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I know it is possible to use missiles to shoot down satellites in orbit but what about using rail guns or mass drivers as some sort of anti orbit weapon. I know the idea of a "space gun" shooting people and satellites into space is something that has been consider by NASA and others before but hasn't work for a variety of reasons and has never been done as a result. However those reasons seem to be more related to the cargo's safety which don't really apply to my purpose of using them as a weapon to attack space ships in orbit. Of course there might be other factors I'm not considering like for example maybe the ammo would burn up before hitting orbit. So I'm basically asking wither it would be physically possible to build a giant rail gun or mass cannon capable of shooting an projectile into space without breaking the laws of physics. I'm not asking in terms of technology since the technology of my world is pretty high just wither I'm gonna be breaking the law of physics by including this into my setting or not?

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  • $\begingroup$ In your world, you get to decide what's technologically possible or not. Unlike other Q&A sites we have restrictions about not just to topics that can be asked but restrictions on the forms of questions as well. Instead of asking for us to brainstorm and generate ideas for you, try coming up with the best idea you can. If that isn't able to suite your needs, edit this post to describe your best attempt, and ask us for help resolving the specific issues you encountered. If you want to learn more about how this site functions you can take the tour or visit the help center. $\endgroup$
    – sphennings
    Nov 21, 2023 at 20:59
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    $\begingroup$ Can you clarify what exactly your worldbuilding problem is? Your query seems kind of contradictory. You state that the technology and science are advanced, when would lean in favour of "yes". You mention such weapons as already exist in the real world. So what actually is the question? You might want to consider approaching this from the other direction: since you've already got the world and the tech and the science sorted, just propose the weapon system and ask about its feasibility given the physics of the universe it's set in. $\endgroup$
    – elemtilas
    Nov 21, 2023 at 21:05
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    $\begingroup$ A couple of suggestions: 1. Have a look at the history of the Strategic Defense Initiative (aka "Star Wars") program - we do expect research before asking questions here. 2. Refine your question to define the target/s better - damaging a fragile late 20th century satellite in low-Earth orbit is a much easier proposition than damaging a space battleship from the far future sitting in geostationary orbit or beyond. (Also check your wording in 2nd last sentence - I assume you mean "hitting objects in space" not "hitting objects into space".) $\endgroup$ Nov 21, 2023 at 21:16
  • $\begingroup$ Hi @MassMedia, welcome to Worldbuilding. It's rare for a question here to have a perfect rationalization like that provided by TheDemonLord. It's breathtakingly rare that it happens with a new user's first question. Congratulations! I've occasionally read stories where authors included background as an appendix for why they implemented a bit of their worldbuilding. You'll have to do a little digging, but the story behind that blasted (hah) iron cap would fascinate your readers as much as your story. I'd tuck that reference in a folder for future use. Cheers. $\endgroup$
    – JBH
    Nov 22, 2023 at 0:28

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Sure

I mean - we already have anti-satellite technology, we have the ability to intercept orbiting vessels.

However - for a real-world example:

The Thunder Well

This is one of those batty 1960s 'Let's use Nuclear everything' ideas - IIRC - you have a Nuclear device, that's in a body of water, in a well, with a Cap on it.

The Nuke goes bang, super-heats the Cap, which is then flung into the atmosphere at obscene velocities.

This was based on what happened here

The infamous manhole cover that was shot into space at an estimated velocity of 66 Kilometers per second.

The theory being that these Thunder Wells would be precisely triggered (something something orbital mechanics) in order to intercept something in outer space.

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    $\begingroup$ The manhole cover referenced here was most likely promptly vaporized due to compressive heating. This isn't a real-life example of shooting something into space, it's a real-life example of why it's rather impractical. $\endgroup$ Nov 21, 2023 at 21:57
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    $\begingroup$ @NuclearHoagie - It was presumed vaporized, so I'm allowed to presume it didn't - plus it's a cool story and with sufficient modification - could work. $\endgroup$ Nov 21, 2023 at 22:07
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    $\begingroup$ I was going to give you +1 just for the phrase, "obscene velocities," but then I read the Business Insider article about Robert Brownlee and that iron cap. Having proven successfully that what the OP is asking for is imminently possible (and that the iron cap beat the Voyagers to interstellar space by a long, long way), I think this is a definitive answer. $\endgroup$
    – JBH
    Nov 22, 2023 at 0:19
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    $\begingroup$ @NuclearHoagie Robert Brownlee, who launched that iron cap, had this to say in the article I just linked: "After I was in the business and did my own missile launches," he told Insider in 2016, "I realized that that piece of iron didn't have time to burn all the way up [in the atmosphere]." Whether it did or didn't, all the OP needs is something more aerodynamic than a 4-inch thick 3-foot wide disk and more durable than plain iron and the problem easily, even trivially, meets suspension of disbelief. $\endgroup$
    – JBH
    Nov 22, 2023 at 0:21
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See also Project HARP. This used long-barrelled guns of up to 16 inches diameter to shoot a projectile into near space. The highest it got was 180 Kms with an 84 Kg projectile. Whatever it shot had to survive an acceleration of 15,000 g. At the time this was seen as an economic alternative to rockets. As history turned out, rockets and rocket guidance developed rapidly. If you were trying to hit an ICBM, rockets were a much better proposition because they could be steered.

Not a success, but HARP did show that you could launch a projectile from Earth's surface to inner space.

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"Yes, but."

Richard Kirk's answer basically tells you what you need to know... humans were able to shoot a projectile above the Kármán line back in the 60s, and technology has marched on a bit since then. The Martlet projectiles were able to carry rockets and useful bits of equipment, so there's scope for steering at things, or just blowing up and forming a nice big debris cloud for things to crash into (and as the debris is going at suborbital velocities, it'll clear itself).

