Author Topic: Casaba Howitzer Space Gun  (Read 10053 times)

Offline nmurali

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Casaba Howitzer Space Gun
« on: 07/06/2018 07:14 pm »
So I've read ideas on building an "atomic verne cannon", but a big problem was the fact that one would need to dig a new launch tube/barrel after every shot. You would also need to somehow build or dig out a huge chamber to fill with water.

What if, instead of using a conventional atomic bomb, you used a Casaba howitzer? While a lot of information is classified, I've seen the figure of 85-95% of the bomb's energy being directed in one direction. It seems like if you put one of these at the end of a giant tube, and put something on top of it, that thing would be flung out of the tube at extreme velocity.

Obviously, you have the problems of thermal ablation and impulsive shock. At the same time, however, the launches are so cheap and huge that you could stick a large amount of sacrificial material/ablative oil and your payload would be fine. Same thing with atmospheric heating - put enough shielding and the payload will be fine.

The biggest problem is G-forces, but if you want to industrialize space, you ultimately need raw materials. You could ship up steel, copper, water, etc, and have robots in orbit (sent up by a conventional rocket) to assemble the materials into orbital factories or spaceships. The gun would ideally be reusable, and since fusion bombs are cheap to scale up (The U-238 tamper, which provides most of the yield, is cheap as 99% of Uranium is U-238), you could get really low launch costs.

Then there is of course politics - but I feel that if something like this was presented as merely a part of a grand scheme to drive humanity into space, it could get support. That's just me. Aside from politics, I'd love to hear criticism of this idea - I'm curious about it myself and I'm wondering if anyone has considered it.

Offline A_M_Swallow

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Re: Casaba Howitzer Space Gun
« Reply #1 on: 07/06/2018 08:55 pm »
We have banned nuclear testing in Earth's atmosphere. So you may be able to use a nuclear cannon on the Moon and possibly Mars but that is it.

Offline RonM

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Re: Casaba Howitzer Space Gun
« Reply #2 on: 07/06/2018 11:32 pm »
It would be better to get raw materials from asteroids or the Moon. No need to set off nukes in Earth's atmosphere or make a new canon for each launch.

A mass driver on the Moon would be a good way to get bulk materials into space and it's reusable.

Offline Paul451

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Re: Casaba Howitzer Space Gun
« Reply #3 on: 07/23/2018 10:00 pm »
So I've read ideas on building an "atomic verne cannon", but a big problem was the fact that one would need to dig a new launch tube/barrel after every shot. You would also need to somehow build or dig out a huge chamber to fill with water.

The latter informs the solution to the former. You hang a disposable tube underwater at the desired launch angle. Set off the nuke at one end. Water is incompressible (beyond a certain distance from the detonation), so if the tube is filled with gas instead of water, it is the only compressible path for the nuclear overpressure to escape.

Offline CameronD

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Re: Casaba Howitzer Space Gun
« Reply #4 on: 07/24/2018 03:30 am »
So I've read ideas on building an "atomic verne cannon", but a big problem was the fact that one would need to dig a new launch tube/barrel after every shot. You would also need to somehow build or dig out a huge chamber to fill with water.

The latter informs the solution to the former. You hang a disposable tube underwater at the desired launch angle. Set off the nuke at one end. Water is incompressible (beyond a certain distance from the detonation), so if the tube is filled with gas instead of water, it is the only compressible path for the nuclear overpressure to escape.

..assuming no marine life (with compressible internal organs) happen by.

Man, the greenies would have a field day with this idea.  ;D
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline edzieba

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Re: Casaba Howitzer Space Gun
« Reply #5 on: 09/12/2018 02:44 pm »
So I've read ideas on building an "atomic verne cannon", but a big problem was the fact that one would need to dig a new launch tube/barrel after every shot. You would also need to somehow build or dig out a huge chamber to fill with water.

The latter informs the solution to the former. You hang a disposable tube underwater at the desired launch angle. Set off the nuke at one end. Water is incompressible (beyond a certain distance from the detonation), so if the tube is filled with gas instead of water, it is the only compressible path for the nuclear overpressure to escape.

..assuming no marine life (with compressible internal organs) happen by.

Man, the greenies would have a field day with this idea.  ;D
They'd be about 40 years too late for that party.

Offline CameronD

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Re: Casaba Howitzer Space Gun
« Reply #6 on: 09/16/2018 11:37 pm »

..assuming no marine life (with compressible internal organs) happen by.

Man, the greenies would have a field day with this idea.  ;D
They'd be about 40 years too late for that party.

Actually the military research you quote is around 70 years later than what I had in mind.

