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lets_bang_blue t1_j6niz5y wrote

Your missing the massive accelerations needed to shoot something that starts on land and makes it into space. Spin Launch is doing something similar but taking time to spin things up so not crazy high gs. Secondly the air resistance of going so fast at low atmosphere provides heat shield issues. Generally speaking when rockets are going their fastest, they are in thin or no atmosphere. When they are in the thick sea level atmosphere, they are going extremely slow relatively speaking.

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robit_lover t1_j6ns886 wrote

I don't know that I would call over 10 000G's "not crazy high".

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[deleted] OP t1_j6nkjqe wrote

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lets_bang_blue t1_j6nlush wrote

25 years from now sure. But what value would raw materials be in space currently? Need to have an assembly team up there, which no one has. Or a robot to assemble, which no one has. The concept or something similar will eventually be used for raw materials but we are not at that stage of space exploration where we can fabricate our structures in space

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[deleted] OP t1_j6nqosz wrote

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zolikk t1_j6nso2v wrote

You have to make a rendezvous with the ISS which means you have to have propulsion on your "vehicle", it can't just be a "cannonball" fired from the ground once. And the engine and other delicate components necessary wouldn't survive being fired out of such a cannon.

To put it simply, you cannot shoot an unpowered object into orbit. Its path intersects the earth again, or it attains escape velocity and leaves earth permanently, but neither path makes an orbit.

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[deleted] OP t1_j6nt4al wrote

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zolikk t1_j6ntj8h wrote

Hmm, I guess it's possible? But then it requires quite a lot of constant fuel for your orbital retrieval vehicle. I suppose you could also "shoot" fuel up with the cannon constantly.

I'm not convinced it could be worth it. From the construction and maintenance of the cannon to the reliability of the method, even if possible, where if you don't catch a payload perfectly it just falls back to earth... rocket launches are probably more worthwhile for all this.

Since you need fuel to get into orbit you're still beholden to the rocket equation where you're using fuel that you catch to put the payload you also catch into orbit... I don't think you're necessarily that far from just using rockets, except the reliability problem.

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lets_bang_blue t1_j6o072p wrote

If it's so hugely beneficial. It would be done or in the works but it's not? So we need to consider there are reasons. Your asking why it's not being done and I am giving you answers which your now saying are not valid. OK so your trying to argue thay the ISS is in desperate need or large steel structures? For what and how will it be assembled?

Water is a valid point but do you think designing an entirely new launch system just to bring water into space is economical.

"It's hugely beneficial for Artemis mission". Can you go into some details here about why Artemis needs to have a massive amount of stuff launched along side it? Does the mission not already have everything needed for success loaded onto a single rocket?

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TheBroadHorizon t1_j6nod5p wrote

You answered your own question. The Nuclear Test Ban treaties would apply for a gun as well.

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[deleted] OP t1_j6nr9vh wrote

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TheBroadHorizon t1_j6nvlha wrote

Nope. The Partial Test Ban Treaty bans atmospheric testing. The Comprehensive Test Ban Treaty of 1996, while it has never entered into force, has been signed and de-facto adopted by all nuclear powers except for India, Pakistan and North Korea. It "bans nuclear weapons test explosions and any other nuclear explosions, for both civilian and military purposes, in all environments".

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svarogteuse t1_j6nirtb wrote

Super guns have been attempted. Space guns comes up fine on google.

What you are missing is the shock of initial launch. In a gun the projectile goes from 0 to its orbital speed virtually instantaneously. Very little other than solid objects survive the massive g forces involved. Certainly not people.

Project Orion lifted of slowly, each bomb pushing the craft (with a massive pusher plate to absorb shock for the payload) just a little higher and faster. That why it took many bombs not just one. A single bomb can launch something pretty high but that wasn't the Orion design because they wanted the payload to be less robust than a solid object.

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[deleted] OP t1_j6nk6l0 wrote

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svarogteuse t1_j6nn0xt wrote

No the g-forces wont exclude humans. A proper Orion craft has a payload section and a pusher plate. The pusher plate and the payload are separated by massive shock absorbers to minimize the forces exerted on the payload.

