We have wind turbines killing birds.
sunlight.
Yet environmentalists are crazy in love with these destructive
technologies.
With SPS we actually have a technology that is benign to the
environment, and actually beneficial when compared to the damage
caused by wind turbines and solar PV arrays.
Space Power Beaming: Nice to Mother Nature's Plants
http://www.space.com/astronotes/astronotes.html
"If the Earth is ever on the receiving end of power-beaming
satellites, the weak microwaves from such a space-based energy
generator are not harmful to green plants.
In a NASA-funded experiment, alfalfa plants were bathed in low-
levels of microwave energy for weeks on end. The result: No ill
effects according to researchers at NASA's Ames Research Center,
near San Francisco, California.
The lab tests were the start of a series of experiments to see if
power-beaming satellites that convert the Sun's solar energy into
microwave power, then beam that energy to Earth, would damage plant
life.
Putting into Earth orbit a constellation of Satellite Power System
(SPS) spacecraft to help meet Earth's future energy needs has been
studied for decades. There is no formal program at NASA to build and
loft such a system.
NASA's Office of Space Flight Advanced Concepts funded the microwave
study.
"A tray of growing plants was illuminated with microwaves while
control plants were grown behind a microwave-opaque shield. Test
plants and the control plants were subjected to the same environment
otherwise," said NASA Ames scientist Jay Skiles, who designed the
experiment.
Another experiment will be to grow cereal plants, including wheat
and oats, to determine the effect of microwaves on the kinds of
plants that humankind depend on for food, Skiles said.
Skiles said plans are being designed to test whether or not
microwaves provide a competitive advantage for some kinds of plants
when several different species are growing in the same area. In
another experiment, he is planning to examine the genes of one plant
species to learn the effects of weak microwaves on that plant.
Additional experiments to test effects of climate change, watering
and other conditions also may be conducted."
TangoMan
Plants do not need and can not use all of the energy in full sunlight. So if some light is let through the solar panels, the plants underneath will do fine and one can actually grow crops under them. In fact there are lots of crops that are only grown that way, like poinsettias (the Christmas flower), shade tobacco, etc. Jay Huebner
We have wind turbines killing birds.
We have the ground underneath solar arrays dying from lack of
sunlight.
Yet environmentalists are crazy in love with these destructive
technologies.
With SPS we actually have a technology that is benign to the
environment, and actually beneficial when compared to the damage
caused by wind turbines and solar PV arrays.
Space Power Beaming: Nice to Mother Nature's Plants
http://www.space.com/astronotes/astronotes.html
"If the Earth is ever on the receiving end of power-beaming
satellites, the weak microwaves from such a space-based energy
generator are not harmful to green plants.
In a NASA-funded experiment, alfalfa plants were bathed in low-
levels of microwave energy for weeks on end. The result: No ill
effects according to researchers at NASA's Ames Research Center,
near San Francisco, California.
The lab tests were the start of a series of experiments to see if
power-beaming satellites that convert the Sun's solar energy into
microwave power, then beam that energy to Earth, would damage plant
life.
Putting into Earth orbit a constellation of Satellite Power System
(SPS) spacecraft to help meet Earth's future energy needs has been
studied for decades. There is no formal program at NASA to build and
loft such a system.
NASA's Office of Space Flight Advanced Concepts funded the microwave
study.
"A tray of growing plants was illuminated with microwaves while
control plants were grown behind a microwave-opaque shield. Test
plants and the control plants were subjected to the same environment
otherwise," said NASA Ames scientist Jay Skiles, who designed the
experiment.
Another experiment will be to grow cereal plants, including wheat
and oats, to determine the effect of microwaves on the kinds of
plants that humankind depend on for food, Skiles said.
Skiles said plans are being designed to test whether or not
microwaves provide a competitive advantage for some kinds of plants
when several different species are growing in the same area. In
another experiment, he is planning to examine the genes of one plant
species to learn the effects of weak microwaves on that plant.
Additional experiments to test effects of climate change, watering
and other conditions also may be conducted."
TangoMan
Message But that doesn't get us around the fact that crop energetics is directly related to the amount of solar energy available. Also, I think food crops are more the issue here.
Mike Combs
Plants do not need and can not use all of the energy in full sunlight. So if some light is let through the solar panels, the plants underneath will do fine and one can actually grow crops under them. In fact there are lots of crops that are only grown that way, like poinsettias (the Christmas flower), shade tobacco, etc. Jay Huebner
But that doesn't get us around the fact that crop energetics is directly related to the amount of solar energy available. Also, I think food crops are more the issue here.
