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  #1  
Old 03-19-2007, 06:31 AM
Martini Enfield Martini Enfield is offline
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Has anyone ever fired a gun in space or on the moon?

Inspired by This thread on whether or not the Space Shuttle can defend itself, it's gotten me wondering: Has anyone ever fired a gun in space or on the moon? I can't imagine it would be possible to actually hold or operate a firearm in a conventional space suit, but surely it would be possible to mount a gun on a moon buggy or rover vehicle for scientific purposes (measuring ballistic effects, gravity, etc).

Anyone know if it's ever been done or attempted?
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  #2  
Old 03-19-2007, 06:45 AM
Cisco Cisco is offline
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I misread the title as "Has anyone ever fired a gun in the space of a room" and I was going to tell the story about the time my dad was cleaning his .45 while on his 3rd espresso. If you just want to know the end, my mom cried.
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  #3  
Old 03-19-2007, 06:52 AM
RickJay RickJay is offline
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Quote:
Originally Posted by Martini Enfield
Inspired by This thread on whether or not the Space Shuttle can defend itself, it's gotten me wondering: Has anyone ever fired a gun in space or on the moon? I can't imagine it would be possible to actually hold or operate a firearm in a conventional space suit
With some clumsiness, it would be possible. Some weapons have removable trigger guards so they can be fired while wearing thick mittens in cold weather. I imagine the same would apply to space suits.

That said, I'm pretty certain the answer is "no" and 100% certain it's "no" for the on-the-moon part of your question. The followup question is "why would anyone have wanted to?" It's a bizarre way to measure gravity.

I'm pleased we didn't immediately get someone posting "but a gun can't fire in a vacuum, where would the oxygen come from." You usually get that at least once in these threads.
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  #4  
Old 03-19-2007, 07:15 AM
Martiju Martiju is offline
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Quote:
Originally Posted by RickJay
The followup question is "why would anyone have wanted to?"

You're Americans, it's what you do!!

(You have the right to bear arms (on the moon))
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  #5  
Old 03-19-2007, 07:44 AM
Cisco Cisco is offline
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Quote:
Originally Posted by RickJay
I'm pleased we didn't immediately get someone posting "but a gun can't fire in a vacuum, where would the oxygen come from." You usually get that at least once in these threads.
I'm interested in why you decided to condescendingly bring this up and shoot it down, but couldn't be arsed to provide an answer to your own question. SDMB tradition, I guess.

Here's an interesting FAQ on the subject. I'm still curious where the oxygen comes from; I looked up gunpowder in Wikipedia expecting it to be oxidized but I'm still unclear on whether it is or not.
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  #6  
Old 03-19-2007, 08:20 AM
Sage Rat Sage Rat is offline
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Quote:
Originally Posted by Cisco
Here's an interesting FAQ on the subject. I'm still curious where the oxygen comes from; I looked up gunpowder in Wikipedia expecting it to be oxidized but I'm still unclear on whether it is or not.
I would have to assume that bullets are airproof. So whatever boom they get is formed entirely with what is in the cavity behind the bullet.

I likewise don't know how much oxygen is in the bullet (and I'm a bit dubious on the idea that a thing can't burn in space without oxygen*), but obviously there is enough.

* Burning is just atoms that have been excited. Now I can imagine the amazing cold of a vacuum immediately damping out this excited state, but I don't see why you would need oxygen given as that anything which has atoms can become excited just the same as oxygen can. I suspect that oxygen is just a good ingredient for continued thermic reactions that don't burn themselves out.
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  #7  
Old 03-19-2007, 08:29 AM
slaphead slaphead is offline
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Quote:
Originally Posted by Cisco
I'm still curious where the oxygen comes from; I looked up gunpowder in Wikipedia expecting it to be oxidized but I'm still unclear on whether it is or not.
I seem to remember that in traditional gunpowder it comes from salpetre (KNO3) - nitrates contain plenty of spare oxygen with which to oxidise the charcoal and sulphur, once they have been persuaded to decompose into NO2 etc. Modern propellants use the same principle, but using different chemicals.

