The shuttle Discovery glided to a picture-perfect landing Monday, triumphantly closing out the first post-Challenger flight and heralding a new and safer era for America's space program.

Preceded by a double sonic boom, shuttle skipper Frederick Hauck and co-pilot Richard Covey gently set Discovery down on a dry lake bed runway at 10:37 a.m. MDT, thrilling an estimated 340,000 spectators who gathered to witness the end of the first American manned spaceflight since Challenger blew up 32 months ago.Barreling down the broad desert runway at more than 200 mph, the 194,000-pound spaceplane kicked up a billowing cloud of dust as Hauck guided it to a halt under a crystalline blue sky.

A few seconds later, Discovery stood motionless on the smooth floor of California's high desert, its 64-orbit, 1.7 million-mile odyssey finally over and NASA's shuttle program finally back on track after the worst disaster in space history.

"Wheels stop!" Hauck radioed.

"Roger, wheels stop," said astronaut Blaine Hammond in mission control in Houston. "Welcome back. A great ending to the new beginning."

Hauck, 47, Covey, 42, and their three veteran crewmates - John "Mike" Lounge, 42, David Hilmers, 38, and George "Pinky" Nelson, 38 - struggled out of their bulky 70-pound emergency escape spacesuits before climbing out of the orbiter to greet a throng of well-wishers.

Joining the crowd of spectators for Discovery's landing was George Bush, who said he decided to visit Edwards for the touchdown in his official capacity as vice president and not as a presidential candidate.

The astronauts planned to return to the Johnson Space Center in Houston late in the day after meeting with their families and Bush.

"This is a great day for our country," Bush said when the shuttle landed.

Hauck and Covey fired Discovery's two braking rockets over the Indian Ocean for two minutes 48 seconds to slow the spaceship by 222 mph, just enough to drop it out of orbit for the hourlong, powerless glide to California.

Discovery's flight path carried it across the California coast just south of Santa Barbara at an altitude of 115,400 feet and flying at more than four times the speed of sound.

About four minutes later, Discovery banked through a sharp left turn and lined up on runway 17, a 71/2-mile

long landing strip with plenty of margin for error in the event of problems. But it was smooth sailing, and Hauck guided Discovery to a flawless touchdown.

Fifteen of the 24 previous shuttle landings were marred by brake damage, but Discovery was equipped with beefed-up brakes and landing gear as part of a post-Challenger effort to improve overall shuttle safety.

Left behind in orbit was a $100 million NASA Tracking and Data Relay Satellite crucial to the space agency's plans for a space-based communications network between shuttle crews, other satellites and mission control.

But the satellite launch, no matter how important to NASA's long-range plans, was insignificant compared to the resumption of the nation's manned space program after a 2 1/2-year hiatus.

Readying Discovery for its descent, Hauck and company took time out Sunday to read an emotional tribute to the seven astronauts who died Jan. 28, 1986, in the Challenger disaster.

Killed on that cold, bitter day were commander Francis "Dick" Scobee, co-pilot Michael Smith, Judith Resnik, Ellison Onizuka, Ronald McNair, civilian satellite engineer Gregory Jarvis and New Hampshire schoolteacher Christa McAuliffe.

"Today, up here where the blue sky turns to black," Hauck read, "we can say at long last to Dick, Mike and Judy, to Ron and El and Christa and Greg: Dear friends, we have resumed the journey that we promised to continue for you.

"Dear friends, your loss has meant that we could confidently begin anew. Dear friends, your spirit and your dream are still alive in our hearts."

In keeping with the conservative flight-test philosophy of the 26th shuttle mission, Discovery's crew faced a relatively light schedule throughout the four-day flight, operating 11 largely automatic experiments, taking pictures of Earth and checking out Discovery's systems.