Silly question about shooting a gun in space.

Would a loaded gun fire in outer space? I don’t mean inside a space shuttle filled with air, I mean in space itself.

And what if a gun were fired inside the space shuttle 9where I assume it would fire because there is oxygen) but the bullet traveled through an opening into space itself. What would it do? Slow down to a stop?

The gun would need oxygen to fire. I don’t know how airtight standard bullets are, so there is a chance there would be enough oxygen within the casing to support combustion, but I don’t think it’s likely.

However, if the bullet was fired where oxygen would present, it would travel on forever until it hit something that stopped it. An object in motion and all that – and without an atmosphere, there is no drag.

No outside oxygen necessary. The powder in the bullet contains its own oxidizer, and will fire just as readily in space as it will anywhere else.

A rifle fired in a vacuum should in theory be more accurate than a rifle fired at sea level, because of the lack of wind and the friction of the air.

Gunpowder contains its own oxidizer so no external oxygen is necessary to fire a gun in space.

They also work under water, testing was done on this some years ago. Not real accurate and loose velocity very rapidly, the tests were done with Colt M1911A1 army issue handguns, do not attempt this at home!

And don’t forget about the effect of shooting the gun on the person shooting it. Every action has an equal and opposite reaction. Not saying you would go flying at bullet speed. You have much more mass than the bullet. But you would definately move.

Bullets on earth slow down because of air friction and gravity will eventually pull it to the ground.

Space is a vacuum and unless acted upon by an outside force the bullet will keep on going for a long time. Okay, I have to qualify that. If you were away from a planet or other large body that would be true. If you fired from the shuttle you’re only in low earth orbit. You’re still in vacuum so you don’t have to worry about air friction but I don’t think a bullet would have enough energy to even achieve a stable orbit so earth’s gravity would eventually drag it back to into the atmosphere where it would burn up on reentry.

In HS I remember taking some sort of moon survival quiz made (allegedly) by NASA. The idea of the test was that your ship crashed on the moon and you had to travel to the other side of the moon to get to a base and safety.

On the list of things you had at your disposal was a gun. (plus things like oxygen and a life raft) You were supposed to take the gun with you and use it to propel yourself along.
If you were sitting on the front poarch of the ISS and fired a gun at the sun would the bullet break earth’s gravity and hit the sun? How about the Moon?

Whether or not the bullet fired would toodle off into space will depend on 1) the direction fired and 2) muzzle velocity.

If it is being fired from the ISS it is, we shall say, at 22,500 miles above the earth which is 26,600 from the center of the earth. The surface of the earth is 4,000 (in my perfect world anyway) from the center and excape velocity is about 25,000 miles per hour. So the ISS is 6.6 times further from the center of the earth. Since gravitational effects fall off as the square of the distance it would be only 1/43.9 times as strong at the ISS. Excape velocity would be about 570 miles per hour or 835 feet per second. Most pistols/rifles probably beat that.

No, a bullet fired from the ISS will not break away from earth orbit. The ISS is in low earth orbit, which means it’s travelling at about 7 km/sec. Escape speed is 11 km/sec so a bullet needs 4km/sec extra speed. That’s 12 times the speed of sound in air, and I don’t believe bullets are quite that fast.

By the way, vacuum is a very harsh environment for mechanical devices. Most lubricants boil away and leave metal surfaces to cold weld to each other. I don’t know much about guns but they have quite a few moving parts, don’t they? I don’t think they work well in vacuum unless you replace the lubricant with vacuum-compatible ones.

If one considers a bullit fired from the space shuttle with its trajectory strictly within the plane described by the shuttle’s orbit, it occurs to me that for a given muzzle velocity m, with* m* being less than escape velocity, and a shuttle orbit speed of 17,500 miles per hour that more than one but definitely a limited number of solutions for an initial trajectory inclination would allow the bullit to impact the shuttle on any one of several subsequent orbits. Of course their must be a minimum velocity for m.

I’d be curious to find out:

  1. What is the minimum muzzle velocity required that would allow a bullit fired from a shuttle to impact the shuttle? What is the angle of inclination from the tangent of the shuttle orbit?

  2. At what *m *will we be able to determine the maximum number of impact solutions for variable inclinations of initial bullit trajectory?

I’m not holding my breath :smiley:

It wouldn’t matter. The bullet’s already in orbit–the firing of it would change the velocity, and depending on the direction of the firing, it would ascend or descend in orbit and at any rate, it’s orbit will become more elliptical.

Picture this: you have a high-speed sniper rifle and you’re out on an untethered spacewalk. You turn around, to where you’re facing opposite the direction of travel. You pull the trigger, like this:


The bullet loses velocity and in consequence, you gain velocity. Say the bullet’s travelling at 2000 mph–admittedly, pretty fast for a bullet, even a high-speed round, but I’m sure it can be done by a good rifle. The bullet loses velocity, and using my simplistic understanding of physics, it slows to 16,000 mph, while you accelerate to 20,000. The bullet descends and you ascend. The bullet might return to Earth, having, in effect, performed a de-orbit burn, and your orbit will become more elliptical. But you probably won’t reach escape velocity in a low-Earth orbit, at which the Space Shuttle operates.

You might be able to at higher orbits, or from the surface of the Moon–for the Moon, the escape velocity’s around 3,000 mph, IIRC, but I’m sure there are small arms that can accelerate a chunk of metal to that speed in a vacuum.

In the classic Abbott and Costello Go to Mars, while they are in outer space, Costello fires a gun at one of the bad guys who have stowed away in the rocket ship. The bullet simply drops to the floor, “because they have moved away from Earth’s gravity,” IIRC.

If you think that’s goofy, the title is really crazy. They visit New Orleans and Venus, but never Mars.

I’ve seen the calculations run before (I believe it was on a movie physics lampoon site) for the velocity picked up when an average sized man was shot with a 12 gauge shotgun under the assumptions of complete inelasticity and being close enough to be effectively absorbing the full brunt of the shock. His change in velocity would be roughly equal to that of the man firing the gun, and was found to be around 1 mile per hour. To calculate it for any speed, just use the simple relation of the conservation of mass: the mass of the bullet multiplied by its muzzle velocity would be equal to the mass of the person firing it multiplied by the velocity they pick up from firing it. (it will hold true assuming the rifle and bullt are a negligable amount of mass compared to the person and that the rest frame and bullet frame velocities are less than about 50-60% speed of light. Both very safe assumptions)