Russian Cosmonauts Oleg Kononenko And Nikolai Chub Set A Record-Breaking 374-Day Stay Aboard The ISS, Landing In Kazakhstan With American Astronaut Tracy Dyson. Kononenko Set A New Record For Longest Cumulative Space-Time At 1,111 Days. However, Valeri Polyakov Holds The Record For The Longest Unbroken Space Stay At 438 Days On Mir In 1994-95.