Mars halo mirror for terraforming?

There is another way to heat up Mars and cause a runaway greenhouse
event, a sufficiently large impact event, engineered by moving
asteroids to impact Mars

http://www.lpi.usra.edu/meetings/six...3/pdf/3247.pdf

On 7 Feb, 18:37, "Mike Combs"
wrote:
"Alex Terrell" wrote in message

oups.com...



Which means a significant tension force (no problem) and a significant
compressive force (solvable, but with difficulty).

O'Neill compared the compressive member to a terrestrial radio tower.
Remember that at this distance from the sun, the cylinders only have to turn
about 1 degree a day. The forces have to be designed for, but they're not
any particular kind of headache.

A radio tower several km high? I agree it's doable, but it might be
easier to have the colonies rotating around a "vertical" axis,
especially since I don't think much of the mirror arrangements.

two counter rotating also provide a massive energy store, in the event
of power disruption.

I'm minded to think
they should be on an axis parallel to orbital axis - makes the mirrors
more complex, but their weight is trivial.

That's the solution favored by the designers of the Stanford Torus, as well
as this MIT design:http://ssi.org/assets/images/Ch06p08...s/Ch06p086.gif

On 8 Feb, 06:45, wrote:
There is another way to heat up Mars and cause a runaway greenhouse
event, a sufficiently large impact event, engineered by moving
asteroids to impact Mars

http://www.lpi.usra.edu/meetings/six...3/pdf/3247.pdf

This is certainly one way of aiding terraforming. The trouble is, its
not compatible with surface habitation.

On 8 Feb, 05:43, wrote:
The Lagrange Point (L1 and L2) are

r = R * ( M2 / (3*M1))^(1/3)

FOR MARS

M2 = mars mass = 6.2e23 kg
M1 = solar mass = 2e30 kg
R = 2.28e11 m

r = 2.28e11 * ( 6.2e23 / 2e30)^(1/3) = 1.54e9 m = 1.54 million km.

FOR EARTH

M2 = earth mass = 6.0e24
M1 = solar mass = 2.0e30
R = 1.50e11 m

r = 1.50e11 * (6.0e24 / 2e30)^(1/3) = 2.16e9 m = 2.16 million km

We want to heat up Mars, and cool down Earth.

So, mirrors that intercept the sunlight falling on Earth would cool
Earth.

Mirrors that redirect sunlight falling past mars toward Mars, would
heat Mars.

Mars planetary radius is 3,400 km. A toroidal mirror 154,000 km in
radius and 958 km wide angled at 2.87 degrees relative to a line
between Mars and Sun, would cause light levels on Mars to rise to
Earth normal levels on Mars, and the light would come from the general
location of the Sun. The Sun would have a bright halo around it.

This would be extremely inefficient. Close to 1 trillion km2, but at
an angle of only 2.87 degrees. It would be better to have a double
mirror , or base it on the L2 position.

I believe you haven't taken into account solar light force in your
calculations. Zubrin and McKay estimate a distance of 214,000km, and
their mirrors are heavier (and hence further) than the mirrors you
proposed.

A 1272 km diameter disk centered on a line drawn between Earth and Sun
at L1, reduce the total influx of light on Earth by 1%. These light
levels are sufficient to reverse global warming despite higher levels
of CO2. The sun on Earth would have a dark spot in the center of it
covering 1% of its area.

Might be needed. Its fairly trivial for an orbiting infrastructure to
do this.

In both cases, the mirrors can operate solar pumped IR lasers, to beam
energy to both planets to power industrial infrstructure there.

2.16 million km is quite some distance - makes microwave transmission
impossible. What's the efficiency of IR lasers? And aren't they
distorted and absorbed by the atmosphere?

I would propose lasers to send power from Earth Moon L1 to a lunar
base, which is only 60,000km. I assume a grid to grid efficiency of
25%.

On Feb 8, 6:02 am, "Alex Terrell" wrote:
On 8 Feb, wrote:

There is another way to heat up Mars and cause a runaway greenhouse
event, a sufficiently large impact event, engineered by moving
asteroids to impact Mars

http://www.lpi.usra.edu/meetings/six...3/pdf/3247.pdf

This is certainly one way of aiding terraforming. The trouble is, its
not compatible with surface habitation.