Mike Combs
Plants do not need and can not use all of the energy in full sunlight. So if some light is let through the solar panels, the plants underneath will do fine and one can actually grow crops under them. In fact there are lots of crops that are only grown that way, like poinsettias (the Christmas flower), shade tobacco, etc. Jay Huebner
> We have wind turbines killing birds.
>
> We have the ground underneath solar arrays dying from lack of
> sunlight.
RELATIVELY benign, not perfect. SPSS will have it's own problems.
Among them, the launch rate necessary to develop support large scale
SPSS power production will add significant amounts of materials to the
upper atmosphere. This doesn't mean SPSS is bad, any more than killing
some birds means wind power is horrible or creating some shade makes
solar arrays unusable.
The materials in one asteroid (the largest ) are sufficient to make
orbital space colonies with ~150 times the surface area of the Earth in
usable real estate. See http://lifesci3.arc.nasa.gov/SpaceSettlement/
for details.
Al Globus
CSC at NASA Ames Research Center
http://www.nas.nasa.gov/~globus/home.html
Views expressed in this email are only my opinions and are not the
position of any organization I'm familiar with.
Message But is what you're saying the same as saying if we take a corn field and reduce the amount of sunlight falling on it to one half or one third normal that it wouldn't have significant consequences for yield? It's just that even Bob Zubrin, who champions Mars as the only place besides Earth where crops can be economically grown, freely admits that plant energetics is directly related to the amount of solar energy available. If crops would grow just as well with 1/2 normal sunlight because they can't really use the otherhalf anyway, I think he'd be shouting that fact from the rooftops.
Regards,
But is what you're saying the same as saying if we take a corn field and reduce the amount of sunlight falling on it to one half or one third normal that it wouldn't have significant consequences for yield? It's just that even Bob Zubrin, who champions Mars as the only place besides Earth where crops can be economically grown, freely admits that plant energetics is directly related to the amount of solar energy available. If crops would grow just as well with 1/2 normal sunlight because they can't really use the otherhalf anyway, I think he'd be shouting that fact from the rooftops.
Regards,
But is what you're saying the same as saying if we take a corn field and reduce the amount of sunlight falling on it to one half or one third normal that it wouldn't have significant consequences for yield? It's just that even Bob Zubrin, who champions Mars as the only place besides Earth where crops can be economically grown, freely admits that plant energetics is directly related to the amount of solar energy available. If crops would grow just as well with 1/2 normal sunlight because they can't really use the otherhalf anyway, I think he'd be shouting that fact from the rooftops.
Regards,
As for Mars, Mr.. Zubrin is just plane wrong if he says that, for the obvious reason that the moon offers a much better environment already, and is rather closer. Zubrin's argument was that on the moon the greenhouse windows have to be extraordinarily thick to screen out radiation, making lunar greenhouses uneconomical. For orbit, O'Neill recommended slag shields and arrays of mirrors to bounce light around them. Zubrin dismisses this possibility, saying that trying to buildmirrors on the same scale as your crop lands would get you into "preposterous engineering problems". What these problems are, exactly, he does not share with us. Even if there is no water on the Moon, there is plenty of solar energy, and water can be produced out of it. Mars may have water but has very little solar energy, so it's at least as bad as the moon AND it's a quintibazillion miles further away. Mars sucks, sorry. Oh, you're preaching the the choir here. Nothing makes me speak out more quickly than many space advocate's automatic assumption that it's easier (or better) to build habitats on Mars than anywhere else.
Mike Combs
So, now we need translucent solar cells (with very specific specs on the
amount and type of light that gets through for each family of plants). What
do we do about all the other kinds of plants? How about the scenic value of
everything covered by solar panels? What about the critters that live there,
how do they feel about having their sunlight interrupted? How about
addressing, again, the environmental impact of producing all those solar
cells (which I imagine would have to sacrifice some degree of effiency in
order to let the right kind of sunlight through for the plants)? And, how
about following the power consumption vs. time curve - how do we keep up
with the power rates in 2050? 2100?
Except that with SPS the timeframe for signifigant direct interference with
the environment has a scheduled terminus - the ssame can't be said for
turbines or terrestial PV.
