Analysis: Shaping the new shuttle reality

JOHNSON SPACE CENTER, Texas, Sept. 24 (UPI) -- While NASA struggles to fulfill requirements to return its aging space shuttle fleet to flight, one of the most noticeable changes in the works is the spaceships will not be flying all that much.

Although the missions will continue -- for one thing, the International Space Station remains only partially constructed -- new restrictions are likely to cut NASA's launch opportunities in half. Among those limitations: The board that investigated the Feb. 1, 2003, Columbia accident has recommended NASA launch only during daylight hours to make sure cameras have a clear view of any debris impacts.

Columbia's left wing was struck and damaged by a chunk of thermal insulation that fell of the ship's external fuel tank 86 seconds after liftoff on Jan. 16. The strike was discovered during a review of launch video the next day. Managers, however, did not view the impact as threatening, partly because of the video's poor quality and limited perspective. The shuttle broke apart, killing its seven astronauts, as it attempted to return to Earth 16 days later.

In the wake of the accident, investigators recommended NASA only launch during daylight hours to assure better picture and video quality. The Columbia Accident Investigation Board, which released its findings last month, also wants the phase of flight that includes external tank separation -- which occurs 8 minutes and 30 seconds after launch -- to take place in daylight conditions as well, for the same reason. Cameras mounted in the shuttle routinely videotape the tank separation. Post-Columbia missions also will have a digital still camera installed in the umbilical region.

Coupled with technical constraints -- including the shuttle's ability to reach the station's orbit, the occasional meteor shower, shade requirements to keep the shuttle from overheating, and the notoriously fickle weather at the Florida launch site -- the new requirements effectively eliminate launches for periods of time totaling about six months, NASA managers say. The fewest launch opportunities will fall between October 2004 and March 2005.

Last week, NASA quietly backed off its previously announced launch date target of March 2004, saying its safety upgrades will not be complete in time. The new launch restrictions mean if the shuttle is not ready to fly by next October, there is a good chance it will stay grounded until after the two-year anniversary of the accident.

Despite the hurdles, NASA managers say schedule pressures will not be factor in deciding if the shuttle is ready to fly.

"We have to guard against that," said John Shannon, who manages the agency's shuttle flight operations and integration. "Everybody who's worked here for a long time looks at that (blackout chart) and says, 'Wow, we need to get something going here and here and here!' And you say, 'No, we are not going to do that. That is not the way we're going to operate.'"

Accident investigators cited pressures to complete space station construction as a factor in the Columbia accident, as managers first became de-sensitized to the repeated problems of falling foam insulation, then failed to distinguish true danger when debris hit and slightly damaged a shuttle solid rocket booster during a launch four months prior to Columbia's fatal flight.

The focus of NASA's post-Columbia safety upgrades is preventing foam loss. The troublesome area, where a hand-made aerodynamic slope of foam slid off during Columbia's launch, as well as on several previous missions, is being redesigned. The insulation where the tank attaches to the orbiter is being eliminated entirely. Instead of foam, heaters will be installed to keep ice from forming on the outside of the tank. Before Columbia's fall, NASA thought ice breaking loose during launch and striking the shuttle represented the potential debris threat -- not the foam itself.

The second thrust of the agency's return-to-flight plan is to keep the space station stockpiled with enough supplies to shelter a shuttle crew aboard the outpost until a rescue mission could be launched. Preliminary studies have shown nine people could live in the space station for about 80 days before running out of fresh air or water, said station program manager Bill Gerstenmaier.

Last, the agency has launched a massive effort to develop a "Band-Aid" technique to patch holes in the shuttle's heat shield while the ship is in orbit. Materials and techniques for repairing the black silica tiles are fairly mature.

"Once we get to the work site, it's very do-able," said astronaut Scott Parazynski, an experienced spacewalker who is helping to develop the application techniques.

For the tile repair, NASA resurrected a research program from the early days of the shuttle, when engineers had no proof the tiles would even stay on in orbit. Before the next shuttle flies, NASA wants the capability to repair in orbit a tile hole as big as 10 inches by 30 inches by 4 inches.

Although NASA has struggled with tile damage on every flight since the shuttle's debut in 1981, an in-orbit repair would have been necessary only once, when a tile actually floated away, leaving a gap in the shield. Fortuitously, an antenna shaded the area during re-entry.

"We want to have the availability (for tile repair), but we don't expect to use it," said flight director Paul Hill.

Patching tiles is the easier, but tangential, hurdle toward return to flight. Columbia's demise was due to a breach in the leading edge wing panel, which is made of an entirely different substance.

"We don't know yet what size holes we will be able to fill," said Bradley Files, who is heading the effort to develop a repair for the wing panels. "But if we're ever going to be able to use any of this for flight, it's going to have to work."

A firm plan for wing panel repair remains in the distant future and may not, in fact, be possible to achieve, acknowledges Steve Poulos, who heads NASA's shuttle engineering office at the Johnson Space Center.

"There is a fair chance that we'll have a capability (for wing panel) repair before return-to-flight," said Poulos, "but if cannot make that work, then we as an agency need to sit down and... decide (if that is) a risk we're willing to take."