American astronaut Scott Kelly returns from space younger than his twin

Strange discovery: Scott Kelly (right) returned from space younger than his twin Mark (left)
Robert Markowitz/NASA
Fiona Simpson3 February 2017

An American astronaut has returned from space younger than his twin, scientists have said.

Scott Kelly was subjected to a number of tests after he landed in Kazakhstan last year following 340 days in space.

The same tests were also carried out on his identical twin brother Mark.

Scott was found to be 2ins taller and 15lb lighter than when he travelled in to space.

Twins: Mark Kelly and Scott Kelly are both astronauts 
Robert Markowitz/NASA

Now, researchers have discovered a growth in the 52-year-old’s telomeres - repetitive sequences at each end of a chromosome, The Times reported.

Telomeres typically shrink with age, however, Scott’s grew longer than his brother’s before shrinking back after a few months on Earth.

The discovery could jeopardise future space expeditions as the lengthening of telomeres has been linked with cancer.

Christopher Mason, assistant professor of physiology and biophysics at Cornell Weill Medicine in New York, told the Times: “It may be because the astronauts exercise extremely regularly on the International Space Station (ISS).

“On Earth you might go to the gym on Tuesday and then decide you can’t be bothered on Thursday and go to the pub, but you can’t do that on the ISS.

“Food and exercise are very controlled and you don’t have so many margaritas.”

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