Eleven school experiments that spent nearly four years outside the International Space Station were returned to students by NASA on Wednesday.

"It was our pleasure to take them up there. ... We can't wait to find out how they behaved," Patrick Forrester, one of two spacewalking astronauts who mounted the experiments outside the station, told students during a program at the National Museum of the United States Air Force.

Forrester presented the experiments with Frederick Sturckow (search), the space shuttle Discovery's pilot on the mission.

Elementary and secondary students at 14 Ohio and Kentucky schools spent two years designing experiments to study how the harsh environment of space would affect clothing, germs, seeds and other items.

The experiments were to spend about a year outside the station, piggybacking on two science racks designed by researchers at Wright-Patterson Air Force Base (search).

But the Columbia explosion in February 2003 caused NASA to ground its shuttle fleet for more than two years, disrupting space station activities. The experiments languished on their 240-mile-high perch far longer than anyone had planned.

Another Discovery crew finally retrieved them in July on the first shuttle mission since Columbia.

Only a few among the roughly 500 students who attended the program were among the original experimenters.

The students, though, hadn't lost their enthusiasm for the project, said Ryan Becraft of Piner, Ky., a 2003 Simon Kenton High School (search) graduate.

"I didn't forget about it. I knew when it was coming back," said Becraft, who said the experiment exposed pine seeds to space.

The pine seeds will be planted outside the school, said Bill Schneider, Becraft's science teacher who supervised the experiment. If they germinate, future students will monitor the trees' growth.