Problem is though, a gun-fired projectile has to get up to useful speeds before it leaves the barrel, and even for very long-barelled guns (and the HARP guns had barrel lengths between 36 and 54 metres!) this requires significant accelerations and hence needs electronics and rockets that can survive that sort of punishment. Clearly humans can make stuff that can survive thousands or tens of thousands of gees of acceleration, but they can also make stuff that has a much more relaxed performance envelope that's either more capable or cheaper or both. Even the Sprint missiles "only" hit 100 gees. HARP projectiles had a muzzle velocity of over 2.1 km/s, but that was the fastest they would go. The Sprints topped out at 3.4 km/s, but the ASM-135 could manage 3.9 km/s with lower accelerations and the SM-3 hits 4.5 km/s and all those missiles hit those speeds higher up than an artillery shell and so waste less energy battering through the thickest layers of the atmosphere. Speed is range, and unless you can hit a good 250 km upwards your gun isn't going to be much use for hitting things in orbit.

A more powerful gun can shoot higher, but it will probably exert even higher acceleration forces on its projectile and will suffer even more from atmospheric effects. A railgun or coilgun also involves very high electrical or magnetic fields, to add to the payload's woes. You could shoot a dumb projectile, but shooting straight over hundred of kilometres whilst subject to significant aerodynamic loads to hit a (probably) small object travelling at may kilometers per second? Seems dubious. Also, suborbital projectiles gonna come back and risk falling on something. If you managed to shoot something out of the atmosphere on an escape trajectory into interplanetary space that's less hazardous, but still space junk (and requires an extraordinarily powerful weapon).

A single antisatellite missile has a lower performance requirement for the hardware it carries and for its launcher and has a much better ability to steer itself and drop some suitable kill vehicle at a place where its prey will find itself in due course. You could potentially order it to abort (eg. self-destruct) if you changed your mind, or it missed, or there was a problem, which reduces the chances of collateral damage.

You could use a railgun to do the same job, but honestly you probably shouldn't.

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  • $\begingroup$ There was a more recent plan to launch reflectors out to L1 to stop a few percent of the sun's radiation to combat global warming. That would have been a cloud of rotating thin mirror discs. There would be a lot of them so using a gun to keep the launch costs down would make sense. Those would have had some active components so they could stay on station using the solar radiation and wind. That sort of thing might survive the launch stresses, and been able to get back on target. Not a weapon, though. $\endgroup$ Nov 22, 2023 at 20:29
  • $\begingroup$ @RichardKirk depositing stuff in a relatively stable cloud around a lagrange point, presumably an earth-sun one which is quite a long way away, basically requires rockets just to get everything lined up nicely. You could use a gun for launch assist, but you can only launch comparatively small payloads and you might need many cargo busses to get your cloud of tinsel to the right place which starts making stuff look less economical compared to a big dumb rocket. Even for cubesats around the earth, the additional cost to make them kilo-gee tolerance might tip the balance in favor of rockets. $\endgroup$ Nov 23, 2023 at 9:05
  • $\begingroup$ Agreed. I wouldn't do it with a gun. But it shows that space guns are an idea that gets taken down from the shelf and dusted off from time to time. The last time I know about was less than 10 years ago. But, so far, it has always gone back on the shelf. $\endgroup$ Nov 24, 2023 at 10:08
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The problem is the atmosphere. Its what creates friction and resistance and is as much a hold back as gravity. So lets imagine for a moment a rail gun, slightly slopped that leaves the harshest part behind, with the barrel evaccuated and lifted.

Another hypothetical solution might be to create a "add-hoc" vacuum tunnel. Meaning.. you shoot a laser ahead of the barrel, ionizing the air into a plasma-channel, charge the channel and basically turn it into one long lightning. And where there is lightning, there is thunder -aka air rushing in to fill the vacuum left by the plasma. And in that vacuum, your bullet traverses into the outer atmosphere.

https://llr-fet.eu/ https://en.wikipedia.org/wiki/Lightning

All the other problems apply to the project though. High G-Load on the projectile.

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Its an excellent question and I don’t know why people are falling on it as a pack of wolves. In fact the edit isn’t necessary either.

Some people have mentioned the high velocities. Well we have Project Thor, which proposed sending thin but long aerodynamic tungsten rods in excess of mach 25 through the atmosphere. They would lose a lot of speed in the process, but I don’t see much reason yet that you can’t just increase the velocity even further. After all, you are on the ground in a pretty high sci-fi setting. Your power production would make orbital bombardment look like fireworks. Or as Isaac Arthur put it, if they throw rocks down at you, you throw mountains back up.

You might have to replace the rails for each shot, but for a high sci-fi setting it wouldn’t be that difficult to have disposable rails that are simply dumped into an industrial cycle to be remade in a couple of days while you store enough rails alongside your ammo to fire thousands if not hundred’s of thousands of shots. And that is assuming you don’t have some fancy maglev hovering launch vehicle which doesn’t degrade the rails.

If your gun is mostly vacuum, opening the front for fractions of a second to launch the projectile, the acceleration would become exceedingly easy. You’d likely have several stages of airlocks at the end of your gun so it doesn’t instantly slam into the full air, each opening and closing in a moment to let the projectile pass and then changing the air content again to what you want. This is actually something proposed for a maglev train in a vacuum tunnel for quick transport, which a high sci-fi would have access to and mean the technology base exists both in military and civilian sectors.

So yes, you could use it.

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