Re: forests on orbit

The advantage of using off-world resources is that we do not harm
Earth's biosphere in building our industry.

Also, Ceres 9.46e+20 kg of material is fully available. So, Ceres if
broken into a powder and laid on the surface of the Earth would form a
layer 1.17 km deep. This is deeper than most mines on Earth. The
high gravity of Earth produces tremendous pressures the weights that
make penetrating Earth's surface difficult. the 1/40th gravity of
Ceres means that present methods can easily penetrate to the very
center of Ceres, making the entire volume of the 950 km diameter dwarf
planet available for mining.

What this tells us is that Ceres represents a greater volume of
mineable materail than the entire surface of Earth.

Now what does it take to bring stuff back from Ceres. Speed which
takes energy.

Energy is abundantly available off-world.

You people are talking without really analyzing what you're talking
about in detail.

So, lets go over it rationally.

First off, a robot system that is laser or grid powered rather than
heat powered is more efficient and so requires less overall energy
than I compuited for Brads fantasy of a plutonium powered robot..

Human industry currently uses energy at a rate of 15 trillion watts.

Solar panels on orbit are more efficient than solar panels on Earth

Solar panels on orbit collect 1.36 GW per sq km 8,766 hours per year.
At 40% efficiency 0.54 GW useful per sq km 8,766 hours per year.

Solar panels on Earth collect 1.00 GW per sq km 1,700 hours per year.
At 40% efficiency that's 0.40 GW useful per sq km 1,700 hours per
year.

Collected at Earth orbit and converted to beamed energy and useful
work with 40% overall efficiency - this means that 27,452 sq km of
sunlight must be intercepted on orbit to meet humanity's energy
needs.

Collected on Earth surface and converted with 40% overall efficiency
means that 193,367 sq km of sunlight must be intercepted on Earth
surface to meet humanity's energy needs.

Both are far smaller than all the farmlands and forests of Earth. In
fact two surface mine owners today each own over 200,000 sq km of
desert lands that must be reclaimed and have expressed a wiillingness
to license them for that use when they are done..

So, energy is not a problem if you can convert solar energy to
hydrogen gas or laser beams efficiently - whether you collect solar
energy in space or on Earth depends on your cost of getting to orbit
and building stuff there.

Now, there are 6.6 billion people on 'Earth and they consume energy at
about 180 watts each. That means 1.2 trillion watts is consumed this
way. This is not included in the industrial energy total - and the
inefficiency of farming is seen by considering the total area of farms
9 million sq km and forests 20 million sq km to provide this meager
energy input to humans in the form they can process.

Converting biomass to industrial fuels increases the cost of fuels,
and foods simultaneously and is a bad idea. Farmlands are best used to
produce edible foods deserts or space stations used to harvest solar
energy.

Robots until we solve some difficult software problems are driven by
humans, and there are likely no more than 1/6th the population of
Earth until that problem is solved- (3 shifts per job = 3 working
people to 1 robot, and fewer than half people work - chidlren elderly
do not work) - and 180 watts each - powered from the grid. So, we're
talking 0.2 trilion watts or 1.3% total current demand - even in a
fully automated world where every single job is performed
telerobotically.

There may be more than 1 billion robots around - but if they're driven
by humans, they won't all be active, so the power level won't change.

The number of robots on Ceres needed to extract all thei industrial
materials used by humanity is likely to be less than 1 million human
equivlant workers - which is 250,000 robots - which s 45 million watts
- a tiny peaking generator plant This is nothing.

Now, lets figure out the energy to send things to and from Ceres.

This all boils down to delta vee and how you get it.

To send something from Earth or bring something back from Ceres
requires that an 8 km/sec delta vee is applied. About 3 km/sec is
needed at Ceres and about 5 km/sec is needed at Earth.

Using rail guns or magnetic launchers at Ceres and aerobraking at
Earth means 3 km/sec must be added to every ton of material
retrieved. This is;

E = 1/2 * m * V^2
= 0.5 * 1000 * 3000 * 3000 = 4.5 GJ/tonne

Using rockets at either end, and energizing them in ways that use
minimum energy, means that each ton of material requires the ejection
of 1.72 tons of propellant at 8 km/sec - this is the high end of
energy

E = 0.5 * 1720 * 8000 * 8000 = 55.04 GJ/tonne

This is how stuff gets sent to Ceres

Each robot masses 50 kg (110lbs) - that's 0.05 tonnes. So, 1 million
human equivalents - equal 250,000 robots - that's because humans work
42 hours a week, and there are 168 hours in a week. So, four humans
are needed to drive one robot.

The robots then mass a total of 12,500 tons. So at 55.04 GJ per ton
that's 688 trillion joules to send them by rocket to Ceres.

They have a lifespan of 40 years that's 1.26 billion seconds.- which
is an aeverage poer of 0.55 megawatts.for the 250,000- or 2.2 watts
per robot.

So, to SEND the robot to Ceres in the first place adds only 2.2 watts
to its 180 watt basal rate. Obviously things are not that energy
intensive

Lets imagine humans retrieve 1 ton per year of raw materials from
Ceres. This requires 4.5 GJ of energy per ton. Dividing this by the
31 million seconds in a year obtains 143 watts of power per person.
Summing over 6.6 billion people obtains.941 giga-watts for the
planet. This is only 6.3% of our current total.

So, we're talking the following power levels

15,000.0 gigawatts current human industrial consumption
941.0 gigawatts transport 6.6 bilion tons/yr material from
Ceres
200.0 gigawatts 1.1 billion telerobots
0.2 gigawatts 1 million robots at Ceres
0.006 gigawatts transport 1 milion robots to Ceres
..

Powering robots is not a problem, sending robots to Ceres is not a
problem energywise, and retrieving significant amounts of material
from Ceres is not a problem energywise - especially if we capture
solar energy efficiently in space.

.

Relevant Pages

  • Re: Cerian submarines
    ... far less energy to get a lot of water from Ceres than from earth to ... Spectra of organic compounds have been observed from Ceres. ... bodies with lots of water in space. ...
    (sci.military.naval)
  • Re: Cerian submarines
    ... far less energy to get a lot of water from Ceres than from earth to ... You want to run a pipe between Ceres and the moon to power up a ...
    (sci.military.naval)
  • Re: Cerian submarines
    ... far less energy to get a lot of water from Ceres than from earth to ... You want to run a pipe between Ceres and the moon to power up a ...
    (sci.military.naval)
  • Re: What happens to a rock hitting a Neutron Star?
    ... An asteroid the ... size of Ceres would cause as much energy as 100,000,000 H-bombs when ...
    (sci.physics)
  • Re: The Silly Future, Or What Was Pohl Drinking?
    ... > large amount of energy it takes to heat and melt ice, Ceres is still a ... They both contain roughly the same amount of energy, ...
    (rec.arts.sf.written)