Astronauts and cosmonauts have now spent 1,000 hours spacewalking for assembly and maintenance of the International Space Station. Spacewalkers Mike Fincke and Greg Chamitoff surpassed the 1,000th hour 4 hours and 47 minutes into today’s spacewalk, at 5:02 a.m. EDT. It is the final spacewalk of this mission and the last ever by space shuttle astronauts.