The gumdrop-shaped capsule, initially to be launched at least aboard an Atlas-5 rocket, is designed to provide low-cost access to low-Earth orbit and the International Space Station, configured for five people but accommodating as many as seven.
Development of the CST-100, SpaceX’s Dragon and Sierra Nevada’s Dream Chaser spacecraft are being funded in large part by NASA’s Commercial Crew Program (CCP).
So far, NASA has awarded $570 million to Boeing for the design and development of the CST-100.
Boeing, SpaceX and Sierra Nevada are all part of the Commercial Crew Integrated Capability (CCiCap) initiative, but will be competing for NASA's business to ferry astronauts between Earth and orbit.
Astronauts Randy Bresnik and Serena Aunon donned orange launch-and-entry pressure suits and strapped themselves into the capsule mockup to test the interior design.
The astronauts spent a few hours inside the capsule to test maneuverability while Boeing engineers monitored communications equipment, ergonomics and crew interfaces.
"This is our second iteration, our 'Phase 2' iteration, of the interior of the vehicle," Tony Castilleja, a Boeing CST-100 mechanical engineer, told collectSPACE.com. The goal, Castilleja said, was "basically to rapid prototype it and have the NASA customer give us feedback -- the NASA customer being the end user, the NASA astronauts."
Boeing has been a lead space shuttle contractor, and developed the command module for NASA's Apollo program.