Take an old oil well. Stuff some thick steel piping down down the hole. Put some explosives down there and a large bullet. Boom! You have a canon that could probably get to low earth orbit (LEO) for really cheap relative to a rocket.
Sounds simple enough. But how do you actually do it?
OK. Let’s take an old high capacity oil well around 30” in diameter. These wells are much larger than your typical oil well so you could launch a large payload into space. Then let’s lay in some thick steel piping to form the bore. No need to rifle it since we just want to go strait up and the speed would strip the barrel of rifling anyways. Then go ahead and pour some concrete down outside the steel bore to fill in the space and strengthen the cannon. OK. That bore is solid and should be able withstand the blast pressure needed to launch our 1000 pound slug.
How are we gonna launch that slug?
We know a U.S. military Howitzer artillery piece exerts up to 16,500 g’s on its shell during a launch. Lucky for us we have a cannon about 400 times longer. At around 10,000 feet long our cannon can launch something much faster with lower g forces trying to destroy to payload. But to accelerate the payload we cannot use just typical gunpowder or one massive explosion. We need to put in multiple tiers of explosive charges perfectly choreographed to launch our package all the way through the tube and into LEO transit velocity. This multi-stage solution will reduce the acceleration g’s on the payload.
First we use gunpowder as the tier one charge. This charge detonates pushing the next two tiers up as well as the payload. Then the second tier of methane detonates. Finally the tier one hydrogen charge detonates where the pressure from the tier 2 and 3 can still push against it to maximize force exerted on the payload. This hydrogen explosion is fastest and its rapid expansion is more than enough to push the payload out of the giant cannon at around 5 km/s.
Oh but wait. What about atmosphere? At that speed near sea level the payload will either just burn up in the atmosphere or lose too much momentum to get to LEO.
Most people say atmosphere is one of the biggest problem with space canons. But there are dozens of ways to solve this problem.
The Obvious Way
Go find a big mountain and drill a big hole in it. Boom done. cannon made at 25,000 feet in a thin atmosphere and easier to launch from and keep your momentum.
Kilimanjaro Space Launch Facility would be great for the Tanzanian economy.
Slicing Slugs
Ok . This is the real way to do this. No need to drill giant holes in tall mountains.
You know how race cars always tailgate each other in races? They’re doing something called drafting. Drafting lets the rear car conserve fuel by having the front car use more of its fuel driving through the wind.
This atmosphere penetrating idea uses the same principle except instead saving fuel you are saving momentum. By launching a slugs to drive through the atmosphere and your payload behind it you can conserve the payload’s momentum. You launch the slug a split second sooner than the payload and it launches with a pure hydrogen charge. This launch is far faster than the payload. This higher exit velocity enables the slug expend more energy clearing out the heavy atmosphere ahead of the payload. After it has lost most of its kinetic energy getting through the denser low atmosphere it has a perpendicular solid state booster that fires to knock it out of the trajectory of the payload.
With the payload having been drafting in the wind wake of the slug it still has a large amount of its kinetic energy to carry it up to LEO. Well. Almost to LEO. A cannon alone is not going to get you to stable orbit. For that you are gonna need some boosters.
Payload!
This is not just some inert container that ferries packages to LEO. This payload must withstand hundreds of g’s exerted on it. Reenter the atmosphere, detect speed, proximity to the slicing slug and fire solid state boosters to avoid collisions and then, when it has reached its target altitude, the main boosters need to fire to put the container in a stable orbit. Because of the extremely high heat and acceleration the containers endure they need to be able to withstand there needs to be g forces of a launch and still be fully operational and controllable to do the fine adjustments required for orbit stabilization, orbit jumping, and long haul flights to the moon and such.
But if the container is made to withstand 10,000 g’s your typical rocket engine would fail and most other thrusters would have a much higher risk of failure. The boosters on a rocket like this would have to be as simple as possible. Since the weight doesn’t cost much, putting a bunch of smaller single fire thrusters makes more sense than engineering a single complicated multi fire rocket engine that could withstand the g’s just to save a few pounds on launch.
Additionally there needs to be proximity sensors and maneuvering thrusters on the container to avoid the the slicing shell and as well as stabilizing the orbit to assist with docking or getting docked by another object. Since the main purpose of a space cannon is to transfer raw and robust materials cheaply the container needs to be controllable enough to dock with another spacecraft or at least match the speed of the other object to be “caught” and reeled in.
In addition to supplying ongoing building projects around Earth’s orbit. I think a supply launcher like this to be used as a means to supply outposts on the moon. The moon is perhaps the most important means for us to access the rest of the solar system and ultimately the galaxy, but that is for another post. There needs to be an Earth to Moon delivery system. And this could supply the fuel to make lunar trips much cheaper.
If 500 pound to 2 ton launches turn out successful from the oil wells then dedicated wells can be made in the future to launch far larger cargo to aid orbital construction platforms and Moon — Earth delivery routes.
