Watch astronauts walk into outer space live

NASA astronauts Robert Behnken and Chris Cassidy have launched the first of two recent spacewalks.

to complete a 3.5-year effort to modernize the International Space Station's power system. They will replace batteries in one of the two power channels on the far starboard side of the station (S6 truss).

At 7:10 am ET, the astronauts switched their spacesuits to battery power to begin the spacewalk, which is expected to last six to seven hours.

Today's spacewalk began at 7:35 am ET (11:35 am GMT) and NASA's live feed began at 6:00 am ET (10:00 am GMT).

Behnken will act as lead astronaut duringspacewalk time and will wear a spacesuit with a red stripe. There will be no stripes on Cassidy's spacesuit. This is the ninth spacewalk for both astronauts.

Behnken and crew member Douglas Hurley arrived atspace station in May as part of the Demo 2 mission under the Agency's Commercial Transportation Program. The mission is to test the SpaceX Crew Dragon spacecraft and Falcon 9 rocket - including all launch, in orbit, docking and landing operations - before NASA certification of SpaceX's crew transport system for regular crewed flights to the orbiting laboratory.

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