After Endeavour launched into the clear blue sky and reached orbit with teacher-astronaut Barbara Morgan aboard, Mission Control announced that class was in session.

Morgan, zooming with the other crew members toward the international space station, was finally fulfilling the space program’s quest to send an educator into space — a dream that could have died in 1986 with the Challenger explosion that killed teacher Christa McAuliffe and six astronauts.

Once Endeavour was safely past the 73-second mark of the flight, the moment when Challenger exploded, Mission Control exclaimed that Morgan — McAuliffe’s backup for Challenger — was “racing toward space on the wings of a legacy.”

Immediately after the shuttle reached orbit, Mission Control announced: “For Barbara Morgan and her crewmates, class is in session.”

Endeavour was scheduled to dock with the space station on Friday afternoon, after astronauts spend a day checking for possible damage from debris shaken loose during Wednesday’s launch. Midway through the flight, Morgan will speak with students in Idaho, where she taught elementary classes before moving to Houston in 1998 to become the first teacher to train as a full-fledged astronaut. If the mission is extended from 11 days to 14 days as planned, thanks to a new station-to-shuttle power converter, she’ll also have a chance to answer questions from students in Virginia and Massachusetts.

But Morgan’s primary responsibility in orbit will involve helping to operate Endeavour’s robot arm and overseeing the transfer of cargo from the shuttle to the station.

The rest of the crew will be busy installing a huge square-shaped beam to the exterior of the station and replacing a broken gyroscope. Three spacewalks are planned; a fourth is possible. Late Wednesday, Morgan, 55, was all-business as she periodically updated Mission Control on the activation of the shuttle’s cargo-carrying module.

The astronauts were to spend much of Thursday using a 50-foot laser boom on the end of the robot arm to inspect the shuttle’s wings and nose. The scan for damage from fuel-tank insulating foam and other debris from launch, or micrometeorites in space, has been standard procedure ever since Columbia’s catastrophic re-entry in 2003.

Bill Gerstenmaier, NASA’s space operations chief, said early checks showed four or five small pieces of debris from the external fuel tank came off during launch. He said it happened too late to cause concern.

NASA is hoping a successful flight will draw attention from the rash of embarrassments it has faced this year. Most recently, a NASA-commissioned medical panel’s report suggested astronauts were intoxicated on launch day on at least two occasions.

NASA Administrator Michael Griffin said the televised preparations for Wednesday’s launch demonstrated how difficult it would be for an astronaut to drink before takeoff.

“I would defy anyone to find an opportunity they had to do any drinking from the time they woke up this morning,” Griffin said. “They would have to really want to drink and hide it really well.” Endeavour’s liftoff had been scheduled for Tuesday, but last week NASA delayed the flight by a day because a leaky valve in the crew cabin needed to be replaced. This is Endeavour’s first flight since 2002. The shuttle underwent a massive overhaul and was outfitted with complete satellite navigation, improved main engine monitoring equipment and a new system for transferring power from the station to the shuttle. The extra power will allow the shuttle to remain docked at the space station longer than ever before.

Besides Morgan, the crew includes Navy Cmdr. Scott Kelly, the commander; Marine Lt. Col. Charles Hobaugh, the copilot; Rick Mastracchio, Tracy Caldwell, Air Force Col. Alvin Drew and Canadian physician Dave Williams.