After the flight, the wood will be returned to London
A piece of Sir Isaac Newton's apple tree will "defy" gravity, the theory it inspired, when it is carried into space on the next Nasa shuttle mission.
The wood sample is from the original tree from which an apple fell, leading Newton to devise his theory of gravity.
The sample, which is normally held in the Royal Society's archives, has been lent to British-born astronaut Dr Piers Sellers, who will take it into orbit.
The Atlantis shuttle will lift off for on 14 May carrying six crew members.
The 12-day mission is expected to be the Nasa orbiter's last.
The move is part of the Royal Society's 350th anniversary celebrations.
The tree sample will be accompanied on its trip into space by an image of Sir Isaac, which was also donated by the Royal Society.
Dr Sellers, who was selected as an astronaut candidate by Nasa in 1996, said he and the other team members were "delighted" to be taking a piece of the historic tree into orbit.
The astronaut quipped: "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."
Sir Isaac, a physicist and mathematician, is widely regarded as being one of the greatest scientists of his era.
'Pleased and proud'
He recounted the story that inspired his theory of gravitation to scholar William Stukeley and it later appeared in Stukeley's 1752 biography, Memoirs of Sir Isaac Newton's Life.
An image of Sir Isaac Newton will accompany the tree sample into space
In the story, Sir Isaac claimed to have been inspired by a falling apple in his garden to investigate the theory of gravitation.
After the spaceflight, the tree sample and picture will be returned to the Royal Society.
Lord Rees, the academic institution's current president, said it was "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".
He said the piece of tree and picture of Sir Isaac will go on to 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.