Video: OA-7 Cygnus freighter arrives at its orbital destination

The most powerful Atlas rocket to ever fly from the West Coast is poised for launch Thursday to deliver a secret payload into orbit while debuting a new upper stage engine.

A Soyuz rocket arrived at a historic launch pad in Kazakhstan on Tuesday, where ground crews lifted the booster vertical to begin final preparations for liftoff Thursday with two Americans and one Russian heading for the International Space Station.

A $66 million NASA-funded science sensor package bolted on to a commercial communications satellite is ready for a ride toward a 22,000-mile-high orbital perch Thursday on a European Ariane 5 rocket, commencing a two-year mission surveying a rarely-studied region of Earth’s upper atmosphere.