delayed to January
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: December 9, 2007
NASA's Mission Management Team today delayed launch of the shuttle Atlantis on a critical space station assembly mission to at least Jan. 2 to troubleshoot elusive, intermittent electrical problems with low-level hydrogen fuel sensors that derailed launch attempts Thursday and again this morning.
The shuttle's current launch window closes Dec. 13 because of space station power and temperature issues related to the lab's orbit. The window reopens Dec. 30, but NASA managers do not want to conduct a launch campaign during the end-of-year rollover because of countdown software issues.
Given the subtle nature of the problems with the engine cutoff - ECO - sensors at the base of Atlantis' external tank, managers concluded there was not enough time to attempt repairs before the current launch window expires.
Bill Gerstenmaier, chief of spaceflight operations at NASA headquarters, said the delay to January would not cause a major disruption to the space station assembly schedule. The next two flights in the sequence are scheduled for launch in mid February and late April. The next flight after that is an August mission to service the Hubble Space Telescope.
"If you look at what this means moving into January from a big-picture standpoint, it's not that big an impact to us overall, it won't impact the next mission, the February flight, we'll be able to accomplish that on time as planned," he said. "There's also some schedule time between that February flight and the April flight, there's a couple of weeks of margin in there so that can slip to the right.
"So from a big-picture standpoint, it's really not a big impact to us overall from an assembly of space station standpoint. There's enough margin in the system that we can accommodate this move into January without a big impact."
That's assuming, of course, engineers can track down and correct the ECO sensor problem by then. LeRoy Cain, director of shuttle integration at the Kennedy Space Center, said engineers plan to brief NASA managers Tuesday on possible troubleshooting options.
"We set up what we're calling our short-term KSC troubleshooting team to put together, brainstorm ideas and troubleshooting methods that we might want to go do for the system we have out at the launch pad," he said. "They're going to report out for the first time to the program board, the PRCB, on Tuesday of this week.
"From there we will determine what steps we take in the way of troubleshooting ... to include possibly a tanking test, to include possible looks at some of the feed-through connector areas and other wiring and cabling areas. ... They will bring their recommendations to us Tuesday."
How NASA might proceed from there, he said, will "depend on what we find out when we go begin to do some more in depth troubleshooting."
"We feel like we need to find root cause and we're going to make every effort to do that. Beyond that, as far as our path forward, it would be speculation for me at this point. Our main focus at this point is, given the repeat failure that we had today ... we're very hopeful it will repeat again in a fashion that we can capture it and be able to narrow down the area that's causing the problem, whether it be in the tank or outside of the tank or somewhere in the connectors. That's really our main focus right now."
Said Gerstenmaier: "Data is data. Whether it helps us find the specific failure or it rules out all the things that can't be causing the failure, that helps us figure out a way to build better operational rules to fly safe and continue with the manifest."
He was referring to the possibility of developing rationale for flight with one or more failed ECO sensors by incorporating procedures utilizing new instrumentation to monitor the status of each sensor.
"We have a lot of options in front of us before, if and when, we would need to roll back" to the Vehicle Assembly Building where Atlantis can be removed from the tank for more extensive troubleshooting. "So we're going to consider the recommendations the team brings forward Tuesday. The Tuesday recommendations and any troubleshooting we might do while we have this system out at the launch pad allows us the opportunity to fly as early as Jan. 2. If we determine subsequently that we need to roll back and do more invasive kind of work, then that probably does not support Jan. 2."
Telemetry indicates a possible open circuit somewhere between an electronic unit in the shuttle's engine compartment and the sensors themselves. Launch Director Doug Lyons said the box is easily accessible at the launch pad, along with much of the wiring that runs through the belly of the shuttle and into the tank.
"In terms of our capabilities out at the launch pad, we've got very good access, particularly inside the orbiter aft so that there's almost limitless troubleshooting we can do there," Lyons said. "And we've got very good access to the tank. So we can do extensive troubleshooting out there before we would entertain rolling back. There's not many things we can't do out at the launch pad that we could do in the VAB."
In the meantime, flight controllers informed space station commander Peggy Whitson and her crewmates of the launch delay and told her she and Tani likely will be asked to carry out a spacewalk later this month to inspect a problematic solar array rotary joint on the right side of the lab's main power truss.
If Atlantis had gotten off the pad during the current window, NASA managers planned to add a fourth spacewalk to the shuttle mission to carry out the solar alpha rotary joint - SARJ - inspection.
Because of recently discovered contamination in the massive gear-driven joint, used to rotate outboard arrays to keep them face on to the sun, the starboard SARJ has been locked in place pending additional analysis.
NASA needs to fix the joint and restore it to normal, or near normal, operation before a sophisticated Japanese research module can be launched in April.
A SARJ inspection spacewalk by Whitson and Tani likely would be carried out before Dec. 21. An unmanned Russian Progress supply ship is scheduled for launch from the Baikonur Cosmodrome in Kazakhstan on Dec. 23 with docking on tap the day after Christmas.