Updated: 2007-08-15 20:37

HOUSTON - After days of anxiety about a gouge in the belly of the shuttle Endeavour, NASA finally got some good news: tests suggested repairs may not be needed, and the agency fulfilled a longstanding dream of a teacher talking to students from space.

This image provided by NASA shows the Space Shuttle Endeavour's orbital maneuvering system (OMS) pods and vertical stabilizer backdropped by the blackness of space in this image photographed by a crewmember while docked with the International Space Station during STS-118 flight day six activities Monday Aug. 13, 2007. [AP/NASA]

Space agency managers said they were cautiously optimistic that they wouldn't have to send two spacewalking astronauts to repair the gash, which is about the length and width of a business card. A sliver of the wound penetrates through a pair of inch-deep thermal tiles, exposing a thin felt fabric that is the final barrier before the shuttle's aluminum frame.

But thermal analyses have so far shown Endeavour could safely return to Earth as it is, said John Shannon, chairman of the mission management team. All the testing and analyses should be completed by Wednesday.

In another positive development, two decades after Christa McAuliffe's doomed Challenger mission, her backup in the teacher-in-space program carried out the dream of an educator turning the space shuttle into a classroom.

Teacher-astronaut Barbara Morgan took questions and spoke to hundreds of youngsters packed into the Discovery Center of Idaho in Boise, less than 100 miles from the elementary school where Morgan taught before joining the astronaut corps.

One child wanted to know about exercising in space. In response, Morgan lifted the two large men floating alongside her, one in each hand, and pretended to be straining. Another youngster wanted to see a demonstration of drinking in space. Morgan and her colleagues obliged by squeezing bubbles from a straw in a drink pouch and swallowing the red blobs, which floated everywhere.

Morgan was also asked how being a teacher compared to being an astronaut.

"Astronauts and teachers actually do the same thing," she answered. "We explore, we discover and we share. And the great thing about being a teacher is you get to do that with students, and the great thing about being an astronaut is you get to do it in space, and those are absolutely wonderful jobs."

Morgan's 19-year-old son, Adam, wrote and performed Wednesday morning's wakeup song, "Good Morning, World": "Wake up big shuttle crew, you've got a lot to do," he crooned, accompanied by a guitar. "Orbiting over land, but don't forget the view/Outside your window lies your world in brown and blue/So proud of you."

The Endeavour crew is halfway through their two-week mission to the international space station. The astronauts have completed most of their main goals, including attaching a new truss segment to the space station and replacing a gyroscope that helps control the station's orientation.

In a spacewalk scheduled for Wednesday, astronauts Clay Anderson and Rick Mastracchio were to perform tasks to prepare one of the station's solar arrays to be moved to another spot on the orbiting outpost during a later mission.

Any repairs to Endeavour would be conducted during the shuttle's fourth spacewalk, scheduled for Friday. If more time is needed to prepare, NASA will keep the shuttle at the station longer and bump the spacewalk to Saturday.

The gouge on Endeavour was not considered a threat to the crew, but NASA was debating whether to send astronauts out to fix it in order to avoid time-consuming post-flight repairs.

The hole on space shuttle Columbia was considerably bigger and in a wing, which is exposed to higher temperatures than the 2,000 degrees that scorch the ship's underside during re-entry.

Even though the repair itself would be relatively simple, the astronauts would be wearing 300-pound spacesuits and carrying 150 pounds of tools that could bang into the shuttle and cause more damage. All spacewalks are hazardous, Shannon noted, and so NASA would not want to add more outside work unless it was absolutely necessary.

A piece of foam broke off of Endeavour's external fuel tank during the Aug. 8 liftoff. The debris, which may have contained some ice in it as well, weighed less than an ounce, and was 4 inches long, almost 4 inches wide and almost 2 inches deep. It peeled away from a bracket on the tank, fell against a strut lower on the tank, then shot into the shuttle's belly. It weighed less than an ounce.

These brackets, which hold in place the fuel lines that feed the tank, have shed foam more frequently since shuttle flights resumed following the 2003 Columbia disaster, Shannon said. Engineers speculate more ice could be forming on these brackets because the super-cold fuel is being loaded an hour earlier than before.

NASA is redesigning the brackets, but the new ones won't be ready until next year.