Well, since no one is inhabiting the surface right now, and the
surface is more habitable after, then, its not really a problem.

Since Mars doesn't seem to have been subject to major collision
events, as the Earth and Venus and Mercury have, there may be
considerable water deep inside the planet. In fact, there may even be
forms of life deep inside Mars. So, this IS a problem if we are
sensitive to the 'rights' of that life - we need to assure ourselves
there is no other life form we would be harming in reprocessing Mars
on a massive scale.

On Feb 8, 6:19 am, "Alex Terrell" wrote:
On 8 Feb, wrote:





The Lagrange Point (L1 and L2) are

r = R * ( M2 / (3*M1))^(1/3)

FOR MARS

M2 = mars mass = 6.2e23 kg
M1 = solar mass = 2e30 kg
R = 2.28e11 m

r = 2.28e11 * ( 6.2e23 / 2e30)^(1/3) = 1.54e9 m = 1.54 million km.

FOR EARTH

M2 = earth mass = 6.0e24
M1 = solar mass = 2.0e30
R = 1.50e11 m

r = 1.50e11 * (6.0e24 / 2e30)^(1/3) = 2.16e9 m = 2.16 million km

We want to heat up Mars, and cool down Earth.

So, mirrors that intercept the sunlight falling on Earth would cool
Earth.

Mirrors that redirect sunlight falling past mars toward Mars, would
heat Mars.

Mars planetary radius is 3,400 km. A toroidal mirror 154,000 km in
radius and 958 km wide angled at 2.87 degrees relative to a line
between Mars and Sun, would cause light levels on Mars to rise to
Earth normal levels on Mars, and the light would come from the general
location of the Sun. The Sun would have a bright halo around it.

This would be extremely inefficient. Close to 1 trillion km2, but at
an angle of only 2.87 degrees. It would be better to have a double
mirror , or base it on the L2 position.

Correct, there are more efficient mirror structures one can design to
deflect light the 3.75 degrees needed at that distance. One can also
operate at 5,000 km at a shallower angle.

I wouldn't operate in the L2 position though, because it would produce
2 suns, not 1 - but that's just an artistic decision,you are quite
right, L2 works well for adding light to the planet. Just make it big
enough to provide an additional 147% of the solar side.

One could combine the two ideas. An increase of 23% in the sunlight on
the L1 side, and a second sun 123% as bright on the L2 side - might
work.

So Mars would have 2 suns and 2 moons. lol. Which would be
interesiting.


I believe you haven't taken into account solar light force in your
calculations.

Correct. That's more detail, but an easy one to figure out with
numerical methods. You can balance gravity, centrifugal and light
pressure forces to 'fly' a mirror system in this region of space.
Absolutely. The original Lagrange points are approximatons based
solely on gravity and centripetal forces.

Zubrin and McKay estimate a distance of 214,000km, and
their mirrors are heavier (and hence further) than the mirrors you
proposed.

I merely used the formula for Lagrange points without taking into
account light pressure forces. (or solar wind forces) I would like to
look at their calcuations. Are you sure it wasn't 2.14 million km?
Because on the L1 side, you'd have to go toward the Sun, to balance
light pressure. On the L2 side you'd have to go toward Mars, which
would bring you closer, perhaps considerably closer.

Yes, my mirrors are very light weight, a ton per square kilometer.
Maintaining their position in the face of solar wind is a problem.
There are many potential solutions however. The best will be selected
after a detailed analysis which hasn't been completed yet.

A 1272 km diameter disk centered on a line drawn between Earth and Sun
at L1, reduce the total influx of light on Earth by 1%. These light
levels are sufficient to reverse global warming despite higher levels
of CO2. The sun on Earth would have a dark spot in the center of it
covering 1% of its area.

Might be needed. Its fairly trivial for an orbiting infrastructure to
do this.

I agree. Its interesting that Gaia is telling us to begin thinking
about leaving the cradle. lol.

In both cases, the mirrors can operate solar pumped IR lasers, to beam
energy to both planets to power industrial infrstructure there.

2.16 million km is quite some distance - makes microwave transmission
impossible.

Agreed.

What's the efficiency of IR lasers?

