Gigantic Air Gun To Blast Cargo Into Orbit 384
Hugh Pickens writes: "The New Scientist reports that with a hat tip to Jules Verne's From the Earth to the Moon , physicist John Hunter has outlined the design of a gigantic gun that could slash the cost of putting cargo into orbit. At the Space Investment Summit in Boston last week, Hunter described the design for a 1.1-kilometer-long gun that he says could launch 450-kilogram payloads at 6 kilometers per second. A small rocket engine would then boost the projectile into low-Earth orbit. The gun would cost $500 million to build, says Hunter, but individual launch costs would be lower than current methods. 'We think it's at least a factor of 10 cheaper than anything else,' Hunter says. The gun is based on the SHARP (Super High Altitude Research Project) light gas gun Hunter helped to build in the 1990s while at the Lawrence Livermore National Laboratory (LLNL) in California. With a barrel 47 meters long, it used compressed hydrogen gas to fire projectiles weighing a few kilograms at speeds of up to 3 kilometers per second."
G-forces ???? (Score:5, Interesting)
Just wondering how they plan to address the problem of controlling the G-forces and prevent damages to the cargo.
The cannon idea was tried before ...... not a test single cargo survived the trip (or made it to orbit).
Gerald Bull (Score:5, Interesting)
Gerald Bull was Canadian engineer who died (bullet in the head) trying to build such a cannon.
See http://en.wikipedia.org/wiki/Project_HARP [wikipedia.org]
Re:nothing new here (Score:1, Interesting)
Sounds like a great way to send up food and water actually. With some work maybe even oxygen.
If this was useless, it would already be funded (Score:4, Interesting)
$500 million is what BART wants to spend to build a 3.2 mile stretch of elevated rail to connect the Oakland Coliseum to the Oakland Airport, and this boondoggle of a project is already funded. Imagine the progress we would make towards space travel if we spent the same amount of money on technology that will move cargo into space as opposed to moving people too lazy to take the already existing BART Shuttle to the airport?
G force. (Score:4, Interesting)
I may be wrong in this calculation but running the numbers I get a weird result.
The gun is 1.1K long with a final velocity of 3km/s.
So the payload would be in the gun for 1.1/(3/2) = 0.73 seconds.
In that 0.73 seconds the payload would accelerate to 3 kms/sec The continuous acceleration would be 3000/9.8/0.73= 417 Gs. That is sure a lot of Gs. Much more than the 3.2 the shuttle produces.
Re:nothing new here (Score:1, Interesting)
To Darfur :)
Though - seriously, it's a gun that can launch a payload to any spot on earth, and the payload is way smaller than any ICBM, thus harder to detect.
1670 g (Score:4, Interesting)
All you need is a booster rocket (and a cargo) which can stand 1670 g of acceleration (possibly higher, if the gun does not provide uniform acceleration.)
v^2 = u^2 + 2*a*S
u=0, v=6000, S=1100 => a=16,364 m/s^2 = 1670g
Re:nothing new here (Score:2, Interesting)
If we try hard enough we should be able to think up a form of rocket fuel that survives the transit. Oh, there it is: water ice. Just freeze a slug and toss it up to the satellite with solar power to be remanufactured into oxygen and hydrogen for use as a fuel or breathable air or potable water while in orbit.
The idea works better shooting from Mars, but whatever...
Launch loop (Score:2, Interesting)
Re:G-forces ???? (Score:4, Interesting)
They probably hope to discover "inertia canceling."
I could not find it in the article, so:
What are the power requirements for such a mechanism?
Where will it be located?
What about ITAR issues?
Why not make it longer for smaller accelerations?
The concerns about the hypersonic regime of fluid flow should not be an issue if they fire from a mountain, there are a hand full of craft that can handle the plasma, although none accelerate like that at such a low altitude.
Aside, what happens to fuel (liquid and solid) under such high g-load? I can find no studies on it.
P.S. I am an Aerospace Engineer.
Re:G-forces ???? (Score:5, Interesting)
Actually, the ability to cheaply fill fuel depots in orbit does a significant amount to reduce the problems associated with current launch technology. Consider Apollo. The massive Saturn V rocket was required because in addition to taking the CM, SM, and LM to orbit, it also had to take the fuel to get it from LEO to the moon -- fuel was the most significant fraction of the mass (2:1 or 3:1 if I remember correctly). Instead, if this had been available to move fuel to orbit on the cheap, you could have used a couple of Saturn IB rockets and rendezvoused in LEO with a freshly filled Earth departure stage. I wouldn't be surprised if it would have been able to cut the cost of Apollo in half. This could also allow a new moon mission architecture without the massive Ares V.
