MELBOURNE, Fla. -

Boeing on Monday showed off a mockup of a spacecraft that could be the first to carry astronauts from the Space Coast into orbit since the shuttle's retirement nearly three years ago.

U.S. Sen. Bill Nelson climbed into the CST-100 capsule inside the former shuttle engine shop at Kennedy Space Center, where Boeing plans to assemble and test the capsule's service module, Local 6 News partner Florida Today reported.

"We look forward to manufacturing CST-100 right here in this facility," said John Elbon, vice president and general manager of Boeing Space Exploration.

Boeing is one of three companies hoping to win a NASA contract in August or September to launch crews to the International Space Station by 2017.

That work could eventually mean up to 550 jobs in the engine shop and a former orbiter hangar that are being renovated with state support.

Nelson called the event a celebration of a great public-private partnership.

The capsule itself, occupied by two mock astronauts in orange pressure suits, featured five black seats with an overhead display and tablets for the crew, blue interior lighting and room for some small cargo bags.

The CST-100 would launch atop United Launch Alliance's Atlas V rocket. ULA displayed a model of an access tower the company plans to build to support crewed missions from Launch Complex 41.

If it wins a contract, Boeing plans to launch an uncrewed test flight in early 2017 and then a crewed test flight by mid-2017.

Nelson said the CST-100 and its competitors "are paving the way to a whole new era in spaceflight" marked by more commercial operations.

Boeing's event came nearly two weeks after SpaceXunveiled a Dragon capsule designed to carry astronauts. Sierra Nevada also is competing to fly crews in its Dream Chaser mini-shuttle.