A pair of astronauts are out on a spacewalk 220 miles above Earth, getting ready to install a new set of solar wings at the international space station.
It's the top job for the space station and shuttle Discovery crews.
Spacewalkers Steven Swanson and Richard Arnold II floated outside early Thursday afternoon. They will help hook up the $300 million framework that contains the folded-up wings.
The shuttle delivered the new wings this week. It's the last set of solar wings to be installed at the 10-year-old space station and will bring it to full power.
Thursday's spacewalk is the first of three planned for Discovery's space station visit. There should have been four spacewalks, but delays in launching the shuttle cut the mission short.