Snapshots from Atlas 5 launch

United Launch Alliance called off the planned liftoff of a Delta 4-Heavy rocket and a classified National Reconnaissance Office spy satellite from Vandenberg Air Force Base in California on Wednesday after indications of elevated hydrogen concentrations around one of the launcher’s main engines. Three previous launch attempts were scrubbed by technical concerns and bad weather.

NASA’s OSIRIS-REx spacecraft today moved a step closer to starting a voyage to explore an uncharted world in our solar system — the mountain-sized Asteroid Bennu — by joining the booster rocket that will propel it from Earth next week.

Launching the commercial WorldView 4 Earth-imaging satellite for DigitalGlobe, a United Launch Alliance Atlas 5 rocket thunders away from California’s Vandenberg Air Force Base today at 10:30 a.m. local time (1:30 p.m. EST; 1830 GMT).