America is back in the space business.

The shuttle Discovery made a picture-perfect entrance into the partly cloudy Florida sky at 11:37 a.m. EDT Thursday, slightly delayed but most certainly welcome.

Within two hours of the liftoff, light rain began to fall over the cape. "Well, to start with, WOW!" said NASA administrator James C. Fletcher. "That was really something."

The liftoff was delayed from 9:59 a.m. to 11:37 a.m. EDT while weather watchers waited for meteorological data from two balloons. Winds at the 20,000-foot level were from the wrong direction at the scheduled launch time. Additionally, fuses needed replacing on fans used to help the astronauts breathe during flight.

It was worth the wait.

The launch comes after a nearly three-year dearth of space flights, an intensive redesign project and a shake-up in management at NASA and rocket maker Morton Thiokol.

"It's been a long wait - 2 1/2 years and a little bit better than that," Fletcher told workers at mission control at the Kennedy Space Center. "You guys have been working your tails off."

"It's very important that we get back to flying again," Utah Sen. Jake Garn said before the launch. "Hopefully with flying it will stimulate more support" in the form of congressional appropriations.

"It doesn't just hinge on this flight. It's hinging on flying again," said Garn, a vocal space supporter and veteran of a shuttle mission.

The intensive redesign project in the wake of the Challenger explosion paid off as the orbiter lifted from launch pad 39B in a cloud of smoke and a deafening roar.

The cheers began at T-30 seconds, as reporters, NASA employees and contractors moved closer to the causeway at the press site to get a better view of the return to flight.

The cheering increased as the shuttle lifted off, but silence followed for a minute, with NASA spokesman marking only the 1-minute mark. Officials and watchers held their breath when Discovery passed the 73-second mark - the moment when Challenger exploded in its flight 32 months ago.

The cheers were well-earned as the Utah-made booster rockets separated from the orbiter 2 minutes, 5 seconds into flight.

"You worked long hours overtime, fixed all the problems, it's ready to go, it's time to go, we went," said Fletcher. "All I can tell you is that the nation owes you a lot. And we're going to continue to owe you a lot. And we'll continue to owe you a lot in the months and years to come because this is the first of a new era."

The Discovery crew - Commander Frederick Hauck, pilot Richard Covey and mission specialists David Hilmers, Pinky Nelson and Mike Lounge - is leading NASA into that new era in a four-day orbit of the Earth.

"We're back in business. And it's a good feeling. And it didn't come easy," said Royce Mitchell, solid rocket motor program manager at the Marshall Space Flight Center, who oversaw the redesign project at Morton Thiokol.

Six hours into the flight, the astronauts will launch a satellite that will improve communications between the crew and mission control in Houston, which takes over once the shuttle clears the launch pad.

The mission is short in duration compared with other shuttle flights. But then, the Discovery is another kind of first for America's beleaguered space program.

Discovery took off 32months after the Challenger blew up in a technicolor explosion of debris and dreams. The shuttle fleet, now dwindled to three orbiters, remained earthbound while commissions and engineers decided what was best for continued manned space flights.

More than 200 changes were incorporated into the orbiter and solid rocket boosters in the wake of the Challenger disaster. Thousands of jobs and the integrity of U.S. ingenuity are at stake in this flight.

"Although as I've said in the past this is going to be the safest flight we've ever flown, that does not discount the fact that we've made an awful lot of changes to virtually every system in the orbiter," Hauck said at a news conference 30 days before the astronauts went into isolation.

A successful mission will certainly help America's space program gain congressional support.

Also riding on the mission was the public support of the space program, which celebrates its 30th anniversary on Day 3 of the orbit.

"I think it means a lot to the country," to be flying again, said J.R. Thompson, director of the Marshall Space Flight Center in Huntsville, Ala., which oversees the propulsion systems on the shuttle.

"I think the general public is behind us. I think they rode all the way with us up to space today," the cigar-smoking Thompson said.

The orbiter will land either at Edwards Air Force Base, Calif., or White Sands, N.M., depending on the weather next Monday.