From the AT article: "Atlantis was already undergoing preparation for flight as STS-114, scheduled for launch on March 1. As Columbia thundered into orbit, the

From the AT article: "Atlantis was already undergoing preparation for flight as STS-114, scheduled for launch on March 1. As Columbia thundered into orbit, the younger shuttle was staged in Orbital Processing Facility 1 (OPF-1) at the Kennedy Space Center. Its three main engines had already been installed, but it didn't yet have a payload or remote manipulator arm in its cargo bay. Two more weeks of refurbishment and prep work remained before it would be wheeled across the space center to the enormous Vehicle Assembly Building and hoisted up for attachment to an external tank and a pair of solid rocket boosters." So Atlantis wasn't actually as close to launching as your comments make it sound. Later in the article, they state that it would be a minimum of 21 days to get Atlantis on the pad and ready to launch. And it always took longer than NASA thought; the article author looked for any instances in which a Shuttle moved from OPF to VAB to the pad and launch without errors or faults, and couldn't find a single one. That's why they planned for this contingency in the remaining Shuttle missions, with the so-called "Launch On Need" planned missions. (In all but one case, they assumed that the Shuttle crew could take refuge at the ISS until a rescue mission could be mounted. For the one mission where they couldn't assume that, STS-125, the Hubble servicing mission, they actually had a second Shuttle on the pad before the first one launched.)