Saturday Afternoon: Yesterday was a very long day for us. You’d think that a scrub shortly after noon, shortly after the excitement of witnessing the crew walkout, would mean that we could kick back for the rest of the day. But whenever there’s a significant change in plans, the Kennedy Space Center (KSC) Press Center schedules a briefing at some point. We wanted to stay for that. Besides, we were concerned about traffic. The driver of the bus back from the crew walkout to the Press Center said that he had a long shift ahead of him but that he didn’t mind because he imagined that it would take four or five hours for some of the people who were heading out right away to get home. Indeed, one photographer staying at a hotel about a dozen miles away from the Press Center spent about 90 minutes getting back to his room, and he waited until after 4p.m.
Yesterday’s press briefing was delayed a bit, so that it could focus on two things: the political, or President Obama’s visit to KSC and Representative Giffords’s plans, and the procedural, or what it will take to get Endeavour ready to fly. While we were happy to see the president’s helicopter land behind the Vehicle Assembly Building across the street from the Press Center and then see his motorcade drive by, that wasn’t really our bailiwick for our blog. The procedural boils down to repairing a malfunctioning heater in the orbiter’s left APU, or Auxiliary Power Unit.
As we listened to Launch Integration Manager Mike Moses and Shuttle Launch Director Mike Leinbach, we understood that the problem was either a faulty thermostat, which could be relatively easily switched out, or the larger line of heaters on string B that wraps around a hydraulic fuel line. Had they discovered this problem once in orbit, they would have burned off that system and gone on their way, but the concern about flying with this known problem is the possibility of a frozen line, the possibility that a frozen line would thaw at some point after pressure had built up, and the possibility that a thawed line could catch fire during reentry. This problem meant they were in violation of launch criteria and the decision to scrub was “straightforward” according to both Moses and Leinbach.
We hope that a faulty thermostat is the problem. Leinbach pointed out that changing out the larger system, the box that houses various parts, would take an additional two days of retesting after the fix itself is completed. That would make a Monday or Tuesday launch an impossibility, and then KSC runs into a conflict with the Air Force, which is launching an Atlas rocket this week. If they must delay, they also have to look at the whole mission schedule so that undocking from the International Space Station in preparation to return to Earth doesn’t fall on the same day as the scheduled Soyuz undocking. It’s a complicated syncing up.
We’re now in the Press Center, where we just received the inside scoop that workers have entered the aft section of the shuttle, where the heater is located. It took them a full day to get into the shuttle to take a look because, once the external tank is full of fuel, it takes 24 hours to drain it and let the remaining hydrogen evaporate. In addition, they had to roll the Rotating Service Structure back into position to provide access to the shuttle. We’re hoping that another update is available on the KSC website at about 4:30p.m., or shortly after the Press Center closes for the day. In the meantime, we’re heading to the KSC Visitor’s Complex for further research.