SpaceShipTwo undertook its 23rd glide flight on Dec. 19 in the pre-powered portion of its incremental test flight program. This was a significant flight as it was the first with rocket motor components installed, including tanks. It was also the first flight with thermal protection applied to the spaceship's leading edges.
Credit: Luke Colby/Virgin Galactic
SpaceShipTwo is a spacecraft that is intended to one day take tourists on brief trips to suborbital space. Manufactured by The Spaceship Company, the vehicle is currently in the testing stage, with commercial operations expected to begin sometime in the next few years.
The technology for SpaceShipTwo was forged in competition for the $10 million Ansari X Prize, which was created to spur the development of private spaceflight. After predecessor SpaceShipOne won the prize in 2004, two companies, Scaled Composites and Virgin Galactic, formed The Spaceship Company to work together to commercialize the technology.
Developing SpaceShipTwo has come with its share of setbacks, both privately and publicly, and the date for the first fully operational spaceflight has been pushed back repeatedly. Scaled Composites experienced a fatal explosion in 2007 that delayed development of the rocket engine, and SpaceShipTwo crashed during a test flight on Oct. 31, 2014, killing copilot Michael Alsbury and injuring pilot Peter Siebold.
The tragic accident occurred during SpaceShipTwo's fourth rocket-powered test flight. The third powered flight, which took place in January 2014, sent the vehicle to an altitude of 71,000 feet (21,641 meters) and a top speed of Mach 1.4 (1.4 times the speed of sound).
X Prize ancestry
SpaceShipTwo's ancestor, SpaceShipOne, was designed to win the $10 million Ansari X Prize by becoming the first privately funded vehicle to fly to space and back twice within a two-week span. SpaceShipOne was manufactured by Mojave Aerospace Ventures, a joint venture of Scaled Composites — a firm led by famed aerospace designer Burt Rutan — and Microsoft co-founder Paul Allen.
Rutan had a different vision of spaceflight than usual. Most of the cargo that leaves Earth does so upon a rocket that goes straight from the ground into space. SpaceShipOne launched instead from underneath a carrier aircraft, called WhiteKnightOne, then separated and rocketed to more than 60 miles (100 kilometers) in altitude.
Just before the spacecraft won the X Prize in 2004, Virgin Galactic's Richard Branson announced that he would work with Scaled Composites to manufacture a commercial version that would take tourists to suborbital space. Development then began on SpaceShipTwo.
"We hope to create thousands of astronauts over the next few years and bring alive their dream of seeing the majestic beauty of our planet from above, the stars in all their glory and the amazing sensation of weightlessness," Branson said in September 2004.
Since then, about 700 people have signed up to take a quick joyride into space. Tickets initially cost $200,000 apiece but were raised to $250,000.
As development proceeded, the company focused on putting together a launch area. The state of New Mexico offered Virgin Galactic a taxpayer-funded $225 million facility in December 2005, called Spaceport America. Virgin Galactic would establish its global headquarters and spaceflight operations there.
The company rolled out several construction milestones in the next year, but the momentum halted in 2007. A fatal fire during a ground test sent shockwaves through Scaled Composites and the greater "new space" community. Three Scaled Composites employees died, and others were injured, during a routine ground test. Work was briefly suspended as an investigation into the cause was launched.
Things began to turn around in July 2008, when Virgin Galactic held a major launch event to showcase WhiteKnightTwo, which would carry SpaceShipTwo into the sky. The first carrier aircraft would be called "Eve." Before 2008 finished, Eve had its first successful test flight.
The first SpaceShipTwo was unveiled in December 2009. It was named VSS Enterprise, after the famous "Star Trek" craft. (Enterprise was also the name of the first NASA space shuttle, but it was used for glide tests only and never made it into space.)
Crewed test flights of Enterprise began in July 2010. The company completed a major glide test in late 2012 that had the spacecraft in its "powered flight configuration," meaning that the hybrid rocket motor and all other components were built in. The first rocket-powered test flight took place in April 2013. (The vehicle was destroyed in the Oct. 31, 2014, crash.)
