Mojave Air and Space Port, California
The only problem was the wind, which had chosen this day to break its usual routine.
Out in the desert, mornings are typically calm, with winds building during the day. On June 1, at the Mojave aerodrome 90 miles (145 km) north of Los Angeles, the opposite happened: Strong winds in the morning postponed a planned test flight of Virgin Galactic’s SpaceShipTwo. Anxious technicians watched windsocks scattered around the aerodrome, which dispiritingly refused to agree on where the wind was coming from or how fast it was going.
SpaceShipTwo itself looks like a small, nattily-attired corporate jet with unusually elaborate wings. It is designed to hang from a carrier plane called a White Knight that soars nearly 50,000 feet (15,000 m) into the air. Then, SpaceShipTwo is released to ignite its rocket engine, roar up into space and, after hanging at the peak of its flight path for a few minutes, glide back down to earth to land on a runway. When it’s fully operational, Virgin founder Richard Branson expects it to carry six paying passengers on a 3-gee thrill ride to the edge of space.
Despite more than 12 years of development, the company has yet to put any passengers in its craft. It’s a testament to the challenge of developing a vehicle that can withstand the rigors of space. June 1 was one of only a couple of times the company has hosted reporters at a test flight since an accident in 2014 resulted in the death of one of the company’s test pilots, Michael Alsbury.
The National Transportation Safety Board found that problems in the plane’s design turned a predictable mistake into disaster. Asbury had unlocked the plane’s rotating tail booms, or “feather,” at the wrong time, causing it to break up in flight; nothing prevented him from doing so. The vehicle’s original designer, Burt Rutan, a legend in aerospace—who won the Ansari X-Prize for sending the first privately-funded, crewed vehicle into space—had argued that “if space is going to be cheap, it has to be stick-and-rudder.” But investigators found that this philosophy put too much pressure on the pilot to operate flawlessly.
“During design, Scaled [Composites, Rutan’s company] did not consider the possibility that a pilot would unlock the feather before 1.4 Mach [1.4 times the speed of sound] and as such no safeguards were built into the feather system designed to prevent this,”an NTSB official said after the investigation. “Although program personnel said that they were aware that unlocking [the rotating wings] during transonic flight would be catastrophic, there was no warning, caution or limitation in the pilot operating handbook or test card that specified this risk.”
That accident accelerated a reorganization that had begun in 2012, when Virgin Galactic took complete control of the company manufacturing its airplanes and spacecraft. Previously it had been a joint venture with Scaled Composites. Now, Virgin Galactic would handle all aspects of testing and development itself. The company unveiled a new SpaceShipTwo, called VSS Unity, at the beginning of 2016, with new safety features. One of the company’s pilots, Todd Ericson, a former chief of safety for the US Air Force’s test-flight program, was appointed the safety lead.
Now, the newest incarnation of SpaceShipTwo is deep into its second attempt to be certified as safe for passengers. When will that happen? “When we’re ready,” says Virgin Galactic CEO George Whitesides. This is how they’ll get there.
Push the envelope
The wind eventually cooperates, dying down enough that the team can okay the test flight. This will be the ninth time that Unity has flown into the sky underneath its carrier airplane, and the fifth time it has been released to glide back down to earth on its own. As the White Knight prepares to taxi down the runway, white Range Rovers drive ahead to scare away birds and spot any debris that might interfere with takeoff.
Flight testing, Ericson explains, is a matter of expanding “the envelope”—the performance parameters for a vehicle. The team tests the simplest tasks the craft can perform, making sure the measurements from some 450 onboard sensors match their expectations, refining their predictive model about how the craft will behave under different conditions, then testing it again. This continues until the craft has been tested to maximum performance.
So far, executives say, the glide tests have been progressing as hoped for. A successful test of the feathered wing system a month before had given the design team confidence. The “feather,” which caused the fatal crash in 2014, is the most unique part of Unity’s design. Commonly compared to a badminton shuttlecock, it’s meant to be unlocked as the craft reenters the atmosphere from space. The wings’ tail booms rotate around the fuselage from horizontal to almost vertical, forcing the craft to return to earth belly-first, safely pushing away the heat and friction of reentry.
