The U.S. space agency NASA says it sees no technical problems preventing a resumption of space shuttle flights in May. But it has not formally assigned a launch date yet as it works to eliminate as much dangerous falling debris from shuttle external fuel tank as possible.
A barge carrying the external fuel tank for the next shuttle flight is floating across the Gulf of Mexico toward the Florida launch site from NASA's tank assembly facility in Louisiana. To NASA launch director Michael Leinbach, it is an important step toward a May launch of the orbiter Discovery. "In general, we're just really glad to get another piece of flight hardware here, and it will be one more step closer to the launch," he said.
This time, the external fuel tank is covered with a lot less hard insulating foam than previous shuttle tanks. The reduction is part of the long effort to cut the amount of foam that peels away and threatens the vehicle during lift-off.
A chunk weighing about one kilogram came off the orbiter Columbia during launch three years ago and pierced a wing. This led to the deaths of seven astronauts when the shuttle disintegrated during the searing heat of re-entry.
During the two-year flight moratorium that followed, NASA tried to solve the problem by eliminating some foam and applying it better in other places. But more pieces broke off Discovery's fuel tank last July, causing another cessation of flights.
Now, shuttle program manager Wayne Hale says NASA has eliminated several more areas of the insulation in the hope that any pieces that do fly away will be tiny, weighing no more than a few grams. "Foam will still come off the tank after we have done all these mitigation efforts. What we have done is worked off all the large pieces and we believe that pieces that come off will be small," he said.
But before a May shuttle launch is approved, NASA engineers say they will conduct wind tunnel tests to determine whether the fuel tank modifications are safe.
Hale says technicians are also assessing whether a tiny piece of debris lodged in a shuttle main engine filter screen could catch fire during launch. If so, it must be removed in a delicate time-consuming process. But launch director Leinbach says the work could be finished in time for a May liftoff. "If we run into a significant technical issue, we don't have much time to resolve it, obviously. But I feel personally very good about the schedule," he said.
NASA hopes to launch three shuttles this year to resume assembly of the International Space Station. President Bush has ordered the agency to finish construction and disband the shuttle fleet by 2010. It is also to develop a successor to the shuttle that will play a role in returning crews to the moon by 2020.
Wayne Hale says the agency is working hard to resolve the shuttle foam problem so it can meet that schedule. "Clearly you can't have many more big, long stand-downs and accomplish the number of flights that it's going to take to assemble the International Space Station by that date," he said.