>Two shock absorber designs were explored. The first consisted of three donut-shaped gas-filled cushions, each one meter high, looking like a stack of tires. Six-meter high aluminum pistons rose from these absorbers. This system would limit peak G forces to 3 to 4 G's. But it would be a bumpy ride for the passengers. Therefore the second design was more complex but allowed the shock absorbers to operate in synchronization in order to further even out the G-forces. This would limit peak forces to 1.5 to 2.0 G's.

1.5 -2.0 Gs is less than the 6Gs of early rockets and the 3 of the shuttle.

$200k and radiation over an area, downwind from the fallout and environmental damage noticeable across the world. We didnt stop Orion strictly because of the treaty. If it had been viable (ie worth the environmental damage) we would have negotiated it into the treaty.

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[deleted] OP t1_j6nntob wrote

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svarogteuse t1_j6npt7i wrote

What you are looking for is explicitly spelled out in the Space gun article that I already linked and you couldn't find in the section Technical Issues.

>the acceleration would theoretically be more than 1,000 m/s2 (3,300 ft/s2), which is more than 100 g-forces, which is about 3 times the human tolerance to g-forces of maximum 20 to 35 g[5]

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[deleted] OP t1_j6nq0kw wrote

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svarogteuse t1_j6nqr8d wrote

You are the one looking for help. Read the footnotes. Do the math. Stop telling people they are dumb because of your own laziness and ignorance. The information is right in front of you. Not our problem that you dont want to believe it.

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Kellymcdonald78 t1_j6p24k0 wrote

Orion’s $100k bombs never existed, it was a design objective that they’d have to achieve (and a very hard one) if they wanted it to be economically viable

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PandaEven3982 t1_j6nr9b0 wrote

What you are missing is that it wasn't stopped by treaty. It was stopped by engineering saying we won't build it, its too much risk at our current state of art. TBH, even with as little fallout as we can design, it's really dangerous when its inside a gravity well. Mine the fissile material from asteroids, build it in Lunar orbit? Sure!

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[deleted] OP t1_j6nrof2 wrote

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PandaEven3982 t1_j6ntm34 wrote

Who told you this? Are we discussing Nerva/Heavy Orion, as proposed by Dr. Pournelle and Dr. Kingsbury? Yes they discussed quite a few multistage designs, yes the SatV was the obvious choice of system. No. They never got comfortable enough with the Murphy factor to move forward. There was no acceptable design when the treaty showed up.

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[deleted] OP t1_j6nug2j wrote

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PandaEven3982 t1_j6o1l1e wrote

If you really want to fix the blane on SALT Ii, which I find acceptable, the dirty hands are Ronald Reagan's. Shrug. Yes, Dr. Dyson is on record as saying it's solvable. I deeply respect Dr. Dyson. I don't respect him enough to accept the assertion as the deed.

Bad enough he gave away everything they wanted starwars (orbital target acquisition) and FOBS banned. He gave them High Frontier. Jackass.

EDIT: Reagan, not you. SALT II is the reason we haven't tried using launching lasers. For just 1 thing.

Edit edit: A launch laser is an Orion with the engine on the ground. It needs really excellent targeting. Thie ship leaks fuel vapor into a combustion chamber. The laser fires. Rinse and repeat. Quickly. :-) fuel/air explosion. Get high enough you also bleed in O2.

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[deleted] OP t1_j6o34ud wrote

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PandaEven3982 t1_j6o5kob wrote

I am sorry that treating your question seriously ended up in a fun-suck for you. I was trying to treat your question with respect and give you as close to a truthful answer as I am able. I apologize.

EDIT: You probably, can use them as space guns, actually. The big boom pushes something ballistic. Maybe a rock, or a BFSpear, or another bomb. Their are practical and logistical questions, but sure, you can use an atomic boom as space weapon. Just gotta find the right something that survives the propulsive blast.

Edit: and I can offer a book of fiction that uses an onboard exploding nuke as a weapon of attack. Peace offering. :-)

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[deleted] OP t1_j6o7uvg wrote

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OwnLet6739 t1_j6obiua wrote

Yeah, you're just too smart. That's what it is.