It's the sort of question that most people familiar with ammunition or guns would regard as too obvious to answer - let's face it, if firearms relied on sucking air down the barrel past the bullet, or through holes into the firing chamber, it would be pretty noticeable.
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  #8  
Old 03-19-2007, 09:49 AM
muldoonthief muldoonthief is offline
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Quote:
Originally Posted by Sage Rat
I would have to assume that bullets are airproof. So whatever boom they get is formed entirely with what is in the cavity behind the bullet.

I likewise don't know how much oxygen is in the bullet (and I'm a bit dubious on the idea that a thing can't burn in space without oxygen*), but obviously there is enough.

* Burning is just atoms that have been excited. Now I can imagine the amazing cold of a vacuum immediately damping out this excited state, but I don't see why you would need oxygen given as that anything which has atoms can become excited just the same as oxygen can. I suspect that oxygen is just a good ingredient for continued thermic reactions that don't burn themselves out.
Umm, no. Burning is not just atoms that have been excited. Burning, or combustion is an exothermic chemical reaction between a fuel and an oxidant, usually oxygen. No oxidant, no combustion.
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  #9  
Old 03-19-2007, 09:54 AM
ShiefferSaw ShiefferSaw is offline
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Quote:
Originally Posted by Cisco
I misread the title as "Has anyone ever fired a gun in the space of a room" and I was going to tell the story about the time my dad was cleaning his .45 while on his 3rd espresso. If you just want to know the end, my mom cried.

haha... i have a priceless mental picture right now
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  #10  
Old 03-19-2007, 11:21 AM
mks57 mks57 is offline
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The Soviets launched a Salyut with a 30mm Nudelman cannon. I don't know if it was ever test fired in orbit.
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  #11  
Old 03-19-2007, 02:19 PM
T_SQUARE T_SQUARE is offline
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Quote:
Originally Posted by mks57
The Soviets launched a Salyut with a 30mm Nudelman cannon. I don't know if it was ever test fired in orbit.
That's interesting. Did they do it as part of an experiment or did they anticipate needing to use it in anger? I'd think they would go ahead and try it out after going to all the trouble.
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  #12  
Old 03-19-2007, 04:29 PM
ParentalAdvisory ParentalAdvisory is offline
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Wouldn't a fired round stick around in orbit? That might be one reason. Unless they're powerful enough to break orbit, that loopback would be a bitch.
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  #13  
Old 03-19-2007, 04:42 PM
neorxnawange neorxnawange is offline
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Quote:
Originally Posted by RickJay
The followup question is "why would anyone have wanted to?"
For the same reason Shepard played golf on the moon - just to see what'd happen, for fun even. Though I think having a loaded firearm aboard a spaceflight may be asking for a catastrophic accident.
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  #14  
Old 03-19-2007, 04:44 PM
Bobotheoptimist Bobotheoptimist is offline
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I've fired a gun at the moon (it pissed me off), does that count?

At $10,000/pound or so for LEO, the price for hauling up my beloved Colt could buy me a new car. Wasn't there a probe that fired a projectile at an asteroid? Probably didn't use gunpowder...

Wait a minute, didn't Bond do it in Moonraker? I think Dirk Pitt did it once as well.
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  #15  
Old 03-19-2007, 04:49 PM
groman groman is offline
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Quote:
Originally Posted by ParentalAdvisory
Wouldn't a fired round stick around in orbit? That might be one reason. Unless they're powerful enough to break orbit, that loopback would be a bitch.
From here:

Quote:
Salyut 3 conducted a successful test firing on a target satellite.
I would imagine bullets travel fast enough so that they either re-enter the atmosphere or attain a different, fairly screwed up orbit which would degenerate quickly.
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  #16  
Old 03-19-2007, 04:53 PM
CynicalGabe CynicalGabe is offline
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Well, assuming you can fire it (what with the bulky space suit and all), then at least it would be pretty accurate since there would be no bullet drop (ignoring gravity from nearby planetary bodies).
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  #17  
Old 03-21-2007, 09:07 PM
RickJay RickJay is offline
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Quote:
Originally Posted by Martiju
You're Americans, it's what you do!!

