Would shooting payloads into orbit with a big gun be cost effective?

I saw this about Iraq’s “Babylon Gun”:

In pure cost-per-kg, is this better or worse than using rockets?

(Not having read the link…)

I think there would be a problem with accelleration. Have you ever fired a gun? There is recoil. (i.e., for every action there is an equal and opposite reaction.) In a rocket launch, the “recoil” is spread out over time.

Imagine you are in a car and you accellerate to 70 mph over 20 or 30 seconds. Now imagine that you are stopped and instantly accellerate to 70 mph. You are more likely to suffer injury in the latter case than the former. Given that space payloads are often relatively fragile, I’m guessing that the impact of a “big gun” launch would be more damaging than that of a normal launch.

I thought of that, and there may or may not be ways around that, but I’m mainly asking about cost of payload.

$600/kg is FAR cheaper than any known method of getting payloads into orbit.

The shuttle, for example, costs about $220,000/kg.

But Johnny’s point is valid - a gun puts a tremendous acceleration on whatever is fired out of it. To get something relatively fragile into orbit, the barrel would have to be huge.

There have been lots of concepts for using guns to orbit things. They are called “Mass Drivers”. Heinlein proposed a few designs in “The Moon is a Harsh Mistress”, and they were all possible from a strict scientific standpoint. Start at the equator, find a big mountain so that you’re up above most of the atmosphere. Find a nice, long flat spot pointing East, to take advantage of the Earth’s rotation. Then build a bunch of magnetic coils in a long line. Put your payload inside a steel capsule, and use the coils to accelerate it like a Maglev train. Zoom!

Even if it worked, it would never see the light of day in the US. It would put too many people out of work, not only in NASA and whatever assorted government bureaucracies, but in the private sector contractors who actually supply the parts.

I don’t know about that. If it did work, you’d never be able to launch, say, people with it. More delicate methods would not be made obsolete.

One issue is that you still need a rocket to provide tangential velocity. A projectile launched from sea level cannot go into orbit; its “orbit” must necessarily intersect the surface of the Earth.

If a projectile is launched from a high mountain (say 20,000 feet), the low point (perigee) of an eliptical orbit will be the launch elevation. A circular orbit will be constantly 20,000 feet. Neither is stable or possible due to atmospheric drag.

In Heinlein’s book, payloads were being launched from the Moon at a speed above the Moon’s escape speed, not into orbit around the Moon. Aimed properly, they could be launched so as to go into orbit around the Earth, though. (I suspect that maneuvering rockets would still be required for course correction, though.)

[Now that I read the link, it does say that the proposed projectile to be placed into orbit is indeed rocket-assisted.]

Everything’s a conspiracy, huh? :rolleyes:

The problem is technogical feasibility. Here are some issues right from the link:

The acceleration required would be incredible. As Achernar mentioned, you couldn’t put people into orbit, nor delicate electronics. Think you can launch a space telescope with a device like this?

Launched at a low elevation, you have to deal with issues like preventing the projectile from burning up on the way out of the Earth’s atmosphere. Launching at a high elevation would help, but building a launch facility 20,000 feet or so up presents difficulties of its own.

These are just a few issues off the top of my head. There are plenty of technogical challenges to keep the government/industrial complex busy, should such a project be contemplated in the U.S.

Again, not everything is a conspiracy.

On re-reading my post, this came off, I believe, as more sarcastic than is probably appropriate for this forum. My apologies, Mjollnir.

At worst, NASA and its suppliers may be guilty of bureaucratic inertia. I sincerely doubt there is a deliberate attempt to hold back alternative technologies.

I saw a documentary on TLC or Discovery about the history of canons or something… they talked about the guy who was assasinated in Belgium I think… the guy who was developing a big gun for Iraq.
Anyways, they said that the US was/is looking to build a gun that can send stuff into orbit as it would be much cheaper than using the space shuttle…
I don’t really remember specifics, but I thought I’d throw this out here…

The only use for such a gun would be to put raw materials into space where they could be used to construct other things. This topic has been done many times before.

That was probably Gerard Bull, the man that designed the Babylon gun mentioned in the OP. It was watching a movie on HBO about the guy that got me interested in this in the first place. Interesting flick!

Does such a place exsist? What is the highest mountain on the equator?

From: http://hypertextbook.com/facts/2001/ChristinaWong.shtml

I’m not sure that I am buying the logic that the equator is further from the center of the earth than any other point on the surface…
I need to think about that for a second…

Ideally in a perfect sphere it wouldn’t be. However, Earth’s rotation causes radial bulging along the plane of rotation.

Ie, the Earth spins fast enough that the equator actually bulges out.

The earth is not perfectly spherical.

Wow, interesting, I never knew that the bulge was that big. Learn something new every day.

In the Heinlein book, mass drivers on Earth were proposed for launching payloads to the moon, not for putting things into Earth orbit.

But unless I’m missing something, I think you could theoretically put something into orbit around the Earth from a gun. I agree that without an atmosphere, the orbit would intersect the original launch point. But you could use aero-braking to circularize an orbit. So I’m thinking you’d have to fire the shell into a high energy, highly elliptical orbit, then circularize it by dipping into the atmosphere a bit on each pass. But that would require guidance rockets on the projectile, so I guess maybe it doesn’t count.

There’s a book on Gerald Bull called Super Gun, it’s out of print, IIRC. I skimmed the book and Bull did come up with a way to keep the electronics intact after a launch. However, I don’t think that such a gun would be really useful for anything other than sending small payloads into space. Trying to launch, say an ISS, component with such a thing would probably be more trouble than strapping it to a Proton rocket (or whatever the biggest Russian rocket is) and sending into space.