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McCaffeteria t1_j6oc47s wrote

You should add the /s so they don’t think you’re being serious

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PandaEven3982 t1_j6og4pa wrote

I can't actually tell if that's sarcasm/snark/other...or you meant it? If I'm smart, how come I don't know what /s means?

(What does/s mean? Gramps is asking for help)

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OwnLet6739 t1_j6oua56 wrote

/s means sarcasm. Hard to read sarcasm through text. I was responding to OP though, not you.

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PandaEven3982 t1_j6o9rwi wrote

Thank you. I'm not really sensitive to up/down voting yet. Lol and I'm weird enough I might never get there:-)

Do you mean as a payload or as a warshot? We are really close to fusion powered induction IMHO, but as a transport system or at least a bootstrapper....is my head following?

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A40 t1_j6nlq86 wrote

Yeah.. no. Materials.. no. Physics.. no. Costs.. no.

Politics? Never.

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cjameshuff t1_j6nn9ty wrote

Yeah, even ignoring the politics, Starship should be able to get launch cost <$200/kg, lower than just the energy costs for the space elevator in Edwards' study. You're not going to get launching something with a nuclear fission bomb and a massively hardened nuclear space gun to be lower than that, just due to the costs of the bomb itself, never the massive propellant costs and complications of snagging it from a suborbital trajectory with a Starship.

Just put the payload on a Starship.

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mellotron42 t1_j6ngzdp wrote

In a way, that's what Spin Launch is trying to do, except it's yeeting it instead of shooting it. Would be easier on an airless world.

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CantThinkOfOneUs t1_j6njht5 wrote

>"ya but if you screw it up you now have 10t of raw iron hitting St. Louis at 30 km/s"

Nothing lost /s

For real, a large concern with nuclear pulse for launching is introducing radioactive material into our atmosphere. I wish I could back this up with a source right now but I recall a study saying that using nukes to launch something to orbit would, on average, give 10 people terminal cancer due to the radiation released per launch.

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Bewaretheicespiders t1_j6nlalb wrote

I'ld like to see the abort capabilities on that one.

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New_Acanthaceae709 t1_j6nt3f2 wrote

Moving an airplane sized thing that's already in orbit, any push makes it go faster.

Moving it from the ground, you don't just need shielding from the blast, but also shielding from the *air* in front of you.

https://nuclearweaponarchive.org/Usa/Tests/Brownlee.html

This is a manhole cover going 75 kilometers a second; it went too fast to burn. But human beings and most cargo can't possibly survive going from 0 to escape velocity instantly; the speed you'd have to fly would, well, have the time to burn through most things.

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joshuakyle94 t1_j6nxlxi wrote

Why do we need space guns lol. There is nothing in space SO FAR that’s hurting or threatening us.

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mindlessgames t1_j6o0kvk wrote

You have to design a payload that can survive a nuclear explosion imparting the entire launch energy in an instant.

Sure, maybe you can launch a solid 100T block of steel. What do you do with that once it's in orbit? There's no space lathe to turn it into anything useful. Can you actually design a survivable vehicle to carry any other payload?

Assuming we have some reason to launch 100T blocks of steel into space, where are you sourcing them from? How can you transport them to the site? How are you going to load them into the gun? Does anyone need 100T blocks of steel in space right now?

How long do you think your barrel is going to survive repeated nuclear blasts for launch? How are you going to replace your barrel when it needs to be changed?

How much is it going to cost to build your gun? How many decades of launching 100T steel blocks into orbit, for which we have no orbital manufacturing capability whatsoever, will it take to make your money back?

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Kellymcdonald78 t1_j6p1j6u wrote

Research was most definitely not “done” for Orion. From miniature warheads, to a system capable of delivering them reliably, to the shock absorbers. It was a high level concept that was simply validated as an avenue of research with potential. Years of additional research and billions of dollars would be been needed to actually design and build an actual vehicle. It’s the difference between Robert Goddard’s experiments and the Saturn V

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McCaffeteria t1_j6nxmyv wrote

I think you are just missing one important detail about Project Orion that would clear up you confusion: they theorized used a series of smaller nuclear explosions in order to continuously propel a spacecraft.

This video is a great visual example of the project, I highly recommend you watch it if you haven’t already. Honestly his whole channel is great.

