Barring weather or mechanical delay, the space shuttle Discovery will launch at approximately 1:51 p.m. MDT today.

The Discovery mission is NASA's first manned space launch since Columbia broke apart over Texas more than two years ago, killing all seven crew members. Columbia's mission was doomed during launch when a briefcase-sized piece of insulating foam fell from an external tank and damaged the shuttle's left wing. The accident horrified the nation, still healing from the 9/11 attacks. It also renewed concerns about the enormous risks of space travel.

Some two years and hundreds of millions of dollars later, it is hoped that today's launch from Cape Canaveral, Fla., will be a success. Hundreds of millions have been spent on new safety equipment and testing for the shuttle, which NASA has proclaimed "safer than ever."

Optimism must be tempered with reality, because space travel is inherently risky. That's been the case since Soviets' launch of Sputnik in 1957, which spurred the United States to be the first nation to land on the moon.

The stakes are high because of the nation's renewed ambition for space exploration, spurred by President Bush's goals of a return mission to the moon, the first since 1972, and an eventual manned mission to Mars.

A successful launch of the Discovery will mark the beginning of the end for the shuttle program, which went into service with the 1981 Columbia mission. This mission is slated to last nearly two weeks. The crew is scheduled to test new safety equipment and deliver supplies to the two-man crew on the space station.

Although NASA has had considerable successes in recent years with its unmanned Mars Rover expedition, as well as the recent comet-busting Deep Impact mission, which took place 83 million miles from Earth, NASA officials fully appreciate the importance of Discovery's safe launch and return. An accident could devastate the agency.

Discovery's crew members are to be commended for their bravery and commitment to space exploration. They are true American heroes.