forests on orbit

http://www.fas.usda.gov/ffpd/Newsroom/2007%20Wood.pdf

The US uses 1 cubic meter of softwood and 0.4 cubic meter of hardwood
per person per year. If the entire world were to use paper and wood
at this rate the world would need 6.6 billion cubic meters of softwood
and 2.7 billion cubic meters of hardwood each year. This is 11x the
annual production of these products in the world today.

http://www.earth-policy.org/Books/Eco/EEch8_ss6.htm

Forest plantations produce 4 cubic meters of wood product per hectare
per year. That means 2.8 people may be supported per hectare. 280
people per square kilometer. Approximately 1/10th the number of
people supported by an equivalent area of ag satellite.

Clearly, forestry satellites will be built later than ag satellites
since to take advantage of learning curve effects as well as existing
capital in place following an ag build out - to reduce plantation
costs.

I wrote earlier about a collection of 676,000 satellites in a sun
synchronous polar orbit above Earth forming a band 1,000 km to 1,026
km above the Earth made from 1,000 select asteroidal fragments
retrieved from the asteroid belt.

These satellites fly in an orbital plane that is constantly
perpendicular to the sun. Thus the satellites are in constant
sunlight. Each consists of cylinders 1 km in diameter intercepting
0.785 km2 of sunlight - and illuminating 3.140 km2 of cylinder area.
Thus, the cylinder is 1 km tall.

Each of these satellites can support 879 persons in their wood
needs.

The light falls on a shaped conical reflector that has two lobes.
Each lobe reflects incident light across 90 degrees of cylinder
circumference - with constant intensity along the height of the
cylinder. There are two regions of highest intensity - which peaks at
1,000 w/m2 - separated by 180 degrees - so these are two lines on the
cylinder on opposite sides. The intensity falls off along a cosine
curve to zero intensity at plus and minus 45 degrees. from 45 degrees
to 135 degrees and from -45 degrees to -135 degress - the cylinder is
in darkness - simulating night.

To maintain 1 gee force the cylinder rotates once every 44.8342
seconds. The two lobed mirror described above rotates once every
44.8458 seconds. The slight difference in rotation rate means that
the two bright lobes sweep across the cylinder every 24 hours -
simulating the day night cycle of Earth.

With 6.6 billion people a total of 7,508,533 satellites are needed to
supply them all with wood.

At an altitude of 1,026 km above Earth the ag satellite system ends.
Capturing another 1,000 asteroids and operating at 1,186 km altitude
in the same orbit above Earth as the agicultural cylinders - each
asteroid is separated from the others by 47.5 km. These are equipped
with productive capabilities that allow them to produce 7,520
satellites from each of the captured asteroids in a plane extending
downward 160 km.- 47 km wide - 7520 cylinders in all each 1 km in
diameter. A total area of 23.6 million sq km forestry plantations.

A total of 3.44 cubic meters of wood per day is produced by each
satellite - an average weight of 1800 kg per day of wood. A very
small flow rate reflecting the longer grow times of woods. Total flow
for humanity is 13,536,000 metric tons per day for the whole
plantation system.

This may be increased slightly due to the coproduction of consumable
products in a forest setting. Products like mushrooms, nuts and
various fruits may be produced in parallel.

Roughly speaking on a recurring basis, this system requires about 76%
of the flow rate of the ag system described previously. A total of
200 years of production may be supported with this system. About four
harvests of most woods.

Just as the food products may be processed on orbit with telerobotic
labor, so too may the wood products be similarly processed. Furniture
and building components may be produced on orbit and delivered to end
users.

Other fibers include wool and cotton.

http://www.ers.usda.gov/briefing/cot...milldemand.pdf

Total fiber demand is about 15 kg and approximately 7 kg is cotton for
the average American. Translating this to the entire Earth means
271,040 metric tons per day - which is but a slight adjustment,
especially when given the short life cycle of cotton and the foodstuff
of sheep.

The transition from ore processing to finished good processing to
fabrication to high intensity agriculture to forestry is nearly a
continuous transition in intensity per unit area

http://www.steeldynamics.com/investo...2010k-2001.pdf

Modern steel producers require about 3 sq km of surface area to
produce 1 million metric tons of steel per year from iron ore.
Factories process 100,000 metric tons of products in the same area per
year. Agricultural systems produce 10,000 metric tons of food
products per year from the same area. Forestry systems produce 1,000
metric tons of wood and fiber products per year from the same area.

Raw materials 1,000,000 metric tons per year per satellite
Finished goods 100,000 metric tons per year per satellite
Agricultural goods 10,000 metric tons per year per satellite
Wood & Fiber 1,000 metric tons per year per satellite
Private Residences 100 metric tons per year per satellite

Number of Satellites

Raw materials 10,000
Finished goods 100,000
Agricultural goods 1,000,000
Wood and Fiber 10,000,000
Private Residences 2,000,000,000

Habitats with daily commutes to Earth and back process approximately
100 metric tons per year - given that each person masses approximately
80 kg with 3.5 people per satellite on average.

Again, as the volume of satellites increase and their use spreads, it
is reasonable to conclude that residential use will expand.

The large 20 fold increase in the number of residences when compared
to the growth in number of satellites needed for other uses suggest
some sort of disconnect. This can easily be remedied by observing
that we have assumed the per capita income of the average American, as
a global standard of consumption. While this represents a massive
increase in the standard of living world wide (11x) it would be naive
to believe this to be an end point in human development. In fact, we
can look at the amount of wood, fibers, metal and so forth, used by
different income groups throughout the world, compared to the surface
area projected for the private residences, and we see that by
increasing per capita income from $45,000 per year (US average) to
$1,000,000 per year - the disconnect disappears as the number of
satellites grow to meet this need.

Raw materials 200,000
Finished goods 2,000,000
Agricultural goods 20,000,000
Wood and Fiber 200,000,000
Private Residences 2,000,000,000

So we build for a 220x increase in consumption, from the global
average today, not the 11x to meet today's US per capita
consumption.

We could of course increase the number of people aboard each satellite
increasing them to 75 people per satellite. This is about 20 hectares
per household. But to maintain a lower mass flow rate requires
visiting the Earth once every 3 weeks or so - which makes the orbiting
community pretty isolated from the Earth.

Of course every satellite will be operated for a profit - so the
numbers will continue to grow until the marginal profits decline below
the returns available from other investment vehicles. In short there
are no arbitrary limits as to when people will use residences, or how
dense they will be an so forth. The only thing this calculation is
intended for here is to determine when MOST people will use MOST of
the off-world assets, what the largest use rate will be, and plan
systems around that.

It seems most reasonable to me, notwithstanding early developments in
the field - i.e. a space hotel, or a lunar golf community, etc., that
when most people leave Earth they will have per capita incomes in the
$1 million range and each family will inhabit space stations
comprising of 314 hectares -

As rocketry costs decrease and sophisticated robotic and automation
and AI systems are added to each station - along with sophisticated
medical treatments - propulsion systems will be added to individual
satellites and families will have the option of moving beyond the
intense industrial belts of Earth - for regions beyond Earth orbit -
and even with the development of very powerful lasers near the solar
surface - regions beyond the solar system.