Let’s start at the beginning: What is a space gun and how does it work?

A space gun is very simple geometry. It’s basically a tube and the only difference between it and a regular gun is it uses hydrogen as opposed to gunpowder. If you go to physics 101, you know that gases can expand at a certain rate. It turns out that rate is a function of the sound speed, which is a function of the molecular weight of the gas. Air has a molecular weight of 28 or 29, as it’s largely nitrogen. Gunpowder has a molecular weight of 22, but it’s very, very hot — so that’s why it gets extra performance, because it’s so damn hot — the sound speed goes as the square root of temperature. But it turns out that helium and hydrogen are far, far lighter than air. Helium has a molecular weight of four and hydrogen has a molecular weight of two as it’s diatomic. So they have extraordinarily high sound speeds, particularly hydrogen.

So a gas gun is a tube made of steel where you evacuate the cylinder and you have the projectile in an appropriate shape for atmospheric exit, and you basically release the hounds — you let the hydrogen push this thing down the barrel.

I was a theoretical physicist for the first nanosecond of my career, and then I got involved in actually building stuff because I got tired of no one ever building anything. It was apparent to me after some time at Livermore National Laboratory that we needed more guys that build stuff and fewer guys that would just think deep thoughts. So I stopped thinking deep thoughts and started building stuff.

“I stopped thinking deep thoughts and started building stuff.”

It turned out that a hydrogen gas gun is something that I could teach you how to do in 30 minutes. There’s about 10 rules: Here’s how you deal with steel, here’s how you deal with hydrogen, here’s how you deal with controls, and so on. Get some engineers and you could build a system very straightforwardly.

What would you generally use one of these guns for in the context of space exploration?

Well, I favor that application because I’ve always been concerned about arms races. It turns out that hydrogen guns are not really weaponizable, because you can’t fire them every 10 seconds. If you want a weapon, you want something that you can shoot every 10 seconds, or every minute in the case of some big, big systems.

So it’s sorta good in the sense that you can only fire these things probably once an hour. For high performance, you’ve got to pull a vacuum on the barrel, you’ve got to clean it out very, very carefully, you’ve got to keep the barrels aligned, and so on. They’re not trivial to maintain. Did that answer your question?

What I’m trying to get at is why are they superior to, say, a rocket for getting something to space?

Oh, certainly, it’s because of the reusability issue. If you could reuse a rocket a hundred times, or a thousand times, then you would never want to use a gun. The rockets are made out of metals and some composites. They have typically a three or four percent payload fraction — these are SpaceX-type numbers. So if you could reuse this thing time and time again — the first stage, second stage, third stage — you’d only pay for them once. And you’d pay a little bit of money to maintain them, right?

The problem is, that doesn’t work. Because typically you kick your first stage off, and it’s traveling maybe Mach 10 when it departs from the second stage — and trying to recover that first stage is a bear. I’ve shot things at high Mach numbers and you just don’t recover them at those speeds. On the other hand, Elon Musk is trying to do this, and I’ve always been impressed by this guy — so if anyone can pull it off, he’ll pull it off. I’ve been out of the field of shooting big guns for over 10 years, but he’s going to run into an issue recovering high-Mach number objects. It’s a very difficult issue.

“I’ve shot things at high-Mach numbers and you just don’t recover them at those speeds.”

So here’s where the gun comes in — the gun is essentially the first stage. We’re launching these things at — in my case it looks like six kilometers per second [3.7 miles per second] is a really nice number. At six kilometers per second, you don’t have significant barrel erosion, and the vehicle survives the exit of the atmosphere easier because all the bad things go at high powers of velocity. So the faster the thing comes out of the barrel, the more you’ve got to worry about as it goes towards some space depot. Six kilometers per second is a good number.

So we have this gun, it launches things repeatedly at six kilometers per second — think of that as the first stage, so the first stage essentially becomes infinitely reusable.

So you’re essentially putting a rocket into a gun?

Yes — it’s a single-stage rocket now instead of a two-stage. The first stage becomes reusable, because the gun is the first stage.

How did you get interested in this subject in the first place?

