NASA defers rollback decision to Monday
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: August 27, 2006
NASA managers met Sunday evening and agreed to wait until Monday morning to make a decision on whether to roll the shuttle Atlantis back to the Vehicle Assembly Building, preserving for now the option of launching the ship Tuesday on a space station assembly mission.
"We plan to get together early tomorrow morning and take a final look," said LeRoy Cain, chairman of NASA's Mission Management Team. "Based on the current timetable, we plan to make our decision one way or the other by 7 a.m. tomorrow morning."
At issue is the progress of tropical storm/hurricane Ernesto and an updated forecast that calls for 40-knot winds at the Kennedy Space Center early Wednesday. A rollback would take 42 hours, so NASA could afford to wait until Monday morning before making a decision.
If Ernesto weakens or its path changes, NASA could simply press ahead and make a run at launching Atlantis Tuesday at 3:42 p.m. Engineers have concluded there is no need to conduct time-consuming booster and self-destruct system tests in the wake of a launch pad lightning strike Friday. Forecasters say the forecast for Tuesday is favorable.
But if Ernesto continues to threaten, however, NASA's Mission Management Team will order engineers to begin preparing for rollback early Monday.
"With the current storm predictions, it would take a relatively significant change from the current forecast we're seeing to prevent us from going into rollback preparations," Cain said. "If we see a change like that, then we'll press on. If we don't, then we'll be getting into our rollback preparations."
Before Atlantis can be moved from the launch pad, engineers must first drain liquid oxygen and hydrogen from the ship's fuel cell system, a hazardous operation that requires the launch pad to be evacuated. After that, a variety of pyrotechnic charges would have to be disconnected and Atlantis would not be ready to roll until Tuesday afternoon.
Draining the fuel cell system would preclude any chance of launching Tuesday. But if the forecast changes before rollback begins, NASA could keep Atlantis at the launch pad and avoid a long delay that would threaten to use up the available launch window. In that case, subsequent launch attempts could be made after Ernesto passes and after engineers reload the shuttle's fuel-cell system.
If a rollback is ordered, Atlantis likely could not be returned to the launch pad until Saturday or Sunday. From that point, engineers would need at least eight days to ready the ship for launch. That would prevent any chance of launching Atlantis by Sept. 7, the current end of the launch window.
NASA managers said earlier Sunday a rollback decision was needed by midnight based on earlier predictions that high winds could reach the Florida spaceport Tuesday night. While the shuttle can endure, in theory, 70-knot winds at the launch pad where wind and lightning protection is available, a shuttle cannot be rolled back to the VAB in winds higher than 40 knots.
"We're going to get some effects from the storm at the Kennedy Space Center," said launch director Mike Leinbach. "It remains to be seen how bad those effects are and that's the risk trade we make when these storms threaten us. Do we stay at the pad and accept some amount of wind? Or do we expect to have those levels of winds that would harm the orbiter and we have to roll back and protect her?"
The goal of Atlantis' mission is to deliver a new set of solar arrays to the international space station. To reach the station, the shuttle must launch into the plane of its orbit during periods when the angle between that plane and the sun doesn't result in lower-than-allowable temperatures. Such temperature problems occur when the so-called beta angle drops below 50 to 60 degrees.
In this case, the launch window also is affected by a self-imposed NASA requirement to launch in daylight for photo documentation of the shuttle's heat shield and external tank. Based on all three constraints, Atlantis' launch window extends through Sept. 13.
The Russians plan to launch a fresh crew to the space station in mid September and to bring the lab's current crew home 11 days later. The Russians do not want to launch past Sept. 18 at the latest to avoid a dead-of-night landing for the returning station crew. This will be the first Soyuz recovery carried out under civilian management.
As it now stands, Atlantis must launch by Sept. 7 to complete its docked mission and depart before arrival of the Soyuz.
Mike Suffredini, space station program manager at the Johnson Space Center, said Sunday he planned to open discussions with the Russians early Monday about possible options.
"My opinion is, I think the system is fairly robust for night landings but again, you're weighing a risk to the crew with the schedule to go fly," he said. "We're responsible for shuttles. It's up to us to say we feel comfortable. They're responsible for Soyuz. So a really big part of this is not my opinion on risk trade, but whether they're willing, whether they want to take that risk because they're ultimately responsible for the crew. And just like how we feel about protecting our crews, they feel the same way."
If Atlantis misses the September window, NASA would be faced with the prospect of just three lighted launch days between then and the end of the year - Oct. 26-27 and Dec. 23. The next lighted launch window after that opens Feb. 19, and that assumes NASA would launch with a beta angle of less than 50 to 60 degrees.
Asked if NASA might be willing to relax the daylight launch constraint to open up more opportunities, Bill Gerstenmaier, NASA's senior space flight manager, said "we really want to keep the daylight launch" to ensure photo documentation of the shuttle's external tank, especially so-called ice-frost ramps that are still considered potentially dangerous.
"We really want to see how the ice-frost ramps perform, we really want to gather this data," said Bill Gerstenmaier, NASA's administrator for space flight. "So I think it's a pretty strong requirement. We may kind of nibble around the edges, do we need umbilical camera lighting? Do we need lighting during ascent? Are there other things we can do that might allow us to shave a little bit one way or the other? But I think from where we are really in this flight test mode, this data's pretty important to us and it's going to carry a pretty high priority."
The official crew patch for the STS-115 mission of space shuttle Atlantis to resume orbital construction of the International Space Station.
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