The space shuttle Discovery dropped from a starry pre-dawn sky and coasted to a smooth, safe stop in the California high desert early Tuesday, capping the nation's first return to manned spaceflight since sister ship Columbia exploded over Texas in February 2003.

The uneventful descent and apparently perfect landing concluded a voyage of 5.8 million miles and 219 orbits around Earth over 14 occasionally nerve-racking days. Shuttle crew and controllers confronted the hazards posed first by a piece of foam insulation that ripped away on takeoff -- a shocking event that forced the delay of all upcoming missions -- and later by protruding tile filler that was removed in a historic spacewalk, and finally by the ominous clouds hovering over the original landing spot in Florida.

In the end, the landing was diverted from Kennedy Space Center because of bad weather on both Monday and Tuesday mornings. On the West Coast, Discovery met clear skies, gentle crosswinds and the cheers of a NASA team still recovering from the disastrous last attempt at a shuttle landing that caused the deaths of seven astronauts.

Shuttle commander Eileen Collins, noting that some critics have questioned whether the shuttle program is worth the risk to astronauts' lives, pleaded for the nation's support. "The Columbia crew believed in their mission, and we are continuing their mission . . . exploring space and making life on Earth better for all of us," said Collins, a veteran of three previous flights, at a news conference after Discovery's landing.

Still, NASA officials were careful to characterize the mission's success as only a first step in getting the program back on track. The shuttle fleet remains grounded -- threatening President Bush's push to finish building the international space station within five years and return humans to the moon within 15 -- until engineers can identify what caused the Discovery to shed foam insulation.

While the foam loss apparently left no scars, similar foam shedding during Columbia's takeoff left damage to its exterior that caused the orbiter to disintegrate and burn upon reentry into Earth's atmosphere.

The grounding of the shuttle fleet cast serious doubt on the possibility of a shuttle launch next month, and Tuesday's landing was perhaps the coup de grace as Discovery may need 10 days to get back to Kennedy Space Center before NASA technicians can begin preparing it as the backup vehicle for Atlantis's upcoming mission.

Agency Administrator Michael D. Griffin noted that Discovery's mission, the 114th by a shuttle, marked only the 145th trip by humans into space. "We're still in the very first stages of spaceflight," he said. ". . . What the American people can count on from us is our very best effort to make it easier every time."

He added: "We are going to try as hard as we can to get back into space this year. But we're not going to go until we're ready."

From his ranch near Crawford, Tex., Bush hailed the mission as "an important step for NASA as it regains the confidence of the American people."

Although the fate of Columbia was much on their minds, Collins and her fellow astronauts said after their landing that they were not nervous or fearful during their mission. "You're really concentrating on what your job is," co-pilot Jim Kelly said.

Even so, Kelly acknowledged "a moment of trepidation" when Collins fired the auxiliary engines to turn the craft back to land -- a point of no return known as the "de-orbit burn."

Kelly described experiencing "a moment of reflection thinking about the Columbia crew and obviously hoping we'd make it further than they did, and wishing that they'd made it all the way home."

NASA referred to Discovery's mission as a "test flight," devoted largely to exercising new sensors, imaging devices and inspection systems. Astronauts conducted three spacewalks, including the one in which they became the first to work beneath an orbiting shuttle and make repairs to the thermal shielding. And they spent nine days at the space station to deliver supplies and retrieve garbage.

The space agency had hoped to land Discovery at Cape Canaveral so engineers could quickly begin preparing it for its next flight, and to spare the cost of transporting it cross-country on the back of a specially modified Boeing 747.

But lightning flashed across the central Florida sky, and rain fell sporadically from cloud banks within the 30-mile radius of Kennedy's shuttle landing facility that NASA requires to stay dry before attempting a landing. At Mission Control in Houston, flight director Leroy Cain waved off the first space center reentry attempt at 3:05 a.m. Eastern time, a full two hours before the scheduled landing. The weather improved dramatically during the ensuing 90-minute orbit, but lightning ambushed a reconnaissance flight.

Meanwhile, Edwards Air Force Base -- 2,300 feet above sea level in the Mojave Desert and about 90 minutes north of Los Angeles -- offered immaculate weather. And its runway is well known to Collins, who in 1990 became the second woman to graduate from the Air Force test-pilot school there.

Discovery was flying upside down, stern first, just north of Madagascar over the Indian Ocean when Mission Control ordered the orbiter to begin its de-orbit burn. While slowing Discovery's 17,500-mph speed by 186 mph, it sent the craft on a direct line to Edwards -- a 227,000-pound glider traveling at 25 times the speed of sound and dropping like a stone.

In the next 34 minutes, Discovery fell from its orbit altitude of 219 miles to the edge of Earth's atmosphere, a mere 75 miles above the ground, flipping gently until it faced forward at a 40-degree angle of flight and presenting its heat shield directly at the rush of gas building to temperatures of 3,000 degrees.

The shuttle then made four sweeping turns in 25 minutes, slowing to 1,000 mph. Picked up by infrared cameras, it appeared on NASA television screens around 8:06 a.m. Eastern time.

"We can see you approaching," Mission Control communicator Ken Ham radioed to the crew. Collins's answer: a simple "copy that."

Launch director Mike Leinbach later said: "That's when I started to feel better."

In its final approach, the orbiter flew over the California beach communities of Ventura and Oxnard. It then made a 190-degree right turn over the Mojave Desert, where the barest smudge of pink on the horizon illuminated thunderclouds a safe hundred or so miles away.

From the ground, the craft was virtually invisible until it fell suddenly into the brilliant lights of the tarmac and rolled silently to a stop.

Gugliotta reported from the Kennedy Space Center in Florida.

Discovery commander Eileen Collins and her crew tested new sensors on the shuttle and visited the space station during their 14-day mission.The shuttle was directed to land in California when conditions in Florida proved unfavorable. It will be taken cross-country on a modified 747.The landing prompts a gathering in Chigasaki, Japan, the home town of astronaut Soichi Noguchi. During the mission, he performed a spacewalk.Discovery will be taken from Edwards Air Force Base in California to Kennedy Space Center in Florida, where it will be prepared as a backup to Atlantis.