I think we are at the dawn of a new era in space exploration, which is extremely exciting. And it’s not just SpaceX, there’s a number of other companies that have developed new approaches.
From a technical standpoint the biggest thing that's happened in the last couple of years, which I'm really excited about and I think makes a difference for access to space, is the landing of the Falcon 9 rocket booster. All the other rockets, like the European rockets and the Boeing and Lockheed rockets, all of their stages basically just smash to bits, and land somewhere at the bottom of the ocean. Every other rocket in the world the rocket stage is basically smashed into the atmosphere, explodes and then further explodes when they hit the ocean, or the steppes of Kazakhstan or something like that - if it's a Russian rocket. There's a whole industry collecting rocket parts out there in Kazakhstan.
The really major breakthrough that's needed in rocketry, the pivotal one which we're aspiring to make, is to have rapid and complete reusability. A fully and rapidly reusable rocket. I think it's extremely important to re-fly the whole rocket. This is fundamentally something that has to be solved. This has not been achieved before.
I think it may not be completely intuitive, but I think if one refers to other modes of transport, it makes more sense. All other modes of transport are fully and rapidly reusable. That applies to a bicycle, a horse, a plane, ships. In fact, in normal life, it would be quite silly to discard your horse after every ride, you know, or dump the plane after you flew it. It would be obviously very unfortunate in the case of the horse. Every mode of transport that we use, whether it's planes, trains, automobiles, bikes, horses, is reusable, but not rockets.
Going back to the founding of America, if ships had not been reusable in the days of the Mayflower, the United States would not exist. Nobody could afford the journey, they might have sent a few people as an exploratory thing, and of course since ships would be expendable you would need to tow your return ship behind you. So they might have said: “Oh yes, turns out there is a continent out there, but of course we can’t afford to go there because it costs two ships every time we make the return journey.” but in fact, ships can be used repeatedly, airplanes can be used repeatedly, and in fact, every mode of transport can be used repeatedly, and if that were not the case, we would not use that mode of transport, whether it’s plane, train, automobile, bicycle, or whatever. So we must solve this problem in order to become a space-faring civilization.
I think the aircraft analogy is appropriate here. If you bought say a small, single-engine turboprop aircraft, that would be one and a half to two million dollars. To charter a Boeing 747 from California to Australia is half a million dollars, there and back. The single-engine turboprop can't even get to Australia. So a fully reusable giant aircraft like the 747 costs a third as much as an expendable tiny aircraft. In one case you have to build an entire aircraft, in the other case you just have to refuel something. So it's really crazy that we build these sophisticated rockets and then crash them every time we fly. This is mad. So yeah, I can't emphasize how profound this is and how important reusability is.
You could imagine that if an aircraft was single use, almost no one would fly.
A Boeing 747 costs maybe a quarter of a billion dollars, you can buy, like say a 747 might be $250 million, $300 million, something like that. You need two of them for a round trip, so why doesn’t your air ticket cost half a billion dollars? Nobody’s going to pay millions of dollars per ticket to fly, to do air travel. I don't think anyone has paid half a billion dollars to do that. Nor would one want to. You can imagine a scenario where aircraft were thrown away with each flight that no-one would be able to fly, or very few, maybe a small number of government customers. There'd be a lot of travel by boat and train and that sort of thing, if that was the true cost. All you're really paying for is fuel, and pilot costs and incidentals. The capital cost is relatively small. That's why it's such a giant difference. Because you can reuse the aircraft tens of thousands of times the air travel becomes much more affordable, and the same is true of rockets. Really, it’s no different than air flight.
What a lot of people don't realize is, the cost of the fuel, of the propellant, is very small. It's much like on a jet. If you look at say the cost of a Falcon 9 rocket, it’s a pretty big rocket with about a million pounds of thrust, the Falcon 9 is $60 million and that's for something which has four times the thrust of a 747, and about the same liftoff mass, so that's a good deal. But the propellant is only $200,000. It costs about as much to refuel our rocket as it does to refuel a 747 within-- well, pretty close, essentially. Falcon 9 uses quite expensive fuel, relatively speaking. I think there are a lot of lower cost options. But the propellant cost-- which is mostly oxygen-- it's two-thirds oxygen, one-third fuel-- is only about $200,000. The cost of reloading propellant on Falcon 9 is about $200,000 and the cost of the rocket is $60 million roughly. So the capital cost if it can be used once is $60 million. So obviously, if we can reuse the rocket say 1000 times, then that would make the capital cost of the rocket per launch only about $60,000. That means that the potential cost reduction over the long term is probably in excess of a factor of 100. The cost of the propellant is only about 0.3% of the cost of the rocket. Obviously, that's a humongous difference. Now, there'd be maintenance and other things that we'd factor in there, there would still be some external costs in terms of service, and fixed costs and some overhead allocation, and what not, just like you do on an aircraft, you have inspections and servicing and do all that sort of thing, so there'd be that cost to take into account, but still, it would be dramatically more cost effective to get to orbit. It would allow for about a 100 fold reduction in launch costs, and this is a pretty obvious thing if you think of it applied to any other mode of transport.