I was hired at Livermore to build magnetic guns. I had a background in theoretical physics, and I knew about magnetics — the standard stuff you learn in graduate school. This was during the Star Wars era, so launching stuff into space. I worked for a forward-thinking guy named Lowell Wood, who was a weapons lab guy but was extremely talented — he now consults for Bill Gates and those guys. Lowell was my boss, and he was a genius who was a little quirky, personality-wise. He and I didn’t always get along — eventually I left his group, though we actually became better friends after I left. But I was hired to build magnetic launchers.

A year into my soujourn there, in 1988, I ran into the head of the lab at a cocktail party — John Nuckolls. Nuckolls had heard about my work — I was looking at superconductors and generators and all sorts of exotic gizmos, and he said: “This is fantastic John, because our gas guns only get seven or eight kilometers per second [4.3 or five miles per second].” I replied: “What’s a gas gun?” I was one of the uninformed masses at the time about gas guns, but thank God I’m an alcoholic, otherwise I never would have met this guy at the cocktail party! I’m only partially kidding there.

So John Nuckolls told me that gas guns existed, and they used gas guns at these laboratories because there’s no other way to get to high speeds. Livermore was a weapons lab in those days. Now it’s become an environmental-type lab with a bit of weapons stuff on the sides. They use these guns to test equations of state of metals — when you hit, say uranium on steel, what happens there? What happens to these materials under stresses and pressures and things like that.

There was some classified fusion stuff, which was the thermonuclear stuff, and then we had the unclassified fusion, which was like the NOVA laser and the NIF laser and those kind of things. Livermore needed to know how materials behave under immense pressure, and so the only way to get that pressure was to slam things into each other at high speed. And the only way to do that was a hydrogen gas gun.

“Livermore needed to know how materials behave under immense pressure, and so the only way to get that pressure was to slam things into each other at high speed. And the only way to do that was a hydrogen gas gun.”

They had two or three little gas guns at Livermore, but when I heard about this stuff I immediately got permission from Lowell to build one that was about 30 centimeters [11.8 inches] long, and it mocked up a particular weapon that our enemies — in those days of the Cold War — were using. I got it to work, and I was shocked because I got experimental results within a month, and it worked within one percent of my code predictions!

Where I come from, in quantum chromodynamics and string theory, and these arcane things, no one ever gets an answer that works. It’s very unsatisfying if you ever want to get results. Sadly, 30 years later, still nothing has been calculated. It’s been a disaster in my opinion. But I was tickled pink that ordinary, one-dimensional fluid dynamics calculated these results so accurately.

That was done within one month, and I used that as leverage to get permission to build a second gun that was three meters [9.8 feet] long. We got that to work within two months — which shocked Livermore, because they’d been working on a similar system for three years. When they heard I was progressing on this one, they sped up and got their first shot the same day I got my first shot. I gave them some motivation!

That gun ultimately managed eight kilometers per second [five miles per second], which far surpasses any real gun that’s historically ever been made — electric guns never came close to the gas gun for performance, and still don’t. It’s such a simple geometry and methodology. But then Lowell and I got mad at each other — I got ticked off at Lowell and left the group. I walked out.

“Electric guns never came close to the gas gun for performance, and still don’t.”

I went to another division, which was lasers. They sent me there, but then I made a presentation at the lab about gas guns, and I came in number two out of more than a hundred presentations, and I got $800,000 to build a 122-meter [400-foot] system. This was the one I was going to use to put things in space, five kilograms [11 pounds] at a time. That was called Super-HARP.

How did SHARP differ from past space gun projects, like the original project HARP?

The original Project HARP was run by this guy called Gerald Bull, who had a very colorful past and was eventually executed by some people — let’s just say most likely from an area near Tel Aviv. He made the mistake of going out late at night, and ignoring two painters that snuck up behind him and put a few rounds in the back of his head. He was a very talented aerodynamicist and what made him special was he was a guy who would really build the hell out of things.

Public domain.

He got into artillery, and he made some improvements in our long-range artillery in the United States, I’m told. He did things involving base bleed, and exotic projectiles, for conventional 16-inch guns. But then he was pretty talented and he was able to raise money to do project HARP — the one in the mid-60s. He went to Barbados, and he went to Yuma, and he set the world record for altitude out of Yuma — it was the Y28 shot in 1966. I was in Yuma Proving Grounds two years ago and that gun is still there — and it’s in really good shape — so you could go to Yuma now with a little bit of cash and do another series of shots with that powder gun. It’s a nice system. That’s only 120 miles [193 kilometers] from where I am right now!

