Wednesday, October 28, 2009

A Village in Space

This post is for entertainment purposes only.

I like to imagine what life would be like if (when) humans start to live in space. My imagination starts with the idea that people are not going to begin with the most elaborate systems imaginable. Real progress will be as simple as possible.

Under this assumption, I imagine the construction of a city in space that goes as follows:

It starts when the builders park next to an asteroid - a rubble heap that is made up mostly of rocks and gravel in a loosely packed ball - and starts to harvest that material to make a cylindrical shell.

Just to throw out some numbers, I imagine a shell 2 kilometers (1.2 miles) in diameter and 6 kilometers (3.6 miles) long, with a skin 1 meter thick. The skin will consist of an inner and outer wall, with the middle filled with rock harvested from some convenient asteroids. The purpose of this skin is to protect those living inside the shell from cosmic radiation. It does not matter what the material is that makes up this skin, only that it has enough stuff in it for the cosmic rays to collide with.

One of the things our occupants are going to need is some form of artificial gravity.

Typically, we are taught to imagine the whole station spinning in space. However, there is a problem with that scenario. If you set all of that mass spinning, it will want to fly apart. A lot of work will need to go into building the shell to withstand those kinds of forces.

However, why should this skin rotate? We could keep the skin stationary, and simply rotate what we build inside the skin.

After we get our cylinder built, imagine putting a track in the form of a big loop around the inside, and putting a train, of sorts, on that track. As the train moves around this track it will generate what, in space, will be known as 'artificial gravity'. Yet, we have saved ourselves the cost of engineering a whole station that can survive that rotation.

Now, physics being what it is, the train will transfer some of its energy to the shell. As the train spins in one direction, the shell will slowly start to spin in the opposite direction, picking up speed over time.

This problem is easy to avoid. In the early days, the train will have to stop often to pick up and unload passengers and cargo. When it starts up again, it need not travel in the same direction. It can take off in the opposite direction.

Eventually, the plan will be to build a 'train' goes around the whole station and, once set into motion, stays in motion. This inside ring is where the residents will build their homes and businesses. It will not stop from time to time. Rather, occupants will step onto a train that stops, then accelerates to 'catch up' to the spinning platform.

We could stop this rotating village from time to time anyway and set it moving in the opposite direction. Or, another alternative is to build two rings that rotate in opposite directions. One will cause the skin to want to rotate clockwise, while cause the skin to the want to rotate counter-clockwise. The two forces will work against each other. With some careful management (within very high tolerances), the skin does not rotate.

In imagining these rotating rings, it would be a mistake imagining the villagers living on what we now see as a conventional train. There is no need to imagine these vehicles being as narrow as conventional trains. They could be quite a bit wider. There would be sleeping cars, dining cars, and places set aside for recreation of different types.

Whenever the workers needed to get off of the train, the train may stop, let the workers out, and then start up again. During these stops, the train itself would become weightless, and the passengers would step off into a weightless world. Then the train would take off again.

However, eventually, a second track can be laid beside the first. Once the train on this second track started to move, it would never stop. The first train will stop to pick up passengers from the shell itself, accelerate, then the passengers would stop onto the second train. The first ring could be as wide as a house. A second ring, built next to the first one, would combine to make a platform as wide as city street. The village would grow wider like this over time.

Eventually, we would end up with two villages inside of a common cylinder. Each village will be 3.0 kilometers (1.8 miles) wide and 6.3 kilometers (3.8 miles) long. They would rotate in opposite directions. At the line in the middle where the two villages meet and speed past each other, a commuter train will take people from one town to the other.

A passenger in one village will step on the train, the doors will close, and she will experience herself becoming weightless. At the mid point of the trip, she will actually be weightless. Then her weight will come back until she is back to her original weight. At the point, the doors on the opposite side of the train will open and she can step out onto the second village.

That will be one of the unique experiences of living in a space station.

Weightlessness will be short hop away by commuter train.

The ends of our cylinder will likely not be connected to the rotating villages. They will be fastened to the skin, set up to transfer people and materials through the skin into the villages, and out of the villages into space perhaps for trade with other cities, or to visit the processing plants that turn asteroid material into something useful, or work on the nearby solar power plant that provides power to the station, or to work in the agricultural pods that are built for peak agricultural efficiency, or to visit zero-g businesses and sports arenas, or to enjoy the view.

While we are focusing on what we are doing inside of this cylinder in space, we should not forget that this is a village IN SPACE, with all of the limitless options that energy and materials make available to the human imagination.

NAL said...

Whatever part does the rotating will experience the weight of the buildings and people just like on Earth. It will have to be make strong enough to withstand this force. Keeping out cosmic particles is not going to be as easy as you present. Then there's the problem of collisions with space debris.

Alonzo Fyfe said...

(1) While it is true that the weight of "whatever is rotating" - buildings and people - will need to be built to handle the stresses, it is still the case that (1) these stresses will be less than if the whole thing is rotating, and (2) the non-rotating shell can bear a certain amount of that load without adding any load of its own.

(2) Keeping out cosmic rays is not the goal. Reducing their intensity is the goal. We experience cosmic rays on the surface of the earth - more when we fly.

(3) There is no problem with collison with space debris if the station is not built in low earth orbit. I envision this being built in the vicinity of the asteroid providing the raw materials. The thick skin of the station will provide protection from the vast majority of "space debris" - though this will not help those living and working outside the station. Yet, there are also risks of hurricanes, tornadoes, tsunamis, volcanic eruptions, landslides, avalanches, lightning strikes, blizzards, heat waves, and the like on earth.

anton said...

I enjoy having these insights into your imagination. I found that my childhood imagination started with some of my constructions using Mecano. Later in life, my favorites were Geodisic Domes, of which I ended up building a couple. I envisioned someday that super large domes would house several thousand families in their "skins" while the space inside provided space for gardens, recreation, etc. I still doodle "new thoughts". Domes, of course, didn't "make it" as "all domes leak" -- over time, uneven expansion and contraction stresses out the building material connections. My best dome was a giant 2-story dome back in the 70s. It was inside an industrial complex and housed my printing plant, computer system and offices. It was a heck of lot cheaper than "conventional" construction and cheap to heat and air condition. Being inside another structure it didn't suffer from 'uneven exposure to the sun".

Alonzo, this was an entertaining post that took me back 40 years. I can only imagine what lies ahead. Keep them coming!