LAS CRUCES, N.M. — Sierra Nevada Corp. announced Aug. 14 that it will use United Launch Alliance’s Vulcan launch vehicle for sending Dream Chaser cargo spacecraft to the International Space Station starting in late 2021.

In a joint announcement at SNC Space Systems offices in suburban Denver, the companies announced that SNC had selected Vulcan to launch six Dream Chaser missions to the ISS under SNC’s Commercial Resupply Services (CRS) 2 contract awarded by NASA in 2016.

Dream Chaser will launch on a version of the Vulcan with a five-meter payload fairing, four solid-fuel strap-on boosters and a two-engine Centaur upper stage. That configuration will allow Dream Chaser to deliver more than 5,400 kilograms of cargo to the ISS. Dream Chaser will dispose of about 3,175 kilograms of cargo and bring back “large quantities” of cargo to Earth, landing on the runway at NASA’s Kennedy Space Center.

Dream Chaser will be the “commercial debut” for Vulcan, with the first mission in late 2021 flying on the rocket’s second flight, said Tory Bruno, president and chief executive of ULA. “This is a very competitive launch market nowadays,” he said, “and to be selected by SNC to fly this block of missions on our Vulcan launch vehicle is just a tremendous honor.”

SNC originally planned to use ULA’s existing Atlas 5 for at least the initial Dream Chaser mission, then scheduled for late 2020. Last year, though, the company said it was looking at options other than the Atlas 5 for later Dream Chaser missions, including the use of European or Japanese launch vehicles.

The company settled on the Vulcan for the full block of at least six CRS2 missions. “This was the choice that I feel is best for this program, that I went to Eren and Fatih [Ozmen] to tell them this was best for this program,” said John Curry, Dream Chaser CRS2 program director at SNC, referring to the president and chief executive, respectively, of SNC.

Eren Ozmen said the company looked at five different launch options, including European and Japanese vehicles — likely the Ariane 6 and H3, respectively — “and also, obviously, Elon Musk and Jeff Bezos,” the founders of SpaceX and Blue Origin. “They all have really good capabilities.”

But, she added, “ULA had a pretty significant advantage because we have been working with ULA from day one,” a relationship that dates back to plans under NASA’s commercial crew program to launch a crewed version of the spacecraft on an Atlas 5.

“Not to mention,” she added, “that we had a really good competitive price.” The companies, though, declined to give financial details about the deal, including if SNC received a discount for flying on the second Vulcan launch, which ULA classifies as a “certification” flight of the vehicle. Bruno said pricing information was “obviously proprietary.”

Technical performance was another factor. “We spent a lot of time learning about this vehicle to make sure it was right,” Curry said. “Safety and reliability was a major reason why we chose this team and this rocket.” The companies said that, should Vulcan suffer delays, there is an option to shift launches to the Atlas 5.

In addition to the six missions under the CRS2 contract, SNC is pursuing additional opportunities for Dream Chaser, which could fly on vehicles other than Vulcan. “We’re maintaining the ability to fly on other launch vehicles,” said John Roth, vice president of strategy and business development at SNC. “We’re launch vehicle agnostic.”

The company also won’t rule out developing a crewed version of the spacecraft, which was set aside nearly five years ago when NASA selected Boeing and SpaceX over SNC for commercial crew contracts. Curry noted that SNC has retained an earlier Space Act Agreement for commercial crew development, which the agency has extended on an unfunded basis, to support potential crewed versions of the vehicle.

“We meet with them regularly to talk about what our cargo capability with the CRS2 vehicle, and what the bridge would be to the crew vehicle when and if it were to come,” he said. “It wouldn’t be that long to get from the cargo version to the crewed version.”

Bruno, who called himself a fan and a “cheerleader” of Dream Chaser since he first saw it, said he looked forward to launching the vehicle on Vulcan. “Eren and Fatih, you have trusted us with your baby, this amazing Dream Chaser vehicle,” he said. “We will not let you down.”