So Mr. Bull built this powder gun — he took two ordinary 16-inch guns, he smooth-bored them out because at high speeds you tear the rifling out, put thin liners in, and then attached them together with flanges. Then he was able to work on the gunpowder burn, using big grains that burn slowly. He did everything right, went through a whole lot of experimentation, got it to work rather well, and did a lot of shots out of Barbados. He was probing the ionosphere for some of his customers — primarily I think it was the U.S. Army in those days. Then he went to Yuma and did some more shots. He was working in conjunction with the ballistics research laboratory, the U.S. Army, and Canada in those days.

So then that thing ended in the late 1960s, and he went on to making money with Space Research Corporation. My impression was he crossed wires with the CIA, spent a few months in the slammer, got a little bit embittered, and took SRC to Brussels. The rest is history — he got zapped — and they put me in all the books as the evil guy that got away. I’m only one-tenth as evil as they think. Maybe 20 percent.

So did you ever meet or speak to Bull?

No, I came really close. I was going to call him a month before he got shot. I heard he was doing some stuff, and I had intended the name SHARP to be complimentary. Maybe I’m sorta weird, but I was thinking Super High Altitude Research Project would make people recall his earlier work, so I suggested we call ours Super HARP. Maybe he thought I was belittling him, because I heard through the author of one of the books that I drove him nuts — that he didn’t like the fact that I used his name and added an “S” to it. Then he thought I had a billion dollars of funding, because there was a typographical error in an Aviation Week article. I only had a few million.

So Bull apparently didn’t like me because of this — I was going to call him up and be nice to him, explain things, but one of my consultants told me not to do it. He said that Bull is dealing weapons on the international market — if you call him up, you’re going to get Livermore involved, which is a government-funded agency. My consultant was right about that, so I didn’t call him, and a month later he’s dead. That’s as close as I got to Gerald Bull.

“I didn’t call him, and a month later he’s dead. That’s as close as I got to Gerald Bull.”

Later on I met his collaborator, Murphy, and we exchanged pleasantries — he autographed a book for me. Bull and Murphy wrote a nice book called the Paris Guns — a nice coffee-table book, I’d recommend it if you can still get them. It tells the whole history of the Germans’ 1917 gun.

The one that become the V-3 cannon?

It never really became the V-3 — it was just to rain terror on the poor Parisians — a weapon of mass destruction. They killed about a person per round — they shot a few hundred rounds and killed a load of kids and churchgoers and so on. It was just the Germans trying to intimidate Paris in those days.

But then the V-3, which was in the Second World War, was a different beast. It was a side-injected system with powder; it was supposed to fire 90 miles across the English Channel. Strangely enough, Joseph P. Kennedy Jr. was killed on a mission to destroy the V-3 — he was on a glider that had a lot of explosives in it, but the thing blew up in mid-air. I heard the gun had timing issues. It was supposed to give a bit of extra oomph, but it was dismantled at the end of the war.

Project Babylon was dismantled at the end of the first Gulf War. Public domain.

So you had no relationship with Bull?

I just respected his work. I never knew what kind of person he was, and later on I read that he had a bit of an unusual personality — but he was a damn good scientist.

But you weren’t aware of any of the Project Babylon work?

No, not until after it had already happened. After it happened I ended up helping our guys dismantle it — my engineer and I helped our side because there was a question of what would happen if the thing was pointed in a different direction. In the Middle East, every third project is called Project Babylon. They apparently like that word. There were 120 different Project Babylons all babbling in different directions. It was like a tower of Babylons.

“In the Middle East, every third project is called Project Babylon. They apparently like that word.”

But I did help some of our guys, nameless guys, on that topic with my main engineer — we nailed it.

So going back to Project SHARP, what happened to that? How did that all end?

Well, Project SHARP got some internal funding from Livermore — the $800,000 I mentioned before. Then in the second year they liked the project so they gave us another $800,000. Then the Strategic Defence Initiative Organisation kicked in half a million, these were the Star Wars guys. Then later on the Air Force kicked in some money for hypersonic scramjet testing — so those were our funding sources.

