International Space Station (ISS) Mission Commander Jeff Williams, returned to Earth today after clocking up a cumulative total of 534 space-days. Along with fellow Expedition 48 Russian cosmonauts Alexey Ovchinin and Oleg Skripochka, Colonel Williams touched down outside Dzhezkazgan in Kazakhstan on September 7 at 7:13 am local time (September 6 at 9:13 am PDT) in the Soyuz TMA-20M capsule.

This marked the completion of Williams' fourth mission. His first visit to the ISS was in 2000 when the station was still under construction, and on his latest mission he carried out two spacewalks, one of which was to complete the installation of a new docking adaptor to accept manned commercial spaceflights and another that retracted a spare thermal control radiator and installed two new high-definition cameras.

Though Williams is the most experienced US astronaut, the single-longest flight by NASA is still held by Scott Kelly, who spent 340 days in space on a single ISS visit. The Russian single-flight record set by Valeri Polyakov aboard the Mir space station is 437-days, and the all-time cumulative space endurance record is held by cosmonaut Gennady Padalka, who clocked up 879 days over five missions to Mir and the ISS.

"No other US astronaut has Jeff's time and experience aboard the International Space Station," says Kirk Shireman, ISS Program manager at NASA's Johnson Space Center in Houston. "From his first flight in 2000, when the station was still under construction, to present day where the focus is science, technology development and fostering commercialization. Jeff even helped prepare the space station for future dockings of commercial spacecraft under NASA's Commercial Crew Program. We're incredibly proud of what Jeff has accomplished off the Earth for the Earth."

The video below shows the Soyuz spacecraft separating from the ISS before returning to Earth.

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