Thank you for having me.
[Can you elaborate on what we saw on the video.] Okay, there was quite a lot. Well, what we're seeing there is - and, like, our communications team just put it together so I just saw it for the first time in the back there. There's probably a little bit too much slow-mo. What we're seeing there is our Falcon 9 rocket and our Dragon spacecraft and we're seeing some of the initial tests of the reusable version of Falcon 9 that is capable of taking off and landing. Which is - reusability is really, I think, the critical breakthrough needed in rocketry to take things to the next level. [When will you do that?] Well, we've been able to soft-land the rocket booster in the ocean twice, so far. Unfortunately, it sort of sat there for a couple of seconds and then tipped over and exploded. Yeah - like that it's quite difficult to reuse. Unfortunately - it's as tall as a 14 story building, so when a 14 story building falls over it's quite a belly flop. So, what we need to do is be able to either land on a floating platform or, ideally, boost back to launch site and land back at the launch site. But before we boost back to the launch site, and try to land there, we need to show that we can land with precision, over and over again. Ya know, otherwise something bad could happen, if it doesn't boost back to where we intended. For the upcoming launch, I think we've got a chance of landing on a floating landing platform. We actually have a huge platform that's being constructed at a shipyard in Louisiana right now. Which is - well, it's huge, huge-ish, it's about 300 feet long by 170 feet wide. That looks very tiny from space, and the leg span of the rocket is 60 feet, and this is going to be positioning itself out in the ocean with engines that will try to keep it in a particular position - but it's tricky, you've got to deal with these big rollers and GPS errors. It's not anchored, because it's out in the Atlantic. But we're going to try to land on that on the next flight and if we land on that I think we'll be able to refly that booster, but it's probably not more than a 50% chance or less of landing it on the platform for the first time, but there's a lot of launches that will occur over the next year. So there's at least a dozen launches that will occur over the next 12 months and I think it's quite likely, probably 80% to 90% likely that one of those flights will be able to land and refly. So, I think we're quite close.
[Why not wings?] There's a couple of reasons. The longterm ambition of SpaceX is to develop the technologies necessary to establish a self-sustaining city on Mars, or civilization on Mars, and wings and a runway don't really work if you're going somewhere other than Earth. Ya know, the Moon doesn't have an atmosphere, so wings and wheels are - there's no runway and there's no atmosphere. Not a good choice for the Moon. Then, on Mars, there are also no runways, and the atmosphere is very thin. So, unless you like trying to land something at supersonic velocity, it's just not a good choice for Mars either. You basically have to go with propulsive landing if you want to go someplace other than Earth, which is why you have rockets, because obviously aircraft work quite well on Earth, but even for Earth recovery, when you really look at it, even if other planets had atmospheres the penalty for propulsive landing quite low. You can just do an easy calculation of what's the terminal velocity and then how long you have to fire the engine, at what g-level, to get to zero velocity. If you then do some interesting things, like look at our landing gear, they're essentially like giant body flaps, so the drag - when we deploy the landing gear, the drag massively increases, so we have dual use of the landing gear as giant body flaps and as landing gear. That actually cuts the terminal velocity in half and therefore the fuel - the propellant we need to stop the vehicle in half, and actually it's quite an efficient method of landing precisely. You use less mass if you want to use parachutes to a water landing, but then reusability is negatively affected.
[What about the second stage?] The next generation vehicles after the Falcon architecture will be designed for full reusability. I don't expect the Falcon 9 to have a reusable upper stage, just because the - with a kerosene-based system, the specific impulse isn't really high enough to do that, and a lot of the missions we do for commercial satellite deployment are geostationary missions. So, we're really going very far out. These are high delta-velocity missions, so to try to get something back from that is really difficult. But, with the next generation of vehicles, which is going to be a -