(You have the right to bear arms (on the moon))
I'm American now? I don't remember taking the citizenship test or anything...
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  #18  
Old 03-21-2007, 09:27 PM
Rysdad Rysdad is offline
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Quote:
Originally Posted by Bobotheoptimist
I've fired a gun at the moon (it pissed me off)
Ok, that's the second one today. The first one was Sampiro's "Ladel Ladel Ladel".

I haven't laughed this hard in months.
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  #19  
Old 03-21-2007, 09:43 PM
GiantRat GiantRat is offline
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Quote:
Originally Posted by Cisco
I misread the title as "Has anyone ever fired a gun in the space of a room" and I was going to tell the story about the time my dad was cleaning his .45 while on his 3rd espresso. If you just want to know the end, my mom cried.
I read it the same way, and was going to tell the story of a friend who's grandfather (who raised him) decided to get rid of a bat that got into the house by shooting it. With a shotgun. In the house. With SLUGS instead of buckshot. Squeezed off about three wall/ceiling destroying rounds before deciding another approach might be better.
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  #20  
Old 03-22-2007, 03:11 AM
Tuckerfan Tuckerfan is offline
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Quote:
Originally Posted by muldoonthief
Umm, no. Burning is not just atoms that have been excited. Burning, or combustion is an exothermic chemical reaction between a fuel and an oxidant, usually oxygen. No oxidant, no combustion.
Right, combustion is "merely" rust at high speed.

We've had this discussion before about weapons being fired in space. AFAWK, no crew has carried a firearm into space, much less test fired one. It could be done, however. One of the problems for someone in orbit would be the recoil, every action having an equal reaction and all that. One science writer once theorized that a scimitar would be a better weapon for astronauts to carry than anything else.
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  #21  
Old 03-22-2007, 03:39 AM
Blake Blake is offline
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Quote:
Originally Posted by Sage Rat
Now I can imagine the amazing cold of a vacuum immediately damping out this excited state...
A vacuum is neither hot nor cold. A vacuum, by defintion, has no temperature beyond that provided by any radiation passing through. IOW a vacuum in the same orbit a the Earth will be incredibly "warm" in full sunlight and incredibly "cold" in the shade.

Moreover a vacuum can't dampen out anything. A vacuum is an absence of matter. With no matter to absorb energy or combine with reactants there is no dampening process possible.
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  #22  
Old 03-22-2007, 06:38 AM
mks57 mks57 is offline
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Quote:
Originally Posted by Tuckerfan
We've had this discussion before about weapons being fired in space. AFAWK, no crew has carried a firearm into space, much less test fired one. It could be done, however. One of the problems for someone in orbit would be the recoil, every action having an equal reaction and all that. One science writer once theorized that a scimitar would be a better weapon for astronauts to carry than anything else.
The Russians have included a firearm in their Soyuz survival kit for decades. It's a useful item if you land in some remote region of Siberia.
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  #23  
Old 03-22-2007, 07:46 AM
Pushkin Pushkin is offline
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Quote:
Originally Posted by mks57
The Russians have included a firearm in their Soyuz survival kit for decades. It's a useful item if you land in some remote region of Siberia.
As did the crew of Voskhod 2

Using a gun on the moon was included in a lateral thinking test Dad got from work. The idea was that you'd point in the opposite direction you wanted to move in and shoot to propel yourself across the surface of the moon without having to walk this saving energy.
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  #24  
Old 03-22-2007, 08:28 AM
Maus Magill Maus Magill is offline
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Quote:
Originally Posted by Pushkin
As did the crew of Voskhod 2

Using a gun on the moon was included in a lateral thinking test Dad got from work. The idea was that you'd point in the opposite direction you wanted to move in and shoot to propel yourself across the surface of the moon without having to walk this saving energy.
While I can see the eloquence in this solution, I have to wonder at its practicality. To keep from falling over, the astronaut would have to jump then fire and worry about landing. Even then, there would be the question of how far a shot would propel the astronaut. I would guess the mass differential between a fully loaded moonwalker and a .45 slug is pretty great.

Maybe if they were to carry sawed off shotguns loaded with slugs.

Great, now I have images of Gangsta Astronauts in my head. There goes production for the rest of the day.
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  #25  
Old 03-22-2007, 09:09 AM
Rysdad Rysdad is offline
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Why bring along firearms?

