Abort this mission

CRITICS OFTEN COMPLAIN THAT NASA is good only at fixing its last problem. That’s too generous. The agency plans to launch the space shuttle Discovery on Saturday despite warnings that it still hasn’t fixed the problem that killed seven astronauts aboard the shuttle Columbia in 2003.

What NASA hasn’t been able to solve is the shuttle’s perplexing habit of shedding pieces of foam that insulate its external fuel tank during launch. In February 2003, one such piece slammed into Columbia’s wing as it lifted off, punching a hole in the orbiter’s protective heat shield. During the shuttle’s fiery reentry, that hole allowed superheated gas to act like a blowtorch on Columbia’s wing, causing the craft to incinerate in the atmosphere above Texas. The problem resurfaced when an errant foam chunk was spotted during Discovery’s most recent launch almost a year ago.

Instead of risking another tragic or humiliating setback Saturday, NASA should abandon the shuttle and focus on more productive missions.

The shuttle was intended as a reusable spacecraft that would require only routine maintenance between missions. But NASA has been working on the foam problem for more than three years. It’s becoming increasingly clear that the issue with the shuttle isn’t age but a design flaw.

In fairness, the officials who advised against Saturday’s launch -- the agency’s chief engineer and its chief safety officer -- say there isn’t much risk that the shuttle’s crew could die. If debris punctures Discovery’s skin, its astronauts can abandon the craft for the International Space Station; the shuttle would burn up in the atmosphere without a soul on board.

NASA Administrator Michael D. Griffin has said that in order to finish the construction of the space station, the shuttle needs to carry out 16 more missions through 2010, by which time Discovery will be 26 years old. But the space station also has questionable scientific value. Intended as a platform for exploration, the station is stuck unfinished in low-Earth orbit and will end up costing the U.S. and other countries more than $100 billion. Finishing the station is no excuse to keep an obsolete, unsafe shuttle flying.

Retiring the space shuttle now wouldn’t spell the end of manned spaceflight for NASA. The space agency in September unveiled its blueprint for the Crew Exploration Vehicle, an Apollo-like capsule that NASA hopes will fly by 2012 and take astronauts to the moon by 2018. A six-year gap in manned spaceflights shouldn’t be discouraging. In the meantime, the space agency could focus on more science-rich, unmanned missions that could be better funded without the costly shuttle program.

Each shuttle mission costs about $450 million for a few days in low-Earth orbit. An awe-inspiring blastoff by Discovery on Saturday could make many people forget about the price. But it won’t change the fact that the shuttle is an unsafe, expensive way for humans to explore space just a few hundred miles above Earth. The problem with the shuttle isn’t chunks of foam, it’s the shuttle itself. NASA should mothball the program and put the nation’s scientific and technological expertise to better use.