Besides the physiological and psychological effects of space travel, the actual journey—launch and re-entry— poses a great risk to the lives of astronauts. Two of the most famous disasters in NASA’s history are the Challenger STS51-L shuttle accident and the Columbia shuttle accident. In 1986, the Challenger space shuttle burst into flames 73 seconds after launch. An o-ring failure in the right solid rocket booster (a solid fuel motor that provided the necessary thrust to lift the shuttle off the launch pad and achieve desired altitude) killed the crew of seven. [21] In 2003, the Columbia STS-107 spent 17 days in space to conduct scientific experiments on MG. On re-entry, the space shuttle broke apart, killing the crew of seven. The cause was
