The primary structure o SNC’s first Dream Chaser is ready to be integrated with other components over the next 18 months. Credit: Sierra Nevada Corp.

A decade ago, the idea of relying on commercial spacecraft to deliver cargo to the International Space Station was still very much of an experiment. NASA awarded contracts in late 2008 to both Orbital Sciences Corp. and SpaceX as part of its Commercial Resupply Services (CRS) program for cargo transportation, but both companies were still years away from flying their vehicles. Another company, Rocketplane Kistler, had already been dropped from the program by NASA when it failed to meet funding milestones; it eventually went bankrupt.

That experiment has become a clear success. Today, NASA relies on Cygnus spacecraft from Northrop Grumman (which acquired Orbital ATK in 2018) and Dragon spacecraft from SpaceX as the station’s lifeline, delivering everything from crew supplies to experiments to the ISS, while bringing back cargo and disposing of garbage. The two companies have flown 29 missions to date: 18 by SpaceX and 11 by Northrop, including one failure for each company.

Those missions have delivered more than 68,000 kilograms of cargo to the ISS since the first SpaceX Dragon mission in October 2012, with a similar amount of cargo brought back to Earth or disposed during reentry, noted Ven Feng, manager of the ISS Transportation Integration Office at NASA’s Johnson Space Center during a panel discussion at the International Symposium for Personal and Commercial Spaceflight (ISPCS) Oct. 10. “It’s hard to believe that we sit here, just seven years later, with 29 missions under our belt,” he said.

In January 2016, NASA awarded a new set of commercial cargo contracts, known as CRS-2, to Orbital ATK, Sierra Nevada Corporation (SNC) and SpaceX. The first CRS-2 mission, a Cygnus mission called NG-12, is set to launch Nov. 2 on an Antares rocket from Virginia. Over the next two years, all three companies will begin CRS-2 flights, with changes ranging from modest improvements to entirely new vehicles.


Of the three companies, Northrop’s transition to the CRS-2 contract is the smoothest. The company will continue flying the Cygnus spacecraft on its Antares rocket with only modest changes to the Cygnus.

On the last mission, NG-11 in April, Northrop tested a “late load” capability where up to 20% of the cargo for the mission can be placed on the spacecraft just 24 hours before launch, said Dave Hastman, vice president and CRS program manager at Northrop Grumman, at ISPCS. That late load capability, which already exists for SpaceX’s Dragon, is essential for time-sensitive payloads like biological experiments.

Northrop Grumman’s Cygnus cargo craft is released from the International Space Station’s Canadarm2 in February. Credit: NASA

Cygnus can now do more once it leaves the station. On the early CRS missions, the Cygnus deorbited within days of being unberthed from the station. However, the NG-11 Cygnus remains in orbit more than two months after its Aug. 6 departure from the ISS, demonstrating it can be a platform for hosted payloads or other experiments. “We’re looking at missions where we could be up there for as long as a year,” Hastman said.

Other changes don’t involve the spacecraft or rocket. Northrop has opened labs at or near the Wallops Flight Facility where science payloads can undergo final preparations before launch, like those at the Kennedy Space Center. “When we set out to do CRS-2, we wanted the ISS user to have the same experience at Wallops as they have at KSC,” he said.

SpaceX still has two more missions under its CRS contract. The first, SpaceX-19 (which the company and even sometimes NASA call CRS-19) is scheduled for launch in December, with CRS-20 to follow in early 2020. SpaceX will shift to the CRS-2 contract with the CRS-21 mission later next year.

Those CRS-2 contract missions will use a version of the Crew Dragon spacecraft SpaceX has been developing for NASA’s commercial crew program. That vehicle has already flown the equivalent of a cargo mission on its Demo-1 test flight in March, including demonstrating the autonomous docking that those missions will use, rather than berthing by the station’s robotic arm as with current Dragon missions.

Switching to the Crew Dragon design allows SpaceX to develop just one Dragon that can be used for cargo or crew missions, as well as other improvements. Benji Reed, director of commercial crew mission management at SpaceX, said at ISPCS that the new cargo Dragon will have 30% more pressurized payload volume than the current Dragon. It will be able to remain at the station for 75 days, rather than the approximately 30 days of the current Dragon.


The newest vehicle to service the station is taking shape in an industrial park in the Denver suburb of Louisville, Colorado. Inside a building across the street from a FedEx distribution center, SNC is assembling its first Dream Chaser spacecraft.

SNC marked a milestone in the construction of Dream Chaser Oct. 15 with the arrival of the primary structure of that vehicle. That structure, made entirely of carbon composite materials, was produced at a Lockheed Martin facility in Fort Worth, Texas, that makes components for the F-35.

“We took our space know-how 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, a subcontractor to SNC.