Efficiencies of light pumped lasers have achieved 40% in the lab.
There is no reason that something close to this couldn't be attained
by solar pumped lasers. I assume in early stage planning that 20%
efficiencies are attained. Of course, low efficiencies are not a
problem when the mirrors that concentrate the sunlight to pump the
lasers, are being used to shadow the Earth. Adding energy to Mars
makes this use more of a problem.

And aren't they
distorted and absorbed by the atmosphere?

There are seveal windows in the Earth's atmosphere. One of these
occurs around 1,000 nm wavelength. Clouds reflect this pretty
efficiently. But, there are regions of Earth's surface, that are
largely devoid of clouds.

Also, 1,000 nm is very near the 1,108 nm bandgap energy of silicon.
So, a centralized solar collector site in a cloud free region,like a
desert, can be used as a solar pumped IR laser receiver station.

A solar collector in the desert, like in Nevada, Arizona,or
California, is illuminated about 1,900 hours per year. There are
8,766 hours in a year. So, this is 21.6% of the time.

Sunlight has a total energy of 850 watts per sq m. Conversion
efficiency of silicon is about 18% - so, we're talking 153 watts
electrical per sq m.

Combining these two figures, each sq meter of solar panel produces
290.7 kWh of electrical energy per year.

IR energy totals about 380 watts per square meter when the sun is
shining. So, if an IR laser beams 380 watts per square meter at these
same panels, it doesn't send any more IR energy than the sun
provides. The silicon converts this IR beam to electrical energy with
over 90% efficiency - that's 342 watts electrical per square meter.

Now, in the desert where these panels operate, they are cloud free 85%
of the time, so, that's .7,451 hours per year.

Combining these two figures each sq meter of solar panel, used as a
power receiver for IR solar pumped lasers, produces 2,548.2 kWh of
electrical energy per year.

Since the sun still shines on this power reciever, the addition of the
satellite raises total output to 2,838.9 kWh of electrical energy per
square meter per year. Nearly 10x as much!

Which gives the ratio of value of the two systems.

I produce solar panels at $0.07 per peak watt. I could add solar IR
laser in space and pay as much as $0.63 per peak watt, and still be
ahead operating this way. If I get paid through carbon credits, or
some sort of UN funding mechanism, then, its all to thte good.


I would propose lasers to send power from Earth Moon L1 to a lunar
base, which is only 60,000km. I assume a grid to grid efficiency of
25%.- Hide quoted text -

Well, that's possible, but it doesn't reduce energy on Earth.

I would say that a large mirror array at L1 be used to reduce heating
of Earth, and a portion of that energy 20% - be beamed to an IR
reformer in GEO and that GEO sat redirect the energy with nearly 100%
efficiency, to ground receivers in the desert that convert it to DC
electricity with nearly 90% efficiency.

Those recievers drive electrolysis units that break down water into
hydrogen and oxygen. The hydrogen is distributed by pipeline
throughout North America, and is used first,to power coal fired
plants. The coal is traded for hydrogen, and more hydrogen is used to
hydrogenate the coal into liquid fuels like gasoline, diesel fuel,fuel
oil, and jet fuel and gas fuels, like propane, butane, methane. The
hydrogen is also liquified locally and used directly as demand grows
for it. Hydrogen is also piped to homes and industry, and used in
fuel cells. The water created is filtered and consumed. Hydrogen is
also combined with nitrogen in the air to form ammonia on demand for
agriculture.

Once operating in the US, similar systems can be set up in the major
deserts around the world, and a hydrogen gas pipe network is
established in every major land area of Earth, and a hydrogen economy
is established worldwide.

"Hop David" wrote in message
...
Joe Strout wrote:

And in addition, O'Neill never proposed a single cylinder; they come in
pairs, joined at the ends, so that the system's net angular momentum is
zero.

Does that negate the rotating object's tendency to stay aligned in one
direction?

Yep. It might help if you think of each cylinder as helping to turn the
other. But of course to the mathematician, it's that the two momentums
cancel out, and an object with 0 net angular momentum will not experience
the gyroscope effect.

--


Regards,
Mike Combs
----------------------------------------------------------------------
By all that you hold dear on this good Earth
I bid you stand, Men of the West!
Aragorn

On 8 Feb, 13:58, wrote:
On Feb 8, 6:02 am, "Alex Terrell" wrote:

On 8 Feb, wrote:

There is another way to heat up Mars and cause a runaway greenhouse
event, a sufficiently large impact event, engineered by moving
asteroids to impact Mars

http://www.lpi.usra.edu/meetings/six...3/pdf/3247.pdf

This is certainly one way of aiding terraforming. The trouble is, its
not compatible with surface habitation.

