The majority of the scientific experiments conducted in space have had to do with space
itself, such as its effects on astronauts or spacecraft.
But some experiments, while uncommon and without immediate practical value, still pose interesting
questions.
For instance, what happens if you fire a gun in space?
You may remember from elementary school science class that a fire needs three things: heat,
fuel, and air, in order to work.
A gun works by using the power of fire, in a manner of speaking.
It creates an explosion that propels the bullet from the chamber of a gun.
However, since there's no air in space, a key part of the equation is missing.
That's not a problem, however, as modern-day ammunition contains an oxidizer, a chemical
that allows combustion to take place in the absence of air.
Since everything you need is right there in the cartridge, the gun and bullet would work
in space just as well as they would on the ground.
There would be some minor differences, of course.
Unless you shot it from inside a spacecraft, which would be a terrible idea, you wouldn't
hear the explosion.
This is due to the lack of air in space to propogate the sound waves.
And instead of a wispy vapor trail like you see in the movies, the smoke would just expand
in a sphere from the tip of the barrel.
On the ground, gravity and friction mean that the bullet will only fly so far.
In space, gravity and friction are still factors, but their effects are completely different,
and this would be particularly evident if you fired a bullet up there.
Harvard astronomer Matija Ćuk said that once the bullet is fired, it's likely going to
travel in space until the heat death of the universe.
He notes that the bullet would never stop.
This is because the universe is expanding faster than the bullet can ever travel, meaning
it’ll never run into anything.
"It's no use, we were going full speed when we fired him.
So he's going even faster than that.”
"You mean, we can never catch up to him?
Not even if we rub the engine with cheetah blood?"
Of course, this assumes that the bullet won't be captured by the gravity of a star or planet
and be pulled into its orbit.
Consider though, that objects with mass, like stars and planets, take up very little of
the universe compared to the vast emptiness of space.
So the likelihood of that happening is extremely small.
When a gun is fired it produces a recoil, or "kick," that the shooter has to brace for.
Holding a gun the wrong way can produce a kick that could injure the shooter, to say
nothing of interfering with the gun's aim.
The kick is the result of one of the foundational rules of physics: Newton's Third Law, which
says that for every action, there is an equal and opposite reaction.
In space, absent gravity and friction, that means that the bullet will be sent off into
space in one direction, the shooter in the other.
Just how fast the bullet and shooter will be sent off in their respective directions
depends on the velocity and weight of the shooter and bullet.
Firing a rifle will send the shooter backward at .068 miles per hour, while firing a small
handgun, with a slower-moving but heavier bullet, will send the shooter in the opposite
direction at about twice that speed.
Imagine being an astronaut orbiting above the Earth, on a spacewalk for example, far
enough away from your spacecraft that you could fire your gun without endangering your
crew.
You, your craft, and everything else at that altitude are all orbiting the Earth.
If you fire your gun at exactly the right angle, the bullet would also go into orbit
around the Earth.
You may see why this would be a problem, but if not, here's what could happen:
Since orbits are circular, the bullet will eventually make a circle around the Earth,
and come back to where it started.
And since you are now positioned between the bullet and the starting point to which it’s
returning, you will have effectively shot yourself in your own back.
If this all sounds a bit theoretical rather than practical, keep in mind that scientists
have considered "self-hits" in space.
The idea is to investigate impacts with tiny asteroids, space junk, and so on, but ultimately
no one has ever actually attempted it.
As it turns out, the matter of shooting guns in space isn't just a thought experiment.
Rather, it was an experiment that the Russians performed.
The Soviets didn't fire a gun so much as a cannon, but since both machines work on the
same principle, the results were the same.
It happened in 1975, according to previously hidden documents that were unearthed following
the fall of the Soviet Union.
The entire experiment was done remotely from the ground.
No cosmonauts were up there at the time.
The scientists secured the cannon to the Salyut-3 spacecraft, pointed it somewhere, and fired
it three times.
Being acutely aware of Newton's Third Law and all that, the Soviets turned on the spacecraft's
rocket thrusters to counteract the recoil from the explosions.
The results of the experiment remain under wraps.
However, it's safe to say that, pending the cannon's aim, its projectiles are still hurtling
through space to this day.
Guns in space aren't just theoretical, at least not for the Soviet, and later Russian,
space programs.
For decades, cosmonauts took guns into space, but not with the intention of firing them
while in flight.
In the early days of the U.S. space program, returning astronauts landed in the middle
of the Pacific Ocean, where the Navy would scoop them up out of the water.
The Russians, however, did and do send their crews back to the ground.
Specifically, they land in the vast grasslands of Kazakhstan.
And there they may have to wait hours, if not days, for rescue.
As such, they were and are given survival kits that include food rations, first aid
kits, and at one time, firearms, just in case they encounter dangerous wildlife, or perhaps
hostile locals.
Space journalist James Oberg, writing in IEEE Spectrum, claims that the Russians have stopped
including firearms in the kits cosmonauts take into space, although the Russian Space
Agency has refused to comment on the matter.
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