Photos: Tuesday’s Atlas 5 rollout

Two astronauts floated outside the International Space Station Sunday for the first in a series of spacewalks to upgrade the lab’s aging solar power system, assembling a support fixture that eventually will hold a new solar blanket.

Follow the unclassified portion of the Atlas 5 rocket’s ascent to space from Cape Canaveral’s Complex 41 launch pad with the U.S. National Reconnaissance Office’s NROL-61 satellite. Launch is scheduled for Thursday at 8:37 a.m. EDT (1237 GMT).

The U.S. Defense Department’s internal watchdog has opened a probe into whether the Pentagon’s contracts with United Launch Alliance were properly awarded after a former ULA executive implied the government rigged a recent procurement in favor of the company.