Planet Maxwell next stop

In all probability our descendants in less than four billion years' time will look a bit different to us or even a lot different but they will still have a problem with a sun that is nearing the end of its life and becoming a big red.

This would necessitate finding a new home for us and all other life on Earth. Now that is a long time away. It is less than four billion years since our beginning ancestor formed as a simple cell. Great, great, great, great ...., great granddaddy was a single cell, and we are talking about a time as far in the future that we have to depart the Earth, so we can be confident we will be different. We can also be confident that long, long before that event our great, great, great ..., great grandchildren will be witness to frequent commercial space travel. There are companies now that are proposing visiting the asteroid belt to bring back asteroids rich in resources needed on Earth, and they know which asteroids they need to go and get. So while your great, great, ..., great grandfather may have been used by the Romans to make roads in England your progeny as far in the future may be making roads on the Moon, Mars or Maxwell, a planet orbiting a sun ten light years away. Even today getting to the former two is feasible but Maxwell requires something new. If light travelling at 300,000 km/second takes ten years to get from here to there it will take at least as long again as from the Romans to now. That is a lot of breakfasts, lunches and dinners and the food to make them. It will take more than the dried beef and biscuits your great, great, great grandmother had on the convict ship that brought her to Australia. A habitat will be needed that can grow crops and an energy source that can light it all and move it up to the speeds necessary to get there which means Australians will have to be happy using nuclear energy.

For growing crops you would need to have some gravity. The outside surface of the cylinder providing the habitat for the Maxwell immigrants would be down.

The habitat would be supported by a magnetic field like the high speed trains so there was no contact necessary hence no friction.

The habitat would be a rotating cylinder made from steel 2 cm thick. If this is inadequate I will do the calculations again later but for the present assuming that is enough, and that the cylinder is 300 km long and 80 km in diameter it would require a lot of steel. It would correspond in area with a section of countryside from the Murray River to Melbourne long and Bendigo to Bright wide.

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The following calculations are for a gravity equal to that of the Earth, 10 m/s/s and for 0.4g, that is 4 m/s/s. Could you check the calculations and let me know if I have made a mistake.

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The next calculation is if the habitat uses a gravity only 0.4 that of the Earth's gravity, that is an acceleration of 4 m/s/s.

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The structure of the habitat will be a cylinder 300 km long and 80 km in diameter made from steel 2 cm thick. The volume of steel required to make such a structure, which would consist of two cylinders, is shown here.

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This is a lot of steel. Comparing it to annual production in 2013 for the whole world we get the following result.

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Hence annual production of steel 2013 is not enough to produce a spaceship of this size. Asteroids come in all sizes. Assuming 100% iron the size of the asteroid is calculated here.

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Hence r is about 900 m or 1 km which by asteroid sizes is quite small. So we get our iron from the asteroid belt.

Then what?

There are already businesses preparing to extract asteroids from the asteroid belt. Obviously moving a 10 km radius iron rich asteroid into an orbit around the Earth would provide thousands of years supply of iron at 2013 production rates.

But would you make your spaceship from iron. Carbon nanotube technology promises better strength at much lower densities.

We'll think about that later.