And we have a low cost rocket, it's not like our rocket is expensive. It is the lowest cost rocket in the world. It’s just like a plane, if you were to refuel a plane, not very expensive, if you want to buy a new plane, very expensive. As long as we continue to throw away rockets and spacecraft, we will never have true access to space. It will always be incredibly expensive.
Often I'll be told, 'but you could get more payload if you made it expendable.' I say ‘yes, you could also get more payload from an aircraft if you got rid of the landing gear and the flaps, and just parachuted out when you got to your destination.’ but that would be crazy and you would sell zero aircraft.
The other similarities with aviation is that it was extremely risky and extremely expensive, but over time that improved to the point where today you can buy a non-stop flight from Houston to London, a return ticket for $500. That never used to be possible and then even when it was possible initially it used to cost ten times that amount and now it's very affordable. That was brought about by there being constant improvement in aviation over time.
I think it will open up options that today are hard to appreciate, just as in the early days with the Sopwith Camel, I was in the camel room, I don't think people could have envisioned that you could take a 747 non-stop from Los Angeles to London. It’s similar when we say today that we can’t see where things will be in the future. But if we enable that capability and improve the technology, then all sorts of things happen.
We've gotta make that happen. We've gotta achieve that goal. And that's going to take a bit of effort. It's not going to happen overnight, but we'll keep going in that direction until ultimately it's as close to aircraft-like reusability as one can achieve. If we can help set space transportation on a path with continuous improvement in cost and reliability as we saw with aviation, it's possible to achieve, let's say, roughly a 100-fold improvement in the cost of spaceflight if you can effectively reuse the rocket.
Essentially, the rocket needs to come back and land at the launch site, and then reload propellant and take off again. Like an airplane in its reusability. You do not send your aircraft to Boeing in-between flights. We believe we can get to the point where in the not too distant future the Falcon 9 booster can be re-flown within 24 hours.
Once we have reusability, I think improvements to reusability are going to be pretty important. That's really a fundamental one. I can't think of anything that's on-par with that, short of maybe warp drive.
Yeah, so we landed the Falcon 9 rocket booster and then prepped it for flight again and flew it again. It was the first re-flight of an orbital booster where that re-flight is relevant. The primary booster is the most expensive part of the rocket. The boost stage is about 70% of the cost of the rocket, which is somewhere in the order of $30-$35 million.
I think we are quite close to being able to recover the fairing, a huge nose cone on the front of Falcon 9. It’s a 5.2 meter diameter nose cone, you can basically fit a whole city bus in there. Just that fairing alone, with all of it’s systems, and acoustic damping, qualification and all that, and separation system, is about a 5 or 6 million dollar piece of equipment. The analogy I use with my team is like, “imagine we had like 6 million dollars on a pallet of cash that was falling trough the sky, would we try to catch it?” Probably yes that sounds like a good idea, so yeah we want to get it back. So we won't have to make another one. I say we do, I say we give it a shot, worst case it’s gonna end up on the bottom of the ocean, but maybe we do catch it, then hey.. 6 million dollars. You know, it might as well be a pallet of cash, because it costs 6 million dollars.
That just leaves the upper stage of the rocket, upper stage is about 20% of the cost of the mission. So if we get boost stage and fairing we are about 80% reusable. We think can probably get to something like somewhere between 70 and 80% reusability with the Falcon 9 system. I think for a lot of missions we can even bring the second stage back, so we are going to try to do that. The key to that is, all you do is inspections, and no hardware is changed, not even the paint, this is very important. I think we got at least a technical path to achieving that.
Then if you get to; why don't we have fully and rapidly reusable rockets? Why doesn't someone just do it? Well, it's quite tricky, that's the reason. We live on a planet where this is not easy. It wasn't obvious to me that one could achieve full and rapid reusability, because Earths gravity is right on the cusp of where that is possible or not possible. In order to achieve that really every aspect has got to be done super well. It's amazing how much gravity effects things.