Remember, space missions are like exponential Russian nesting dolls. If you remove a layer (in my example, the EDS), you can reduce the initial launch mass drastically. This is why things like ISRU and various electric propulsion schemes are such hot topics, even though they don't help you get off the ground either.
Re:1670 g (Score:3, Interesting)
> What I always wondered was if the aircraft carrier had not come along, would
> we have seen some terminal guidance systems for naval and land artillery?
We did. The US Army had artillery shells with terminal guidance in the 1970s.
Re:nothing new here (Score:5, Interesting)
Matterafact, the proximity-fuzed antiaircraft shells of WW2 had a vacuum tube in them.
rj
Re:G-forces ???? (Score:5, Interesting)
Actually, it solves a LOT of current issues. Maneuvering fuel, food, water, and medicines for example are quite durable under G-force. Those are a large part of what the ISS resupply missions are carrying. The Progress mission hardware isn't reusable either but is likely considerably more expensive than a solid booster with a dumb cargo capsule.
Re:G-forces ???? (Score:1, Interesting)
Well.. if they can make a 1.1 km gun, why not make a 4km one and accelerate the cargo much more slowly at first?
That would cost more of course, but if you could "gently" (x 10g's) send something into orbit, you've got a winnar!
Short-term Project (Score:4, Interesting)
Send up consumables, for sure. Fuel, water, compressed air, freeze-dried food, etc. Even if just used for that, this is not a bad plan. There's no rule that says you have to use only ONE method to get stuff off-planet.
One good criticism would be that this is a short-term project. You'll need conventional lift to get the tools up into space to build an orbital mining facility. This air-gun can be used to lift all the materials that those tools will use to build the mining facility and fuel for the crafts that will go get the asteroids and coax them back. But once that's done, we ought not need the air gun nearly as much or at all.
Still, compared to the costs of things like shuttles or ISS, this is pocket change.
Re:Gerald Bull (Score:5, Interesting)
Bull was killed by Mossad because he was helping Iraq build a "supergun". You make it sound like he was killed because of Project HARP.
Gerald Bull designed his "super gun" to put payloads into orbit. He approached the US government with the idea and they rejected it as a launch method but wanted a weapon. Disgusted and disillusioned (he was apparently treated very poorly) his response was to create a truly powerful weapon. Iraq hired him to build one for them. The Mossad killed him in Belgium, a country that exports arms all over the world. It's important to remember that the US military has done this with a number of inventions. The guy who invented the x-ray laser had wanted to use it for medical purposes; excising tumours etc. The US military classified it and now it's a weapon. Another Canadian invented polymorphic encryption for secure banking and corporate communications...US military classified his work and as far as I know he can't even talk about it with his peers.
Re:G-forces ???? (Score:3, Interesting)
It had to be said.
Re:Short-term Project (Score:3, Interesting)
Just keep sending up loads of water and compressed air, etc., for however long you can afford to do so
I've heard it argued by folks who sounded like they knew their stuff that it's much cheaper to do it by dragging in asteroids (maybe one with a cubic mile of ice in it) than to shoot it up from earth. I admit, I haven't seen the numbers.
And, yes, it seems unlikely that governments will get this done.
Re:Starting to get afordable (Score:3, Interesting)
Only if you want them to arrive on orbit as people paste.
Scotty wouldn't have minded this technique. At least he would not have been spread across Puget Sound by a rocket failure. http://en.wikipedia.org/wiki/James_Doohan [wikipedia.org]
Put one on the ISS (Score:3, Interesting)
The cost would be higher, of course, but I'm sure obtaining funding would be even easier. The ground-based version would be a necessary stage in development, used to launch the parts into orbit.
Re:Not nearly enough (Score:1, Interesting)
If the gun were built right on the equator, not only would it get the maximum benefit from Earth's rotation, but one could fire it as often as one wanted without regard for orbital planes. One just has to tweak the phase of the orbit by moving slightly higher or lower until one meets up with the depot.
Re:Gerald Bull (Score:3, Interesting)
"Gerald Bull designed his "super gun" to put payloads into orbit. He approached the US government with the idea and they rejected it as a launch method but wanted a weapon. Disgusted and disillusioned (he was apparently treated very poorly) his response was to create a truly powerful weapon. Iraq hired him to build one for them. The Mossad killed him in Belgium, a country that exports arms all over the world."
100% unadulterated bullshit. The US Government sponsored his work in HARP, and it set altitude records for guns. The reason why the program was terminated was that HARP showed that putting a satellite into orbit using ballistic means wasn't feasible using the technology at the time. Aside from the fact that the projectiles couldn't make it to orbit, no one had yet figured out a way to have the electronics survive. And the US military didn't want a "supergun" - experience in WWII showed that they weren't tactically effective and were vulnerable.
