food from space

NASA did studies on space colonies back in the 1970s and 80s. Gerard
O'Neill wrote on them in The High Frontier.

http://space.mike-combs.com/SCTHF.html

The costs do not take into account the ability of developing the
technology more gradually in a way that sees it more of an investment
that earns profits, which are then re-invested in technology
development.

One interesting finding was that farms in space support 40,500 people
per square kilometer at US per capita levels of consumption. This
amounts to 730 kg per person per year. To fee 6.6 billion people at
this level requires 162,963 square kilometers of pressure vessel
area.

103,745 spheres each 1 km in diameter each housing a spinning cylinder
707 meters in diameter and 707 meters deep, support 1.57 square
kilometers of growing area - each supporting 63,585 persons.

Each satellite has a rail gun and fires 2 meals per second - to people
all over the Earth aided by low cost GPS guidance systems and ceramic
aerogel thermal protection systems with aerodynamic features. MEMs
based rockets forming a propulsive skin to execute a soft landing at
the desired location for each meal. Terminal velocity of the aerogel
encased meal is about 200 m/sec following re-entry - which requires a
propellant fraction of 4.3% or 30.4 grams of propellant for a 700 gram
meal. The rail gun fires it to the targeting envelope and the kinetic
energy and tail fins of the falling meal are adjusted to bring it to a
precise GPS cooerdinate. A solid state doppler radar determines
precise altitude to ignite the engines, and bring the meal to a halt
at zero altitude at the desired location.

The mass of 2 meals per second is 1.47 kg per second. With an
ejection speed from the rail gun of 500 m/sec to deorbit each meal,
this exerts a 75 kgf thrust on the station. This is made up for by
burning of hydrogen and oxygen made from water at a rate of 0.17 kg
per second.

Orders are taken via satellite cell phone or satellite internet, and
delivered within 30 minutes or less anywhere on Earth. . .

10 billion tons per year of asteroidal materials, principally water
and carbon-dioxide - are imported from the asteroid belt by nuclear
pulse deflection of asteroidal material selected for quality and
variety of materials.

The satellites are made from asteroidal material as well brought from
the asteroid belt earlier..

7,255,410 equilateral triangles composed of aluminum framing encased
in PET film are manufactured as a flexible 'string' 3,627 km long. An
assembly head welds the aluminum frame, and seals the PET film in a
spiral pattern to form a 1 km diameter stationary sphere. A 707 meter
diameter cylinder 707 meters wide, rotates freely inside this sphere
supported by magnetic bearings at the edges of the cylinder. The
cylinder rotates once every 37.7 seconds. The interior of the
cylinder has an oblate thin film reflective surface that reproduces
over the course of 24 hours the same day/night conditions one finds on
Earth which rotates along with the cylinder, but in such a way that it
completes one rotation every 24 hours - giving a day night cycle to
the plants and animals on the cylinder surface.
..
40 farmers and 200 farm helpers are present tele-robotically to grow
the foods at the station. Additionally, there are 360 cooks cleaners
and handlers at each station to prepare meals and package them. Thus,
600 people are needed to support 40,500 in their food needs. All
stations together require a total of 62,247,000 telerobotic workers.
Each station has a set of 10 people present in person, thus
1,037,450 people are living on orbit in the 103,745 stations.

The world presently spends $9 trillion per year on food. The network
here captures the bulk of this, and at $50,000 per person on average
$3.15 trillion is salaries, and the balance is capital cost and
profits. A total of $46 trillion may be supported in this way - This
allows $440 million per satellite as the target price in this
quantity. This is $282 per square meter - allowable cost.

This is the fourth step in a seven step process of lowering cost of
space borne pressure vessels

1) mining - highest cost
2) smelting
3) forming/assembly
4) farming - mid-range
5) forestry
6) residential <-- high frontier level
7) private home - lowest cost

Moving entire asteroids from the asteroid belt into MEO seems to me
more 'doable' than lifting things piecemeal from the lunar surface.
Since substantial ice is present in the asteroid belt, that is also a
plus.

10 billion tons per year requires the expulsion 17 billion tons of
'propellant' vaporized from the surface of the asteroids moved in this
way. Expelling the materials at 7 km/sec requires an average
expenditure of only 20 terawatts - averaged over the entire year. .
856 tons per second are harvested and 317 tons per second are made
availale. Of this, half is turned into food and deposited on the
Earth.

Four asteroid fragments, each roughly spherical each 100 meters in
diameter, arrive at Earth orbit from around the asteroid belt every
hour to resupply the ring of farm satellites. They have taken 3 years
to get to Earth and enter a MEO to be processed at centers that build
the satellites in the first place. Each fragment has sufficient raw
material to feed a farm satellite for 3 years. Each moves to an
appropriate position next to a satellite, and is fed into it - and raw
materials are processed on board into air, water, fertilizer and
nutrients- to replace the constant stream of materials falling to
Earth.

The satellites form a Saturn like ring in polar orbit above the Earth
- and each satellite flies over the entire Earth several times per
day.

.

Relevant Pages

  • Re: food from space
    ... Earth, and at the very least move our commercial agriculture into LEO ... Each satellite has a rail gun and fires 2 meals per second - to people ... The mass of 2 meals per second is 1.47 kg per second. ... the asteroid belt earlier.. ...
    (sci.space.policy)
  • Re: China now equals US in space
    ... What can you get from an asteroid that is not available on earth for ... Possibly iridium. ... be a major engineering challenge just to get the cost of transportation ... and deployment to an asteroid to a smaller number of orders of magnitude ...
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  • Re: DIRECT HIT
    ... satellite was launched into POLAR orbit (much more costly than a lower ... I'm pretty sure it was a high-inclination orbit, I want to say 50+ degrees, but not polar. ... changes with temp and the the nuke wont work). ... the cost of a nuke warhead remains high by comparison. ...
    (sci.military.naval)
  • OT - Yet another Bush Boondoggle
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  • Re: A magic Space Station that flies too...
    ... I do not see cost as the bottleneck to this or any other project, ... see the prohibition on launching *nuclear* reactors and warheads into ... orbit next month) or waiting several years to reach one small asteroid ... stand in the way of human progression under manners, ...
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