Such high-energy action is still many months away at this point. The test on this day is fairly simple: Making sure that the craft will still be aerodynamically stable when its heavy rocket motor is installed and the center of gravity has moved backward. To simulate this, the company has put in a special water tank weighing about 2,500 lbs (1,130 kg). The craft will maneuver with the full tank before dumping it and returning to land. Though it is gliding, the craft will go as fast as 0.75 Mach. A German-made stunt plane will follow closely behind, watching the process.
Mike Moses, Virgin Galactic’s president, is standing beside the runway with a crowd of employees (sample t-shirt: “Space is Virgin territory”) and family members. A radio earpiece connects him to mission control as he describes the flight test. The carrier climbs to 50,000 feet, far beyond the range of the naked eye, but as it moves to release Unity, it releases white contrails so it can be seen. The spacecraft is at first a dot, plunging from the sky.
And then a tiny puff of white appears next to the craft, prompting anxiety in the team on the ground. After a quick discussion, Moses explains that controllers had seen something they didn’t like during planned maneuvers and told the pilots to “knock it off”—that is, skip that step of the test. Later, we learn that the maneuver—one of 15 distinct steps in the 10 minutes or so of independent flight—had been a steep climb. During the climb, sensors found the forces on the plane exceeded the planned 2 gees, or twice the force of gravity, and the flight controllers told the pilots to quit. The spaceship is designed to withstand up to 4 gees, Ericson says. The puff of white was a little bit of water burping from the back of the tank.
The craft continues its glide above the airport, now clearly visible from the ground. At the appointed time, it dumps its load of water, spilling a white cloud into the sky.
After one more pass overhead, the craft glides in for a smooth landing on the runway. The Range Rovers rush out to greet it, one picking up the two grinning pilots and the other hooking up to the front of Unity, towing it away as easily if it were a rented trailer.
“Now the real work begins,” Ericson says. The test team immediately debriefs the pilots, and engineers will spend two to three weeks looking over the data gathered during the flight for anomalies. The test flight we have witnessed is just the most tangible aspect of the program, which began weeks ago with hours of practice in the simulator.
The previous version of SpaceShipTwo performed more than 20 glide flights over two and a half years before it began powered testing. Unity has flown five times in the last seven months. This seems to jibe with the Virgin engineers’ view that they can now move faster, thanks to the data they collected on the ill-fated previous vehicle.
The next steps will be to complete more glide tests to simulate more variables in flight—for example, how Unity responds aerodynamically to the sudden shift in weight when its rocket engine fires. The company will test this by doing a glide flight with propellant tanks installed but no combustion chamber; the tanks will rapidly dump propellant to partially simulate the effects of an engine burn.
But powered-flight testing still remains the biggest challenge, and while the company’s engineers have been refining their rocket engines in ground tests, it’s safe to say that there’s little chance of a passenger flight within the next year. Still, the Virgin team is already planning a mass exodus from its Mojave test center to the New Mexico spaceport that will host its commercial operation.
The company, once almost the only aspiring space tourism firm with the capital and engineering know-how to demonstrate a space vehicle, now faces new competition as well from Jeff Bezos’ Blue Origin, which has developed a reusable vertical-take off rocket and plans to begin flying humans as soon as 2018. It’s not clear yet how much each service will cost, but suddenly aspiring space passengers will have options. That doesn’t bode well for either company making back its initial investments, though both are backed by deep-pocketed billionaires and, in Virgin’s case, Abu Dhabi’s sovereign-wealth fund.
Whitesides, Virgin’s CEO and a former NASA chief of staff, understands this skepticism. Flying six people on tourist jaunts to space isn’t the end goal but “phase one of a bigger strategy,” he says. If the Ansari X-Prize that birthed this design was the equivalent of Charles Lindbergh’s prize-winning transatlantic flight, then SpaceShipTwo could be the equivalent of barnstorming pilots who flew planes around the country, demonstrating their capabilities to a wide range of people in a way that wasn’t obviously productive.
The next step is actually transporting people from point to point. Virgin has the somewhat contradictory reputation of being an earth-focused space company: Suborbital flights could drastically speed up long journeys, if the economics works. Such a business would need a new vehicle, but the lessons learned from developing SpaceShipTwo would help with that. And, Whitesides says, while the rockets built by SpaceX or Blue Origin may be good for reaching orbit, Virgin Galactic’s system will fit in much better when it comes to daily operations in airspace currently regulated for aviation.
But first, they need to expand the envelope.