Astronaut Don Pettit is carried to a medical tent after he and Roscosmos cosmonauts landed in their Soyuz spacecraft near the town of Zhezkazgan, Kasakhstan on sunday. (Photo credit: Bill Ingalls/NASA)

April 20 (UPI) -- Veteran NASA astronaut Don Pettit celebrated his 70th birthday as he returned to Earth from a seven-month stay at the International Space Station, during which he completed Expeditions 71 and 72.

Pettit is the oldest currently serving astronaut in the U.S. and has flown to space four times, logging some 590 days in orbit throughout his career. He is the second-oldest American astronaut to visit space after John Glenn's famed 1998 mission at the age of 77.

The Soyuz spacecraft seen as it lands (Photo credit: Bill Ingalls/NASA)

"The feeling of being home is directly proportional to how far you have traveled. When going out to dinner, you feel home when pulling into the driveway," Pettit wrote in a post on social media ahead of his return.

"When our capsule goes thump on those desert flats, I will be literally on the opposite side of Earth, nearly 12000 miles from home. Yet I will be home. I can picture sometime in the future, a crew returning from Mars and after inserting themselves into low Earth orbit, they will look down at this blue jewel circling below and say, 'I am Home.'"

Pettit on Saturday evening returned to Earth aboard a Russian Soyuz MS-26 spacecraft that landed in a remote area near the town of Zhezkazgan, Kazakhstan, with Roscosmos cosmonauts Alexey Ovchinin and Ivan Vagner. The crew left the space station around 5:57 p.m. EDT on Saturday before landing around 6:20 a.m. Kazakhstan time on Sunday.

NASA said in a news release Saturday that the three crew members, after landing, would then fly on a helicopter from the landing site to the recovery staging city of Karaganda, Kazakhstan. Pettit would then return home to Houston on a NASA plane.

Pettit first went to space as a science officer during Expedition 6, launching aboard Space Shuttle Endeavour in November 2002 and returning in May 2003 aboard a Russian Soyuz capsule after the Columbia disaster grounded the shuttle fleet.

The astronaut again voyaged to the ISS for a 15-day stay in 2008 to deliver equipment and supplies to enable larger crews to stay at the space station. He was then on-board the ISS again in 2012 when he participated in the first capture and berthing of a commercial spacecraft, the SpaceX Dragon, to the ISS.

During his most recent visit, Pettit conducted research to enhance the capabilities of in-orbit metal 3D printing and advance water sanitization technologies, NASA said in a news release. He also explored plant growth under varying water conditions and investigated fire behavior in microgravity.

Beyond his scientific work, the astronaut is also popular with the public for his unique astrophotography, capturing artistic photographs of Earth as seen from space.

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