Is This Tiny Shuttle the Future of Spaceflight?
Dream Chaser could be a cheap, reusable astronaut transport
Late last month, the future of spaceflight — a mini-space shuttle dubbed the Dream Chaser — made its first unpowered glide-flight. It was highly successful, at least until it touched down on the runway at Edwards Air Force Base and promptly flipped over onto its back.
Ignominious start though it may be, it’s just the beginning. Designer Sierra Nevada Corporation plans to quickly repair the vehicle and fly it again. A second Dream Chaser is under construction.
The Dream Chaser has an airplane-like “lifting” body. That means it can reenter the atmosphere relatively slowly in comparison to traditional capsules, and can glide to a graceful landing rather than plummet down to Earth. No lifting bodies have been used before on operational flights and testing was rare, which makes it a riskier than approach capsules. While the space shuttle’s wings generated some lift, the fuselage (as in most aircraft) was aerodynamic deadweight, so it had a poor glide ratio and fast atmospheric re-entry.
But the idea has been around a long time, and Sierra Nevada is taking the least-risky option for such a craft: Dream Chaser is an exact replica of an earlier design ground-tested by NASA, so the company has plenty of wind tunnel data. The NASA design is itself a copy of a Soviet lifting body that flew a handful of times in testing.
Dream Chaser and two other vehicles — the SpaceX Dragon and Boeing CST-100 capsules — are being built largely by government funds through NASA’s Commercial Crew Integrated Capabilities (CCiCap) program, which has dished out just over $1 billion to date in an attempt to build a crewed, reusable spacecraft. In many ways, this is a situation that closely parallels the state of aviation in the 1920s, when government funding kept commercial airmail services viable and wealthy individuals paid to test the boundaries.
Much like aviation during that time, access to space is about to get much easier. Satellites are getting smaller and cheaper with the maturing of satellites the size of shoeboxes or smaller (CubeSats, nanosats, picosats, and the like) such that even small colleges can afford to send satellites into orbit. One group even launched the electronic guts of a cellphone into orbit as an experiment (it worked). Such small satellites allow previously unheard-of funders: wealthy individuals, small groups, and Kickstarter can now put satellites into space.
The largest cost to satellite builders is usually launch costs, which vary widely depending on the rocket and necessary orbit. The long-held belief in the space industry is that demand for launches will rise exponentially when the liftoff price drops to $1,000 per pound; the newest systems have brought the cost down around $2,000, and continue dropping with incremental improvements and efficiencies. Getting closer to that goal and (perhaps most importantly) interest from wealthy entrepreneurs and government support has allowed the flexibility to pursue relatively riskier approaches, and more of them.
Getting into space is incredibly hard. Reaching orbital velocity — about 17,000 miles per hour — requires perfect coordination and a rocket that can withstand enormous pressures and temperatures, built with high-grade materials and immaculate machining. The complexity means that rockets do not tolerate minor mistakes or the unexpected, such that every single launch is a nail-biting experience for the builders. As such, they are immensely expensive, but usually useful for less than 15 minutes — several hours at the most if the second stage is required to maneuver once in space. Once done with the job, they are nothing more than expensive scrap, generally left to decay at the bottom of the sea or burn up during atmospheric reentry, or cases simply float around in space for eternity.
Reusability has long been a Holy Grail for spaceflight, and it’s easy to understand why. Despite the higher cost of each flight and decreased payload, amortizing the engineering and material costs over a series of flights would be enough to ultimately drag the price down. Though launching is almost always the most expensive part of spaceflight, the obvious first target for reusability is the spacecraft that sits atop the rocket. Spacecraft are relatively small compared to their launch systems and need not be able to do more than basic maneuvering in the vacuum of space, so great margins can be reserved for the weight of heavier structures required for reusability.
Until now, however, it has simply been too risky and expensive to bother with. Only the iconic space shuttles have succeeded in flying twice. And they belonged to a special breed of beast; though conceived to be easily reusable, the shuttle cost well over $1 billion dollars per flight and required months of reconditioning to fly again. The program was largely considered a failure in those terms.
Today’s space entrepreneurs want to do more than build a reusable spacecraft, however. They want to fly the entire launch vehicle over and over again. The first stage is the biggest part of the launch vehicle, but is only used for several minutes at most to power the rest of ‘the stack’ through the thickest part of the atmosphere. Nothing is ever easy with space launches. Making a first stage survivable means both strengthening its structure and figuring out a way to land softly; because each moving part adds complexity, weight, and cost, it has been considered impractical. But the same amortizing logic holds, and several companies are working towards solutions. Elon Musk’s SpaceX has recently retired its Grasshopper hover test bed and is building a larger successor. Jeff Bezos’s Blue Origin has flown a small suborbital test bed at least once. (It blew up. They are reportedly building another.)
Musk, for one, has sworn to build a fully reusable rocket. The biggest challenge (which Musk describes as “super-damn hard”) is a reusable second stage. The second stage (on some systems topped by a third and even fourth stage) is what actually brings the spacecraft into space, so making it reusable means it must withstand the full stresses of atmospheric reentry. Oh, and by the way, it must work in a vacuum, and it must be light enough to loft significant payloads at competitive prices, and somehow it must land softly after all that.
Because of the immense costs and risks, launch systems, spacecraft, and satellites have always had a very high barrier to entry. Lowering that barrier means room for more and better versions, and better tolerance for risk — which itself encourages more of the same. One day someone will break through the $1,000-per-pound barrier, and when they do, just as aircraft builders of the 1920s could not possibly envision modern aviation, we cannot predict the future of spaceflight — but it is exciting. The sky, to use an old expression, will no longer be the limit.