We did 20 or 30 shots, in total, with every shot taking a couple of days of preparation and a day or two afterwards to clean things up, because this was a giant gun — it wasn’t made for shooting every hour. I built the thing so cheap and so quickly that it didn’t have capability to reload fast. We used human beings and trolleys — we tried to use the wheel wherever we could.

It was pretty unusual that we pulled it off, because in that era people were building systems similar in size and they were coming in at $30 million. They’d build 10 percent and run out of money. We built SHARP for $2.3–$2.5 million, which was pretty phenomenal, because I tried to avoid as much bureaucracy as I could, so I kept the manpower costs down and the hardware costs up. We were focusing on getting a lot of steel in place. So as soon as I got my first check for $800,000, I started ordering steel as opposed to more studies. Most theoretical scientists just want to study things until they can retire and smoke their pipe all the way to the grave. I just wanted to put hardware in the ground and get the thing going.

“Most theoretical scientists just want to study things until they can retire and smoke their pipe all the way to the grave.”

We were doing shots for the air force — lethality tests during the first Iraq War, when we were concerned Saddam was going to be nerve-gassing Tel Aviv and places like that. We wanted to see if we could destroy his warheads, because he was thinking of putting nerve agents on SCUD missiles. We ended up doing some shots on simulated warheads that were quite effective — we were killing these things at Mach 9. That was one of our clients — we did five or 10 shots doing that.

Then we segued into doing shots for the air force on hypersonic engines — hydrogen-burning engines. During those days, people postulated you could have very high-Mach number aircraft — well above Mach 3, we’re talking Mach 12, Mach 20, these fantastic numbers. In reality, I’m not as sanguine on the prospects of civil transport above, say, Mach 2, because it turns out that the level of difficulty goes up as a high power of the velocity. I’d be shocked if we ever got civil transport above Mach 2 or Mach 3. We had the Concorde and the Tu-144, and so on, but there’s all kinds of difficulties — the guys have to wear spacesuits because of the heating issues. If you make a mistake at high Mach numbers, it tends to be fatal. Whereas you can recover at low Mach numbers. But in those days there was interest in doing civil transport at high speed, and we were part of that.

“If you make a mistake at high Mach numbers, it tends to be fatal.”

We did tests shooting scramjets at high Mach numbers. It was one of these classic government programs where they just wanted to study it forever and keep making money, but people were reticent to actually do testing. Because when you do testing you can actually fail — which is embarrassing. Better to study things forever. I was scolded by the head of the program because we did tests and got real data. We got the first free-flight data above Mach 7 in the world with these engines. He reprimanded me for doing this work for the air force, even though he didn’t fund me, because I think it embarrassed him. “Here are these guys, going out without permission and getting real data!” As opposed to just studying materials for the next 20 years. They’ll spend $5 million studying halfnium diboride to coat the outer layers of the wings, as opposed to just flying the *bleep.* Pardon my French.

We were getting better and better at collecting data, but we never showed thrust. We couldn’t confirm or deny that we were getting thrust — high-speed photographs were taken, but the thing was only flying 30 meters [90 feet] before it vaporized, because it would run into a sandbag. That’s why I said Elon is going to have some issues recovering, because he’s going to have to collect his first stages as they come down, tumbling through the atmosphere, but he’s got to slow them down from Mach 9 to Mach 0 to recover them. I never had any luck doing that, but I didn’t have his resources, and I didn’t have a lot of atmosphere to work with, so who knows? He might pull something off that I couldn’t figure out.

The project ended because I got bored. I was doing a shot every six months towards the end, the funding dropped down to a trickle. So I got bored and decided to take my kids to San Diego to see their grandparents so they would see them while they were still alive. I left the project in the hands of my collaborators. They did a couple more shots, and I came in as a consultant on a few more shots, but then the funding turned off and so there was a dead period — no shots from 1998 through maybe 2000. Then in 2000, just before 9/11, there was some interest in the stuff through DARPA. Long story short, they were able to take the supergun — SHARP — to Vandenberg Air Force Base for storage for potential shots, but the funding never materialized.

