Now that the last Space Shuttle has been retired, much debate has focused on the reliability of the Russian Soyez capsules as the sole means of reaching the $100 billion International Space Station (ISS). Prior to that , our July 11th blog discussed the overall 
reliability of the Space Shuttle, which at Rs=.98 suggested one fatal crash every 50 missions (and indeed there were 2 crashes in the 135 flight life of the Shuttle). But, interestingly little has been mentioned in the press about the reliability and safety of the ISS itself.
Today’s Orlando Sentinel (July 25,2011) brings to light 3 important facts: (1) the ISS will be abandoned in any event by 2020 (if it lasts that long), (2) the probability of it taking a disabling strike from space debris is 16.6%, and (3) the probability of a fatal collision is 1 in 13. NASA’s own task force found slightly worse odds, with a 0.125 probability that an astronaut will die or the station would have to be abandoned.
The problem is space junk–those 1,000’s of pieces of old rockets and satellites that were destroyed in space. “The orbit they are flying in is the worst possible. The Russians blew up all kinds of things in that orbit”, says a retired NASA exec. (That 1 in 13 chance of a disastrous collision with space junk is, of course, the same as what a card player faces in drawing an Ace from a deck). NASA estimates that there are 500,000 pieces between 1-10 centimeters (large enough to do damage) floating around –and 20,000 more deadly pieces (larger than 10 cm). Just 4 weeks ago, a piece of debris caused a big enough scare to send the 6 astronauts on board the ISS scrambling to Soyez escape capsules. The debris passed within 1,100 feet of the Space Station–the closest near-miss yet.
Discussion questions:
1. Discuss the role of manned space exploration in light of the probabilities given.
2. What are the main operations issues vis-a-vis the ISS?