edkyle99 - 2/12/2006 2:29 PM

Only three launches worldwide in all of November. Now three are planned for one day - 12/8/06.

Funny, isn't it, how China performed a launch on 9/9/06, the day of the STS-115 liftoff, and is now planning a launch on 12/8/06, the planned launch date for STS-116 (and for an Ariane 5, for that matter)? What are the odds that two of the three space shuttle launches of 2006 would occur on the same days as two of the six Long March liftoffs of the year?

- Ed Kyle

O.K., I'm probably going to butcher probability theory now, but here's a try at answering my own question.

Assuming that three space shuttle launches and six Long March launches occur during the calendar year, that the launches are randomly distributed, and that no more than one shuttle or one Long March launch on a given day, the probability that one space shuttle and one Long March would launch on the same day once during the year is:

(3/365) x (6/365) = 0.00013511, or about 1 in 14,802

The probability that such an event would happen twice during the same year is

0.00013511 x 0.00013511 = 0.0000000182547, or about 1 in 219,122,230

- Ed Kyle