It is similar to the Orion, a spacecraft being built for NASA by Lockheed Martin. The capsule has a diameter of 4.56 meters (15.0 ft), which is slightly larger than the Apollo command module and smaller than the Orion capsule. The Starliner is to support larger crews of up to seven people. The CST-100 is designed to be able to remain on-orbit for up to seven months and for reusability for up to ten missions. It is to be compatible with multiple launch vehicles, including the Atlas V, Delta IV, and Falcon 9, as well as the planned Vulcan. The initial launch vehicle would be the Atlas V.
On September 16, 2014, NASA selected the CST-100, along with SpaceX's Dragon V2, for the Commercial Crew Transportation Capability (CCtCap) program, with an award of $4.2 billion. The spacecraft is expected to fly to the International Space Station with an astronaut aboard by December 2017.