Originally posted by Essan
The strong implication being that there have been many previous occasions when 2 shuttles have been on the lauch pads at the same time. And therefore
it's unusual only insofar as it's not likely to happen again.
Correct. Here are all the previous times that there have been 2 shuttles on the pads simultaneously:
STS-61-C (Columbia) and STS-51-L (Challenger) Dec. 22, 1985 (rollout of 51-L to Pad B)
to Jan. 12, 1986 (launch of 61-C from Pad B)
STS-31 (Discovery) and STS-35 (Columbia) April 22, 1990 (rollout of STS-35 to Pad A)
to April 24, 1990 (launch of STS-31 from Pad B)
STS-38 (Atlantis) and STS-35 (Columbia) Oct. 14, 1990 (rollout of STS-39 to Pad B)
to Nov. 15, 1990 (launch of STS-38 from Pad A)
STS-37 (Atlantis) and STS-39 (Discovery) April 1, 1991 (rollout of STS-39 to Pad A)
to April 5, 1991 (launch of STS-37 from Pad B)
STS-45 (Atlantis) and STS-49 (Endeavour) March 12, 1992 (rollout of STS-49 to Pad B)
to March 24, 1992 (launch of STS-45 from Pad A)
STS-50 (Columbia) and STS-46 (Atlantis) June 11, 1992 (rollout of STS-46 to Pad B)
to June 25, 1992 (launch of STS-50 from Pad A)
STS-56 (Discovery) and STS-55 (Columbia) Feb. 7, 1993 (rollout of STS-55 to Pad A)
to April 8, 1993 (launch of STS-56 from Pad B)
STS-64 (Discovery) and STS-68 (Endeavour) Aug. 19, 1994 (rollout of STS-64 to Pad B)
to Aug. 24, 1994 (rollback to VAB of STS-68 from Pad A)
STS-71 (Atlantis) and STS-70 (Discovery) May 11, 1995 (rollout of STS-70 to Pad B)
to June 8, 1995 (rollback to VAB of STS-70 from Pad B)
STS-71 (Atlantis) and STS-70 (Discovery) June 15, 1995 (rollout of STS-70 to Pad B)
to June 27, 1995 (launch of STS-71 from Pad A)
STS-70 (Discovery) and STS-69 (Endeavour) July 6, 1995 (rollout of STS-69 to Pad A)
to July 13, 1995 (launch of STS-70 from Pad B)
STS-69 (Endeavour) and STS-73 (Columbia) Aug. 28, 1995 (rollout of STS-73 to Pad B)
to Sept. 7, 1995 (launch of STS-69 to Pad A)
STS-73 (Columbia) and STS-74 (Atlantis) Oct. 12, 1995 (rollout of STS-74 to Pad A)
to Oct. 20, 1995 (launch of STS-73 from Pad B)
STS-95 (Discovery) and STS-88 (Endeavour) Oct. 21, 1998 (rollout of STS-88 to Pad A)
to Oct. 29, 1998 (launch of STS-95 from Pad B)
STS-103 (Discovery) and STS-99 (Endeavour) Dec. 13, 1999 (rollout of STS-99 to Pad A)
to Dec. 19, 1999 (launch of STS-103 from Pad B)
STS-104 (Atlantis) and STS-105 (Discovery) July 2, 2001 (rollout of STS-105 to Pad A)
to July 12, 2001 (launch of STS-104 from Pad B)
There was also a previous rollout of STS-400 to 39B for the hubble mission last year before it was bumped until now.
I would be asking why NASA are si sure it won't happen again?
Well for one thing, pad 39B is already being renovated for use in the constellation project. They've already erected new large lightning towers
around the pad to be used with the taller ares 1-X rocket. After this mission they'll start tearing down the rotating service structure and
returning it to an apollo-like clean pad configuration. All other shuttle missions will go to ISS and have plenty of time for a rescue shuttle to be
rolled out to 39A should it be needed.
[edit on 20-4-2009 by ngchunter]