Almost a year in space caused an astronaut’s gene expression to change and his immune system to enter high alert, researchers announced on Friday.

Identical twins Mark and Scott Kelly, both US astronauts, are participating in a unique study into the biological toll of space travel on humans.

Led by Cornell Medicine, the study compared data collected from earth-bound Mark and space-bound Scott.

They found that prolonged space presence changed which of Scott’s genes switched on and off. Though Scott’s gene activation pattern mostly regained normalcy back on Earth, 7% of the changes in expression remained when the study ended.

Last year, researchers had already reported increased DNA repair rates, mitochondria in blood, and immune hyperactivity.

Ahead of new challenges like the Mars missions, NASA directors found the latest findings “encouraging”.

Commercial interest in extraterrestrial minerals has skyrocketed, and more nations seek space presence.

NASA recently involved private-sector companies in its $2.6 billion Commercial Lunar Payloads programme. The space industry’s predicted value within 30 years is $3 trillion.

As business ventures enter the fray, both martian exploration and lunar prospecting become more likely.

But what effect will extreme space travel have on the human genome?

Page 2 of NASA's pdf explaining the various molecular systems being examined by the Twins Study. Source: NASA

Credit for this article's header image goes to NASA.