“9/11 came along and everything changed — in terms of R&D, this country lost almost a decade because of that.”

Then 9/11 came along and everything changed — in terms of R&D, this country lost almost a decade because of that. I got wrapped around the axle, too — I had a nephew in the battle of Fallujah, so I ended up going and working on armor for a year or two, which was a righteous cause because you don’t want your guys to be killed by these other folks. We might have been successful and pulled off some funding and done some shots into space, but who knows — you can’t go back in time.

Project SHARP firing in Livermore National Laboratory. Public domain.

Then in 2010 you founded Quicklaunch, right?

Yeah — it might have been 2009. I was one of the three founders of Quicklaunch. There was the three of us that had been involved with the supergun stuff, so we all kicked in some cash and some sweat equity, and pursued that. I don’t want to say anything out of line, so I’ll just say that you have to be able to get along with people, and everyone’s got to be willing to do their fair share.

Can you talk about the idea behind the company and how you were planning to make money from it?

Let’s say I was a third party. Let’s say I had a totally clean sheet of paper, I’d say: Well — this is a reusable first stage. You know what the cost of the space gun is — if you do the math, after a couple of lines of algebra, you know how long it takes to amortize the gun. Maybe it’s 10,000 shots, maybe it’s a thousand shots, some number in there — because you’re reusing this thing, so at some point it’s all paid off because you’re dividing by n. Say the gun’s a million dollars, and you do a thousand shots, then that’s a thousand dollars a shot.

You also have to circularize the orbit. You launch out of the atmosphere — say at a 30-degree launch angle, so you burn through a lot of atmosphere. You burn three or four inches of nose off the forebody of the vehicle, you get an aeroshell made out of carbon/carbon. As Elon showed, these ablatives can be anything — an ablative material to protect the nosecone is not exotic. Some of the earliest ablatives were just wood — people used oak, cork, anything. Even steel can work. Anything’s an ablative. But carbon/carbon is pretty nice. Water is even better, so you can do exotic, weird things with that. You can do ablation, no problem.

Then you can do a rocket motor that takes high G-forces — that’s been done before. So that’s the second part of the technology pyramid. You can do either a liquid or a solid — solids are much easier to build than liquids, they don’t have the internal plumbing issues that you have with a liquid. The problem with solids is turning them off. I like hybrid motors. They all work.

That’s inside the projectile, right?

Correct, that’s inside the projectile. You launch that at six kilometers per second, and you lose half a kilometer per second [.3 miles per second] going through the atmosphere. But your total delta-V budget is about nine kilometers per second [5.6 miles per second] to get it to low Earth orbit, so you need to add three with the rocket motor. When all the smoke clears, you have a payload fraction that’s close to 20 percent — of the original weight of the vehicle inside the barrel. That’ll fly through the air, it’s easy to calculate the shocks off this thing and it’ll survive the atmosphere. You’ll burn a little bit of the nose off of it.

“When all the smoke clears, you have a payload fraction that’s close to 20 percent.”

Once it gets to 100 kilometers [62 miles] of altitude, you blow the aeroshell off because that’s the part that absorbed the heat and gets trashed by the atmosphere. Then you have a nice, pristine little rocket that’s gravitationally coasting to 300 or 400 kilometers [186 to 249 miles] above the Earth. When it gets close, you turn the rocket motor on and then it supplies the remaining push to to get the rest of the way into a nice orbit — a circular or elliptical or whatever orbit you want.

What’s so great about this stuff to me is that it’s so simple compared to the stuff I used to do. The equations of motion — Newton’s laws — are so nice. You can get a little spreadsheet and work them out in three minutes. It’s all quite understandable — that’s what I like about it.

With Quicklaunch, how close did you get to actually building something?

Well, let’s just say that internal issues superseded anything like that. That’s all I can tell you.

But you still think that there’s a market out there for space-gun technology?

Yeah, but it’s a virtual market at this point because no one really realizes it exists. Until you do the first shot into space, no one’s really going to believe it — and I don’t blame them, because we’re herd animals.

“Until you do the first shot into space, no one’s really going to believe it.”

We’ve survived by being herd creatures for all these years — I guess at one time we were herd monkeys, if you believe that stuff. But there’s nothing wrong with being a herd animal, so that means the burden is on the inventor to do the first shot into space, deliver the first payload.