Well, since no one is inhabiting the surface right now, and the
surface is more habitable after, then, its not really a problem.

Just a question of appropriate project planning then.

However, to go get a KBO for Mars ramming would take several decades,
making habitation in the mean time temporary.

Since Mars doesn't seem to have been subject to major collision
events, as the Earth and Venus and Mercury have, there may be
considerable water deep inside the planet. In fact, there may even be
forms of life deep inside Mars. So, this IS a problem if we are
sensitive to the 'rights' of that life - we need to assure ourselves
there is no other life form we would be harming in reprocessing Mars
on a massive scale.

Interesting question: Would such life have more rights than equivalent
life on Earth? i.e about zero.

on 8 Feb 2007 11:03:15 -0800, Alex Terrell sez:
On 8 Feb, 13:58, wrote:
On Feb 8, 6:02 am, "Alex Terrell" wrote:

On 8 Feb, wrote:

There is another way to heat up Mars and cause a runaway greenhouse
event, a sufficiently large impact event, engineered by moving
asteroids to impact Mars

http://www.lpi.usra.edu/meetings/six...3/pdf/3247.pdf

This is certainly one way of aiding terraforming. The trouble is, its
not compatible with surface habitation.

Well, since no one is inhabiting the surface right now, and the
surface is more habitable after, then, its not really a problem.

Just a question of appropriate project planning then.

However, to go get a KBO for Mars ramming would take several decades,
making habitation in the mean time temporary.

Since Mars doesn't seem to have been subject to major collision
events, as the Earth and Venus and Mercury have, there may be
considerable water deep inside the planet. In fact, there may even be
forms of life deep inside Mars. So, this IS a problem if we are
sensitive to the 'rights' of that life - we need to assure ourselves
there is no other life form we would be harming in reprocessing Mars
on a massive scale.

Interesting question: Would such life have more rights than equivalent
life on Earth? i.e about zero.

Of far more importance, the value of such life will be in the
incredible wealth of information it brings, being a data point
hopefully fully independent of the evolution of life on earth.
The scientific value is huge, but so is the technological
value. Presumably all the problems of conduction of the processes
of life will have been separately solved, and this will provide
a whole new landscape of possibilities for genetic engineering,
potentially enabling the creation of organisms which have
minimal interaction with our native organisms, or possibly
the development of chimeric biota using organelles from both
sources.

However, once a thorough sampling and mapping of the natural history
of the martian ecology is completed, and cultures of all the
varieties of organism are safely established, I doubt there would be
any significant opposition to planetary urban renewal stemming from
such concerns. The main objection will probably come from people who
feel that dropping large objects onto Mars is a waste of good
material which could go towards orbital colonies outside of deep
gravity wells. I imagine this debate will get quite heated at some
point in the future when we have the capability and hardware
sufficient to do one or the other, but don't yet have sufficient
infrastructure to do both.


--
================================================== ========================
Pete Vincent
Disclaimer: all I know I learned from reading Usenet.

Alex Terrell wrote:
On 8 Feb, 13:58, wrote:

On Feb 8, 6:02 am, "Alex Terrell" wrote:


On 8 Feb, wrote:

There is another way to heat up Mars and cause a runaway greenhouse
event, a sufficiently large impact event, engineered by moving
asteroids to impact Mars

http://www.lpi.usra.edu/meetings/six...3/pdf/3247.pdf

This is certainly one way of aiding terraforming. The trouble is, its
not compatible with surface habitation.

Well, since no one is inhabiting the surface right now, and the
surface is more habitable after, then, its not really a problem.


Just a question of appropriate project planning then.

However, to go get a KBO for Mars ramming would take several decades,
making habitation in the mean time temporary.

If a big object hits Mars with sufficient velocity, much of the
asteroidal material as well as the atmosphere above the tangent plane at
point of impact is sent into space. Loss of most of the asteroidal
material, kinetic energy and a good chunk of Martian atmosphere wouldn't
contribute to terraforming.

The slower the asteroid impacts, the better. So Jupiter Trojans or
asteroids from the main belt would be better to toss at Mars than KBOs.

Hop