That primary structure, the fuselage for Dream Chaser, will be the core around which the rest of the vehicle will be assembled. “Now we have something to hang things on,” said John Curry, SNC’s Dream Chaser program director for its CRS-2 contract. The company will spend the next 18 months doing just that, with the goal of completing the vehicle in April 2021.

From there, SNC will fly Dream Chaser on a C-5 cargo aircraft to NASA’s Plum Brook Station in Ohio for three months of acoustics, vibration and thermal vacuum testing. Then it will be flown to Florida for final preparations for its first mission, slated to launch no earlier than September 2021 on one of the first flights of United Launch Alliance’s Vulcan rocket.

That late 2021 mission will be the first of at least six under its CRS-2 contract through 2024. The company expects to fly all six with the same Dream Chaser vehicle, which Curry said is designed to fly at least 15 missions. (Each mission will use a new cargo module attached to the back of the vehicle, since that module separates after undocking and burns up on reentry.) Steve Lindsey, SNC senior vice president of space exploration systems, said the company plans to build at least one more Dream Chaser, but hasn’t committed to a schedule for it.

Both SNC and NASA have emphasized the unique attributes of Dream Chaser. The vehicle can carry up to 5,500 kilograms of cargo, pressurized and unpressurized, to the station, more than other vehicles. Dream Chaser can bring back to Earth 1,850 kilograms of cargo, landing on the Shuttle Landing Facility runway at KSC.

That runway landing will allow researchers immediate access to experiments returned to the station. That’s a challenge today since the only way to get payloads back is on Dragon missions that splash down in the Pacific, hundreds of kilometers from port, or small amounts of cargo stashed on returning Soyuz spacecraft.

Even Soyuz returns have their problems. Kirk Shireman, NASA’s ISS program manager, recalled a recent Soyuz mission that brought back samples, with a requirement they be in a lab within 48 hours. “You’re thinking that’s not so hard. Well, it turns out we didn’t make 48 hours,” he said. The samples were flown by helicopter to a jet bound for the United States, only for that plane to suffer mechanical problems en route. “So we went through multiple airlines, multiple airports and cross-country cab rides to get the samples home, and we missed it by about five hours.”

An uncrewed SpaceX Crew Dragon on approach to the International Space Station in March. Credit: NASA

With Dream Chaser, the company says, crews will be able to get immediate access to payloads after landing on a runway that’s just a few kilometers away from labs at KSC. Curry said the company reconfigured the vehicle’s interior to ensure those time-critical payloads will be nearest the aft hatch on Dream Chaser that will be used to get inside after landing. (SpaceX’s Reed said at ISPCS they plan to get critical payloads back to labs within three hours of splashdown on CRS-2 missions, using the same infrastructure for getting astronauts home after commercial crew missions.)


Each company is guaranteed six CRS-2 missions through 2024 but, with the expectation that the ISS will be extended through the end of the 2020s, likely will fly more. Feng said that additional missions will be competed among the three.

That guarantee is important given the uncertain commercial demand for such vehicles. While SpaceX’s Falcon 9 has been highly successful on the commercial market, every Dragon mission to date has been for NASA. Similarly, every Antares launch after its initial test flight has been of a Cygnus cargo mission for NASA. “We struggled a little bit on CRS to supplement it with commercial users,” acknowledged Northrop’s Hastman.

With growing interest in commercial modules for the ISS and commercial space stations, the companies do see opportunities for their vehicles. “We’re actively engaged with many of those other customers,” said Curry. He noted that Dream Chaser itself can be used as a free-flying space lab, able to stay in orbit for up to a year.

Another opportunity is from NASA, which seeks to replicate the success of CRS for the lunar Gateway. In August, the agency issued a request for proposals for its Gateway Logistics Services program, where NASA will buy cargo transportation services for the Gateway like it does for the ISS. Proposals were due to NASA in mid-October, which expects to issue one or more contracts by the end of the year.

Both Northrop and SNC said at ISPCS they were interested in that program. (Reed didn’t comment on any plans SpaceX has for that program.) Northrop plans to offer a version of Cygnus with a larger propulsion system, which Hastman said would launch on a larger rocket. Curry said SNC would base its system on the Dream Chaser cargo module, rather than the reusable lifting body. “It doesn’t make sense to send a winged vehicle all the way out to the lunar Gateway and back.”

Those companies are worried, though, about what they see as a lack of guarantees from NASA to buy missions, particularly without other customers for lunar cargo systems. “It’s looking tougher now, where the risk seems to be leveraged more on the commercial provider side,” Curry said.

“There is a concern about how the lunar model works if there’s not going to be a certain amount of guaranteed government work,” Hastman said.

One other market is human spaceflight. SNC, which originally developed Dream Chaser for the commercial crew program, still expects to one day fly people on the vehicle. 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.”

This article originally appeared in the Oct. 21, 2019 issue of SpaceNews magazine.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...