Former astronaut and retired U.S. Navy Commander John Herrington has resigned from Rocketplane Global, an Oklahoma company which hopes to offer commercial space travel. Herrington, who was hired in September 2005 as the company's vice president and director of flight systems, resigned on Dec. 21, according to a news release from the Chickasaw Nation media relations office. Herrington is a member of the Chickasaw Nation. He became the first American Indian to fly in space in 2002, when he was a mission specialist on the space shuttle Endeavour. Herrington did not immediately return an e-mail message sent Thursday morning, and Rocketplane's chairman and chief executive officer, George French Jr., did not immediately return a phone message left Thursday at the company's Oklahoma City office. Herrington has retired from the Navy and from NASA. When he joined Rocketplane, plans were for him to serve as the pilot on the first test flight of Rocketplane XP in 2006 and to fly commercial spaceflights that were expected to begin this year. But the company has yet to get its spacecraft off the ground and NASA dropped a multimillion dollar space transportation agreement with Rocketplane Global's sister company, Rocketplane Kistler, in October. "I was fortunate during my tenure at Rocketplane to work with an incredibly talented group of professionals," Herrington said in a statement issued by the Chickasaw Nation. "My decision to leave was a difficult one." Herrington said in the release that he plans to continue working in the commercial space industry, because he believes "commercial space is the next great adventure in aerospace." He said he will continue working with the Chickasaw Nation, for which he has appeared in television commercials, and to serve as an adviser to the national Institute for Space, Science and Security Centers at the University of Colorado at Colorado Springs.