Snapshots from Atlas 5 launch

Launch of an Atlas 5 rocket from Cape Canaveral with a U.S. Air Force infrared surveillance satellite was scrubbed Thursday evening after engineers encountered a balky valve associated with the first stage’s liquid oxygen system.

NASA announced Monday it will order at least six reusable Orion crew capsules from Lockheed Martin for $4.6 billion to fly astronauts to the vicinity of the moon in the 2020s, and the agency said it plans to purchase hardware for up to 12 Orion vehicles by 2030.

A commercial Cygnus resupply ship named for Robert H. Lawrence, Jr. — the first African American selected as an astronaut — is awaiting liftoff Sunday evening from NASA’s Wallops Flight Facility on Virginia’s Eastern Shore to begin a 35-hour trip to the International Space Station.