Bend over, pick up a rock, jump, throw rock in the opposite direction of where you want to go, land, repeat.

Probably easier to just bounce along.

Last edited by Rysdad; 03-22-2007 at 09:10 AM.. Reason: cuz
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  #26  
Old 03-22-2007, 09:54 AM
Tuckerfan Tuckerfan is offline
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Quote:
Originally Posted by Pushkin
As did the crew of Voskhod 2

Using a gun on the moon was included in a lateral thinking test Dad got from work. The idea was that you'd point in the opposite direction you wanted to move in and shoot to propel yourself across the surface of the moon without having to walk this saving energy.
Where the hell were you when this thread showed up?
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  #27  
Old 03-22-2007, 10:31 AM
Pushkin Pushkin is offline
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Quote:
Originally Posted by Tuckerfan
Where the hell were you when this thread showed up?
Ah, the raft is a nice touch
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  #28  
Old 03-22-2007, 11:36 AM
Stranger On A Train Stranger On A Train is offline
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Quote:
Originally Posted by Maus Magill
While I can see the eloquence in this solution, I have to wonder at its practicality. To keep from falling over, the astronaut would have to jump then fire and worry about landing. Even then, there would be the question of how far a shot would propel the astronaut. I would guess the mass differential between a fully loaded moonwalker and a .45 slug is pretty great.
A 230 grain .45 ACP bullet moving at 900 feet per second would have a momentum of about 4 newtons, or 0.9 lbf. (That's about 29.5 poundals, for any psychotic who wants to use that system.) This isn't enough to move even a small person more than a fraction of an inch. Even a shotgun with slugs wouldn't shift a person more than a couple of inches, even in the Moon's gentle field.

Stranger
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  #29  
Old 03-22-2007, 12:05 PM
AtomicDog AtomicDog is offline
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If not a gun, do explosives count?

Apollo active seismic experiments


Too bad the rover cameras were deactivated before the mortars were set off. I would have liked to have seen those fireworks.
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  #30  
Old 03-22-2007, 12:20 PM
Triskadecamus Triskadecamus is offline
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Firing a bullet from a handgun in space is a pretty extreme step. You are going to tumble, for sure, and the bullet is going to be a navigational hazard as well. It will have a new orbit, that intersects with your orbit once each orbital cycle. So, from any useful orbit, it becomes a big problem for you. If you hit your target, the orbital mechanics of hazards change, but mostly just the number of projectiles from your shattered target.

There is way too much trash in orbit already. Target practice doesn't seem warranted.

Tris
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  #31  
Old 03-22-2007, 12:32 PM
Duke of Rat Duke of Rat is offline
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Quote:
Originally Posted by Triskadecamus
Firing a bullet from a handgun in space is a pretty extreme step. You are going to tumble, for sure, and the bullet is going to be a navigational hazard as well. It will have a new orbit, that intersects with your orbit once each orbital cycle. So, from any useful orbit, it becomes a big problem for you. If you hit your target, the orbital mechanics of hazards change, but mostly just the number of projectiles from your shattered target.

There is way too much trash in orbit already. Target practice doesn't seem warranted.

Tris
Wouldn't a bullet fired from a gun already in Earth orbit have enough velocity to leave Earth orbit?
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  #32  
Old 03-22-2007, 12:47 PM
Chronos Chronos is offline
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Quote:
A 230 grain .45 ACP bullet moving at 900 feet per second would have a momentum of about 4 newtons, or 0.9 lbf.
Check your units, there. Newtons and lbf are both units of force, not momentum. The unit for momentum doesn't have any standard name, beyond "kg m/s" (although many intro physics teachers have nonstandardly attached their own names).
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  #33  
Old 03-22-2007, 02:03 PM
Trunk Trunk is offline
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This question might completely display an ignorance of the scope of the moon, but could a bullet fired from the surface of the moon enter moon orbit? Say from the highest powered rifle we have available?
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  #34  
Old 03-22-2007, 02:04 PM
Stranger On A Train Stranger On A Train is offline
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Quote:
Originally Posted by Chronos
Check your units, there. Newtons and lbf are both units of force, not momentum. The unit for momentum doesn't have any standard name, beyond "kg m/s" (although many intro physics teachers have nonstandardly attached their own names).
Urk! I neglected to include the seconds on those momentum numbers. That should be 4N·s and 0.9 lbf·s respectively. It's a common convention in rockets to speak of impulse in units of force, even though the proper units are force·time, and of specific impulse ("weight specific impulse") in seconds rather than impulse/mass (lbf·s/slug or N·s/kg).

