Students at Fairfax County’s Colvin Run Elementary made an unusual long-distance phone call Tuesday, connecting with NASA astronauts orbiting Earth aboard the International Space Station.

The video conference was part of a NASA effort to promote science in schools and allowed 19 curious students the rare opportunity to pose questions about the effects of gravity, or lack thereof, to the astronauts as they floated upside down in space.

Or at least upside down from the youngsters’ perspectives inside the Colvin Run gym in Vienna, as flight engineer Reid Wiseman explained to the students that because there is no gravity in space, there is no “up” or “down” either. Wiseman pointed out that he even sleeps “on the ceiling” of the space station.

“Without the effect of gravity, even eating M&M’s becomes difficult,” Wiseman said, noting that he trained for more than two years to prepare for his space mission. Once he arrived and experienced the disorienting lack of gravity for the first time, “it was as if I had never trained for anything.”

Space station commander Steve Swanson helped demonstrate to the students how a paper airplane doesn’t so much as fly in space as float. Wiseman described how the astronauts aboard the station had recently grown heads of lettuce and onions in space.

Through a special phone hookup at the school, sixth-grader Mia Parnaby was able to ask the astronauts about how low gravity affects human bone density and muscle mass. The astronauts pointed out that being in such a low-gravity environment forced them to work twice as hard to stay in shape, exercising two hours a day to keep their muscles from losing strength.

As the two astronauts spoke, they told the students they were hurtling above the planet at 17,500 miles per hour. Swanson and Wiseman each performed flips in the air as they talked to the students, sometimes taking their hands off their microphone, letting it hover near their lips as they spoke.

“It’s just like being a kid and finding the best playground on the planet and getting to live there,” Swanson said.

Principal Ken Junge said that preparations for the event, which lasted about 30 minutes, began a month ago. He said the school applied for the special chance to talk with the astronauts by promoting Colvin Run’s ample science programs and laboratory work. Junge said that students build Lego robotics models in class, “experiencing science the way it’s meant to be: hands-on.”

The Colvin Run students also met Dan Tani, a former NASA astronaut who had hands-on experience on the space station. Tani, a Great Falls resident who lives close to Colvin Run, spent four months in 2007 and 2008 on the station.

He said he completed multiple space walks, known as an extravehicular activity, totaling about 36 hours outside of the station.

“Inside the space suit, you are your own satellite equipped with everything you need for hours,” Tani said. “The view is spectacular. But I just kept thinking ‘Don’t screw this up.’”

After duties during the day, Tani said he relaxed by watching DVDs of the old “Get Smart” spy series and reviewing the 1,000 pictures he’d take daily from space.

Speaking to the students, he said, was exciting “to hear how young minds think through the questions they ask.”

Sixth-grader Kavye Vij, 12, said that it was neat to talk to someone in space from Earth. He wants to pursue a career in medicine, but he’s unsure if he’d like to be an astronaut.

“The scarier part would be going up in space,” Vij said. “They said its like a roller coaster, and they kind of freak me out.”