I think for a lot of people there's not a clear distinction between getting to space and getting to orbit. There's a huge difference between space and orbit. Space you can think of as like the international waters boundary in the Pacific ocean. If you go 100 miles offshore you are technically out of coastal waters, now you're in the Pacific. It is like technically you're in the Pacific. But orbit is like circumnavigating the globe, it's a really giant difference. Space is somewhat of a loose definition, it's kind of 'where does the atmosphere get thin?' and you can sort of define, 'how thin is thin?'
It's pretty darn thin at 60 miles altitude, but you can't have a satellite up there because the orbit would decay very quickly and it would reenter.
Going up and staying up is actually about how fast you're zooming around the Earth. It takes much more energy to do that zooming around the Earth bit than it is to get to altitude. In fact the only reason you need altitude at all is to get out of atmospheric drag. If the Earth had no atmosphere you could be orbiting Earth at an inch off the ground. The reason why things go up and stay up is because you are zooming around the Earth so fast that the outward radial acceleration is equal to the inward acceleration of gravity. Those balance out and you have a net zero gravity.
When you see the Space Station, the thing that's sort of counter intuitive is that the Space Station is zooming around the Earth at 17,000 miles an hour. It seems really still but it's moving really really fast. To put that into perspective, a bullet from a 45 handgun is just below the speed of sound, the Space Station is going more than 25 times faster than that. That is what is actually needed to go up and stay up. That's why there's the term escape velocity and not escape altitude, there's no such thing as escape altitude only escape velocity.
The force of gravity, at say the nominal boundary of space of 100 kilometers, is almost exactly the same as it is on the surface of the Earth. It's a few percent lower than on the surface of the Earth. You can think of gravity as like a funnel in space time. If you spin a marble, when it's far out it spins slowly and if it gets closer it spins faster and faster. So in order to go up and stay up the only thing that matters is how fast are you going horizontal to the Earth's surface. It's the outside acceleration that matters. So when the rocket is going to orbit the only reason it's going up is to get out of the thick part of the atmosphere, because at high velocity the atmosphere is thick as molasses.
It goes up very briefly, but if you look at the long exposure of the rockets trajectory it goes up, but immediately curves over and starts going horizontal. So at the point at which the stages separate, there's two stages, the point at which the staging occurs it can be as high as Mach 10, so it's going away from the launch site at 10 times the speed of sound. In order to get back to the launch site you would have to have enough fuel and oxygen to reverse out that velocity, and boost back all the way to the launch site. It's physically impossible, because the other sort of thing about it is if you are in space there is nothing to react against. Aircraft can circle very easily because it's reacting against air. In vacuum there is nothing to react against, so the only way to go back the other direction is to apply twice as much force as it took you. The bottom line is this thing is zinging out there 10 times as fast as a bullet. The point of separation is not that far away it's maybe 100 km away from the launch site, but it's going like hell away from the launch site. The only way to really land it is to continue on that ballistic arc and then land out to sea on a ship that's prepositioned to a particular latitude and longitude, to very precise within about a meter.
Why is it so expensive to send something into space? Well, let me tell you what makes a rocket hard. The energy and velocity required to get into orbit is so substantial that compared to, say, a car or even a plane, you have almost no margin to play with. It's a tricky thing, Earth’s gravity well is quite deep, Earth has a fairly high gravity, it is really quite strong. It's possible, but quite difficult. If we lived on Mars, this would actually be a quite easy thing. But at 1 g this is just barely possible. The difficulty of making a rocket reusable is much greater than the difficulty of making aircraft reusable. That’s why fully reusable rocket has never been developed thus far.
The reason it hasn't occurred in the past, is that when people try to design a rocket, and even one that is expendable, after a lot of smart people have worked on the rocket using advanced materials and various techniques, you typically get 2 to 3% of liftoff mass to orbit. That's for an expendable rocket. Now, if you say okay, we want to make it reusable, we want to bring it back to the launch site, then it's gotta survive the rigors of reentry, all the systems have to be capable of surviving multiple firings and thermal fatigue and it's just really - you add a lot of mass when that happens. Previously, when people have tried to make a reusable system, they found that they would get some portion of the way and conclude that success was not one of the possible outcomes.
Typically a launch vehicle will get about 2% of it's lift off mass to orbit, and that's the case for Falcon. So if you can only get 2% of what your rocket weighs to begin with to orbit, if you're wrong by 2%, you're not going to get anything to orbit. You know, it’ll come crashing down in the Pacific somewhere. That means all of your calculations have to be right. If you miss calculate something, you get an answer wrong, it blows up. And it's very expensive trying to get all your answers right, and then double checking if they're right. And testing them all and doing as much as you can on the ground. I think that's a lot of what makes rockets expensive.