We can make materials that can “withstand the ablation of a nuclear explosion,” but we can’t make materials that can withstand the force of any arbitrary explosion, nuclear or otherwise. We have to limit the size of the explosion to the material properties of our pressure plate and our spacecraft. There is an upper limit in terms of instantaneous G-forces that our constructions can withstand and that prevents us from just building a canon as you suggested (not to mention you would still have to do another burn once you are in space to actually circularize your orbit otherwise you’ll orbit once and hit the ground where you launched from lol).

Someone else mentioned Spin-launch in the comments and they are right. The whole point of spin-launch is to generate the kinetic energy and momentum you would have had to generate to get into space, but they are doing it over a longer period of time to protect the payload. Same concept with project Orion: they are distributing the total energy over many separate explosions so that the ship would actually be possible to build with real materials.

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[deleted] OP t1_j6nzdjr wrote

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McCaffeteria t1_j6o61p6 wrote

This attitude is exactly why you are getting downvotes.

The manhole example is a back of the envelope assumption that it reached orbit and an assumption it actually stayed a manhole. No one is arguing whether an explosion has enough theoretical energy to move a hypothetical point-mass to a certain altitude, people are arguing that you are overestimating the strength of materials.

Even if you got a chunk of raw materials like steel or water into space and plan to intercept them with starship you still have huge problems. The first one is that you need to be able to dock with the payload if you plan to adjust it’s orbit, and you aren’t going to be able to dock with a fused reverse-meteor of steel. You actually need the structure to survive.

You are also going to have to circularize it’s orbit which is not as easy as you’d think. Your “manhole” example is one thing, but if you’ve played kerbal literally even once you’d know that going straight up is not a good way to get into orbit. You are going to have to angle your trajectory so that the relative speeds of your intercept are more similar than a straight vertical shot, and that is going to take way more explosive power. Add on top of that the fact that you’d have to travel sideways through the atmosphere if you want to Rendezvous in a single impulse and you need exponentially more explosive to overcome drag, plus more mass to protect from the atmosphere, which requires even more explosives.

And none of this even mentions the extreme difficulty of hitting your ideal trajectory in a single impulse with no way to error correct. Yeah it’s mathematically possible in a simulation, but you need to be able to adjust for error in the real world. Changes in the wind or air pressure at a certain altitude will have significant effects on your final altitude and position which will make to miss your intercept.

This tech would be much more useful on the moon sending water back to earth. There is no atmosphere to fight and your chances of making the Rendezvous are probably higher because you could circularize a bit using atmospheric braking. You’ve still got lots of other problems that make it difficult, like getting the nuclear material to the moon which is exactly why a spin launch installation on the moon makes way more sense, but whatever.

You could launch a solid chunk of titanium to the altitude of the ISS, sure, but that isn’t a “working solution.” You need “machines” to be able to interact with the other spacecraft. You need to move able to adjust your trajectory. You need to be able to reuse your launch site and not destroy/irradiate it every time you launch. You need to be able to stop once you get to altitude, or you need to be able to somehow punch through the atmosphere and overcome the “I need more mass to block the atmosphere but that means I need more thrust but that means I need more reinforcement but that means I need more mass…” problem.

I think you are falling into that trap where you have a neat idea and then feel personally attacked by anyone who points out flaws. That’s not how you solve engineering challenges. Instead of arguing with the haters and insisting “trust me bro,” I encourage you to do the math. Get on kerbal and demonstrate an ISS rendezvous using a single impulse and a starship. I’d watch that video, for sure. Do some research on the g-force ratings for modern docking adapters and explain how they would be able to survive your hypothetical launch. You’ll get way better results than arguing “nuh ah” with people and then complaining about being downvoted.

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[deleted] OP t1_j6o80t9 wrote

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McCaffeteria t1_j6ob6yf wrote

For someone who spends all their time telling other people that they “missed the point” you’d think you’d be able to understand that my comment was addressed to you instead of Reddit in general and it did, in fact, make it’s way there.

As I said, this whole shitshow of a post is entirely your fault because you aren’t mature enough to hear criticism. Read my comment or don’t, it’s your choice whether you want to grow up or not.

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