Boeing's Starliner and Dream Chaser space plane launch dates delayed.

Sierra Space's Dream Chaser, one of NASA's commercial cargo spacecraft, will delay its first launch to the International Space Station until December, a five-month delay from August, due to unknown reasons. The spacecraft will be launched using a new booster from United Launch Alliance called Vulcan. Vulcan is also facing development issues of its own ahead of flying the two certification missions. This will leave NASA with a single operational rocket type that supplies cargo vehicles: The SpaceX Falcon 9.