Reworked to: Asteroid Resources Could Create Space Habs For Trillions; Land Area Of A Thousand Earths

Space colonization is unintuitive to us because we have never done it before. It is much easier to establish space habitats in orbit around Mars than on the surface and the materials to make them are just “as at hand” as on the surface since it is easy to move things around in space from one place to another if you just allow enough time.

Related blog posts:

Value of Pristine Mars

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Surface mission to Mars, terrible idiea, easily made wonderful

If you ask where the habitats are best constructed - one natural interesting location is in Mars orbit. There the population of the habitat can be usefully involved in exploring the surface of Mars driving vehicles and operating robots on the surface via telepresence. Orbit around Mars reduces the light speed delays which make current missions to Mars so slow moving and impossible to control in real time from Earth at any speed at all.

In site resource utilization is just as easy in space as on a planetary surface

If just using cargo transport, no worry about transfer times, you can transport anything from almost anywhere in the solar system to almost anywhere else at almost zero cost in fuel using the “Interplanetary Transport Network”

http://en.wikipedia.org/wiki/Interplanetary_Transport_Network

But even for faster transport then there is lots of material within easy access of a Mars orbit.

There is also more space to expand there. Space is almost unlimited, you could have trillions of humans living in space habitats with gravity supplied by rotation.

How much material is needed for space habitats with surface area same as the land area on earth?

Suppose for instance you want a surface area the size of the land area of the Earth in space habitats - also roughly same by coincidence as the surface area of Mars.

Let’s take the estimate of 4 metric tons per square meter for radiation shielding, then that’s 2 cubic meters roughly at the density of Ceres.

http://en.wikipedia.org/wiki/Space_habitat#Protection_from_hostile_external_environment

https://en.wikipedia.org/wiki/Ceres_(dwarf_planet)

Then - double that for a margin to allow for air, buildings, landscaping etc etc. This is just a “back of the envelope” type calculation and will overestimate.

So, let’s make it four meters thick (about the height of a one story house including roof), likely to be easily thick enough for the walls of rotating space habitats and radiation shielding.

What size of asteroid is needed to make space colonies for all the inhabitants of Earth (all the animals, plants, humans etc on the land)?

Let’s calculate it. Land area of the Earth in square kilometers: 148,300,000 sq km (Mars is 144,798,500 km²)

As a four meter thick area of living surface in space habs, 4 meters is 0.004 km so that gives

593,200 km3

Solve for the radius (google calc: (593,200/(4*pi/3))^(1/3) = 52.1239729841)

You need an asteroid 52 km in radius to make that much space habitat. (104 km in diameter)

Asteroids such as Ceres could easily supply that several times over

There are many asteroids in the asteroid belt much larger than that http://en.wikipedia.org/wiki/List_of_notable_asteroids#Largest_by_diameter

The largest, Ceres at 952 km diameter has a volume of 451,761,760 cubic kilometers (4*pi/3)*4763 So, with only 593,200 km3 required for the surface area of the Earth, that would be enough for space habitats for 700 times the land area of Earth - and that is including enough space to replicate the tropical rain forests, deserts, coral atolls, outback of Australia, Himalayas etc etc. as well as all our cities teaming with humans.

Remember that’s the outer shell of the habitat - on top of it you can build multi-story cities and all sorts in the larger Stanford Torus type space habitats - obviously the earlier habitats will be small but later on they will surely be huge. http://en.wikipedia.org/wiki/Stanford_torus

What about resources immediately accessible from Mars orbit?

If you look at the resources available for Mars orbit - then the moons of Mars, and the Near Earth Orbit asteroids (easily accessible to mining companies on Earth) are the obvious resources to start with.

Deimos the tiny outermost moon of Mars has a volume of (4*pi/3)*6.3^3 or 1047.39442434 cubic kilometers enough to make space habitats covering 261,848 square kilometers of living area with that four meters thick estimate, so more than the surface area of the United Kingdom, and similar to surface area of New Zealand

https://en.wikipedia.org/wiki/List_of_countries_and_dependencies_by_area

In terms of US states, that’s a larger surface area than any except the very largest of the states, a little less than the surface area of Texas

http://en.wikipedia.org/wiki/List_of_U.S._states_and_territories_by_area

So it is clear we aren’t going to run out of resources for making space habs in orbit around Mars any time soon :)

Space habs can provide far more land area for colonization than planetary surfaces in our solar system

It is pretty clear that in the future free orbiting space habs or habs orbiting planets will house a far larger population than the surface of any planet, so long as humans continue to colonize the solar system.

Eventually we will surely easily have trillions of people living in space habitats when you take account of the Kuiper belt, Oort clouds etc.

We don’t even need to live in the Kuiper belt etc (though I’m sure some will once fusion power is practical with mini suns powering the habitats)

Via the "Interplanetary Transport Network" you can simply move all the material you need to wherever in the solar system you want to put it, over time especially with an automated robotic spacecraft controlled transport network.

In particular there is absolutely no practical need for the surface of mars for land area for future colonization

So any arguments along the lines that we must colonize the surface of Mars because we will need the space in the future simply don’t add up when you do the sums.

It is likely if anything to be easier to construct space habs than habs on the surface of Mars in the near future even with use of on site resources

Remember on the surface of Mars all work is done in space suits and tearing the space suit or smashing the visor will kill you, just as in space as you are working in a laboratory vacuum - and in the distant future space hab construction will probably get so automated that humans hardly have to do anything except supervise the machinery occasionally to make sure no major mistakes are made.

In site resource utilization is just as easy in space as on a planetary surfaceIn site resource utilization is just as easy in space as on a planetary surfaceIn site resource utilization is just as easy in space as on a planetary surfaceWorking conditions would be safer in orbit around Mars, more controlled environment, and much much easier to get back to Earth in case of illness or accidents.

Related blog posts:

Value of Pristine Mars

Terraforming Mars needs great care

Surface mission to Mars, terrible idiea, easily made wonderful