Quote:
Originally Posted by Duke of Rat
Wouldn't a bullet fired from a gun already in Earth orbit have enough velocity to leave Earth orbit?
The escape velocity at any altitute is √2 of the circular orbital velocity at that altitude. For an escape velocity for a bullet moving 900 ft/s (0.274 km/s) the orbital radius would have to be r = 2μ/ve2 = 21.2 million kilometers. This is well beyond the Moon's orbit and indeed outside of Earth's nominal sphere of influence (SOI), so any spacecraft at this point would by default be in orbit of the Sun rather than Earth. (Obviously, there's a closer boundary at which a spacecraft would transition from Earth-oribtal to Sol-orbital, but that depends upon the position and relative velocity of the spacecraft and bullet.) At Low Earth Orbit the projectile would just become another piece of hazardous orbital debris.

Ditto for the Moon. The speeds and momentum at orbital velocities are truly beyond anything we experience in everyday life.

Stranger

Last edited by Stranger On A Train; 03-22-2007 at 02:06 PM.. Reason: Added reference to Moon
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  #35  
Old 03-22-2007, 02:35 PM
Duke of Rat Duke of Rat is offline
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Thanks for the answer, that's surprising (to me at least). I would have thought the bullet would just head out on it's merry way.

Any idea what the (average diameter, I'm guessing it would start out eliptical)orbit would be for say a 180 grain bullet fired at 2500 fps from LEO? Could you hit the Moon with such a shot (or at least intersect its orbit) fired from LEO?
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  #36  
Old 03-22-2007, 03:51 PM
Stranger On A Train Stranger On A Train is offline
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Quote:
Originally Posted by Duke of Rat
Thanks for the answer, that's surprising (to me at least). I would have thought the bullet would just head out on it's merry way. Any idea what the (average diameter, I'm guessing it would start out eliptical)orbit would be for say a 180 grain bullet fired at 2500 fps from LEO? Could you hit the Moon with such a shot (or at least intersect its orbit) fired from LEO?
Actually, I screwed up by an additional factor of two; the correct radius should be about 10.5 million km, still well outside the Earth's SOI. I should note, however, that I'm assuming firing from a stationary (non-orbiting) platform there. If you fire from a platform in orbit in the tangential direction (or indeed in any direction that doesn't have a component opposing motion or below the horizon) then the escape velocity of your bullet relative to the platform reduces to vbullet=(√2-1)·vo and the radius is (√2-1)2·μ/vbullet2, which gives a mere 911000 kilometers, which is still about two and a half times the orbital radius of the Moon.

At LEO (200-2000km altitude) escape speed varies from 11.0 km/s to 9.8km/s, and orbital velocities are 7.79 and 6.90 respectively, so in order to escape you'd have to make up the difference. (If you can come up with a man-fireable gun that can shoot projectiles at ~3km/s I can find you a multi-billion dollar defense contract.) At 2500 fps (0.762 km/s) you'd have to have an orbital radius of 118000 km, almost a third of the way to the Moon, and way higher than geostationary orbit (GEO, 42200 km orbital radius). The mass of the projectile is immaterial, assuming that it is significantly smaller than the bodies exerting gravitational influence upon it.

We're used to seeing images of the Space Shuttle in orbit, slowly nudging its way toward a satellite, and thinking, "Boy, those things don't move very fast." But they're just not moving fast with respect to one another; relative to an observer on the ground, they're moving about an order of magnitude faster than a bullet. This is why talking blythly about the ease of "hit-to-kill" intercepts of ballistic missiles or launching the spacecraft too the Moon enjoins such scathing laughter among engineers and scientists. It's not impossible but it's very, very difficult, requiring a lot of energy and very precise guidance and control. When I look at the numbers, I'm amazed that we actually managed to seen Apollo capsules to the Moon, repeatedly, without getting lost or putting the astronauts in a deadly slow overshoot orbit.