It's a short story by a legendary Australian author written well over a hundred years ago and still worth reading today:
https://www.amazon.com/Loaded-Dog-Henry-Lawson/dp/1502339064

« Last Edit: 09/16/2018 11:50 pm by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline Zed_Noir

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Re: Casaba Howitzer Space Gun
« Reply #7 on: 09/17/2018 10:21 am »
If you want to shoot something into orbit. There are easier ways to do it.

Of course said object must able to withstand at least a few hundred Gs in acceleration and the thermal stress from atmospheric friction.

The Nazis and Gerald Bull both attempted to build an orbital capable cannon at different times.

Offline TrevorMonty

Re: Casaba Howitzer Space Gun
« Reply #8 on: 09/17/2018 04:41 pm »

Google SHARP (Super High Altitude Research Project).


Headed by John Hunter, the SHARP gun fired projectiles using expanding hydrogen and achieved velocities of 3 km/s (6,700 mph) or Mach 8.8 for 5 kg (11 lb) projectiles. Had the project continued, there were plans to elevate the tube and begin space launch trials potentially reaching speeds of up to 7 km/s (16,000 mph), or about Mach 21.[1]

John Hunter appeared on SpaceShow a couple years back, do search under his name.


I can see it launching materials off moon surface. This is one of few mass driver systems that struggle when trying to do earth launch but could well on moon.

Offline ChrisWilson68

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Re: Casaba Howitzer Space Gun
« Reply #9 on: 09/17/2018 04:59 pm »
So I've read ideas on building an "atomic verne cannon", but a big problem was the fact that one would need to dig a new launch tube/barrel after every shot. You would also need to somehow build or dig out a huge chamber to fill with water.

The latter informs the solution to the former. You hang a disposable tube underwater at the desired launch angle. Set off the nuke at one end. Water is incompressible (beyond a certain distance from the detonation), so if the tube is filled with gas instead of water, it is the only compressible path for the nuclear overpressure to escape.

When you add up the costs of the nuke, the disposable tube, the disposable ablative covering to get the payload through the atmosphere, and whatever mechanism you are going to use to circularize the orbit so it doesn't re-enter the atmosphere, I believe this launch system is going to be more expensive per pound of payload than BFR/BFS.

Offline RobLynn

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Re: Casaba Howitzer Space Gun
« Reply #10 on: 09/18/2018 01:02 am »
The latter informs the solution to the former. You hang a disposable tube underwater at the desired launch angle. Set off the nuke at one end. Water is incompressible (beyond a certain distance from the detonation), so if the tube is filled with gas instead of water, it is the only compressible path for the nuclear overpressure to escape.

When you add up the costs of the nuke, the disposable tube, the disposable ablative covering to get the payload through the atmosphere, and whatever mechanism you are going to use to circularize the orbit so it doesn't re-enter the atmosphere, I believe this launch system is going to be more expensive per pound of payload than BFR/BFS.

Nukes are pretty cheap on a dollar per GJ basis.  Tsar bomba 210PJ about 200 million GJ, which in natural gas terms is worth about $0.5-1billion.  CH4-LOX rocket fuel of same total energy is about $1-2billion.  thermo nuclear bombs only cost on the order of $10million each so have an energy cost as little as 1% of rocket fuel.  Hydrogen bombs can be pretty clean too - <3% fission for tsar bomba

If you could get sufficient energy-coupling into the projectile and if you were only interested in launching oversized man-hole covers (Pascal-B nuke test 900kg manhole cover capping a 150m deep shaft estimated speed of 66km/s :) ) it might be worth it.  Getting a large amount of steel or aluminium or other metals in orbit or to Mars or moon cheaply to build with might have great value.

[Edit]  Also a very cheap way to launch a lot of mass from the Moon or Mars for orbital construction.
« Last Edit: 09/18/2018 11:36 pm by RobLynn »
The glass is neither half full nor half empty, it's just twice as big as it needs to be.

Offline stefan r

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Re: Casaba Howitzer Space Gun
« Reply #11 on: 09/21/2018 10:43 pm »
Nukes are pretty cheap on a dollar per GJ basis.  Tsar bomba 210PJ about 200 million GJ, which in natural gas terms is worth about $0.5-1billion.  CH4-LOX rocket fuel of same total energy is about $1-2billion.  thermo nuclear bombs only cost on the order of $10million each so have an energy cost as little as 1% of rocket fuel.  Hydrogen bombs can be pretty clean too - <3% fission for tsar bomba

If you could get sufficient energy-coupling into the projectile and if you were only interested in launching oversized man-hole covers (Pascal-B nuke test 900kg manhole cover capping a 150m deep shaft estimated speed of 66km/s :) ) it might be worth it.  Getting a large amount of steel or aluminium or other metals in orbit or to Mars or moon cheaply to build with might have great value.

[Edit]  Also a very cheap way to launch a lot of mass from the Moon or Mars for orbital construction.

How would you avoid the ablation cascade?