If you say, okay, well, what if you want to add in the reusable bits? adding the reusability tends to take another 2 to 3% so then you end up with zero or negative. There’s not much point sending a rocket to orbit with nothing on it, that’s obviously not helpful. The trick is to try to shift that from say 2%, 3% in an expendable configuration. To make the rocket mass efficiency, engines efficiency, and so forth, so much better that it moves to maybe around 3.5% to 4% in expendable configuration. And then try to get clever about the reusability elements, and try to drop that to around the 1.5% to 2% level, so you have a net payload to orbit of about 2%. The trick is to make a rocket that is so mass efficient that it gets close to 4% of its payload to orbit in an expendable configuration, and then improve the weight of the reusability bits, push that down to around 2% and you get a net of four minus two - so, on the order of 2% of your payload to orbit in a fully reusable scenario.
That requires paying incredibly close attention to every aspect of the rocket design. The efficiency of the engine, the weight of the engine, the weight of the tanks, the legs, even the secondary structure, the wiring, the plumbing, and the electronics, making sure your guidance system is extremely precise, and just pulling all sorts of tricks - every trick in the book - and then coming up with some new ones. In order to achieve that level of mass efficiency.
If you use the most advanced materials, most advanced design techniques, and you get everything just right, then I’m confident that you can do a fully reusable rocket. Fortunately, if Earth’s gravity was even 10% stronger, I would say it would be impossible.
The low launch rate typically is also what makes rockets expensive. If you had thousands of flights a year then it would be a lot cheaper. Although it's a bit of a chicken and egg, because it needs to be cheaper in order to have thousands of flights a year. But at the end of the day, in the final analysis, I would say, that rockets really should be a lot cheaper than they are today. I think the way they're build, the way they're operated is just very inefficient.
The only semi-reusable rocket system that's ever flown really was the Space Shuttle. The Space Shuttle was an attempt to achieve that, but it was not a successful attempt, unfortunately. The Russians briefly flew one, but it didn't work out. They retired it because they thought it didn't make any sense.
The Space Shuttle was semi-reusable, it was partly reusable, I say partly because the main tank, the big orange thing, was not reusable, that was guaranteed to be expendable every time. The main tank was thrown away every time, and it wasn't just the tank, the big orange thing was actually the primary ascent aero-frame to which the orbiter, the plane part, and the side boosters were attached.
The plane thing is not a good idea in my view. If you consider that every mode of transport is designed to its medium. If you're in space, wings are not very useful because there is no air. And if you want to go somewhere other than Earth there's also no runways. So these are important considerations.
The Space Shuttle was extremely difficult to refurbish for flight, 10,000 people needed to work for nine months to refurbish the Space Shuttle. The parts that were reusable were so difficult to reuse that the Space Shuttle cost about four times more than an expendable vehicle of an equivalent payload capability. The Space Shuttle ended up costing a billion dollars per flight, and you could only go into low Earth orbit. So even in the best case scenario it would not have been reusable in a substantial way. It took an army of 10,000 people nine months to refurbish the Shuttle for flight. Which is obviously not rapidly reusable. The Space Shuttle was the only operating example of something with even partial reusability. It was the right goal, but didn't hit the target.
We are now beginning serious development of the BFR, ... well we’re sort of searching for the right name, but the code name at least is BFR. To have a vehicle that can do everything that's needed in the greater Earth orbit activity.
We were really searching for, you know, how do we pay for this thing. We went through various ideas, with Kickstarter, you know, collecting underpants, these didn't pan out. Essentially we want to make our current vehicles redundant. We want to have one system, one booster and ship that replaces Falcon 9, Falcon Heavy, and Dragon. If we can do that, then all the resources that are used for Falcon 9, Heavy, and Dragon can be applied to this system. That’s really fundamental, and this was really quite a profound -- I won't call it breakthrough, but realization -- that if we can build a system that cannibalizes our own products, makes our own products redundant, then all of the resources, which are quite enormous, that are used for Falcon 9, Heavy, and Dragon, can be applied to one system. You can think of this as essentially combining the upper stage of the rocket with Dragon. It's like if Falcon 9 upper stage and Dragon were combined.
Some of our customers are conservative and they want to see BFR fly several times before they're comfortable launching on it, so what we plan to do is to build ahead and have a stock of Falcon 9 and Dragon vehicles so that customers can be comfortable if they want to use the old rocket, and the old spacecraft, they can do that, because we'll have a bunch in stock. But all of our resources will then turn towards building BFR, and we believe that we can do this with the revenue we receive for launching satellites and for servicing the Space Station.
