Space Equilibrium

Asteroids are not only a source of metals and minerals, there are also asteroids with large amounts of water. From water we can make rocket fuel. That means instead of bringing fuel to the asteroids, we can manufacture it there. To bring 1 kg of space craft to an asteroid only takes 4.3 kg of fuel. If fuel is manufactured there, it could bring back any amount of material back to earth orbit at the same cost - 4.3 kg of fuel per kilogram of material. Sending 1 kg of space craft requires 4.3 kg of fuel, it then generates 430 kg of fuel for every 100 kg of payload to return to Earth orbit. Part of this payload could be water making it possible to generate fuel from Earth orbit without sending it up from Earth at a cost of 27 kg of fuel for every 1 kg of fuel in orbit. Bottom line : By establishing fuel generators on asteroids, we have nearly unlimited resources available from the asteroid belt.

In some ways "space" is actually very close. A low Earth orbit is typically about 100 km above the surface. That's a distance you can drive in about an hour. Getting up that high isn't the hard part. It takes a delta vee of 1.4 km/s to get up to 100 km. It takes the additional 8.6 km/s to be going fast enough to orbit the Earth. Asteroids are very far away - the asteroid belt is hundreds of millions of kilometers away and close approaches are millions of kilometers away. However, because many of them orbit in the same direction as Earth at about the same distance from the sun, the delta vee required can be as low as five kilometers per second. Half the delta-v doens't mean half the fuel required. The trade-off is exponential. Accelerating 1 kg to 5 kilometers per second takes 4.3 kg of fuel. Compare this to 27.0 kg of fuel to reach 10 kilometers per second, and it's less than a sixth the cost. After making it to an asteroid, you might want to co

So far we have determined: Producing 1 kg of rocket fuel a day on Earth requires 38.1 square meters of solar panels and 1 kilogram of water. 77,466,483.6 kg of people and seats to launch into space every day. To launch 1 kg into low earth orbit requires 27.0 kg of rocket fuel. Putting this together means every day we need to generate 2,091,595,057.2 kg of rocket fuel a day which requires 79,689,771,679.3 square meters (79,690 square kilometers) of solar panels. It's about the size of one of the smaller states in the USA: South Carolina or the Czech Republic.

A rocket moves forward by pushing propellant out in the opposite direction. It can't pull its way through the air like an airplane can do with its propellers. It can't push its way along like a car does with its tires. By pushing propellant out at a high velocity, a rocket accelerates. The velocity of the propellant is a measure of the efficiency of the engine and is called the Specific Impulse or the Effective Exhaust Velocity. We can calculate the ratio of fuel to payload using the Tsiolkovsky rocket equation. initial mass / final mass = mass ratio = exp (delta-v / exhaust-velocity) To reach low earth orbit from Earth, it requires a change in velocity of about 10 kilometers per second. The effective exhaust velocity of Hydrogen-Oxygen engines can be up to 3 kilometers per second. Applying the rocket equation, yields a mass ratio of 28.0. Bottom line: To launch 1 kg into low earth orbit requires 27.0 kg of rocket fuel.

Rocket fuel is easy to make: Water + Electricity = Rocket Fuel. More specifically, electrolysis of water to break it down into hydrogen and oxygen. When it burns, it just makes water again which falls as rain; it just might be the cleanest fuel on the planet. In industrial setups, takes about 80 kilowatt hours of electricity to separate a kilogram of water producing a kilogram of fuel. The theoretical limit is less than half that at 39.4 kilowatt hours. Maybe some advances can be made to get closer to the theoretical limit, but for these calculations, we will use 80 kilowatt hours. Solar is a good option for power. We're going to be needing a lot of rocket fuel, and solar scales well -- you just need to build the panels and have the space somewhere sunny and near the water. Also, we're going to eventually need to be making rocket fuel in space . There is a lot of sunlight in space. There is not very much wind or rain. Solar cell technology is up to 44% efficient

The world population is growing 1.1% year over year. That's 81,400,000 people a year which is 222,861 per day. An average human weighs 80.7 kg, so every day the mass of humans on the planet increases by 17,984,887 kg. That's just the mass of the people. If we want to get these people into space, at the very least, we need seats. For comparison, let's look at the Boeing 747. It's operating empty weight is 162,400 kg. It has four engines each which weigh about 3,905 kg. So, without engines, empty weight is 146,780 kg. It can seat 550 people maximum. That's 266.9 kg of plane for each person. Transporting people to space may require structure more resilient than in the 747, and thus more weight, but some weight of an airplane goes to large wings which are not needed. So, for our estimates, we will stick with this. Together, this brings us to a launch weight of 347.6 kg per person. Bottom line: 77,466,483.6 kg of people and seats to launch into space e

Since 1987 we've been using Earth resources faster than they are naturally created. Though this is a fact is undeniably debatable, it is generally accepted by scientists. There are five basic ways we can reach equilibrium: Do nothing. Eventually Earth will become so inhospitable that the human population will decline, until we go either extinct, or severely reduced. Reduce human population by having fewer children Reduce our consumption of resources through both good will and legislation Reduce our consumption by finding ways to live on Earth with less impact Get people off the planet faster than they are born Here I explore the final option. It is the only option which can sustain unbounded population growth. The resources available in the solar system as a whole greatly outstrip those available only on Earth. Though reaching the limits of our solar system may happen eventually, that point is so far in the future, it will be as realistic to look beyond our solar syste