NASA’s oldest serving astronaut Don Pettit has returned to Earth on his 70th birthday after concluding a seven-month science mission aboard the International Space Station.  Don, along with Roscosmos cosmonauts Alexey Ovchinin and Ivan Vagner, landed in Kazakhstan on Sunday aboard Soyuz MS-26. Pettit has logged 590 days in orbit throughout his career and this one was his fourth spaceflight.