So Bull lost his funding, but just would not accept that his idea wouldn't work at the time. So he started designing weapons. No one cared, until the Iraqis commissioned him to build one to point at Israel. At this point, one can argue that he stepped over the line - when one is actively working on a weapon that could ONLY be used to hit Israel (it was fixed in place, remember?) one could argue that he went from supplier to combatant. I don't endorse what the Mossad did per se, but portraying Bull as some kind of innocent scientist working for the good of mankind until he was ruined by the machinations of the US Military is ridiculous.
Re:NOT a Railgun (Score:3, Interesting)
Rail guns have other issues right now, such as the rails warping. (Imagine having to replace the entire rail after every couple of shots). However, there are some thoughts on using a linear motor to achieve something similar. A linear motor might even be superior under some of the ideas that have been thrown out there. One idea is to create a mile wide circular track that is one long continuous linear motor. You slowly (at your control) accelerate the payload to escape velocity, then switch the payload (similar to train track switching) to a ramp that sends the projectile into orbit. If I remember right, you could even launch humans into orbit this way and have them survive. Wiki calls them Launch Loops [wikipedia.org], and there are a few different designs out there.
I've met Hunter, and visited the SHARP gun (Score:4, Interesting)
Back when I was doing giant space gun work at Boeing :-). Feel free to ask questions. I'm not about to type in several volumes of technical data, but it's nice to see he's converged on the same muzzle velocity we came up with (5.7km/s).
Our desigh: particle-bed heater with Aluminum-oxide heat storage (it's actually #20 sandpaper grit). It's much easier to store hydrogen at room temperature, then heat it just before it hits the barrel. Using small particles, you get lots of area for heat transfer. The particle bed gets warmed up with heaters of your choice over a period of hours, then you fire the gun and in a second or so transfer a good chunk of that heat to the hydrogen.
Why heat the hydrogen? The speed of sound of a gas depends on the molecular weight and temperature, and hot hydrogen works best. The efficiency of a gun drops dramatically as you reach the speed of sound of the working gas. Think of it this way, speed of sound is how fast pressure waves travel.
If the projectile outruns that speed, there is no way for the gas at the back end to send push to the projectile further up the barrel. It's a bit more complicated than that since you are constantly feeding gas from the back end, and the gas right near the projectile is moving almost as fast, so pressure waves can catch up, but on the whole as you get near Mach 1 of the gas, your ability to push drops way down.
Depending on size of the gun, and where you are launching to, the west slope of Hawaii and the Andes are good locations. The first has *long* even slopes, courtesy of lava flows. The second are shorter, steeper slopes, but somewhat higher altitude (less air to fly through), and closer to the equator.
Re:I've met Hunter, and visited the SHARP gun (Score:3, Interesting)
Part 2:
Our projectile was re-useable liquid fueled. And the mission was to feed a fuel depot for geosynchronus satellites. 3/4 of the mass of comsats in low orbit is fuel to get them to GEO, and stationkeeping for 15 years. The projectile was very simple, pressure fed liquid engine. It used part of the fuel to get itself into orbit, the remainder is transferred to a fuel depot.
The projectile uses GPS nav borrowed from artillery shells to get to the close vicinity of the depot, then the depot has the smarts to find and dock (that way the smarts occurs once, not on every projectile).
Once done, we deorbit and land anywhere, even on concrete. There is a couple of inches of ablative heat shield on the nose, backed up with 10cm of crushable honeycomb. A bit of the heat shield burns off going up, and more coming back. The honeycomb lowers the landing shock to under 1000g's. Since that's the g-force being fired up in the first place, the projectile can already stand that landing.
Our design projectile was about 360kg loaded, if I recall, and about 100kg or less empty, Ill have to dig out the documents to be sure.
We factored in a 4% loss rate on projectiles after you had experience (40% on the first 10, declining as you gain experience).
Costs worked out to $300/kg ongoing if I remember.
Old ideas are new again (Score:3, Interesting)
When I first read this, I was thinking of HARP, the (rather obvious) precursor to the SHARP program [wikipedia.org]. His goal of making HARP a space launch platform was a failure, but the lead engineer (Gerald Bull) was so disgusted with the politics, he went on to created Project Babylon for Iraq [wikipedia.org]. I suppose the moral of the story is: keep the big gun makers employed, or they will go work for someone else :)
Back to the original topic: from the press release, they've doubled the velocity achieved by HARP. If that is true, then it's only a small hop with a booster rocket to LEO. This could really work!