To many avgeeks, NASA’s space shuttles will always hold a special place in their hearts. Now retired from service, they were – for a long time – the only reusable, winged “lifting body” vehicles ever employed for spaceflight.
SpaceX and Boeing, who both hold multi-billion dollar NASA contracts to fly astronauts to and from the International Space Station (ISS), are each developing reusable capsules (Dragon and CST-100 Starliner). And while the U.S. Air Force currently operates a hush-hush mini ‘spaceplane’ (X-37B / cargo only), its missions and whereabouts when in orbit are classified.
But there’s one company, Sierra Nevada Corporation, who is developing a reusable, rapid turnaround ‘mini shuttle’, and they currently hold a NASA contract to begin delivering cargo on at least six missions to the ISS beginning in 2019.
The Dream Chaser has been in development for a long time, and a prototype test article recently completed “Phase One” ground testing at NASA’s Armstrong Flight Research Center, located at Edwards AFB, CA, in preparation for its second free flight Approach and Landing test (ALT-2) on the base’s runway 22L.
NASA Langley did a lot of research on it in the 80′ and 90’s, based off a Russian heritage design called the Bor 4. They did thousands of hours of work, and created the control laws to be able to fly it. A lot of astronauts came in to try it and fly it too.
At the time, NASA was looking for a spacecraft to use as a return vehicle from the ISS, so the agency competed a couple of different designs for rescuing crews in case of an emergency. One design was the X-38, the other was the HL-20, which is now the Dream Chaser.
NASA eventually decided to choose the X-38, but after working on that for several years the X-38 was abandoned also, leaving astronauts to rely exclusively on the space shuttle and Russian Soyuz as the emergency vehicles for the ISS.
When SNC wanted a vehicle design, instead of starting from scratch, they built off what NASA had already done with the HL-20 and changed it slightly.
SNC put their test article through ALT-1 at Edwards AFB on October 26, 2013, the first such test since the space shuttle prototype Enterprise did so in the late 1970s. Using an Erickson Air-Crane helicopter, the prototype was dropped from 12,500 ft over Edwards, sending the vehicle into a steep 50-degree nose dive to exactly replicate the spacecraft’s orbital re-entry flight path to prove its design is truly air-worthy.
The test went about as good as SNC could have hoped for, until the command was given to deploy its landing gear. Only two of its three gear deployed, causing the vehicle to skid off the runway, sustaining minor structural damage.
The problem was traced to a mechanical issue with the specific landing gear, rather than something related to bad software (none of the primary systems that gave the commands that control the flight failed or had any problems).
“The 99% of the flight that we really wanted to get – which was does this vehicle fly, is it able to be controlled, does the software work, can we autonomously fly the vehicle in to approach and land on a runway – all that was 100% successful,” said Mark Sirangelo, corporate vice president, SNC’s Space Systems.
A year later, NASA awarded commercial crew contracts to SpaceX and Boeing, but not to SNC and Dream Chaser.
It wasn’t until January 2016, that NASA awarded a cargo contract to SNC’s Dream Chaser, and the company has made significant structural and systems improvements to the test article since. Engineers improved the composite wings and aeroshells, and invested heavily in maturing the vehicle’s orbital avionics, guidance navigation and control, flight software, and employed a number of new processes, all of which will be used on the orbital vehicle as well.
An advanced orbital Thermal Protection System (TPS) was installed on the vehicle’s skid too, in order to do advanced testing of the actual orbital TPS.
The test article will not only aid development of the orbital cargo vehicles, currently underway, but will aid the development of a crewed version as well. Both cargo and crew variants share an 85 percent commonality, and the cargo-version can actually be made crew ready if NASA or another customer needed it.
With the addition of orbital avionics to the test article, the same the actual orbital vehicle will use, SNC will earn direct certification credit out of the upcoming flight test series from NASA. All the testing and certifications will happen on the ground and within the atmosphere, eliminating the need for an orbital flight test.
The loss of two shuttle crews, Challenger STS-51-L in 1986 and Columbia STS-107 in 2003, surely weighed on NASA’s decision to skip another spaceplane design for flying astronauts, at least for now, but the Dream Chaser offers numerous benefits, unique to its design.
It’s capable of staying at the ISS for over 7 months, and can land on virtually any runway at least 8,000 feet long, anywhere around the world, without requiring specialized equipment. This translates to no abort blackout zones and the ability to de-orbit at any time in case of an emergency.
With a propulsion system fueled by Nitrous Oxide and propane, ground crews will have immediate access to the spacecraft after landing, with only 10-20 minutes needed to exit the runway, keeping conflicts with other aircraft to a minimum.
An expected 1.5 G nominal reentry will provide ideal conditions for returning fragile cargo and science experiments too, in addition to making the return to gravity easier on the crew (SNC expects immediate access to crew and cargo upon landing).
And being as small as it is, it can be loaded on small cargo planes for shipment virtually anywhere.
No date has been given for ALT-2, but SNC expects to conduct it soon, and will fly more to validate the aerodynamic properties, flight software, and control system performance of the spacecraft if needed.
The Dream Chaser fleet will call Kennedy Space Center in Florida home, and SNC says it will be ready for its first launch atop a ULA Atlas-V rocket from neighboring Launch Complex 41 at Cape Canaveral AFS in the first half of 2019.
Once the cargo-version establishes itself as a dependable, reusable, and cost-effective space system, SNC expects demand for the crewed-version to increase, taking lessons learned from the cargo-version and applying them to the crew.
And should NASA offer up another round of Commercial Crew contracts in 2020, SNC will put in a bid for their crew-version Dream Chaser again.
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