The seven astronauts aboard the space shuttle Discovery have to be among the bravest people from Earth. They willingly allowed themselves to be sent into space in an aged vehicle that NASA scientists, after two years and $1.4 billion worth of study and work, could still not protect from falling foam.

NASA’s response to this needless situation? After learning that foam insulation fell off the shuttle external fuel tank during launch – the very thing that doomed the Columbia – it grounded future shuttle flights. A prudent step, for sure. But, what about the craft it had just sent into space although there were lingering questions about its safety after the February 2003 Columbia disaster? “The Columbia accident caused us to realize that we’ve been playing Russian roulette with the shuttle crews,” N. Wayne Hale Jr., the shuttle’s deputy program manager, said this weekend.

How reassuring to the Discovery astronauts, orbiting 200 miles above Earth, to know that there are still bullets in the gun, according to Mr. Hale’s analogy.

The astronauts used remote sensing equipment to scan the shuttle’s hull for damage. On approach to the space station, the shuttle did a back flip so that astronauts in the station could take pictures of the underside of the orbiter. The crew also used a boom with a camera and lasers to scan the shuttle’s underside for damage. They found two scraps of insulation hanging from the fuselage. They were apparently damaged by the falling foam. There is concern that the dangling scraps could affect the shuttle’s aerodynamic performance, possibly leading to overheating.

Repair options are limited and largely untested. During a space walk, two repair techniques will be tested. Both involve spreading a gooey substance on either the heat-resistant tiles that cover the shuttle or the reinforced carbon panels that cover the leading edge of the wings and the nose cone. The crew also has an umbrella-like devise it could insert into a hole in the carbon panels.

Crew members have wisely said they are reluctant to trust their fate to untested technologies. Their other option is to wait to be rescued from the space station, either by another shuttle, which NASA says could take up to a month to prepare for launch (and without addressing the falling foam problem would risk the lives of even more astronauts) or, more embarrassing but reliable, a Russian spacecraft.

This shouldn’t have happened. The Columbia Accident Investigation Board recommended eliminated foam insulation, if possible. Despite research into other options, NASA did not do so. “Our expectations were we wouldn’t have an unexpected debris event,” Shuttle Program Manager Bill Parsons said. “We were wrong.”

With seven lives and NASA’s reputation at risk, the agency couldn’t afford to be wrong. If it can’t guarantee the safety of its 30-year-old shuttle fleet, it is time to mothball it and put more resources, financial and otherwise, into the next generation of space vehicles.