The mission’s fourth and final spacewalk with Mike Fincke and Greg Chamitoff is set to begin at 12:46 a.m. EDT and last approximately six and a half hours. The primary task of the spacewalk is to transfer the Orbiter Boom Sensor System from the shuttle to space station. If all goes as planned, the total number of hours spent spacewalking for International Space Station assembly and maintenance is expected to surpass 1,000.
It will be the last spacewalk by space shuttle crew members. (A spacewalk during the program’s final mission, STS-135, is to be conducted by space station residents.)
At about 8 p.m. Friday, Fincke will become the record-holder for the number of days a U.S. astronaut has spent in space, surpassing Peggy Whitson’s total of 377 days.