The payload difference is quite dramatic. The updated design for the BFR in fully reusable configuration, without any orbital refueling, we expect to have a payload capability of 150 tons to low Earth orbit, and that compares to about 30 for Falcon Heavy, which is partial reusable.
So then, just the basics about the ship. It's really quite a big vehicle. 48 meter length. The main body diameter is about 9 meters or 30 feet. The booster is lifted by 31 Raptor engines that produce a thrust of about 5,400 tons, lifting a 4,400 ton vehicle straight up. Dry mass expecting to be about 85 tons, technically, our design says 75 tons, but inevitably there's mass growth. That ship will contain 1,100 tons propellant with an ascent design of 150 tons and return mass of 50.
You've got the engine section in the rear, the propellant tanks in the middle, and then a large payload bay in the front, and that payload bay is actually eight stories tall, in fact you can fit a whole stack of Falcon 1 rockets in the payload bay.
The cargo area has a pressurized volume of 825 cubic meters, this is greater than the pressurized area of an A380. So it’s really is capable of carrying a tremendous amount of payload. I think it's important to note that BFR has more capability than Saturn V, even with full reusability.
The next key element is propulsive landing. As a propulsive lander you can go anywhere in the solar system. So you could go to the Moon, you could go to... Well, anywhere, really. Whereas if something relies on parachutes or wings, then you can pretty much only — well if it's wings, you can pretty much only land on Earth, because you need a runway, and most places don't have a runway. And any place that doesn't have a dense atmosphere, you can't use parachutes. If you saw a movie about the future with aliens landing, how do they land? Obviously it'd be kind of weird if the aliens landed in the ocean with parachutes, we'd be like okay, nothing to fear.
Propulsive works anywhere, it could really lower the cost of getting science instruments to various places in the Solar System, so that's kind of exciting.
Orbital refilling is also extremely important. If you were to just fly BFR to orbit and don't do any refilling, it's pretty good. You'll get a hundred and fifty tons to low Earth orbit, and have no fuel to go anywhere else. However, if you send up tankers and refill in orbit, you can refill the tanks all the way to the top and get 150 tons all the way to Mars. And if the tanker has high reuse capability, then you're just paying for the cost of propellant. The cost of oxygen is extremely low, and the cost of methane is extremely low. So if that's all you're dealing with the cost of refilling your spaceship in orbit is tiny, and you can get 150 tons all the way to Mars.
The size of this being a 9 meter diameter vehicle is a huge enabler for new satellites. We can actually send something that is almost nine meters in diameter to orbit. For example, if you want to do a new Hubble, you could send a mirror that has ten times the surface area of the current Hubble, as a single unit. Doesn't have to unfold or anything, or you can send a large number of small satellites. You do whatever you like. You can actually also go around and, if you wanted to, collect old satellites or clean up space debris. That may be something we have to do in the future.
It's also intended to be able to service the Space Station.
It can also go out to much further than that, like for example, the Moon. Based on calculations we've done we can actually do lunar surface missions with no propellant production on the surface of the Moon. If we do a high elliptic parking orbit for the ship and re-tank in high elliptic orbit, we can go all the way to the Moon and back with no local propellant production on the Moon. I think that would enable the creation of Moon Base Alpha, or some sort of lunar base. It's 2018, I mean, we should have a lunar base by now. What the hell's going on? I think if you want the public fired up I think we're gonna have to have a base on the Moon.
But there's something else. If you build a ship that's capable of going to Mars, what if you take that same ship and go from one place to another on Earth? We looked at that and the results are quite interesting.
Provided we can land somewhere where noise is not a super-big deal, rockets are very noisy, we could go to anywhere on Earth in 45 minutes, at the longest. Most places on Earth would be maybe 20, 25 minutes. So maybe if we had a floating platform out off the coast of New York, say 20 or 30 miles out, you could go from New York to Tokyo in — I don't know — 25 minutes. Cross the Atlantic in 10 minutes. Really, most of your time would be getting to the ship, and then it'd be real quick after that.
The great thing about going to space is there's no friction, so once you're out of the atmosphere, it will be smooth as silk, no turbulence nothing. There's no weather, there’s no atmosphere, and you can get to most long-distance places in less than half an hour. If we're building this thing to go to the Moon and Mars, then why not go to other places on Earth as well? If you can carry a lot of people per flight then you can get the cost of spaceflight to be something not far from the cost of air flight. There’s some intriguing possibilities there.
I think we are at the dawn of a new era. Finally, it took a long time.