Stephen Gerard Bowen is a United States Navy submariner and a NASA astronaut; he was the second submariner to travel into space. Bowen has been on three spaceflights, all of which were Space Shuttle missions to the International Space Station. His first mission, STS-126, took place in November 2008, and his second was STS-132 in May 2010.
In March 2011, Bowen completed his third spaceflight as a Mission Specialist on STS-133, which was Space Shuttle Discovery's final planned flight. Having flown on both STS-132 and STS-133, Bowen became the first and only astronaut to fly on consecutive shuttle missions. Originally Tim Kopra was scheduled to fly on STS-133, but Kopra had a bicycle injury shortly before the mission, and so he was replaced by Bowen.