Donald Roy Pettit ( born 20 April 1955 ) is an American astronaut , a veteran of a six month stay aboard the International Space Station and a six week expedition to find meteorites in Antarctica .
Donald Roy Pettit ( born 20 April 1955 ) is an American chemical engineer and a NASA astronaut . 
 He is a veteran of a six - month stay aboard the International Space Station and a six - week expedition to find meteorites in Antarctica .