Editorial The Shuttle Returns, Safely
Yesterday's smooth landing of the shuttle Discovery ended a flight that was successful in almost every respect but one: the dislodging of a big chunk of foam, like the one that doomed the Columbia. This flight was supposed to vault the shuttle fleet back into space after a prolonged grounding for repairs. But given the repeat of the very problem that two years of retooling was supposed to resolve, the verdict is necessarily mixed. Once again, the space agency has been forced to suspend further flights until it can find a fix for the foam-shedding, and no one seems willing to guess how long that may take.
The Discovery astronauts performed superbly during their two-week mission, and the shuttle looked better than ever in some respects. Space officials were justifiably jubilant that so much had gone well, despite daily hand-wringing over possible perils. The flight clearly achieved its prime objectives.
The astronauts transferred tons of cargo to the international space station, which has been limping along overhead with a reduced crew and limited supplies carried up on smaller Russian spacecraft. They replaced a broken gyroscope, repaired another and carted away a load of trash that had accumulated on the station, showing the shuttle can bring substantial loads back down from space.
This was the most scrutinized shuttle flight ever, with the vehicle undergoing close inspection while still in orbit. New sensing and photographic equipment to look for potentially perilous damage to the sensitive external skin proved valuable. A new back flip maneuver allowed station astronauts to photograph the shuttle's underbelly, and an extra-long robotic arm enabled astronauts to see parts of the shuttle that were previously out of sight.
The flood of images and NASA's openness in discussing its uncertainties about potential hazards sometimes made it appear that the shuttle was about to fall apart. In the end the damage was clearly tolerable. A much-touted spacewalk to repair the shuttle's skin - the first of its kind - moved an astronaut close enough to pluck out some protruding material with his hand. Preliminary evidence indicates that Discovery has far fewer nicks and gouges than shuttles on previous flights, perhaps showing that improvements to reduce the shedding of debris from the external fuel tank have had some success.
The biggest concern was the nearly one-pound piece of foam that fell off the external tank during liftoff and several other pieces of foam debris that exceeded NASA's size limit. NASA has not yet solved the foam-shedding problem, which it claimed to have largely fixed during the long grounding for repairs. Successful as it was, this flight and the visible uncertainties of its managers left the unsettling impression that there is a lot NASA doesn't know about the performance of the spacecraft it has relied on for the past quarter-century.
