SpaceShipTwo crash update: Feathering deployed prematurely.

SpaceShipTwo Crash Update

SpaceShipTwo Crash Update

Bad Astronomy
The entire universe in blog form
Nov. 3 2014 11:57 AM

SpaceShipTwo Crash Update

SpaceShipTwo debris
Debris from SpaceShipTwo lies in a field in the Mojave Desert.

Photo by Sandy Huffaker/Getty Images

On Friday, Virgin Galactic’s SpaceShipTwo broke apart during a test flight, killing co-pilot Michael Alsbury and injuring pilot Peter Siebold. On Sunday, the National Transportation Safety Board held a press conference with what they had found over the weekend.

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

While the cause of the accident is still undetermined, a new fuel was being tested on this flight, and many thought this might be behind what happened. However, during the press conference, a new detail has come to light that may very well prove to be critical.

Advertisement

SpaceShipTwo is not an orbital vehicle; it’s first flown by a mothership plane (called White Knight Two) to an altitude of 15 kilometers (48,000 feet), then disengages from White Knight Two and ignites a motor that accelerates it for a little over a minute. After that it coasts ballistically, like a rock thrown in the air, reaching a height of about 110 km before it slows to a stop and begins to fall back to Earth. At that height there is very little air, so SS2 uses a technique called feathering: The tail and wing assembly of the SS2 rotates to increase the surface area, creating more drag which slows the spacecraft. This is an efficient method and also creates a situation where it automatically descends with the wings perpendicular to the direction of travel, an aerodynamically stable position.

The feathering mechanism is supposed to be deployed when the spacecraft reaches about 1.4 times the speed of sound (called Mach 1.4). First, the mechanism is unlocked, then a handle is thrown which deploys the feathering.

This brings us to what happened on the test flight. Being careful to say this was simply a fact and not necessarily the cause of the crash, NTSB acting chairman Christopher Hart said that video from the cockpit and telemetry both show that the co-pilot, Michael Alsbury, unlocked the feathering mechanism prematurely. The locking handle was moved to the unlocked position when the spacecraft was at just Mach 1, and not 1.4.

However, the actual feathering deployment handle was not engaged. For reasons as yet unknown, despite this, the mechanism deployed anyway two seconds after the locking handle was thrown. At this point, telemetry was lost, and the spacecraft broke apart.

Advertisement

Again, as Hart points out, we don’t know yet if this was the cause of the crash or not. There will be a lot more investigation before firm conclusions can be made. It’s not at all clear why the feathering lock mechanism was disengaged prematurely, and no doubt that will be a focus of the investigators.

This is an awful event, as any death is, and any death when we’re reaching for space. Virgin Galactic is well ahead of its competitors to be the first private company to put paying customers into space (defined as getting higher than 100 km, the Kármán line); in fact, I know people who have tickets to ride once it’s given the go-ahead.

When I heard about the accident, I wondered if some people would overreact negatively, especially since this occurred just days after the loss of the Antares rocket. Within hours of the accident, Time magazine posted an article by Jeffrey Kluger with the headline “Enough With Amateur-Hour Space Flight.” I was frankly disappointed with it, especially given that Kluger recently wrote an excellent piece dismantling Jenny McCarthy’s claims that she’s not anti-vaccine. But this time, he uses ad hominem against Richard Branson, owner of Virgin Galactic, saying he is more of a showman, unqualified to make decisions needed to run a space tourism company (and levels the same claim against Jeff Bezos and Paul Allen, who also run private space tourism companies). But that’s a weird case to make; Branson hired qualified people to make those decisions. Think of it this way: If a Virgin Atlantic plane crashed, would we immediately blame Branson for it?

Mind you, it’s possible that there was a culture of pressure at Virgin Galactic to push forward on tests; this has happened at NASA and has led to disaster. But at this point in time we don’t know. Pointing a finger at Branson at this time is counterproductive at best, and certainly more histrionic than we need after such a crisis.

Advertisement

And what Virgin Galactic is trying to do isn’t just bread and circuses. There is real science to be done using suborbital flights, and the engineering we’ll learn will go a long way toward understanding spaceflight better. And there may be more immediate practical uses as well. While these flights go more or less straight up and then back down, suborbital launches could prove to be revolutionary in rapid travel across the planet; you could transport people and packages from the New Mexico spaceport to China in an hour or so, instead of half a day.

Pricey, yes, but airplane travel was extremely expensive when it first started. Space travel, even ballistic flight, is far more complex and difficult, to be sure, but right now we’re just taking our first shaky steps.

I am very mindful that a life was lost, and my heart goes out to everyone involved, especially to those close to Alsbury and Siebold. If this loss was due to negligence, “go-fever”, or some other malfeasance, then I will be among those who call for justice.

But I will not stop in my support of the idea of what’s being done here: Pushing back the frontiers of space, both publicly and privately. Exploration is what we humans do, and it has never been more important than it is now. As science fiction author Robert Heinlein wrote, “The Earth is just too small and fragile a basket for the human race to keep all its eggs in.”

Advertisement

On a similar note, father of modern rocketry Konstantin Tsiolkovsky also said, "Earth is the cradle of humanity, but one cannot remain in the cradle forever."

I agree, and while I hate the cost in human life this will inevitably entail, I also know this is something we must do. All our progress, everything we are now, has taken its toll that way. Even as we mourn we shouldn’t forget that.

Correction, Nov. 3, 2014 at 15:45 UTC: I originally wrote that feathering makes the spacecraft fall nose first, but it actually falls "flat." My thanks to Patrick Tomlinson for pointing this out. 

Correction, Nov. 3, 2014 at 15:50 UTC: In the original post, pilot Peter Siebold's last name was also incorrectly spelled.