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December 15, 2010

H Cannon

Guest Post by Joseph Friedlander

A NOTE ON Development of THE H-CANNON CONCEPT.
I independently thought of a variant of the Wang Bullet a few years ago (and as the Thunderwell work (which we are trying to find a good reference for-- ) shows, that was not original either-- most young boys get around to putting a can on top of a firecracker, so the idea was basically just a matter of getting a crazy enough boy to put a crazy enough can on a crazy enough firecracker.

Dr. Anthony Zuppero, of >Neofuel fame, told of a nuclear cannon experiment (heard second hand, no confirmation yet...)

c 2009 by Anthony Zuppero inhabit

A review of it is at the register UK
The actual book--- is here



The actual nuclear cannon part of the above-- acknowledgment to Dr. Zuppero---

Our driving out of that canyon reminded Ben of an atomic bomb that deliberately blew out of a tunnel.
"They used an atomic bomb to make an atomic bomb cannon." he said, one hand on the steering wheel, pointing to the side of the canyon we were in with the other.
"What did they do?" I asked, expecting a short story.
"Well, they shot off a small atomic bomb inside the tunnel on one side of this canyon." he started to explain, slowing his words as he looked around, to find just where it had been.
"I don't see exactly where they did it here." he continued, looking around at what was clearly not familiar anymore.
"It's been a while," explained, excusing the fact of his not being able to point right to the tunnel.
"It shot the projectile out the tunnel and hit the other side of the canyon." he said.
"Of course. what you expect?" I asserted. I believed him and could not imagine what else an atomic bomb would do.
"What scared the hell out of them was that the didn't curve like an arc, it went straight, straight across the canyon." he explained.
"Did they ever make a cannon out of it?" I asked.
"Well, if you like dragging a Mountain along." he replied.

I called my own nuclear cannon idea an 'H-Cannon' and the idea was basically to bore out (more plausibly, melt) a blast chamber and long narrow directional barrel deep within a solid iron-nickel asteroid and put cables on it to precess it precisely to a given target vector. (The barrel would serve to channel the plasma, NOT contact the shell) Then, shoot a precursor star probe out at around 1- 3% the speed of light. (at the higher speed, 120+ years to Alpha Centauri. The challenge would be building something ABSOLUTELY solid (i.e. with no tiny voids inside) that could take unspeakable Gs, say 50,000 or up (If it could take a million gs it could heliobrake—slowdown-- in the target star's atmosphere, and then circularize or directly enter and splashdown at the orbit of a planet with atmosphere--- obviously you want huge space telescopes and complete target knowledge before you launch these things. But in principle, THOUSANDS of stars could have (G resistant) robotic orbiters put about their most promising planets, given the H-Cannon-- and time...possibly for as little as $10 million a shell. If you could seed promising planets, manned expeditions arriving centuries later could find oxygen atmospheres, forests, Earth life growable from high-G resistant seeds (fluid-filled) etc waiting for them-- hopefully with good lumber! (This is Larry Niven's old idea of 'seedships' that terraformed worlds preceeding by centuries as yet unbuildable swift manned starships)

Even if you only could seed say blue-green algae, having an oxygen atmosphere would be a huge huge logistical advantage. In case of a colony environmental failure you could camp on the rocks instead of choking and dying. Remember, this is interstellar colonization, no quick help missions possible (using conventional physics which we assume to be 100 pct of the story until proven others)

This, remember, is without nanotech, just a simple (ultra-G hardened) probe that could probably be built within 10 years IF the H-Cannon existed. The propulsion is from H-bombs that could be designed today-- the heliobraking slowdown is completely hypothetical (and not my idea) but very probably possible in terms of heroic materials and clever structures. But this does not to my knowledge require any IMPOSSIBLE materials. With a million Gs heliobraking at the end of flight, (even 50000).
Obviously the material of the probe itself would be as layered as a Sun penetrator. Actually this gives a great cover for developing the kind of device Bolonkin feared. Another example of the dual edge sword of nuclear tech (reactors gives capability for bombs, etc)

Over the years (in my readings of Project Orion and thermonuclear weapons physics and then the Sun Explosion papers and other researches) I have had my 'impossible' goal posts on what conventional matter can take (for very brief periods of time) moved rudely over several times... my (totally unproven) instinct says the system outlined here can be built.

