Astronaut Scott Kelly’s new space record brings US closer to Mars

International Space Station commander Scott Kelly is now the NASA astronaut with the most cumulative days off planet.

Commander Kelly spent his 383rd day away from Earth Friday, eclipsing two-time space station resident Mike Fincke’s record of 382 days. It’s one of a number of records set to be broken during Kelly’s nearly year-long collaborative space mission with Russian cosmonaut Mikhail Kornienko. The two are tasked to investigate the medical, psychological, and biomedical challenges astronauts face during long-duration spaceflight in preparation for NASA’s eventual mission to Mars.

“The pair arrived at the space station in March and are participating in studies during their 342 days in space that provide new insights into how the human body adjusts to weightlessness, isolation, radiation, and stress of long-duration spaceflight,” NASA reports. “The investigations in progress on the space station will help scientists better understand how to protect astronauts as they travel into deep space and eventually on missions to the Red Planet.”

A mission to Mars could last 500 days or longer, and Kelly and his colleagues are conducting experiments on sleep patterns, the effects of stress, and changes in vision. The crew has also grown lettuce aboard the ISS part of an investigation into not only the possibility of growing food in space, but the potential psychological benefits of gardening activities during deep-space missions.

“The farther and longer humans go away from Earth, the greater the need to be able to grow plants for food, atmosphere recycling, and psychological benefits,” Gioia Massa, NASA payload scientist for Veggie at the Kennedy Space Center in Florida, said in a statement. “I think that plant systems will become important components of any long-duration exploration scenario.”

Kelly’s mission also involves his twin Mark, a former astronaut, who remains on Earth as part of parallel studies that allow scientists to compare the effects of long-term spaceflight on the human mind and body.

“Since we're identical twins, researchers have a first-of-a-kind chance to understand how the human body changes in space. Think of it this way: Scott's the test subject, and I'm the control,” Mark wrote in an essay for NBC in September after his brother passed the six-month mark.

“[W]e are headed into unknown but exciting territory – because we have never had an American in space for such a long period of time,” he added. “We simply don't know a lot about what happens to astronauts in space after six months. Scott's mission is effectively doubling the amount of data we have.”

Kelly is set to break another record Oct. 29, when he spends his 216th consecutive day in space. Astronaut Michael López-Alegría, who holds the current record for the longest spaceflight by an American, spent 215 days in space in 2006.

On Friday, NASA tweeted a video celebrating Kelly’s latest achievement, calling the year-long mission a test of “the limits of human research, space exploration, and the human spirit.” Kelly responded: