Mass Driver Repeater

Need I: On Earth and on Venus we have too much CO2. On Mars we have too little CO2.

We need to transfer some CO2 from Earth and Venus to Mars. On Mars this will thicken Mars' atmosphere, and help start greenhouse effect to warm it. On Earth and Venus, this will do the opposite - stop the greenhouse effect.

This way we make all 3 planets habitable! This is like the ultimate free meal - keep your planet and get two more for free!

By the way, after thinking about this independently, I found out that people have already thought about some of this before. See discussions in Quora and in Reddit:

Moving CO2 to Mars

If it was possible to collect half of the atmosphere of Venus and deposit it on Mars would this make both planets more habitable?

So my original contribution here will be only the "how to" part.

Need II: The first humans on Mars will need large amounts of oxygen, water, food, and fuel. We need to transfer these from Earth.

How do we supply both of these crucial needs?

What we want is a huge "pipe" or conveyor belt, that takes a payload (cargo) from planet to planet, but since the cargo can fly freely most of the way, it will be made of a few seperate "stations".

The stations will of course be floating in space. The ones next to a planet can float in a Lagrangian Points so that it follows the planet but doesn't fall onto it.

The "engine" that makes the payload fly from one station to the next is a big coilgun energized by solar power.

Here is a very nice GreatScott video about what coilgun is, and how you can build it yourselves:

In the context of space, it's called a Mass driver and that's not a new idea either.

A video from Space Studies Institute, which was founded by Gerard K. O'Neill, who built the first proof of concept.

So what's new? Up until now, Mass Drivers had only two "flavors":

(1) Anchored on solid ground (Earth or Moon) and shooting payload into space :

   (1.1) Shooting a spaceship to the Moon (like in "Zero to Eighty" by Edwin Fitch Northrup from 1937) or to Earth orbit (like in "The Moon Is a Harsh Mistress" by Robert A. Heinlein from 1966).

   (1.2) Shooting construction material from the moon to a colony in space (like in Nasa's Space Settlements: A Design Study from 1975).

   (1.3) Shooting on a spaceship that "reflects" (like a solar sail) the bombardment to propel a spaceship away from it, or to shoot supply of fuel.

   (1.4) Shooting around the circular track of a Space Fountain to hold up a tall structure.

(2) Floating in space (on a spaceship) and used to propulsion engine to move the spaceship. Like Ion Drive.

So my idea is to combine these two types together: Floating in space + Shooting payload into space!

There are 2 possible routes:

Straight Line

The "straight line" stations will basically be a piece of hollow pipe with both its edges open, floating in space.

Indirect Curve

The "indirect curve" middle stations will basically be a scoop wheel rotating in space.

I'm choosing a shape of a disc and not a sphere, because all the planets in our solar system rotate around the Sun in the same plane. So we NEVER need any flips at all.

The scoop will be a "Clamshell Bucket" which can catch and realease the payload (or the counterweight). This scoop can be connected to some rope or chain, and be shot to catch it's target and then be retrieved.

Since the release needs to be more accurate then the catch, I think we should open the "Clamshell Bucket" after the catch, and rely on an electromagnet to hold and release.

Because the system has to take a lot of beating from catching the payload and counterweights, it has to be tough, something like Bucket-wheel excavator.

I try to save energy as much as possible by compensating (offsetting, deducting) one movement with a movement in the opposite direction;

Nevertheless, all the stations and especially the middle ones must move themselves in space, to align towards the other planet (and the middle ones in the "straight line" case needs to flip).

So this will be done by having each of the payloads carry with it (apart of its main load) also some amount of frozen CO2.

When docked or parked inside a station, the station will connect with a hose and sublime some of this CO2. (dry ice turns right into gas, so no messy liquid).

With the gas compressed in the station, the station can release the gas from the right nozzle into space to move the station in the desired direction.

You can imagine this extra payload of CO2 like a "tax" that each payolad has to pay in order to pass in the station. The middle stations take more tax because they need to maneuver more.

