Artist's illustration of Sierra Nevada's cargo version Dream Chaser docking at the International Space Station. Image credit: Sierra Nevada Corp

Mar 20, 2015 Sierra Nevada offering Dream Chaser cargo ship for station resupply

Sen—Sierra Nevada Corp hopes to bounce back from NASA’s decision to award space taxi contracts to competitors Boeing and SpaceX by flying cargo to the International Space Station instead.

The privately owned company this week unveiled a freighter version of its winged Dream Chaser space plane, covering in one fell swoop all scenarios NASA said it would like its resupply vehicles to provide.

The U.S. space agency is due to decide in June which companies will haul cargo, remove trash and/or return experiments and equipment back to Earth beginning in about 2018 and running through 2024, the anticipated end of the space station program.

Currently, Orbital ATK (formerly Orbital Sciences Corp.) and Space Exploration Technologies, or SpaceX, have contracts worth a combined $3.5 billion for station cargo runs. SpaceX is preparing for its sixth operational mission to the International Space Station, with launch targeted for Apr. 10. Orbital was sidelined by a launch accident in October and is hoping to resume cargo deliveries in late 2015 using a United Launch Alliance Atlas 5 rocket. The company is changing the engines on its Antares booster and hopes to resume flying in March 2016.

Both Orbital and SpaceX are bidding for follow-on contracts, along with Sierra Nevada, Boeing and a surprise offering by Lockheed Martin, which proposes a combination cargo ship and reusable space tug. Boeing, like Sierra Nevada, is proposing to revamp its passenger spaceship to accommodate cargo.

The Dream Chaser Cargo System builds on the mini-space shuttle design Sierra Nevada has been working on for nine years, the last four of which have been in partnership with NASA.

“We feel we’ve got a competitive edge in terms of the design. It’s not like we’re starting from scratch,” Mark Sirangelo, corporate vice president and head of Sierra Nevada’s Space Systems, told Sen.

“Almost all of the work we’ve done is usable in this version. We’re taking some things out to make more room for cargo and we have one or two technical changes that are being made and that will take some time, but they are not technologies that we haven’t looked at before,” he said.

The changes include foldable wings so the spaceship can fit inside standard 5-meter fairings used by both ULA’s Atlas 5 rocket, the baseline vehicle for the proposed cargo resupply missions, as well as Arianespace’s Ariane booster.

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Illustration of the Dream Chaser cargo freighter inside a 5 meter rocket fairing. Image credit: Sierra Nevada Corp.

The Dream Chaser Cargo System also could fly on ULA’s Delta 4, Japan’s H-2B and even SpaceX’s planned enhanced Falcon 9 rocket, should that be an option.  

The spaceship includes a detachable piggyback cargo module that will be discarded during atmospheric re-entry. Equipment and experiment samples flying inside the spaceplane can be returned to Earth quickly, Sirangelo points out.

“NASA’s requirement is to have a return to their receiving station in 14 days … and once there, some of it needs to be offloaded quickly. We beat that by 13 days because we’re home within eight- to 10 hours and we’re off-loading within 30 minutes of landing. It’s a significant increase in what they are requesting,” Sirangelo said.

The company also is offering to carry 20,000 kilograms of pressurized cargo and 2,000 kilograms unpressurized in four flights per year, exceeding NASA’s upmass requirement by 5,000 kilograms per year.

Cargo Dream Chaser also accomplishes both disposal and cargo return and can carry more than twice as much as what NASA is requesting.

“The design becomes really elegant in a lot of ways,” Sirangelo said.

The company plans to resume Dream Chaser test flights at NASA’s newly named Armstrong Flight Research Center (previously Dryden) in California later this year.

After contesting NASA’s Commercial Crew contract awards and losing the appeal, Sierra Nevada decided it would use its Atlas 5 launch contract, originally planned for a late-2016 orbital test flight of the passenger Dream Chaser, for the first operational cargo mission, expected in early 2018, instead, Sirangelo said.

Sierra Nevada also is working on a scaled-down version of its passenger space plane to fly aboard the Paul Allen-backed air-launched Stratolaunch system. 

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Cargo Dream Chaser with detachable cargo module. Image credit: Sierra Nevada Corp.