Hours before President Bush told the nation that "the Columbia is lost," the flag at Florida's Cape Canaveral was lowered to half-staff. For many on Saturday, that, as much as anything else, signaled that its crew of seven astronauts had perished.

Federal employees have seen far too many flags lowered in the past decade.

Last week, a Black Hawk helicopter went down on a training mission in Afghanistan, killing four soldiers. Two years ago, 17 sailors died in the bombing of the USS Cole. Since 1990, four National Park Service rangers have been killed in the line of duty. Few of us will forget the agony caused by the 1995 bombing of the Oklahoma City federal building and the 2001 terrorist attacks on the Pentagon and the World Trade Center.

To a large degree, these horrific events sweep aside widespread perceptions that federal employees are, by nature, averse to risk. That they take government jobs because they cannot be fired. That they find comfort in bureaucracies that hold no one accountable.

In fact, federal law enforcement officers, CIA agents, Internal Revenue Service agents, Customs and Immigration inspectors, park and Forest Service employees and, of course, the armed forces serve the public in jobs that can lead to injury, disability or death.

Sure, many federal employees face no more peril than the ordinary office worker in the private sector. But the government's bean counters and paper pushers carry out their jobs in fishbowls. Sure, the bosses sometimes jealousy guard agency secrets, but more times than not, they have to give them up when the national interest demands an answer.

Now, the employees at the National Aeronautics and Space Administration have the opportunity to show the grit of the federal workforce, to step up and take what went wrong and turn it into what will be right for the agency's future. Despite the pain they feel from Columbia's loss, NASA's employees can reaffirm the excellence of the federal service.

Unlike those folks at Enron who shredded documents in the midst of a crisis, NASA employees face immediate pressure to reconstruct the events and decisions for each of the 16 days of the space shuttle mission.

NASA Administrator Sean O'Keefe, in his first statement to the public, announced that internal and outside investigation teams had been formed. Congressional investigations are in the works.

This is not to say that NASA is not without problems. The agency has been struggling with how to reduce the costs of space launches and replace its aging shuttle fleet. Like many federal agencies, it has an aging workforce and trouble recruiting top-notch replacements. Like many high-tech agencies, it spends most of its money on contractors but has trouble tracking contract costs and managing contracts effectively.

These problems helped land NASA on the "high risk" list -- this year's update came out just last week -- compiled by the General Accounting Office, the congressional watchdog agency. Soaring costs, staff shortages and other problems at NASA "threaten its ability to effectively run its largest programs," the GAO concluded.

The GAO report also shows that NASA employees face high levels of job stress, in part because the agency is short-staffed in engineering, flight software engineering, electrical engineering and shuttle resources management.

In NASA's science and engineering workforce, the GAO found that the over-60 population outnumbers the under-30 population by 3 to 1. About 15 percent of the science and engineering staff can retire, and 25 percent will be eligible to retire in five years, the GAO said.

Under O'Keefe, NASA has been taking steps to address many of these problems, but some will take years to turn around, according to the GAO.

The loss of the Columbia seems certain to put NASA and its employees through a new round of soul-searching and second-guessing. It's hoped that the scrutiny will not crush workforce morale but strengthen the resolve of NASA employees to push ahead in space exploration.

More than ever, NASA -- and the government as a whole -- needs dedicated, courageous employees, just as brave as astronauts Michael P. Anderson, David M. Brown, Kalpana Chawla, Laurel B. Clark, Rick D. Husband, William C. McCool and Ilan Ramon.

Stephen Barr's e-mail address is barrs@washpost.com.