Before each "pass" the "throwing" station aligns the "catching" station using lasers (and clock, and trigonometry).

Recoil Problem - Straight Line

When we shoot any gun, the gun is pushing the bullet forward, and the bullet is pushing the gun backward. This is Newton's third law: action and reaction.

How can we prevent our "mass driver" from being pushed backwards in space?

I got this idea from the Funicular railway which operates underground in my hometown Haifa which is called the "Carmelit".

In the "Carmelit" the two "cars" are tied to both sides of a rope that is hanging on a pulley. Each car's weight balances the other car.

My idea is that every station will simultaneously shoot both forward (the real payload) and backward (a counterweight with the same mass).

Let's think of an example system with 5 stations along a direct line. We'll call them A,B,C,D,E. The end stations A and E are anchored to planets.

We will call the direction from A to E forward, and the direction from E to A backward.

if you can see the colorful icons:

we are moving a full package from the blue planet on the left, to the red planet on the right.

and at the same time,

we are moving an empty package from the red planet on the right, to the blue planet on the left.

each colorful icon shows what happens to his station - NOT to the package!

Initial Condition (before we begin) :

At first everybody is stable. We have a payload in A and a counterweight in E.


Step 1:

A shoots the payload forward to B. A is pushed backward but A is stable because it's anchored to a planet.

E shoots the counterweight backward to D. E is pushed forward but E is stable because it's anchored to a planet.

So B "catches" the payload and B is pushed forward. and D "catches" the counterweight and D is pushed backward.


Step 2:

To balance this, B shoots the payload forward towards C (So now B is stable).

At the same time, D shoots the counterweight backwards towards C (So now D is stable).

C gets them both at the same time from opposite directions, so C is stable.


Step 3:

Now C needs to flip the payload and the counterweight, I think the easiest way is for C as a whole to flip around 180 degrees.


Step 4:

C is the middle station. It shoots in both directions (payload forward to D and counterweight backward to B) so C is stable.


Step 5:

now D "catches" the payload from C (D is pushed forward), and B "catches" the counterweight from C (B is pushed backward).


Step 6:

To balance B, B is shooting a counterweight backward to A (B is now stable).

To balance D, D is shooting the payload forward to E (D is now stable).


Step 7:

now E gets the payload from D (E is anchored to one planet), and A gets the counterweight from B (A is anchored to another planet).


Summary (after we finish) :

So now everybody is stable. And we moved a payload from A to E, and we moved a counterweight from E to A.


Recoil Problem - Indirect Curve

This is similar to the conservation of momentum in the "straight line" case, but here we solve it with angular momentum, like a Flywheel energy storage.

If you don't know what a flywheel is, you can watch this short video by NASA 360 :

In the "straight line" case, we can get back to the original location of the station almost solely by the energy of opposing movements of the payload and the counterweight.

Unfortunately in the "indirect curve" case we both movements have a component away from the sun which we can't compensate for.

BUT if we let the station drift a bit towards the Sun then that's solved! (The rest of the time we need to do corrections with CO2 as explained before).

If the "catch" and "release" will be close in time, the station scoop wheel doesn't move sideways very much.

If there is a chance that the rotating station will recieve both (payload and counterweight) at the same time, we need two "scoops" that can move along the rim of the disc.

So let's draw this step by step like before:

Step 0 :

This is before we start. you can see Blue Earth on the left and our gray payload is on Earth; Red Mars on the right;

As you will see soon, there is no need for the counterweight at all!

Yellow Sun in the middle; and the station is the light-brown "tinkertoy wheel" above which is rotating at the same direction all the time.

Step 1 :

The station catches the payolad and the station is pushed upwards and to the RIGHT.

Step 2 :

The station releases (throws) the payolad toward Mars, so the station is pushed upwards and to the LEFT.

Step 3 :

The payload is on Mars - hooray! The right and left arrows from step 1 and step 2 cancel each other.

So it looks like the UP arrow remains.

Step 4 :

Not so! because the Sun is attracting the station DOWN all the time, which if we position the station accordingly, cancels the up.