Astronauts Give Isaac Newton a Gravity-Free Tribute

Astronauts on the International Space Station have given a zero gravity tribute to famed 17th century scientist Sir Isaac Newton in honor of his pioneering work to understand the laws of gravity ? which they're currently defying.

British astronaut Piers Sellers, while floating in weightlessness on the station, said Thursday that he let a picture of Newton float free alongside a chip of wood from the storied apple tree that inspired Newton's gravitational studies.

"Sir Isaac absolutely loved it, I've got to tell you," Sellers joked. "We had him in the window and he got to watch his little wood chip float by and ponder the laws of gravitation and everything. I think it was a treat for him."

Sellers, a mission specialist on shuttle Atlantis' STS-132 mission, packed the picture and bit of tree with him when he launched May 14. He and five crewmates are about halfway through a 12-day spaceflight to deliver a new room and supplies to the space station.

Sellers brought the memento as a favor for London's Royal Society, thought to be the oldest scientific society in the world.

"I asked the Royal Society if I could fly something for them," Sellers said. "I thought they were going to give me something like a medal, or I don't know, a little telescope or something, but they sent me a piece of Isaac Newton's apple tree."

According to science lore, Newton happened to see an apple fall from the tree, which helped him develop his theory of gravity.

As the apple fell to the ground, Newton wondered if the same force that makes objects fall down toward the Earth might also be responsible for keeping the moon in orbit around the planet, according to the story. It turns out he was correct.

"I've taken this apple tree chip up here and a picture of Isaac Newton, and this'll give him something more to think about I think, 'cause it's floating around, it's not falling," Sellers said.

Sellers and the Atlantis crew are due to stay two more days at the space station before undocking on Sunday. Mission specialists Garrett Reisman and Michael Good are preparing to conduct the mission's third and final spacewalk Friday.

The crew plans to land back at NASA's Kennedy Space Center in Cape Canaveral, Fla. on Wednesday, May 26.

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SPACE.com is providing complete coverage of Atlantis' STS-132 mission to the International Space Station with Senior Writer Clara Moskowitz and Managing Editor Tariq Malik based in New York. Click here for shuttle mission updates and a link to NASA TV.