NASA sets schedule for remaining shuttle flights
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: July 7, 2008
NASA today unveiled a revised manifest for the final 10 flights in the space shuttle program, reflecting previously forecast delays across the board because of post-Columbia external tank safety upgrades that have stretched out deliveries. But shuttle Program Manager John Shannon said he's confident NASA can complete the space station and retire the shuttle fleet in 2010 as planned.
Two more shuttle flights are planned this year, in October and November, five in 2009 and a final three missions in the first half of 2010 to bring the program to a close.
NASA had planned to retire the shuttle Atlantis after a final Hubble Space Telescope servicing mission in October, but the orbiter will make two more flights beyond that, one in 2009 and another in 2010, to provide additional processing margin. Atlantis and Discovery will fly three more times each and the shuttle Endeavour will make four more flights, including the 10th and final mission.
"The original rationale (for retiring Atlantis) was that we would take Atlantis down, it would save some money for the program and we would use it as a spares option for us," Shannon said. "We looked at our spares posture, and it was pretty good, it did not look like there was any pressing need to retire Atlantis.
"From a money standpoint, we were able to continue flying and continue processing Atlantis at no additional cost to the program and that is because we were ramping down all of our return-to-flight efforts and we had gotten more efficient in ground ops processing. So it did not cost us any additional money and on the positive side, it gives us a tremendous amount of manifest flexibility. It makes it much more feasible to finish the program on time."
Unlike Endeavour and Discovery, Atlantis is not equipped with a space station-to-shuttle power transfer system to tap into the station's solar power grid. But Shannon said the two station flights planned for Atlantis do not require the additional docked time the power transfer system provides and "it made a lot of sense to keep Atlantis flying."
Here is the revised manifest:
During a May 1 briefing to preview the just-completed flight of the shuttle Discovery, Shannon announced that STS-125, the Hubble servicing mission, would slip from August to October and the subsequent flight, STS-126, would slip from October to November. He said STS-119, which had been scheduled for launch in December, would move into 2009, all because of external tank processing issues. At that time, no other target dates were revealed pending additional assessment of tank delivery schedules.
The tank used by Discovery for the most recent shuttle launch on May 31 was the first to be built from scratch with post-Columbia safety upgrades and it took engineers at Lockheed Martin's Michoud Assembly Facility in New Orleans additional time to perfect and implement required manufacturing techniques.
Those issues were compounded for the upcoming launch of Atlantis on NASA's final planned Hubble Space Telescope servicing mission. Shuttle crews bound for the international space station have the option of "safe haven" aboard the lab complex, where they can await rescue by another shuttle if any Columbia-class problems occur that might prevent a safe re-entry. That is not possible for the Hubble repair crew because the telescope is in a different orbit and the shuttle cannot reach the station from there.
As a result, NASA plans to have a second shuttle ready for launch on short notice in case of any major problems and that, in turn, means two tanks will be needed.
In May, Shannon said the changes to the way external tanks are built "added about four to five weeks of processing time on those two tanks. The tank team has done a really nice job of taking the lessons learned processing the tank that's about to fly, and the Hubble tank. So I don't expect that to (expand the time needed) on each of the downstream tanks. They have a mitigation plan in place so that the 2009 tanks come in more on a normal template. So we're going to take a one-time hit of this four to five weeks, it will move pretty much all of the tanks in series, the next 10 tanks that will come out, about that four to five weeks."
Even so, Shannon said today that starting with STS-127 next May, the external tank team at Michoud will need to shave about a month off the time needed to manufacture each tank to keep the program on track.
"The schedule we've put together challenges the Michoud Assembly Facility production on the external tanks by about a month per tank," he said. "We partnered with them very closely to try and understand what production efficiencies we're going to have as we go through the next several builds of tanks. And we think we'll be able to get a month back. But that's not proven yet."
NASA managers may opt to move up the next two flights by a few days, in part to provide additional margin for Endeavour. Based on ground processing alone, the Hubble mission likely could be moved up five to six days, Shannon said. But because of payload issues and crew training "they might get two or three days, it doesn't look like much more than that."
But that likely would enable NASA to launch Endeavour on mission STS-126 a few days ahead of the current Nov. 10 target. That's important because it would provide a few additional days of margin to get Endeavour off before a so-called beta angle cutout begins around Nov. 25. If the shuttle isn't off the ground by then, thermal issues caused by the angle between the sun and the plane of the station's orbit would prompt a significant launch delay.
"The beta ends in the middle of December, but we wouldn't launch then because of workforce issues, it would probably be the middle of January or early February," Shannon said. "Right there, you lose two months, almost three months off your critical path and we'd have to really struggle to make that up."
As a result, "we would really like to get 126 off before the beta cutout," Shannon said. "If we move Hubble up a few days, that would make us think we could move 126 up a few days and get a few more days before that beta angle constraint. That's really important to us because we want to keep on the timeline for the (Endeavour) flights."
As with all post-Columbia missions, NASA will have a set of boosters and an external tank available to support an emergency "launch on need" rescue mission for Endeavour's final flight. Congress is considering a plan to use that hardware for one additional flight, a mission to carry a high-tech physics experiment to the space station.
In the wake of the Columbia disaster and the 2010 deadline for completing shuttle operations, the Alpha Magnetic Spectrometer, or AMS, payload lost its ride to the station. Congressional supporters are considering whether to add a flight and Shannon said the agency was protecting that option.
"Right now, we don't have any direction to go fly the AMS from Congress or the White House," he said. "We've protected the option. We've put together a cargo layout that would have the AMS flying, we have had people from the shuttle program involved in integration to determine the long-lead integration items that we need in order to put it in the shuttle payload bay and be able to go fly it. And I am going to have, at the end of the program, hardware available to not only fly an additional flight but I would also have launch-on-need capability for that flight."
He said external tank 122, which was damaged in Hurricane Katrina, could be upgraded and prepared for launch-on-need use if needed. A set of boosters would have to be procured, but "I don't have to make the decision for configuring ET-122 or the extra boosters until the middle of next year," Shannon said. "So we'll wait and see what everybody wants to do."