U.S. astronaut Gene Cernan, the last person to walk on the moon, died at the age of 82 on Monday, NASA announced. No cause of death was given, but Cernan was said to have been surrounded by family when he passed. Cernan, who traveled to space three times as an astronaut, took part in NASA’s last lunar mission—in 1972. “We’d like to dedicate the first steps of Apollo 17 to all those who made it possible. Oh my golly! Unbelievable!” he said at the time, describing a moment that he would continue to express awe over for the rest of his life. Cernan piloted the Gemini 9 mission in 1966 and served as the lunar module pilot of Apollo 10 in May 1969, before taking part in NASA’s final trip to the moon. He was one of only three people to have traveled to the moon twice, and he spent much of his post-NASA life encouraging young people to think big. “Dream the impossible—and go out and make it happen. I walked on the moon. What can’t you do?” he once said, according to NPR. Cernan leaves behind a wife, a daughter, son-in-law and step-daughters, as well as nine grandchildren.