Photographs of the Kelly twin brothers

Double duty

Twin studies in space

Twin studies are often used in biology because twins’ shared genes allow researchers to see whether changes or effects are the result of inheritance or environment: the classic nature–nurture question. Only one set of identical twins has been to space so far – Americans Scott and Mark Kelly (although they went separately).

But, in a ground-breaking experiment, the brothers have now agreed to undertake arguably the most ambitious twin study in history. From March 2015, Scott (above, right) is spending an entire year on the International Space Station – more than any American has clocked up before. His brother Mark (above, left) is staying on the ground, matching parts of his brother’s regime and undergoing medical tests throughout Scott’s time in orbit.

NASA selected ten experimental proposals to research during the unprecedented study, covering physiological, psychological and molecular factors. They include looking at gut bacteria, atherosclerosis (the hardening of arteries) and the effects of microgravity on the immune system. The lessons we learn could help us prepare for the long trek to Mars as well as provide insights into diseases here on Earth.

Lead image:

American astronauts and twin brothers Scott and Mark Kelly.



Downloadable resources

About this resource

This resource was first published in ‘Space Biology’ in June 2015.

Genetics and genomics, Ecology and environment
Space Biology
Education levels:
16–19, Continuing professional development