Columbia Space Shuttle Explosion

Suppose that an unexpected event (called “a contingency”) occurs during, or soon after, a shuttle launch. Is there a way for the astronauts to safely escape?

NASA has four primary "abort methods" if a shuttle develops a contingency:

• Return to launch site (RTLS): This procedure can only happen if the contingency is known within 2 minutes 20 seconds after liftoff (if an engine is not functioning) or within 3 minutes 45 seconds (if all three engines are running);
  
  
• Transatlantic landing (TAL) in Spain (Moron and Zaragoza) or in France (at Istres): Applies if the contingency is known within the first five minutes after launch and requires no orbit maneuvering;
  
  
• Abort to orbit (ATO): Allows the shuttle to fly at a lower orbit so mission control can evaluate problems and choose either an early de-orbit burn (preceding a landing) or a maneuver that would allow the shuttle to go into a higher orbit (and continue the mission);
  
  
• Abort once around (AOA): Permits the orbiter to fly once around the Earth, then make a normal entry (click on "How Shuttle Lands") and landing.

NASA has a defined order of preference for the various abort modes. The type of problem, and when it occurs, would determine what method is selected to remedy the situation or end the mission.

If the contingency is a system failure that could jeopardize the crew and the vehicle, Mission Control would select the method that gets the shuttle on the ground as soon as possible. A return to the launch site, or a transatlantic landing, would take about 35 minutes. An “abort to orbit” would take about 90 minutes.

But if the shuttle launched and all three engines failed, the astronauts would use the in-flight escape system before they “ditched” the vehicle. In more than one hundred shuttle missions, that has never happened.