Spanish-American astronaut Michael López-Alegría set the previous record in 2007.
— Scott Kelly (@StationCDRKelly) October 29, 2015
Kelly, who launched in March, is slated to spend a total of 342 days on the International Space Station before returning to Earth. NASA is hoping to learn on how long-term space travel affects the human body ahead of a potential mission to Mars.
On October 16, Kelly passed Michael Fincke's record for most total days in space by a NASA astronaut, with 382. When the 51-year-old astronaut completes his latest mission, he will have spent a total of 522 days in space over four space flights.
— Mark Kelly (@ShuttleCDRKelly) October 29, 2015
Kelly also completed the first spacewalk of his career on Wednesday, performing maintenance tasks on the ISS with fellow astronaut Kjell Lindgren.
— Scott Kelly (@StationCDRKelly) October 29, 2015
The record for longest consecutive spaceflight is held by Russian Valeri Polyakov, who spent nearly 438 days on the former Russian Mir space station. Gennady Padalka, also Russian, has spent a record 878 total days in space.