Why NASA has a lot riding on Discovery's shuttle mission

After two space shuttle disasters and 14 astronaut deaths, National Aeronautics and Space Administration managers know that the agency's tattered reputation, as well as the future of its human spaceflight program, is on the line with today's scheduled launch of Discovery, the first since the Columbia accident in early 2003.

NASA officials acknowledge that another accident would probably kill the shuttle program, hobble President Bush's plans to send astronauts to the moon and Mars, and endanger plans to finish the International Space Station.

Twenty thousand workers have labored for two years at a cost of $1.4 billion to reach these goals with the launch of Discovery, now scheduled for July 13.

On June 30, NASA officially cleared Discovery for launch despite a report earlier in the week from an independent panel that said the space agency had failed to fully resolve some key shuttle safety problems.

NASA officials said they had analyzed the shuttle from top to bottom to make sure the malfunction that brought down Columbia on Feb. 1, 2003 — a loose piece of insulating foam that struck the craft's wing — would never recur.

Newly appointed NASA Administrator Michael Griffin recently told Congress that the agency had "made more than 100 major maintenance modifications and upgrades" to the shuttle and its supporting systems.

Keeping watch

Those changes include a new surveillance system with about 100 cameras to monitor the craft. If anything were to hit Discovery during its eight-minute ascent, it wouldn't go unnoticed.

NASA has redesigned the giant external fuel tank that attaches to the orbiter to make sure no big chunks of insulating foam fall off.

In case the craft is damaged, Discovery for the first time is to carry repair kits to patch the heat-absorbing tiles and the carbon composite panels on the nose and wings.

But for all the changes, there is lingering concern about NASA and its aging shuttle fleet.

The shuttle is an amalgam of 2.5 million parts and 230 miles of wiring. Once considered the cutting edge of technology, it is now a creaky beast approaching the end of its service life.

Some fear the shuttle is so flawed that solving the problems that destroyed Challenger and Columbia will not guarantee against other potential defects.

"NASA is good at fixing the last accident," said Stanford University physicist Douglas Osheroff, a member of the Columbia investigation panel.

Before the shuttle is retired in 2010, NASA is planning 28 more flights — just enough to complete construction of the space station.

The goal of the shuttle program is to make a graceful exit — a far cry from several decades ago, when it was conceived as the next step into the solar system. Planners envisioned 50 flights a year.

Although the shuttle fleet never made more than nine flights in a year, the launches seemed so routine that NASA began to worry that it was losing the attention of the American public. To bolster interest, the agency began offering rides to people from various nations and walks of life. The launch of Challenger on Jan. 28, 1986, would carry the first teacher into space, Christa McAuliffe.

Unbeknownst to the Challenger crew, engineers from Morton Thiokol Inc., the maker of the shuttle's two rocket boosters, expressed fears the night before the launch that the cold weather predicted for the next morning could cause a failure of the thin, rubbery O-rings sealing a joint.

"My God, Thiokol," a NASA manager exclaimed. "When do you want me to launch, next April?"

The launch went ahead and all seven astronauts onboard died.

NASA promised to reform itself. And for the next 17 years, shuttle flights became almost as routine as before.

And then came Columbia.

Fifty-seven seconds into the flight of Columbia on Jan. 16, 2003, ground cameras saw one large piece of foam and two smaller ones break away from the fitting that attached the external fuel tank to the orbiter. Foam is sprayed on the external fuel tank, which contains frigid liquid oxygen and hydrogen fuel, to keep ice from forming on the outside.

A later analysis showed that the biggest chunk of foam, estimated to be 27 inches long and 18 inches wide, hit the underside of the orbiter's left wing at 416 mph to 573 mph.

Foam had been coming off fuel tanks since the earliest days of the shuttle program. At first, it was considered a critical issue, but as shuttles continued to return home safely, many in NASA came to believe that foam would not harm the orbiter.

Still, a NASA team charged with looking at the foam strike on Columbia was worried. The team made three requests to use military satellites to photograph Columbia's left wing. Each was denied by NASA managers higher up the chain of command.

As Columbia re-entered Earth's atmosphere after 15 days in orbit, the hole in the wing panel allowed air to pour in at temperatures as high as 5,000 degrees. As the orbiter broke apart, debris was scattered from west Texas to southern Louisiana.

An agency under fire

Seven months later, the Columbia investigation board was biting in its criticism: "We are convinced that the management practices overseeing the Space Shuttle Program were as much a cause of the accident as the foam."

"We became overconfident," said Stephen Robinson, a mission specialist on Discovery. "We were convinced we were the most safety-conscious organization in the world. We talked about safety every day. While we were doing that, we were making mistakes."

After redesigning the external fuel tank to eliminate areas that might shed foam, engineers said they believed no orbiter would ever be hit by a blow like the one that downed Columbia.

"We had a 2-pound piece of foam" come off before, said N. Wayne Hale Jr., deputy manager of the shuttle program. "Now the most we'll have is 0.026 pounds."

Some experts, however, contend that even bits of foam known as popcorn could cause trouble in certain circumstances. As it turns out, foam is part of a broader problem with the now-acknowledged delicacy of the craft's skin.

There are no easy solutions, given the myriad objects that could damage the craft.

The latest example was in early May, while shuttle managers were planning for a May 22 launch date.

Ice and debris

NASA engineers had already looked at 175 ways that foam and ice could come off the fuel tank. Tests had shown that ice could form along the bellows, or expansion joints, on the feed lines during fueling, an area that couldn't be covered with insulating foam because it would crack and fall off. Engineers had installed a "drip lip" around the joints to channel moisture to a safe location.

Even though ice had never damaged an orbiter, the test results prompted agency officials to delay the launch by two months to install a heater to prevent ice, and to make other improvements.

NASA has tried to deal with many of the debris problems. It has redesigned the mechanism that catches the 70-pound bolts that fall away after the boosters separate from the shuttle. It has strengthened portions of the orbiter to better withstand hits from stray debris, including the estimated 9,000 pieces of space junk circling Earth. Hardened windows have been installed on the flight deck.

But there is no way for the agency to completely guard against debris. "We have substantially reduced the hazard," Hale said. "But we haven't driven it to zero."

The real question is: What level of risk is acceptable?

Practical considerations limit how far engineers can go to enforce safety.

One recommendation from the Columbia investigation board was for the shuttle to operate with the same degree of safety as the space station.

Making the orbiter meet that standard would require a fivefold increase in its ability to withstand damage. Doing that with current technology would make the craft so heavy it couldn't reach space, NASA officials say.

The alternative has been to design a method for the astronauts to repair their spacecraft in case of a strike from foam, ice or space junk.

One space walk planned for the Discovery astronauts would test two techniques. The first repair system is called an emittance wash, a sticky, caulk-like mixture of fine-grit silicon-carbide granules that is used to seal tears in the insulating tiles that cover most of the orbiter. The second resembles a Flash Gordon ray gun, which applies a substance called NOAX, or "the goo," to seal cracks in the panels.

A personal stake

Weeks before the first scheduled launch of Discovery, in May, internal engineering documents were leaked to The New York Times.

Employees who leaked the documents said NASA managers were fudging numbers to make the results of debris testing look better than they were. NASA managers denied tinkering with equations. Showing that he too was part of the new warts-and-all NASA, Hale let his emotions flare as he answered allegations that he was cutting corners to get the shuttle flying once more.

"It is to my everlasting shame that my name appears in Chapter 6 of the (Columbia accident) report," he said. "I never want to go to another astronaut's memorial service. There will be no corners cut on my watch."

A review of the problems resulted in delaying Discovery's launch until July to make further improvements.