Expedition 26 Commander Scott Kelly (left) is reunited with his twin brother, Mark Kelly on March 17, 2010, following a flight back to Ellington Field, Houston from Kustanai, Kazakhstan. Scott Kelly landed in Kazakhstan on March 16 with his Russian crewmates in the Soyuz TMA-01M spacecraft after 159 days in space, 157 days on the International Space Station. Mark Kelly is in the final weeks of training as Commander of the final flight of Endeavour, STS-134, that will spend more than a week docked to the ISS. Endeavour is targeted for launch on April 19. Credit: NASA/Rob Navias

Melanie Gosling

Environment Writer

THEY are both astronauts and the only twins ever to have travelled into space.

Mark and Scott Kelly are now to become the focus of a Nasa study which will investigate the effects of a year of space travel on the human body and mind, comparing the effects on Scott, who will spend a year in space, with his twin Mark back on Earth.

The purpose of the research is to better understand the physical and psychological effects of spaceflight in order to help reduce the health impacts of human space exploration.

Craig Kundrot, deputy chairman of Nasa’s Human Research Programme, said in a Nasa video clip that the seed for the research project had been sown in November 2012 when Scott had been selected for a one-year space mission on board the International Space Station. He leaves in March.

“Scott asked: ‘Will there be anything special for Mark back on Earth’?” Kundrot said.

Kundrot said researchers realised that having two individuals with the same genetics, one in space for a year and one on the ground, would present a unique opportunity to do a range of studies. The study would help examine some of the classic “nature and nurture” questions, whether certain distinct behaviours of the body and mind are due to genetics or to environmental and social factors.

“We will compare Scott’s changes to the changes – or lack of changes – to Mark on the ground.”

The study will require the 50-year-old twins to give regular samples of blood, saliva, urine and stool, and they will have to undergo physiological and psychological tests at regular intervals before, during and after the one-year space mission.

Kundrot said there were four key areas of research: The first was molecular level, which was why the body fluids would be tested; the second was the microbiome, the bacteria in the gut and whether and how this changed; the third was the effect on the twins’ physiology, the whole body and the last aimed at behaviour and thinking.

“Spaceflight challenges people in several ways. The study will put us in a position to look at how a human responds to these challenges, and help to understand how our human body functions.”

The Kelly twins were both US navy test pilots before they were selected as astronauts in 1996. They have flown seven missions and served as space shuttle commanders.