Image of the 18-inch by 22-inch waffle aluminum panel as it falls off the shuttle (upper left highlighted area)

• Loose panel called minor problem
• 6 heroes, 1 legend
• 1 million spectators?
• 'PS2, loud and clear'

CAPE CANAVERAL, Florida (CNN) -- Less than an hour after their fiery liftoff into a cloudless Florida sky, John Glenn and the six other astronauts aboard the shuttle Discovery began turning their spacecraft into an orbiting laboratory.

NASA officials also reported what they say is a minor problem that occurred during liftoff.

	COUNTDOWN: Mission News CNN Video Archive Panoramic Photos Tour Mission Control FLASHBACK: Whither the Mecury 7? Shuttle Milestones Gallery: Then and Now LAUNCHPAD: Message Boards Space Chat Glenn-Gram e-mail GAMES: Match the Mission Mission Quiz Crossword Puzzle Crew members Brown Duque Glenn Lindsey Mukai Parazynski Robinson

A panel believed to be the door to a compartment where the drag parachute is stored came loose during liftoff and may have struck one of the engines. The panel was described as being of aluminum waffle construction, 18 inches by 22 inches, and an inch and three-quarters thick. It is also covered with insulation.

NASA official Don McMonagle said that video of the takeoff is being studied to determined whether it was the door, the insulation or something else. But he also said that NASA thinks the incident was unlikely to have any impact on the mission or the landing.

Drag chutes are routinely deployed as shuttles land, but McMonagle said that the early shuttles did not use them and that it is unlikely that there would be any risk should the astronauts be unable to use the chute.

Meanwhile, the astronauts left their launch couches 42 minutes after liftoff and removed their orange launch-and-entry suits in favor of more comfortable clothing. Then they began reconfiguring Discovery's cabin so they can begin working on some of the 83 experiments planned for the eight day, 20-hour mission.

Among the activities planned for Friday is the deployment of a Navy satellite. Glenn, a former Marine and Navy aviator, will assist in the deployment of the satellite.

6 heroes, 1 legend

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As Discovery lifted off at 2:19 p.m., launch control at the Kennedy Space Center sent them off with the wish: "Let the wings of Discovery lift us into the future."

"Liftoff for six American heroes and one American legend," added launch commentator Lisa Malone.

Discovery lifted off at 2:19 p.m., 19 minutes late. The countdown was flawless until about 10 minutes before the scheduled launch, when an alarm sounded inside Discovery's cockpit. Shortly after the count resumed, it had to be held twice more when two private planes intruded into the restricted area.

Moments before the launch, NASA played a greeting from Scott Carpenter, one of the original seven Mercury astronauts and Glenn's backup when he became the first American to orbit the earth in 1962.

"Good luck, have a safe flight, and ... once again, Godspeed, John Glenn," said Carpenter, his voice quivering slightly as he repeated his famous benediction for Glenn's first flight.

The launch, the 123rd in the U.S. space program, makes Glenn the oldest person to go into space and marks his much-anticipated return to space 36 years after his first flight made him an American hero.

Glenn in the "white room" about two hours before liftoff

1 million spectators?

The mission includes launching and recapturing a satellite and testing new hardware for the Hubble Space Telescope, but the presence of Glenn, a hero, U.S. senator and senior citizen as well, clearly was the focus.

NASA official Bruce Buckingham estimated that as many as 1 million people in the area may have watched the launch live, some of them coming from as far away as Toronto, Indiana and St. Louis.

Among those attending were President Clinton and his wife, Hillary, entertainers Jimmy Buffett and Garth Brooks, and thousands of representatives from the media.

President Clinton and first lady Hillary Rodham Clinton watch the launch

So intense was the interest in the launch that NASA took the unusual precaution of arming its security guards with semi-automatic weapons.

In nearby Titusville, the public works department ran out of barricades and portable toilets. "We've asked several surrounding counties for help," Public Works director Jim Herron said.

Veteran observers said the launch frenzy rivaled that of missions to the moon and far exceeded most recent shuttle flights.

'PS2, loud and clear'

Aerial view of spectators on the beach in Titusville, Florida

Glenn and the other astronauts -- Cmdr. Curtis Brown, pilot Steven W. Lindsey, flight engineer Stephen K. Robinson, mission specialists Scott E. Parazynski and Pedro Duque, and payload specialist Chiaki Mukai -- grinned broadly at the technicians as they arrived at the launch pad.

Dressed in baggy orange space suits and white caps, they crawled through the hatch into the shuttle where technicians carefully strapped them into their launch couches.

During a routine communications check from Mission Control in Houston, Glenn replied vigorously, "PS2, loud and clear," at his turn. PS2 stands for payload specialist 2, the lowest-ranking member of the crew.

Glenn first captured national attention on February 20, 1962, by orbiting the Earth three times in a one-man Mercury capsule he called Friendship 7. Eventually he turned to politics and is completing his fourth and final term as a U.S. senator from Ohio.

Glenn persuaded NASA to put him on a shuttle crew to study the effects of aging in space and provide information that he said would be valuable to astronauts and the elderly on Earth alike.

He will serve as a medical guinea pig in 10 experiments measuring the effects of weightlessness on the human body. Doctors examining Glenn said he had the body, strength and stamina of a much younger man.

The Discovery is due to return to Kennedy Space Center at Cape Canaveral at 11:50 a.m. Saturday, November 7.

The Associated Press contributed to this report.