Meet Scott and Mark Kelly, the brothers who were at the centre of NASA's twins study on astronauts

Scott Kelly, a former astronaut, was on Fox News with anchor Bret Baier to discuss the return of NASA astronauts Butch Wilmore and Sunita Williams from the International Space Station (ISS).He has an identical twin brother, Mark Kelly, also a NASA astronaut and a Democratic senator from Arizona.

Who is Scott Kelly?

Scott Kelly is a former military fighter pilot, test pilot, engineer, retired astronaut, and US Navy captain. He has completed four space flights and has commanded the International Space Station (ISS) during three expeditions, according to his website.

Scott holds the record for the the most cumulative days spent in space, completing the longest single space mission by an American astronaut in October 2015. He was on a year-long mission aboard the ISS. The former astronaut now resides in Houston, Texas.

Who is Mark Kelly?

Mark Kelly is a retried US Navy captain, former astronaut and is currently the senior senator from Arizona, a position he has held since 2020.


Last week, Mark was seen parting ways with his Tesla in a video, stating that he did not anticipate it becoming "a political issue" at the time of purchase.

He expressed his discontent with President Donald Trump and the Department of Government Efficiency (DOGE) led by Elon Musk, stating that he now finds it difficult to continue driving the car.

NASA's Twins Study

NASA conducted a twins study from 2015 to 2018 and the Kelly brothers participated in it. The study examined the effects of long-duration spaceflight on the human body. While Scott spent 340 days in space, Mark remained on Earth as a control subject. Scientists compared the twins before, during, and after Scott's mission to understand how the space environment impacts the body at molecular, physiological, and psychological levels.