Offline ChrisWilson68

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Re: Casaba Howitzer Space Gun
« Reply #12 on: 09/22/2018 12:14 am »
The latter informs the solution to the former. You hang a disposable tube underwater at the desired launch angle. Set off the nuke at one end. Water is incompressible (beyond a certain distance from the detonation), so if the tube is filled with gas instead of water, it is the only compressible path for the nuclear overpressure to escape.

When you add up the costs of the nuke, the disposable tube, the disposable ablative covering to get the payload through the atmosphere, and whatever mechanism you are going to use to circularize the orbit so it doesn't re-enter the atmosphere, I believe this launch system is going to be more expensive per pound of payload than BFR/BFS.

Nukes are pretty cheap on a dollar per GJ basis.  Tsar bomba 210PJ about 200 million GJ, which in natural gas terms is worth about $0.5-1billion.  CH4-LOX rocket fuel of same total energy is about $1-2billion.  thermo nuclear bombs only cost on the order of $10million each so have an energy cost as little as 1% of rocket fuel.

1. The energy from the CH4-LOX is going to be used much, much more efficiently.

2. It's not just the marginal cost of a nuclear bomb.  You have to factor in all the infrastructure costs to transport the bombs safely to the launch site, and all the security costs of securing the bomb during transit and at the launch site.

3. You still need something to circularize the orbit.

4. You still need to add in the costs of whatever is circularizing the orbit, which will be expensive because it has to withstand such sharp g forces, and the costs of the ablative covering to keep it from vaporizing while going through the atmosphere.

5. Because you need to launch at a near-horizontal angle and you have to accelerate to beyond orbital speed from the ground level, you lose much, much more energy fighting the atmosphere than a rocket does.

Offline hop

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Re: Casaba Howitzer Space Gun
« Reply #13 on: 09/22/2018 09:56 pm »
Nukes are pretty cheap on a dollar per GJ basis.  Tsar bomba 210PJ about 200 million GJ, which in natural gas terms is worth about $0.5-1billion.  CH4-LOX rocket fuel of same total energy is about $1-2billion.  thermo nuclear bombs only cost on the order of $10million each so have an energy cost as little as 1% of rocket fuel.  Hydrogen bombs can be pretty clean too - <3% fission for tsar bomba
This is a spectacularly bad comparison. Even in the fantasy land of atomic space gun launch, you aren't going to be using Tsar Bomba size devices*, you are going to be using the opposite end of the spectrum. Small devices have significantly less favorable cost and pollution characteristics.

The assertion that nukes are cheap also depends on which costs you choose to include. The incremental cost of another unit may indeed be in the tens of millions range, but the nuclear complex as a whole is mindbogglingly expensive. If you have to manufacture new devices with in a way that doesn't result in Hanford style messes, the unit costs are going to be significantly higher. From BOTE, the Hanford cleanup related costs of US weapons alone exceeds $2 million each.

* The neighbors would complain, and by neighbors I mean neighboring continents.

Offline Paul451

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Re: Casaba Howitzer Space Gun
« Reply #14 on: 09/23/2018 04:35 am »
If you have to manufacture new devices

In the real world, this launch system would never happen unless there was no alternative. End-of-the-world scenario, all option on the table. Asteroid/comet impactor with no significant warning, alien invasion, etc. In which case, the existing nuclear arsenal is available and the objections don't matter.

In the less real world, technically even the ocean-tube launch doesn't release a lot of radiation, and virtually none into the air. And it's orders of magnitude safer than an Orion (although less capable). Less radiation released than Chernobyl, maybe more than Fukushima.

Offline Paul451

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Re: Casaba Howitzer Space Gun
« Reply #15 on: 09/23/2018 04:52 am »
I never responded to this part in the OP:

but if you want to industrialize space, you ultimately need raw materials.

Do you? Is bulk material that significant? I mean given where we are technologically.

If a 100,000 tonne nickel-iron asteroid somehow lunar-slingshotted and atmospheric-skipped and chaosed its way into an ~800km Earth orbit, would the space programs of the world change that drastically? You'd still need cheap launch, manned spaceflight, space-rated robotic systems, etc etc. Sure, everyone has a new-shiny to play with for awhile, but how much really changes? (Obviously the asteroid-mining crowd would lose their collective. And there might be some strategic games between nations trying to claim it without breaching OST. But that's not the analogy, it's about the effect of having material up there.)
« Last Edit: 09/23/2018 04:55 am by Paul451 »

Offline RobLynn

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Re: Casaba Howitzer Space Gun
« Reply #16 on: 09/24/2018 10:14 am »
I never responded to this part in the OP:

but if you want to industrialize space, you ultimately need raw materials.

Do you? Is bulk material that significant? I mean given where we are technologically.

