Can someone explain theVirgin Galactic spaceship “feathering” system? How does this work, and why? Any in depth/speculation detail on what may have gone wrong would be appreciated. I’m a newbie on this.
I’m sure someone more knowledgeable than me will be along to explain things better, but basically the wings on SpaceShip Two rotate into a vertical position. This creates a lot of drag, slowing the vehicle. The weight and aerodynamic shape of the passenger compartment, combined with the drag from the now-vertical wings, keep it properly oriented- much like a badminton shuttlecock.
This technique works for a sub-orbital vehicle like SpaceShip Two but would not work for a much faster orbital vehicle like a Soyuz capsule returning from the International Space Station.
Here is the wiki article on feathered re-entry.
This is a better set of pictures and explanations SpaceShipTwo - Wikipedia See especially the diagram at the top of the Design Overview section just below the intro.
The parts that move aren’t the wings. It’s the tails. The vehicle has pretty stubby wings.
Bumbershoot’s second link shows the geometry of the feathered vehicle correctly. But not the descent attitude.
Once feathered the vehicle descends much more nose up, with the hinge point at the bottom and the nose and tail tips more or less at the same level.
The whole point is to make the vehicle very un-aerodynamic, so it has lots of drag. And by doing that in the very, very thin upper atmosphere they can burn off speed safely early and slow to a more normal flying speed without needing parachutes, retro-rockets, etc.
The same approach would not work (or at least not all by itself) for something coming down from orbit; the speeds are vastly greater and the amount of energy to be dissipated is far more than feathering could cope with.
I knew someone more knowledgeable would be along to explain it better! 
Thanks for the clarification, LSLGuy.
So tell me. Would you fly on this bird? Any concerns?
If I had the opportunity (which isn’t going to happen, of course) I would go on the next test flight, whenever that might be. I assume they will learn a few things from this incident and the next one will be safer. And if I had the money I would buy a ticket for a commercial flight, including the inaugural one, if and when that happens. I’d be a little nervous but I’d do it.
There was a quote from Burt Rutan saying the statistical safety level was estimated to be about on a par with 1920s airliners. Which is a far cry less safe than modern air travel. But (total WAG) probably not too much different from the safety level of modern hot-doggy motorcycle riding or maybe skydiving.
*Assuming *Rutan’s got his math anywhere near correct. As Stranger on a train has pointed out on many occasions, making a priori statistical estimates from engineering practice is as much voodoo as it is science. IOW, Rutan can factor in all the known unknowns. But the unknown unknowns, by definition, are not part of the reliability calcs. They can add a blanket fudge factor at the end for them, but they really have no way to decide if that should be an extra 20% or an extra 200%. Scaled Composites probably encountered an unknown unknown the other day.
Speaking for me personally, I’d pass on the test flights. But mostly because they are almost all part-mission operations where you don’t get the full space experience. So 100+ percent of the risk for 30-50% of the payoff; I’ll pass on that. I’ve got some pretty high performance flying in my past, so the attraction of e.g. the mission profile that failed, even assuming 100% success, isn’t that novel from my POV.
Would I go on one of their normal passenger flights, assuming they get that far? Sure. I’d rather wait for the 20th sortie or so to get some experience under their belts. But since I’m only going if they foot the bill, I’d probably go on the first flight if they offered it “now or never”.