Quicklaunch planned to build a kilometer-long [3,280-foot] space gun underwater. Image credit: Quicklaunch

Hypothetically, how do you achieve that?

Well, you’ve got to raise half a million bucks. Believe it or not, I think things like Kickstarter — that sort of thing — is probably a very good channel to do it. What you’ll discover is the usual suspects — the VCs, the guys who fund these things — they’re not dummies. They’re there to make lots of money. So they’ll all jump onboard, say they’re your best friend, as soon as you’re successful. But they’re not going to fund you until that happens, so you need to find someone a little bit more willing to risk.

A guy like me, if he’s had a few beers, he’ll say, “Ya’ know, I want to fund that Quicklaunch gizmo — I’m going to send $20 to those guys so they can go to Yuma and do shots into space.” You get a few thousand guys like that, and before you know it you’ve got half a million bucks and enough money to do the first-phase shots.

Once you’ve done those, then you can find partners in Silicon Valley, just like Elon did, but he wasn’t best friends with the investors until he’d probably had some success — because he had a couple of failures early on. Success has many fathers, and failure is a bastard child, right? So you’ve gotta hang in there, but I think that crowdfunding might be a nice way to fund this stuff.

“I think that crowdfunding might be a nice way to fund this stuff.”

The average scientist is always in the back of his mind thinking, “Well, I’ll find some eccentric millionaire like Howard Hughes who’ll fund my project so I can exercise this fantasy and get to Mars and grow plants.” Well those guys don’t exist — that’s a fantasy. But what does exist is that you have a lot of guys who realize that there is a chance of this happening. They might kick in their beer money for a day or two. So I think that the Kickstarter-type milieu might actually play a part here.

How many years do you think we are away from actually building something like this?

[Laughs.] Well, I’m the only guy that can do it, so it all depends on my other projects.

I sound a bit like a megalomaniac there, but I’m kidding. If anyone wants to, they’re welcome to do it and I would be tickled pink if someone else pulled it off. The problem is that you have different types of people who like guns. I personally don’t love guns — I’ve used them as a tool, my father was a marine in the Second World War. He was in a bunch of engagements in the Philippines. Whereas my mother hated guns, because she knew they killed people.

“I’m the only guy that can do it.”

You’ll find some extremely nutty gun people. Back when I ran Super-HARP, I would get emails from people that would say: “Dr Hunter! I’ve heard about your project, I want to build a Mannlicher 5000 so I can shoot my neighbor’s dog three miles.” Well, before you build a Mannlicher 5000, make sure you build a nice bunkhouse and get a couple of lawyers. I would gets nut cases emailing me, which probably means I was popular, because if you’re popular you get nut cases. As opposed to the Hollywood paparazzi, these guys were like the gunarazzi — they liked me back in those days.

You get some amateur guys who want to hear things go bang, but there’s a little bit of physics involved. You have to know some things — you can’t just take a tube, jam some gunpowder in it, and light it with a match while you’re looking down the barrel — that’s a mistake. You have to have some care. But artillery isn’t really intellectually attractive to great minds. I can teach you everything you need to know in 30 minutes. Whereas with string theory, I can’t teach you anything because no one knows what the hell is going on.

So do you think that guns are the best option for getting stuff into space, sustainably over the long term?

I do. From planet Earth I think it’s probably one of the best. I think Elon Musk’s is certainly, at this point in time, by far the best. He’s the first guy that’s done rockets correctly — without having this massive military-industrial complex attachment. He’s been able to do it in a fairly pure form but he’s smart enough to get funding from the usual suspects — like NASA. They’re willing to bet on him. But the United Launch Alliance is not happy with Elon, I assure you, because he’s taking money from their pockets — these are guys who are used to Cadillac budgets. To have Elon come in and do this is really irritating to those guys.

“Elon Musk is the first guy that’s done rockets correctly.”

I actually think he’s doing a great job. I wish him the best. But he’s going to get down to $1,000 per pound. If he doesn’t get his first stage reusable, he’ll always by asymptoted at $1,000. You’re always going to be buying those 27 exotic Merlin engines for your SpaceX Heavy, and throwing them away each time. That’s not going to be free. So he’s going to have to pay for that every time he does a shot.