Assume it can be. And that the slowdown orbiter could seed the target planet (Earth-like but lifeless) with say a nitrogen/carbon dioxide atmosphere and turn it to a nitrogen-oxygen one. Assuming we get up to 10 percent the speed of light (details below) there are around 14,000 stars within 100 light years or a 1000 year journey. (NASA astro answers - The value given there is 14,600) Say 5% of these have the equivalent of a cold Venus or warm Mars --all these of course being no kidding verified with resolution of hundreds of kilometers at least from super-telescopes in space) and we have 700 mission targets at least. You could seed one with blue-green algae for oxygenation, then 100 years later launch a (100 years more in development) advanced lander package (say with 1000 very tough pods of clustered fluid-filled micromachines that would try to seed land plants, if need be by powdering rock and planting seeds) So year 1000 you plant the algae, year 1100 you plant rock breaking plants, maybe around 1400 you plant forests,, and who knows, perhaps in year 1500 manned starships arrive to a forested planet--- not a second rich virgin Earth, but at least with air to breathe and wood to harvest for structures, shipping and fuel. (In case of a technological breakdown of the colony). They would arrive with stock animals, including horses and many, many more plants, none of which should have any competition-- and the trees should have helped broken down the soil. Is this a naïve model? Of course, but consider that within 2000 years we could have 700 colony worlds for lifeboats in case the human race runs into bad luck at home. 2000 years is not only within historical time, some man-made structures are still around from then. Notice that this plan allows manned starships say at 1/3 light speed to be built 1300 years from now and arrive at known good and seeded planets with a no-kidding good chance to found new nations.

Anyway, you can see that it is a contagious fantasy.

But the idea of using nuclear blasts for space launch and being permitted to in the ultra-cautious, politically correct culture of around 2005 (heck, try right now) was not something I was not imaginative enough to picture. So I am happy that Brian broke that discussion taboo. 'Offend no one, win friends, propose new ideas-- choose any two.' Oh, well...

The limiting exhaust velocity of fusion is higher than fission which is limited to 1 to 3 percent of light speed. Fusion can get to 15 percent of light speed exhaust velocity. However it is not wise to count on getting the full measure of exhaust velocity, so I aimed for 3 percent. 10 percent might be doable, which means Alpha C mission in around 45 years. 100 light years obviously would be 1000 years, as in the scenario above.

The material for the H-Cannon would be native solid iron-nickel. (blast chamber should have sacrificial material to avoid contamination, barrel may need to be re-annealed after each shot, but big deal, you're in space and vacuum and automation and have cheap solar power) You possibly could get a shot a day for decades to centuries. That's a lot of star systems seeded. You could debug the heliobraking (or better yet planetary atmosphere braking) part by practice shots at Jupiter (sure to be spectacular). Just don't hit a deuterium rich pocket, or you may solve Fermi's Paradox (link to Sun Explosion article) inadvertently...

10 percent light speed means theoretically the whole Galaxy seeded in a million years, except good luck engineering a shell that can survive more than a few centuries that is ALSO G-hardened. But repeating the exercise once settled in previously seeded star systems might give the whole Galaxy seeded in say 10 million years... better than never...

Suppose we get colonization out to 100 light years, and after 1500 years they take 500 years to multiply the early colonists (doubling each 25 year generation) 20 times so 1000 colonists become 1 billion. Another few hundred years and they are building their own H-Cannon. This implies an effective rate of spread (if H-Cannon shells are 10 % the speed of light) of around 100 light years each 2500 years. That is effectively 4% the speed of light. So 100000 light years in 4 million years.

Perhaps the deal for colonization is, send your mother world (builder of the H-cannon) a few million heliobraked packages of rare elements around year 3000 for payback. (This obviously assumes no transmutation-- notice what a conservative future this is, no FTL (faster than light) no teleportation, no transmutation---if each package is a ton, we get 700 million tons of rare elements, micro samples, etc. A drop in the bucket compared to the future wealth of a whole star system? Sure, but that is probably the best reason that it would be paid. (and Notice that any life forms developed (or discovered, though we assume no life outside Earth for this scenario ) could probably just be relayed as DNA codes,

The formula for barrel length is .5 x the number of meters per second accelerated times the square of acceleration time in seconds.

The problem is the assumption that it would be constant. However, a million Gs means each second you are accelerating at 10,000 km sec (3 pct speed of light--30 seconds to light speed IF you had infinite energy and no mass gain-- note the IF!) so to get the full 10 percent you would need 3.3 seconds acceleration and the barrel would be like spaghetti extending a mile forward a handgun (from the blast chamber (the asteroid itself).)

Winterberg has suggested staged explosions in space you fly past in a straight line-- quite possible.

That in fact may power the manned missions.

I am going to guess the largest practical single barrel from a few thousand km3 iron nickel asteroid-
- IF you could keep it straight and structurally stable (it has solar tides, think about it) then .5 x 10 million (meters second net acceleration) x 10 (square of 3.3 seconds, about) or 50 million meters (50000 km long). Note that the blast chamber need be very stout, the barrel less so This is a wild guess and totally draft work-- but I'd love to see it work in a science fiction story, and more so in real life...



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