The Washington Post February 10, 2003
Shuttle Failures Raise a Big Question
With a 1-in-57 Disaster Rate, Is Space Exploration Worth the Risk?
By Peter Whoriskey
Washington Post Staff Writer
Successful space shuttle missions over the past decade may have lulled the public into believing that each launch was as predictable as a commercial airline flight, but NASA engineers knew that the risk of disaster on any shuttle flight was far, far higher.
As recently as last October, according to NASA documents, the space agency calculated that the chance of a shuttle disaster was 1 in 265. By contrast, they pegged the risk of an accident when traveling by commercial airliner at about 1 in 2 million and the risk of crashing an F-22 fighter plane at 1 in 10,000.
As congressional and NASA leaders in the coming months decide whether to launch another shuttle, an essential question will be raised: Is the risk of another catastrophe worth taking?
"Is it worth the risk? Yes, absolutely," said Sen. Bill Nelson (D-Fla.), who flew on the shuttle mission immediately before the fatal Challenger disaster in 1986. He said that NASA told him then that the risk of a shuttle accident was 1 in 100.
Since then, he has been a leading advocate for shuttle safety upgrades, but he has said the flights will never be risk-free: "It's exploration. You can imagine what Lewis and Clark thought. Was it risky? You're doggone right it was. Then, the frontier was westward. Now, it's upward."
Still, others said NASA faces a difficult task -- and future. The space agency now "is going to have a real hard time convincing anyone that the odds of catastrophe are anything than about one in fifty," said John Pike, director of GlobalSecurity.org, which studies security and space issues. And "they are going to have a very hard time describing a coherent program that loses an orbiter and crew every decade or so."
The task of assessing mission risk has bedeviled the nation's space program for years. Even as astronauts have exalted the glory of exploration, political pressures on space program leaders to guarantee that their multibillion-dollar project will not yield failure, or frighten a squeamish public, have tainted the already difficult task of assessing and reporting the actual risk.
Before the fatal Challenger mission, for example, NASA managers had estimated the risk to be a thousand times lower than engineers working on the project had figured, according to Richard P. Feynman, a physicist and a member of the Challenger investigative commission.
"We could properly ask, 'What is the cause of management's fantastic faith in the machinery?' " he wrote in an appendix to the commission's report. " . . . One reason for this may be an attempt to assure the government of NASA perfection and success in order to ensure the supply of funds. The other may be that they sincerely believed it to be true, demonstrating an almost incredible lack of communication between themselves and their working engineers."
He concluded: "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled."
Similarly, after President John F. Kennedy announced the moon program, NASA's founders decided that they should keep the risk of harming the crew to 1 in 1,000 or below.
The risk, in fact, was probably much higher.
"These risk analyses are not easy to perform -- that is clear," said Elisabeth Pate-Cornell, a Stanford University professor who has studied NASA's risk assessments. "But the alternative is flying by the seat of your pants."
Skeptics point out, moreover, that the shuttle program's actual rate of catastrophic failure has proved far higher than what has been suggested by the probability reports. With the destruction of the Columbia on Feb. 1, the rate of fatal shuttle missions rose to 2 in 113, or about 1 in 57.
Even without the political pressures, the task of assessing the shuttle risk has proved a gargantuan and perplexing undertaking. Still, NASA does it, and according to NASA briefings given to members of Congress, the safety of the shuttle has improved markedly in recent years.
In 1994, they measured the risk of failure to be just 1 in 145, with the risk of failure during the ascent alone at 1 in 248. By October 2002, they had significantly lowered their assessment of risk -- to 1 in 265 for the mission and 1 in 556 for the ascent.
The model "does not represent a complete shuttle risk," Joseph R. Fragola, a Science Applications International Corp. scientist contracted by NASA to build a risk model, told a House committee in 1995. "However, it is SAIC's belief that the model has been developed to a stage which captures a significant portion of the shuttle risk."
The history of the shuttle has shown that some risks simply have not been well understood.
On a shuttle mission in June 1983, for example, astronaut Frederick H. Hauck, returning to his pilot's seat, noticed a splatter mark on the window, centered on a small crater.
"I said, 'Have you seen this?' " Hauck recalled. "I don't think this was here before."
Analysis later showed that the craft had been struck by a tiny piece of orbiting space debris.
"This was one of the first indicators that orbital debris might pose a hazard to the space shuttle," Hauck would later write as chairman of a panel exploring such risks.
Some who discount the risk estimates because of their uncertainty believe, nevertheless, that they are valuable as a means of gauging whether a safety measure is worth the money. They are useful, for example, in comparisons.
"It's a relative risk measure," said Richard Blomberg, former chairman of the Aerospace Safety Advisory Panel. "These are rough estimates that show you where you should be putting your money."
Regardless of such caveats, new risk numbers likely will be generated in the coming months and reviewed closely in the debate over whether the shuttle should fly again.
In the end, though, it may not be a question of numbers, but of culture. The astronauts and engineers of NASA argue that sometimes risks, even unknown ones, are worth taking.
"If people want absolute insulation from failure, then they should just quit," Hauck said. "But a society that stops taking risks, where people just want to live in a bubble, is a society that is decaying."
Copyright © 2003, The Washington Post Company