So now you want to get below $1,000 per pound, and here’s the metrics that I arrived at back three or four years ago. To get to Mars, for a three-year mission with a crew of 10 people, you need to stage from low Earth orbit. That makes a lot of sense physically. Turns out you need a million pounds of propellant, per person, to start from low Earth orbit, get to Mars, and come back three years later. That’s based on two studies I saw — one by Von Braun, and one was by Boeing, using nuclear thermal rockets. I averaged those two studies, and they weren’t far off in their numbers, and the answer was a million pounds of propellant per person.

So then you ask what the current price of propellant in orbit is. It’s $5,000 per pound. That means that per astronaut it’s going to cost you $5 billion just in fuel alone. That’s why NASA has not jumped at this opportunity — that’s why we keep sending these robotic things that look like they were made at Radio Shack to Mars, because we can’t afford to send a human to Mars at $5,000 per pound of propellant.

Now, Elon’s going to come down to $1,000 — I hope he does. I think he’s probably at $2,000 right now, but he’s probably going to get down to $1,000 by doing his technology well. If he isn’t going to get rid of that first stage, or amortize the first stage with a gun or the other mechanism he’s working on — I think he calls it Grasshopper. Then it’s always going to be pinned at $1,000.

So now instead of $5 billion per person in fuel, it’s only going to be $1 billion per person in fuel. That’s still pretty pricy. My latest numbers go down to $100 per pound. That’s my most aggressive numbers I could ever get to, because you have to pay for the vehicle launched out of the barrel each time. Even if the barrel doesn’t have significant wear — if you pull the liner every thousand shots — you still have to pay for the vehicles, and in my case those are going to be a single-stage rocket motor with an ablative aeroshell. So I’m never going to get below $100 per pound, but now instead of $1 billion per person in fuel I’m now $100 million per person. You can see that number working out — you could send 10 people to Mars at some point with my numbers.

“My latest numbers go down to $100 per pound.”

I was being megalomaniacal a minute ago, saying I’m the only guy that can do it. I’m not at all — anyone can do it. But I’m the only guy that really knows I can do it. I used to play a little basketball when I was a young twerp, and back in the day no one had done a jump shot until the mid-40s. A jump shot is where you jump in the air and then shoot the ball — until 1945, everyone shot from the ground where it’s easy to block.

Well, I know you can jump in the air, and I have jumped in the air. That’s the only thing that distinguishes me.

“I’m sort of annoyed that I haven’t done anything lately.”

But I don’t want to pat myself on the back because I’m sort of annoyed that I haven’t done anything lately. It’s annoying that you start these projects and what happens is human psychology, which a lot of scientists like me are weak on. We’re raised to look at quarks and weird things, but we’re not taught how to deal with people and dissect sociological phenomenon very well.

Bottom line is you need to start a company with guys that like each other — you don’t want to have a company with people with hidden animosity. You want everyone to be straight arrows — to be transparent, and everyone’s got to put in their share of work. Simple stuff.

Finally, you mentioned you’re working on a couple of other things at the moment?

Well, I can’t tell you much about Sundance Solar. You’ve probably seen some solar airplanes in Europe. Solar Impulse, built by a guy named Dr. Piccard who’s a psychiatrist out of Switzerland, who comes from a long lineage of explorers. I’ve never dealt with them but I’ve always followed them.

Solar Impulse seats one person and costs $140 million and it goes 45 miles per hour [72.4 kilometers per hour]. I think it’s a great thing, because it provoked me to think about the problem a little bit — and that’s what Picard said. He said it’s not going to solve a problem but it’s going to inspire people. I think he was right. So the Solar Impulse inspired me, plus I knew Paul McReady sorta well — the guy who did the first solar-powered airplane, back in the 1980s. His plane went eight miles an hour [12.9 kilometers per hour] — it was cute, because you could outrun it. He hired a jockey or a small person to be inside it, and he had solar cells on it. It would just go along very slowly.

So I have this company called Sundance along those lines and I can’t tell you much more than that unless you sign an NDA, but I’ve taken Picard’s inspiration and decided to make a practical version. I think we’ve got an absolute killer.