LOUISVILLE, Colo. — Sierra Nevada Corporation (SNC) says it’s ready to proceed into final assembly and testing of its first Dream Chaser cargo spacecraft, as the company retains plans to eventually develop a crewed version of the vehicle.

At a media event at a company facility here, SNC took possession of the primary structure of the first orbital Dream Chaser vehicle. That structure was built for SNC by Lockheed Martin and recently shipped from a Lockheed facility in Fort Worth, Texas, to SNC.

“This is a really, really complex structure,” said Steve Lindsey, SNC senior vice president of space exploration systems. The company described the structure as one of the most complex all-composite structures ever built in the aerospace industry, serving as the fuselage of the vehicle and the structure around which the rest of the vehicle will be assembled.

Lockheed Martin contributed to the construction using both its space and aeronautics expertise, the latter coming from a facility that makes composite structures for the F-35 fighter aircraft. “We took our space knowhow in our Lockheed Martin space business area and integrated that with our aeronautics division and their manufacturing capabilities to bond composites together,” said Lisa Callahan, vice president and general manager of commercial civil space at Lockheed Martin.

John Curry, the Dream Chaser program director for its Commercial Resupply Services (CRS) 2 contract with NASA, said the other components of the vehicle, including the two wings and a separate cargo module, will arrive late this year and early next year. The goal, he said, is to have the vehicle fully assembled and tested by April 2021.

SNC will then fly the vehicle on a C-5 Galaxy cargo aircraft to NASA’s Plum Brook Station in Ohio for three months of environmental testing. That will include acoustics, vibration and thermal vacuum tests. From there, the spacecraft will be flown to the Kennedy Space Center for final preparations for its launch on a United Launch Alliance Vulcan rocket no earlier than September 2021.

That mission is the first of at least six under the company’s CRS-2 contract to transport cargo to and from the International Space Station. It will join Northrop Grumman’s Cygnus and SpaceX’s Dragon spacecraft, which have been providing cargo delivery services for several years under the original CRS contract and will continue to do so, with some upgrades, under CRS-2.

Kirk Shireman, NASA’s ISS program manager, welcomed the upcoming addition of the Dream Chaser to the fleet of vehicles supporting the station. “This vehicle really offers unique capabilities,” he said. Its cargo capacity to the station of 5,500 kilograms will be the largest of any of the cargo vehicles, and its ability to land on runways will give crews immediate access to cargo. “We’re really looking forward to having this capability.”

Those missions can, in theory, be handled by a single Dream Chaser vehicle. Curry noted that the vehicle is designed to fly at least 15 times. However, the company expects to build more to meet additional demand it foresees developing.

“We’re already working with Lockheed and others, looking at that second structure and when we’re going to start that. Our intent has always been to build a second vehicle,” Lindsey said. Additional vehicles will depend on demand, but, he said, “our intent is to build a fleet of these.”

While SNC received some NASA commercial crew awards to start development of Dream Chaser, Lindsey said the company has invested a “huge amount of money” to complete this first orbital vehicle. “We’re investing over a billion dollars of our own money into this program.”

SNC is still holding out hope that it will still be able to develop a crewed version of the vehicle that was set aside after losing out to Boeing and SpaceX for commercial crew contracts in 2014. The CRS-2 contract, Lindsey said, allows SNC to complete development of the cargo version of the vehicle, whose design is about 85% common with the crewed version.

“I do think this is a great people mover,” Curry said. “So I think one of these days, once we fly our missions to the space station, it’ll be like ‘Field of Dreams’: build it and they will come. I think we’ll be flying crew soon enough.”

While there’s no near-term NASA opportunity for a crewed version of Dream Chaser, Shireman said with an extension of the ISS beyond 2024, which looks likely, there may be opportunities to add new commercial crew providers in much the way SNC was added to the contracts for cargo delivery. “We haven’t forgotten about it,” he said.