Two American astronauts rocketed into Earth orbit today aboard the space shuttle Columbia with everyone concerned jubilant and triumphant despite the loss of a few insulating tiles that were shaken loose in the stress of the launch.

National Aeronautics and Space Administration officials shrugged off the loss of the tiles as a minor matter that would have no effect on the flight.

"This is one fantastic ride," veteran astronaut John W. Young said as he piloted the winged spaceship up through blue Florida skies into the blackness of space this morning. "Flying this thing is just outstanding." Minutes later, rookie astronaut Robert L. Crippen remarked: "John's been telling me about this for three years but there ain't no way to describe it. Fantastic!"

Putting America squarely into a new epoch of the Space Age, Young and Crippen roared away from the Kennedy Space Center at 7 a.m. today and in less than 12 minutes were in orbit where they'll stay until Tuesday when they are scheduled to land Columbia on a runway at Edwards Air Force Base in California's Mojave Desert. In orbit on the 20th anniversary of Soviet cosmonaut Yuri Gagarin's becoming the first man in space, Young and Crippen were the first Americans in space in almost six years.

The only thing that marred an otherwise flawless first day in space was that Columbia lost several of the 30,759 foamed-glass tiles that cover the fuselage of the DC-9 sized shuttle to protect it from the searing heat it will encounter on its return through the atmosphere and about a dozen were damaged.

The loss was not considered serious. A few of the tiles fell from the engine pods, an area of the shuttle not subject to the high heat that might damage other surfaces if they were unprotected during reentry.

There is almost two inches of insulation on the exposed areas, which flight officials said would be more than adequate for reentry. NASA was unable to develop a tile repair kit for this flight but officials said there would be one for the next one.

"We've got a super vehicle up there," flight director Neil B. Hutchinson said this afternoon at Houston's Johnson Space Center where the flight is being directed. "There is nothing we see that will stop us from completing a full-duration mission, nothing at all," he said.

A full-duration mission is 54 1/2 hours, most of it to be spent testing Columbia's maneuvering engines, computers and payload bay doors 170 miles above the Earth. Besides this one, three more test flights will be flown in the next 18 months by Columbia, which with three other shuttle craft now being built will carry all the United States' civilian and military satellites into space for the rest of the century.

Columbia sailed through its first tests. Less than an hour after he reached orbit, Young unlatched the 60-foot-long cargo bay doors, then opened them wide where they'll be kept open until Columbia is ready to return to Earth. If Young had been unable to open the doors, he and Crippen would have to fly back almost at once. Columbia cools itself by radiating heat to space through radiators built inside the cargo bay doors. The shuttle cools itself the way the human body cools itself, by evaporation.

'We saw no distortion in the doors, zero," Hutchinson said. "The doors opened exactly as we expected, exactly."

Four times, the shuttle's two big (6,000 pounds of thrust apiece) maneuvering engines were fired, putting the 214,000-pound Columbia in an orbit 172 miles at its highest and 170 miles at its lowest point. Flight directors had aimed for a 170-mile circular orbit, almost precisely what they got.

It was when Young opened the cargo bay doors that he noticed the missing tiles. Looking through an aftfacing cockpit window, Young televised what he saw back to Earth so flight directors could see the damage.

The lost tiles probably were ripped off when the shuttle passed through the speed of sound on its flight from Earth. The tiles were located in the region of the top pods that are buffeted the hardest by aerodynamic forces during the shuttle's ascent.

Flight directors downplayed the role of the lost tiles, saying none of the missing ones were critical to the rest of the flight. They pointed out that all the tiles on the critical leading edges of the tail and wings were intact, suggesting that the only tiles lost during the upward part of the flight were those on the engine pods.

"We have no reason to believe that any other tiles are loose anywhere on the vehicle," Hutchinson said. "We can see the tiles on the leading edge of the vertical tail are all in place and the crew has said that the leading edges of both wings are in place. We're not worried about the tiles." l

What has long worried flight directors is losing tiles built into the underside of the shuttle's fuselage where electronics and hydraulics systems are housed that navigate the spacecraft on its return, move the elevons that keep it on course the last 1,000 miles back and lower the wheels that land it on the runway. If lost tiles uncovered the housing of the spacecraft's hydraulic system and reentry heat burned a hole through the system, Young would not be able to lower the wheels and would have to crash-land at more than 200 miles an hour.

Nobody was worried that there was any missing tiles on the critical underside of the fuselage, but flight directors were already making plans to find out if there are. Deputy flight operations director Gene Kranz said that the Air Force would train super-secret telescopic cameras in Hawaii and Florida on the shuttle to photograph Columbia when its flies overhead Monday and Tuesday.

Kranz said the photographs would show whether any tiles on the underside were missing, giving the public a rare notion of what the Pentagon's surveillance cameras can accomplish. Picking out missing tiles on a moving spacecraft 170 miles high is akin to identifying the license plates in a Moscow parking lot from earth orbit.

"I am not free to reveal what these cameras are used for," Kranz said. "Their mission is classifed."

If the cameras show that some underside tiles are missing, Kranz said the crew can manage their return a little differently to avoid a possible catastrophe.He said the astronauts can turn off some electrical lines housed in the craft's belly and some of the coolant pipes that run through the spacecraft's wings.

"There are a number of things that can be done differently," Kranz said, "but I want to emphasize that we are not concerned about the tiles."

Young and Crippen appeared completely unconcerned about the tiles. During a six-minute telecast of what it was like inside Columbia's cockpit late in the day, the two astronauts never even mentioned them.

"This spacecraft is performing like a champ," Young said. "The vehicle is flying beautifully." Echoed Crippen: "We've got something here that's really going to mean something to this country and to the whole world."

If their return goes off as smoothly as their departure today, Young and Crippen will have every reason to repeat those remarks. Their liftoff from Launch Pad 39A was a sight and sound to behold, a reminder that the launched of a manned spacecraft is an event unlike any other.

While an estimated 1 million people watched along a 50-mile stretch of Florida beach, Columbia roared into the sky burning 45,000 gallons of liquid hydrogen and more than 100,000 pounds of solid fuel a minute. Trailing clouds of steam, smoke and orange flame, Columbia was clear of its launch tower in five seconds, reached an altitude of 30,000 feet in less than 2,000 miles an hour in two minutes.

"Columbia, the Gem of the Ocean," said astronaut Dan Brandenschein from Mission Control Center in Houston, "you are go for orbit." Replied Young: "What a ride!" Said Brandenschein: "Roger, enjoy it."

Launch operations director George F. Page brimmed with pleasure at a post-launch press conference. Said Page: "I'm thrilled with what happened. What more can I say? We're proud today and it's a proud day for America."

Just before liftoff, Page read the crew a message from a recuperating President Reagan, who watched the live telecast of the launch at the White House. Said Reagan: "Our countryman and poet William Cullen Byrant said America is where mankind throws off its last fetters. With your exploits, we loosen one more . . . Through you today, we all feel as giants once again. Once again, we feel the surge of pride that comes from knowing we are the first and we are the best and we are so because we are free. For all Americans, Nancy and I thank you and the thousands of others who have worked to make this day possible."