A piece of Sir Isaac Newton's apple tree is being carried into zero-gravity space on the next Nasa shuttle mission.
The section of wood, from the original tree from which the apple fell that inspired Newton's theory of gravity, is normally held in the Royal Society's archives.
It was lent to British-born astronaut Dr Piers Sellers, who will be taking it into orbit, as part of the academic institution's 350th anniversary celebrations.
The tree sample will be accompanied on its trip into space by an image of Sir Isaac, also donated by the Royal Society.
Dr Sellers said: "We're delighted to take this piece of Sir Isaac Newton's apple tree to orbit. While it's up there, it will be experiencing no gravity, so if it had an apple on it, the apple wouldn't fall.
"I'm pretty sure that Sir Isaac would have loved to see this, assuming he wasn't spacesick, as it would have proved his first law of motion to be correct. After the flight, we will be returning the piece of tree and a flown picture of Sir Isaac Newton back to The Royal Society."
Lord Rees, Sir Isaac's successor as the current president of the Royal Society, said: "We are both pleased and proud that such an extraordinary part of scientific history and important element of the Royal Society's archive collection can make this historic trip into space.
"Upon their return the piece of tree and picture of Newton will form part of the History of the Royal Society exhibition that the Society will be holding later this year and will then be held as a permanent exhibit at the Society."
Nasa's space shuttle Atlantis will lift off for its final, 12-day mission, on May 14 carrying six crew members including Dr Sellers.
Dr Sellers was born in Crowborough, Sussex, in 1955. He was selected as an astronaut candidate by Nasa in 1996.