NASA Chief Is Confident About Shuttle
Friday, March 3, 2006
Despite considerable uncertainty about the space shuttle's readiness for a planned May launch, NASA Administrator Michael D. Griffin said yesterday that he is confident the orbiter will ultimately be able to make enough cargo flights to complete construction of the international space station by 2010.
Engineers at Florida's Kennedy Space Center took delivery Wednesday of a redesigned external fuel tank to be used by the shuttle Discovery in a launch scheduled for May 10 -- during a window that will last until May 22.
But Wayne Hale, the shuttle program manager, said earlier this week that the task of analyzing changes to the tank's foam insulation could delay the mission until July. NASA has budgeted no extra time during the long run-up to launch, and preparations must be virtually trouble-free to ensure a liftoff in May.
"We're pressing to make it, but we're not pressing so hard that we would do something silly," Griffin told reporters. Still, he added, "whether we fly in May or fly in July . . . is essentially irrelevant."
Griffin, in a call-in news conference marking the end of a "heads of agency" meeting of the space station's partner nations, said NASA has "almost a full year of slack" in its plan to fly 16 shuttle missions to finish building the station.
"We expect to get three flights in this year," he said, in May or July, August, and probably November. "But we can manage just fine if it's only two." The shuttle program has flown 4.56 missions per year for 25 years, he noted, and "if we maintain that rate, we will easily complete the station. That is our challenge."
Griffin also reaffirmed NASA's plans for a 17th shuttle mission to service the Hubble Space Telescope, but he declined to say where it would fit in the schedule. "Right now, we're looking at something in early '08," he said. "But details are still to come."
The shuttle schedule has undergone repeated delays since the 2003 Columbia disaster, and engineers again grounded the program after a large piece of insulating foam broke off Discovery's external tank during last July's launch. It was foam damage that doomed Columbia.
To fix the tank, the shuttle team has eliminated the source of last year's loose fragment, a foam ridge known as a "protuberance air load" ramp -- originally designed to provide aerodynamic protection for external electric cables and pressurized gas lines during the turbulence of launch.
"The computer simulations and paper analysis indicate that the structure" without the ramp "should be able to take the aerodynamic loads," Hale told reporters in a telephone news conference earlier this week. "But the proof is in the wind-tunnel testing."
Engineers have planned two sets of wind-tunnel tests this month to check the turbulence, and if they are satisfied, Discovery will fly in May. If not, they will conduct a third set of tests in June in hopes of launching in July.
The shuttle team is also concerned about foam loss from brackets that hold the pressure lines, and about tiny metal shavings caught in a liquid oxygen filter leading to the main engines. Neither problem concerns Griffin, however. "What may, and I emphasize may , affect the schedule" is the wind-tunnel testing, he said. "We'll let you know when we know."
For Griffin, appointed last year, this week's conference was a first opportunity to meet with his international counterparts to hash out the logistics of a reduced number of shuttle flights that all but ignore science missions in the interest of assembling the station.
"These are painful choices, but the pain of the choice does not make it less obvious," Griffin said.
The agency chiefs tweaked the flight order for transporting new space station components, including heavy trusses to enlarge the station, specialized equipment such as the European Space Agency's Columbus laboratory and Japan's "experiment module," known as Kibo. The partners plan to send a third space station crew member in the next flight, and to double the crew size to six in 2009.
"The most important result of the international space station is partnership," said the European Space Agency's Jean-Jacques Dordain. "Every time we meet, we consolidate our partnership."