The countdown has begun. NASA is scheduled to return to space Wednesday, two and a half years after tragedy struck and the Columbia astronauts were killed as their shuttle headed back to earth.

The investigation that followed that accident indicted the culture at the space agency, which was faulted for its lack of safety precautions.

NASA itself has delayed its return to space already this year to make sure that the shuttle would be safe again to launch.

That leaves us holding our collective breath. First, we are anxious about the safety of this flight &045; not just because of the risks at NASA but because of the risks of space travel in general. Such a massive undertaking comes with no guarantees; we literally continue to go where no man has gone before.

But we cannot help but be thrilled at the prospect that America will finally get its space program back where it belongs.

We will be watching tomorrow as Discovery lifts off again, carrying a crew of seven &045; including the first woman shuttle commander on her second mission with that title.

But that crew also carries the hopes &045; and fears &045; of an entire nation.

When we returned to space after Challenger exploded on liftoff in 1986, the ground crew at NASA erupted in cheers as soon as the shuttle was in orbit.

This time, we won’t lose the anxiety until Discovery’s astronauts are safely back on earth.