Barbara Morgan, the teacher turned astronaut responded on Tuesday to questions sent from students on Earth.

Together with her crewmates Alvin Drew and Dave Williams, Morgan talked for 25 minutes to children at the Discovery Center in Boise, Idaho.

"Astronauts and teachers actually do the same thing. We explore, we discover and we share," she told the class via videolink. "Those are absolutely wonderful jobs."

Barbara Morgan’ association with NASA began more than 20 years ago. Initially Morgan was selected as the backup candidate for the NASA Teacher in Space Program on July 19, 1985.

From September 1985 to January 1986, Morgan trained with Christa McAuliffe and the Challenger crew at NASA’s Johnson Space Center, Houston, Texas. After the Challenger accident Morgan resumed her career as teacher, but she was selected by NASA as a mission specialist in January 1998.

Tuesday’s session was just the first of the three educational events programmed during the Endeavour mission.

Morgan and astronauts Dave Williams, Alvin Drew and Clay Anderson talked about their training, demonstrated the Earth's rotation using a ball and chased drops of juice to show how they stay hydrated.

Questions ranged from the serious, "Can you see global warming from space?" to the more light-hearted, "How fast can you throw a baseball in space?"

The answers: global warming is a long process that you cannot observe in only a short flight, and you can "throw" a ball slowly by simply letting go, but a faster throw might damage the inside of the space station.

Morgan has said she thinks of her friend and the other Challenger astronauts every day and says her experiences as a teacher transfer well to her duties in space.

Earlier Tuesday mission specialists Tracy Caldwell and Barbara Morgan used Endeavour’s robot arm to lift ESP-3 out of the payload bay and to hand it off to the station arm. STS-118 Pilot Charles Hobaugh and Expedition 15 Flight Engineer Clay Anderson used the station arm to attach the platform to the station’s Port 3 truss segment.

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.

Inside the shuttle/station complex, cargo transfers between the two spacecraft continue.

Meanwhile NASA announced that mission managers have determined that damage to a small section of Endeavour’s heat shield poses no threat to crew safety or mission operations.

Sunday’s inspection revealed that the gouge, located near the ship's right wheel well, is 30.5 x 25.5 millimeters (1.2 x 1.0 inches) large (smaller than initially reported) and 28.5 millimeters (1.12 inches) deep. During take off, debris tore a gash in tiles on the underside of the shuttle.

Though a decision about whether to patch the hole during a spacewalk before Endeavour leaves the International Space Station is expected by late Wednesday.

Officials might chose to repair it to make preparations for Endeavour's next flight easier.

According to NASA a computer analysis completed Tuesday and based on the data sent in after Sundays’ inspection indicated the aluminum behind the damaged tile would not exceed 350 degrees, which would be acceptable, but engineers said the test of the model would provide more information.

Any repair will be made during the fourth spacewalk scheduled for Friday, but NASA is considering the possibility to keep the shuttle at the station longer and to bump the spacewalk to Saturday.

NASA officials already extended the ongoing of the US space shuttle Endeavour at the orbiting International Space Station (ISS) with three more days. Under the new schedule, Endeavour is to decouple from the space station on August 20 and to land on August 22.

Initially, Endeavour’s mission was intended to last 11 days, but NASA announced the possibility to add three more days because the Station-to-Shuttle Power Transfer System allows the Endeavour crew to conserve the shuttle's battery power.