By Glen Strom
Whenever a space-related accident happens, people chant “space is hard.”
Not this time. Virgin Galactic’s (VG) SpaceShipTwo (SS2) did not disintegrate and crash on October 31st, 2014 near Koehn Dry Lake, California because space is hard. A July 28th, 2015 public meeting at National Transportation Safety Board (NTSB) headquarters in Washington, DC made that clear.
|One of a series of frames taken over a period of three seconds by a camera on one of the tail booms of SS2, the VSS Enterprise, during its disintegration over the Mojave Desert on October 31st, 2014. This frame shows cracks forming on the outboard root fairings and the lightweight “taco” area. The high definition file also shows the kapton foil failing in the upper left hand corner of the frame, the area near the leading the edge of the left boom structure. The full series of frames is part of the July 29th, 2015 Parabolic Arc post, "The Breakup of SpaceShipTwo Frame by Frame From the Tail Boom" and was originally extracted from NTSB documentation on the crash. Photo c/o Scaled Composites/NTSB.|
The NTSB's main conclusion was that SS2 broke up over the desert and crashed due to failings in planning, design, training, and certification. They didn’t mention unrealistic expectations from impatient know-nothings, but they could have.
Note that the written report, released as part of the minutes of the meeting under the title, "In-Flight Breakup During Test Flight, Scaled Composites SpaceShipTwo, N339SS, Near Koehn Dry Lake, California October 31, 2014," doesn’t include the NTSB’s reasons for its findings. The full report is coming soon.
|As outlined in the July 28th, 2015 VG blog post on "The end of NTSB’s investigation and the future of Virgin Galactic," this photo shows VSS Enterprise pilot Pete Siebold with his arm up in the air to show everyone he was “alive and well” after his craft came apart on October 31st, 2014. But other sources suggest that he was unable to raise his right arm due to the severe injuries he suffered which would make him alive, but hardly well. Photo c/o Mark Greenberg/Virgin Galactic.|
The NTSB said the accident happened because SS2’s co-pilot, Michael Alsbury, unlocked the feathering system too soon.
The feathering system moves the tail assembly of SS2 to a position that increases drag to slow down the ship during re-entry. Although moving the assembly is a separate action from unlocking it, the aerodynamic load at that point in the flight overwhelmed the unlocked assembly, causing it to move prematurely. The resulting drag increased the aerodynamic load to the point where the ship broke up and crashed.
Some people will see “pilot error” and think that’s the main reason for the accident. The co-pilot, although an experienced and competent flyer, made a fatal mistake. The history of aviation is filled with similar stories. Blaming the co-pilot alone, though, is misguided.
Wayne Hale, a former NASA space shuttle program manager and flight director explains in his July 29th, 2015 blog post, “Pilot Error is Never Root Cause,” that pilot error is the end result of systemic failures. Mr. Hale says, “Pilot error is never ever a root cause.”
The NTSB report clearly states that Scaled Composites (SC), the company that built SS2 for Virgin Galactic, should have put in design features to prevent the co-pilot’s mistake. Instead, they ignored human factors entirely in their risk assessment and assumed the pilots would do everything perfectly.
Then there’s the performance, or non-performance, of the the Federal Aviation Administration (FAA).
Doug Messier at Parabolic Arc wrote an excellent article on August 1, 2015 about the FAA’s role in the accident, “Experts: FAA Review Process for SpaceShipTwo Flawed, Subject to Political Pressure." It’s a good read about an ugly situation. Expect to hear more about this.
According to veteran space writer Alan Boyle in his July 29th, 2015 Geekwire article “NTSB’s SpaceShipTwo findings put more pressure on FAA in commercial space,” a number of companies besides Virgin Galactic are also preparing their vehicles for testing. The FAA seems to be ill-equipped to deal with the situation without significant changes to their procedures.
|An undated image of a replacement SS2 under construction in Mojave, CA. The new design will include a safeguard to prevent the pilot from deploying the feathering mechanism early. Photo c/o Virgin Galactic.|
The report may even have convinced flamboyant billionaire and Virgin Galactic chairman Richard Branson, to stop spin-doctoring facts and making rash promises about things he doesn’t understand.
Based on his comments in a July 28th, 2015 blog post at VG’s website, “The end of NTSB’s investigation and the future of Virgin Galactic,” our flamboyant billionaire thinks the NTSB report concludes the design of SS2 is sound. But at least two NTSB members, Chairman Christopher Hart and board member Robert Sumwalt, say otherwise.
Although the report doesn’t find evidence of structural, system, or engine failures, what Branson overlooks is that a single point of failure due to human error is a design flaw. Both Mr. Hart and Mr. Sumwalt say so in a July 28, 2015 CBC News article, “Virgin Galactic didn't prepare for human error ahead of SpaceShipTwo crash, NTSB.”
It does seem that Branson has gotten most of the message. In a document called “VG & TSC NTSB Investigation Press Release,” under recommendations on page 6 it says the company will “Conduct a comprehensive internal safety review of all SpaceShipTwo systems to identify and eliminate any single-point human performance actions that could result in a catastrophic event.”
Under Status it says, “An initial assessment was completed and modifications to SS2-002 are in progress. Virgin Galactic will continually evaluate and improve System Safety throughout SpaceShipTwo’s lifecycle.”
|Richard Branson at Mojave in 2010. Behind him, the original SS2 hangs from the twin-fuselage mother ship, WhiteKnightTwo. The November 13th, 2014 Inc. article, "Virgin Catastrophic: How Richard Branson's Galactic Ambition Backfired," made the case that "the billionaire's manic drive and bold promises played a role in the crash of SpaceShipTwo." Photo c/o Jonas Fredwall Karlsson/ Vanity Fair.|
Going forward, if the recommendations of the NTSB report are acted on industry-wide, experimental commercial space flight should be safer.
For those who still aren’t convinced that “space is hard” didn’t cause the SpaceShipTwo accident, perhaps a quote from NTSB Chairman Hart at the hearing will do the trick. The quote appears in the previously referenced CBC News article:
Many of the safety issues that we will hear about today arose not from the novelty of a space launch test flight, but from human factors that were already known elsewhere in transportation.
Glen Strom is a freelance writer and editor with a background in business and technical writing. He's also the editor of The Gazette Weekly, the newsletter of the Canadian Space Society.
There is design flaw inherent in the hybrid system. Because of the speed of the ascent there is a short window between Mach 1.4 and Mach 1.8 where the feather system is allowed to be unlocked. This is only a few seconds long. Unlock too early, you have catastrophic break-up. Unlock too late then you risk having to reenter without the feather which can also be catastrophic.ReplyDelete
On the other hand if liquids had been used from the beginning then they would have already been flying to suborbit and with a more leisurely ascent that would have a greater margin about when to deploy the feather system.
I fail to see why this crash can be decoupled from "space is hard".ReplyDelete
Space is hard for many reasons, including the ones listed in this article
The key here is to remember that "space" isn't the only thing that's "hard" and the things that make space hard aren't even terribly unique to space.ReplyDelete
And the skills, techniques and strategies we've used to solve other challenges will be the skills, techniques and strategies we use in the conquest of space.