CAPE CANAVERAL, MAY 27 -- NASA reported unusually smooth progress today and predicted good weather for space shuttle Columbia's liftoff Wednesday on a 10-day mission with the $148 million Astro Observatory.

"We're tracking no problems, and we're a couple of hours ahead on some systems," said countdown director Mike Leinbach of NASA. "It's not normal, but it's the way we like it."

The seven crew members, sporting caps with the Houston Astros baseball team logo, traveled in T-38 jets from their training base in Houston to get ready for liftoff, scheduled for 12:38 a.m. Wednesday.

"We know we have a great ship, and we're ready to go. I can't wait to get up there again," said commander Vance D. Brand, a veteran of two shuttle flights and the 1975 Apollo-Soyuz space rendezvous.

Digital timekeepers at the Kennedy Space Center started moving backwards at 1 a.m. today, signaling the start of three days of final preparations for liftoff. The mission was delayed early this month by a problem with its air conditioning system.

Stationed in the shuttle's payload bay is the Astro Observatory, four telescopes capable of detecting light the human eye cannot see.

The telescopes will focus on extreme ultraviolet and X-ray emissions from stars and galaxies thought by astronomers to be either newborn or near death.