If a 100,000 tonne nickel-iron asteroid somehow lunar-slingshotted and atmospheric-skipped and chaosed its way into an ~800km Earth orbit, would the space programs of the world change that drastically? You'd still need cheap launch, manned spaceflight, space-rated robotic systems, etc etc. Sure, everyone has a new-shiny to play with for awhile, but how much really changes? (Obviously the asteroid-mining crowd would lose their collective. And there might be some strategic games between nations trying to claim it without breaching OST. But that's not the analogy, it's about the effect of having material up there.)

It could provide bullet proof radiation shielding even in the van allen belts, and reaction mass for a large spinning space station, perhaps also an interplanetary sling and large counterweight for a cable suspended LEO base with a few 100 m/s delta V saving to get to LEO (any saving there has big impact on space economics).

But with SpaceX having a marginal cost of launch close to $1000/kg now they could launch 10000 tonnes for about  $10 Billion.  So orion propelled asteroid or moon rock exploitation is less necessary for LEO development.
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Offline QuantumG

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Re: Casaba Howitzer Space Gun
« Reply #17 on: 09/24/2018 11:15 pm »
But with SpaceX having a marginal cost of launch close to $1000/kg now they could launch 10000 tonnes for about  $10 Billion.  So orion propelled asteroid or moon rock exploitation is less necessary for LEO development.

... and we could be looking at ~$80/kg to LEO for BFR. Perhaps even less. It'll be mind blowing if it happens.
Human spaceflight is basically just LARPing now.

Offline Dr_Zinj

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Re: Casaba Howitzer Space Gun
« Reply #18 on: 10/08/2018 04:12 pm »
We have banned nuclear testing in Earth's atmosphere. So you may be able to use a nuclear cannon on the Moon and possibly Mars but that is it.

Oddly enough, the United States has NOT ratified the Comprehensive Nuclear-Test-Ban Treaty.  It was only signed, so there is no legal restriction for the U.S. to use nuclear propulsion to launch spacecraft; merely convention and a nice-neighbor policy.  Doesn't mean we don't have a pile of other laws that would make a nuclear launch a litigation hell, EPA being a big one.

Offline RobLynn

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Re: Casaba Howitzer Space Gun
« Reply #19 on: 10/09/2018 02:25 am »
Nukes are pretty cheap on a dollar per GJ basis.  Tsar bomba 210PJ about 200 million GJ, which in natural gas terms is worth about $0.5-1billion.  CH4-LOX rocket fuel of same total energy is about $1-2billion.  thermo nuclear bombs only cost on the order of $10million each so have an energy cost as little as 1% of rocket fuel.  Hydrogen bombs can be pretty clean too - <3% fission for tsar bomba
This is a spectacularly bad comparison. Even in the fantasy land of atomic space gun launch, you aren't going to be using Tsar Bomba size devices*, you are going to be using the opposite end of the spectrum. Small devices have significantly less favorable cost and pollution characteristics.

The assertion that nukes are cheap also depends on which costs you choose to include. The incremental cost of another unit may indeed be in the tens of millions range, but the nuclear complex as a whole is mindbogglingly expensive. If you have to manufacture new devices with in a way that doesn't result in Hanford style messes, the unit costs are going to be significantly higher. From BOTE, the Hanford cleanup related costs of US weapons alone exceeds $2 million each.

* The neighbors would complain, and by neighbors I mean neighboring continents.

Large nukes exploded deep underwater will likely not produce destructive Tsunamis:
https://www.quora.com/Can-a-nuclear-bomb-create-a-tsunami
https://en.wikipedia.org/wiki/Operation_Wigwam

A many km long deep angled single shot tubular steel barrelled nuclear light gas gun (use a big tank full of liquid hydrogen with a bomb at the bottom) and an escape velocity projectile (or less if it is possible to build in a circularising rocket) might be relatively benign if using a high fusion yield bomb like the Russian Tiaga 15kT 98% fusion bombs.  (4.5MT Redwing Navajo was 95% fusion).

Conventional guns can achieve 30% efficiency (propellant to projectile kinetic energy) Light gas guns with 7.5km muzzle velocity have been build with 12% efficiency:
https://www.sciencedirect.com/science/article/pii/S187770581734314X/pdf?md5=ed813ad35083de4426b92e0ba4ab85b0&pid=1-s2.0-S187770581734314X-main.pdf&_valck=1

At 12% efficiency 10000tonnes to 10km/s would take just 1MT of bomb.  That is a huge amount of bang-for-the-buck.  Fired off at Point Nemo 2700km from nearest land in relatively lifeless ocean (in middle of a huge oceanic gyre) it would be barely detectable.  For comparison 550MT of atmospheric bomb testing has been done in 20th Century.

The steel should be mostly recoverable from the sea floor for recycling.
The glass is neither half full nor half empty, it's just twice as big as it needs to be.

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