Two astronauts are currently on a six-and-a-half-hour spacewalk outside the International Space Station to replace a failed power regulator, and relocate a failed cooling pump.

The spacewalk, which NASA is livestreaming, started around 8:10 a.m. ET. NASA flight engineers Reid Wiseman and Alexander Gerst of the European Space Agency are conducting Tuesday's spacewalk.

See also: 7 Oddball Things Found on the Space Station



Broadcast live streaming video on Ustream

It's the first of two walks to repair the station. The next EVA (extra-vehicular activity) will take place on Oct. 15. For this EVA, Wiseman and Gerst are wearing U.S. spacesuits that SpaceX's cargo ship delivered in April.

Wiseman and NASA flight engineer Barry Wilmore, who is a newcomer to the space station, will conduct the next spacewalk. It will also last a little more than six hours.

The series of spacewalks are the first for all three astronauts.