Virgin Galactic bought out Scaled Composites in 2012 to obtain full ownership of The Spaceship Company.
"The completion of the acquisition comes as Virgin Galactic and Scaled begin to plan the handover of the [SpaceShipTwo] development program to Virgin Galactic," Virgin representatives stated at the time. "Scaled [is] fully committed to the final portion of the [WhiteKnightTwo] and [SpaceShipTwo] test flight programs prior to Virgin Galactic commencing commercial operations."
A typical flight profile
When it begins commercial flights, SpaceShipTwo will carry six passengers. The spaceship will fly to 50,000 feet in altitude underneath WhiteKnightTwo, then separate for the trip into space. SpaceShipTwo will fire its engines for about 70 seconds, then shut off for the final coast to 62 miles (100 kilometers.)
The passengers will feel weightless for about five minutes, Virgin Galactic representatives say, with room "to allow for an out-of-seat zero-gravity experience as well as plenty of large windows for the amazing views back to Earth."
Next, SpaceShipTwo will turn back to Earth. It will "feather" its rudders, turning them up to 90 degrees to increase the drag and control the yaw of the spacecraft. This will allow better control as the vehicle travels through the atmosphere.
"The feather configuration is also highly stable, effectively giving the pilot a hands-free re-entry capability, something that has not been possible on spacecraft before, without resorting to computer controlled fly-by-wire systems," Virgin representatives stated.
At 70,000 feet (21,336 m), the spaceship will have enough air around it to move the rudders back to a configuration that allows for gliding. It will then land back on Earth on a normal runway.
Branson had said he hoped to commence commercial flights in earnest around 2015; the test-flight tragedy will push that timeline back, however. Branson aims to be onboard when SpaceShipTwo is ready to go. The billionaire, an amateur adventurer who is famous for his publicity stunts, has been interested in space since at least the Apollo era.
The lengthy delay in the first Virgin flights caused some ticketholders to ask for refunds, but the vast majority stuck around eager for the experience to begin. Industry watchers have applauded Virgin's patient approach.
"They're taking the time necessary to make sure the vehicles are as safe as they possibly can be before they take paying customers up," said John Gedmark, executive director of the Commercial Spaceflight Federation, in a 2011 Space.com interview. "There's never going to be such a thing as perfectly safe spaceflight, but they're going to get as safe as they possibly can."
A tragic accident
Plans to start flights in 2015 were derailed Oct. 31, 2014, when fatal accident killed copilot Michael Alsbury and injured pilot Peter Siebold. The vehicle broke apart during the fourth test flight of the program.
The crash investigation, led by the National Transportation Safety Board, could take as long as 12 months, acting Chairman Christopher Hart said shortly after the incident occurred.
Early results from 2014 indicated that the feathering re-entry system was deployed early during the flight, apparently because Alsbury activated it too soon. That said, the NTSB emphasized the investigation is ongoing.
The design of the system has it activated after two separate actions: a lever must unlock the system, and then the handle is moved to the “feather” position. It appears the system activated on Oct. 31 before the second action occurred; Hart called it “an uncommanded feather.”
After the crash
Branson had some reservations about continuing after the crash, but in a blog post in January 2015, he said he felt the best path was to move forward — especially after talking with the team involved in SpaceShipTwo's engineering.
"In short — was Virgin Galactic, and everything it has stood for and dreamt of achieving, really worth it?” Branson wrote.
“I got a very firm answer to that question immediately when I landed in Mojave. From the designers, the builders, the engineers, the pilots and the whole community who passionately believed — and still believe — that truly opening space and making it accessible and safe is of vital importance to all our futures."
An Associated Press interview with CEO George Whitesides indicated that the company plans to resume test flights in 2015, and to continue using Spaceport America in New Mexico for the program. The first flight date with astronauts has not been announced publicly since the crash.
"I really think we're turning the corner," Whitesides said in the interview. "We've gone through one of the toughest things a company can go through and we're still standing, and now we're really moving forward with pace."