The Schedule is Everything

The folks at NASA are working hard to get Discovery off the ground during the May launch window. For those of you who might not be following along at home, the space shuttles are doomed to the Sisyphean task of pushing space station parts into orbit. In order to maximize the loads they carry, they must launch when the station is properly positioned. After Columbia, it was decided that at least the first two shuttle flights had to take place when both the launch and the point where the external tank is discarded is in daylight, to allow for visual and photographic inspection. This inspection is what showed that huge chunks of foam were still falling off of the tank.

After both Challenger and Columbia, NASA officials were taken to task for creating an environment where adherence to schedule trumped concerns for safety. Now, with an launch window available in May, NASA is doing it again, rather than waiting for the July window.

The external tank that will fly has just left the construction facility outside of New Orleans, having been rushed out a week ahead of schedule. Even still, the normal preflight foam inspections and repairs will eat up every day of contingency time in the schedule. At the same time, leaking helium seals have been replaced in two of Discovery's engines. Unfortunately, three of the four seals don't meet specifications, despite being hand-picked as the best available in the inventory. There are also metal shavings that have been detected in a filter screen in the oxygen line of one engine. More have been found in one of Endeavour's engines. NASA has no idea of where this metal came from or what it's made of.

Even with all of these problems, the shuttle program manager remains very optimistic that there will be three shuttle flights this year. The launch director, Mike Leinbach, has said, "What we've done this time is, we've put together a schedule that has no contingency in it. Some people could call that an aggressive schedule. I like to call it an exciting schedule. It has a reasonable chance of success. If we run into a significant technical issue, we don't have much time to resolve it, obviously. But barring the big 'gotcha' in the processing, we feel pretty good about making that schedule."

There is a reason for all of this haste. Many of the remaining components of the space station have been built and have been sitting for years awaiting launch. For various technical reasons, these parts are reaching the end of their viable storage lives. If they are not put into service soon, they will require extensive (and expensive) refurbishing to replace seals, batteries, and other items. So, just as happened before Challenger and Columbia, NASA has become schedule-driven to meet arbitrary dates. It will be interesting to find out how many variances of the Flight Rules will be needed to get Discovery into the air in time for two more launches this year.