Stranger
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  #37  
Old 03-22-2007, 04:08 PM
Duke of Rat Duke of Rat is offline
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Thanks again, this is fascinating reading.

I suppose the lack of atmosphere in the gun barrel would have a insignificant effect on muzzle velocity?

Last edited by Duke of Rat; 03-22-2007 at 04:12 PM..
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  #38  
Old 03-22-2007, 04:33 PM
Stranger On A Train Stranger On A Train is offline
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Quote:
Originally Posted by Duke of Rat
I suppose the lack of atmosphere in the gun barrel would have a insignificant effect on muzzle velocity?
It would probably be something measurable, but I wouldn't expect much. Air compresses readily, and the difference in pressure between the ambient atmosphere in front of the bullet and the propellant gases behind it is huge. I'd guess the difference to be no more than a few tens of fps, if that; less than the typical variation from round to round.

Stranger
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  #39  
Old 03-23-2007, 12:44 AM
Tuckerfan Tuckerfan is offline
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So what would happen if you were on the ISS and fired a round towards the Earth? Would it drop to a lower orbit, or would it reenter the atmosphere and burn up?
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  #40  
Old 03-23-2007, 02:08 AM
Stranger On A Train Stranger On A Train is offline
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Originally Posted by Tuckerfan
So what would happen if you were on the ISS and fired a round towards the Earth? Would it drop to a lower orbit, or would it reenter the atmosphere and burn up?
Bad idea. The ISS has an average orbital speed of about 7.71 km/s--considerably more than any bullet you might fire from it. Firing laterally is just going to increase the velocity (summing the velocity vector of the ISS with that of the bullet wrt the station), plus it'll come back around to intersect the orbit of the ISS, resulting in a small but not infinitesimal probability that it'll impact the station at some point. If you want to put the bullet on Earth, the best thing to do is to fire back into the path of the station, thus cancelling some of the velocity and driving it into an elliptical orbit that goes down toward the planet. While it'll still nominally intersect the station's path, in reality it'll tend to drift down lower as it sees some drag from the thermosphere, eventually slowing down into reentry and disintegration. Remember, with orbital mechanics, you speed up to slow down (go to higher orbit), and you slow down to speed up (go to lower orbit). In any case, you couldn't cancel enough velocity to just shoot a bullet down to Earth; this would take 7-9 km/s of delta-v, dependant on where you want it to land, vastly more than you'll get out of any kind of small arm.

Stranger
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  #41  
Old 03-23-2007, 03:43 AM
Pushkin Pushkin is offline
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Quote:
Originally Posted by Stranger On A Train
It would probably be something measurable, but I wouldn't expect much. Air compresses readily, and the difference in pressure between the ambient atmosphere in front of the bullet and the propellant gases behind it is huge. I'd guess the difference to be no more than a few tens of fps, if that; less than the typical variation from round to round.

Stranger
So would an automatic rifle with a gas operated mechanism suffer at all?
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  #42  
Old 03-23-2007, 05:08 AM
slaphead slaphead is offline
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Quote:
Originally Posted by Pushkin
So would an automatic rifle with a gas operated mechanism suffer at all?
It doesn't seem likely - the gas is bled off from behind the bullet, and the pressure presumably drops very rapidly after the bullet leaves the muzzle even in atmosphere. Having the weapon overheat (in the light) or the lubricant freeze (in the shade) may be more of a problem.
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  #43  
Old 03-23-2007, 11:08 AM
iamthewalrus(:3= iamthewalrus(:3= is offline
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Quote:
Originally Posted by Pushkin
Using a gun on the moon was included in a lateral thinking test Dad got from work. The idea was that you'd point in the opposite direction you wanted to move in and shoot to propel yourself across the surface of the moon without having to walk this saving energy.
That would work only marginally better on the moon than on the Earth. There's less gravitational force on the moon, for sure, but you still have the same mass. The only reason it would work any better at all is that if you jump on the moon, you stay up longer, so there's a longer time for the (really weak) force the gun applied to you to cover some ground. You'd probably go three or four inches instead of one.

Shooting a gun on the moon might knock you over more easily, but only because you're probably not experienced in keeping your balance at lower g.
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