Sierra Nevada Corporation’s Dream Chaser touches down on the runway at Edwards Air Force Base in California November 11 after a glide flight. (credit: NASA)
This time, they stuck the landing.
A little more than four years ago, Sierra Nevada Corporation (SNC) performed its first glide flight of its Dream Chaser lifting-body vehicle, releasing it from a helicopter in the skies above Edwards Air Force Base to a landing on the runway there. All went well up until just before landing, when one of the vehicle’s main landing gears failed to extend. The vehicle touched down and then skidded off the runway. It was, nonetheless, considered a success because of the data collected during the descent. (The company had already planned to upgrade the landing gear for the flight vehicle.)
On November 11, SNC tried again, using the same engineering test article that flew that 2013 flight but with various improvements—including, of course, the landing gear. Once again released by a helicopter, the vehicle glided to the runway at Edwards. To the relief of everyone involved, the gear extended this time, and the Dream Chaser rolled to a stop on the runway, its flight this time an unqualified success.
“It was, collectively for us, probably the longest minute of our lives watching it,” said Steve Lindsey, vice president of Space Exploration Systems at SNC, in a conference call with reporters two days after the flight. “But it sure was rewarding at the end when it touched down safely.”
That glide flight was the culmination of months of tests at Edwards, including tow tests on the runway and two captive-carry flights: one done in view of the media in August and a second a month later, out of view of the public (see “Learning to fly again”, The Space Review, September 5, 2017). The flight was also the final funded milestone in SNC’s Commercial Crew Integrated Capability (CCiCap) Space Act Agreement that NASA awarded the company in 2012.
At the time of the media briefing, analysis of the data was still in progress, but the company was optimistic that they had met all their requirements to have passed the milestone. “Overall, our parameters in the test were met or exceeded, in our minds, and we feel very, very positive about this test,” said Mark Sirangelo, corporate vice president of SNC’s Space Systems unit.
During that 60-second flight, which started when the vehicle was released from a commercial variant of a Chinook helicopter at an altitude of 3,756 meters, it reached a peak speed of 531 kilometers per hour as it simulated an orbital vehicle’s final descent from orbit. The Dream Chaser reached Runway 22-L at a speed of 307 kilometers per hour, rolling to a stop after about 1,270 meters on the runway. All were within the company’s expectations for the flight.
If the company’s belief that Dream Chaser met all its test objectives on the flight is proven correct, it’s unlikely this test article will fly again. With elements of the company first orbital vehicle already under construction, the company is ready to move ahead. (Earlier plans, when Dream Chaser was being developed for crewed missions, called for additional, piloted glide flights that are not necessary for the cargo variant now under development.)
“We’ll make the decision as we go forward in the coming weeks” about the need for another flight, he said. “If we have all the data that we needed from the test, and if NASA concludes that with us, the vehicle will not need any further flight tests.”
The company is now pushing ahead at full speed into the cargo vehicle program. Sirangelo said the company has completed three milestones on its Commercial Resupply Services (CRS) 2 contract, one of three NASA awarded in early 2016 to continue cargo transport services to and from the ISS. (Orbital ATK and SpaceX, which have the original CRS contracts, won the other two CRS-2 awards.) The next, a critical design review (CDR), is scheduled for mid-2018.
SNC is pressing ahead with construction of Dream Chaser orbital vehicle components even though the vehicle hasn’t completed that CDR, the usual milestone after which vehicle construction begins. Sirangelo said the vehicle successfully passed its preliminary design review earlier this year, giving them confidence there were no major problems with the design. “There are no showstoppers along the way for us to be able to go fly this vehicle,” he said.
Dream Chaser will go through what he called a “progressive CDR,” where individual subsystems go through their own critical design reviews once they’re ready. “At the end of that, there is an aggregate CDR for the entire vehicle,” he said.
Some of the elements already under construction include a primary structure, developed with Lockheed Martin, that underwent stress testing, he said. The flight software flown on this glide test is a “major sub-piece” of the software the company plans to use on the orbital vehicle. The test article also carried tiles from the thermal protection system planned for the orbital vehicle to study any wear and tear from the landing itself.
The test keeps SNC on track to fly the first Dream Chaser mission to the ISS in 2020, launching on a United Launch Alliance Atlas V. No test flights are planned prior to that: Sirangelo said that initial flight will have “additional things and maneuvers” to demonstrate its performance prior to arriving at the ISS.
At least the first two Dream Chaser CRS-2 missions will fly on Atlas V vehicles. However, SNC is keeping open the option to use Dream Chaser on other rockets, be they for CRS-2 missions or other applications the company is considering for the vehicle.
“We did design the vehicle to be what we call ‘launch agnostic,’” he said, not wedding it to a single rocket. “We are currently opening up a competition to receive new information from the providers that are out there. We think there are probably five or six systems, many of them new systems, in the United States and around the world that could take us up to orbit.”
SNC is looking for additional applications for Dream Chaser beyond NASA cargo missions. The company is working with the UN’s Office of Outer Space Affairs to arrange a flight to carry experiments from developing countries that don’t have access to space today. Next month, the Canadian Space Agency will host a meeting at its headquarters to discuss potential Canadian applications of Dream Chaser.
The company also emphasizes that, while Dream Chaser is now being built for cargo, there’s nothing that would prevent the earlier crewed version—which competed for but lost NASA’s commercial crew competition in 2014—from being resurrected at some later date. The test article will be placed what the company calls “flyable storage” so it can be brought back into service at a later date, such as if it’s needed for test flights of a crewed version.
“We certainly leave open options for other variants of the vehicle, one of which could be a crewed version,” said Sirangelo. “Nothing we’re doing in this program does anything but make those other options more viable.”
On those future crewed flights, an astronaut may be piloting Dream Chaser to a landing. But for the cargo flights to come, Dream Chaser will come in for an autonomous landing. Lindsey, a former astronaut who flew the shuttle, described seeing the landing as something of a flashback to his shuttle missions.
So, what did he think of this Dream Chaser landing? “I have to confess that, like any pilot, I grade every landing I see, so in my head I was grading the landing,” he said. “It landed great.”
“I won’t comment on whether I think I could have landed better than it did,” he added, “but being a pilot, you know, we all have big egos, so we all think that.”