RCS as a safety precaution because this area encounters the highest heat of re-entry.
 Photo courtesy NASA Artist's concept of a shuttle re-entry |
Because it is moving at about 17,000 mph (28,000 km/h), the orbiter will hit air molecules and build up heat from friction (approximately 3000 degrees F, or 1650 degrees C). The orbiter is covered with ceramic insulating materials designed to protect it from this heat. The materials include:
- Reinforced carbon-carbon on the wing surfaces and underside
- High-temperature black surface insulation tiles on the upper forward fuselage and around the windows
- White Nomex blankets on the upper payload bay doors, portions of the upper wing and mid/aft fuselage
- Low-temperature white surface tiles on the remaining areas