>
> RELATIVELY benign, not perfect. SPSS will have it's own problems.
> Among them, the launch rate necessary to develop support large
scale
> SPSS power production will add significant amounts of materials to
the
> upper atmosphere. This doesn't mean SPSS is bad, any more than
killing
> some birds means wind power is horrible or creating some shade
makes
> solar arrays unusable.
>
Not.
SPS will be built primarily from lunar and/or asteroidal materials.
The cost of launching from Earth is prohibitive.
The quantity of pollution in the atmopshere will hence be negligible.
SPS is more benign by far than any other energy source.
Best regards,
Charles F Radley
> Yes, this is what I have been told by a botanist. I was thinking
> linearly also, being an engineer and physical scientists, and that
> doubling the light intensity would double the yield, and was told
> that would not work, plants didn't need and could not use most of the
> light they got. Obviously at some point reduced light intensity
> will reduce the yield, but at what level of reduction? How much do
> clouds reduce the light intensity? Do farmers get different yields
> in deserts (with water) over land where it rains but is covered with
> clouds most days? I don't have specific answers, but would think
> relying on what Zubrin suspects is dangerous. Jay Huebner
IANAA (I am not an agronomist).
Assumptions related to sunlight and yield are probably buried somewhere
in the EPIC code some of the models in Garden With Insight simulation
were derived from.
http://www.gardenwithinsight.com/help100/00000281.htm
http://www.gardenwithinsight.com/help100/00000584.htm
http://www.gardenwithinsight.com/help100/00000530.htm
http://www.gardenwithinsight.com/help100/00000424.htm
http://www.gardenwithinsight.com/help100/00000283.htm
[This last one has the equations referenced below]
Frankly, I have trouble understanding them all myself. :-)
In general, looking at plant growth as a system, no matter what the
maximum growth may be (described below), a plant's real growth is
typically constrained by some nutrient (which includes available water).
So, if water of nitrogen constrain growth to a level below the maximum
possible for available radiation, even if there is less solar radiation,
the restraining effect of lower light may not be as large as one might
otherwise expect (or perhaps even noticeable at all).
Basically, from looking at some of those equatiosn just now (it's been a
long time) it seems the EPIC model assumes a linear correlation with
solar radiation (RA).
Equation 255 (Photosynthetically active radiation):
PAR = 0.5 * RA * (1.0 - exp(-0.65 * LAI))
However, there are other factors such leaf area index (LAI) which it
would seem to me might be affected differently by significantly lower
light (outside the range the model expects and have been tested for by
the USDA ARS) depending on the transmission to successive plant layers.
Obviously, lower light levels might effect temperature which can have
positive and negative effects on various plant characteristics,
especially depending on availabilty of water for transpiration
(otherwise the plants wilt etc.).
Equation 258 (Potential Increase):
deltaB(p) = 0.001 * BE' * PAR
BE* = 100 * CO2 / (CO2 + exp(bc(1) - bc(2) * CO2))
BE' = BE* - bc(3) * (VPD - 1.0), VPD > 0.5
I haven't followed through the connection if any of RA to vapor pressure
[related to humidity] which might make the relation other than linear.
Also, the weather simulation has some empirical correlation assumptions
built into it which might also effect this.
There are much more detailed models of plant growth than the one we used
in GWI. For example, there is the CERES models. See for example:
http://www.wiz.uni-kassel.de/model_db/mdb/ceres-maize.html
Other models can be found here in either The Register of Ecological
Models (REM) or ECOBAS:
http://mars.wiz.uni-kassel.de/model_db/
I'm not saying looking at the equations in these sorts of models is a
definitive answer compared to looking at the actual science; just that
they are a place to start in understanding the issues.
In general, to maximize productivity, you want to grow plants with a
physical structure and preferences for temperature and humidity and
water and CO2 etc. for the actual conditions, thus I agree with the
earlier suggestion of choosing shade loving plants. In the GWI model,
some of these preferences are reflected in parameters that vary by
plant, but to be frank they are probably not all that accurate and
haven't been refined enough for each specific plant (we drew mostly from
EPIC which focuses on common field crops, augmented some by SPUR,
another USDA ARS model focusing on rangeland and grasses).
When we started poking around in this we discovered how much basic
research in understanding plant growth in terms of geometry and complete
lifecycle growth information in extreme detail has either never been
done or is effectively lost to current memory; the hot topic has become
cell structure and operation in terms of biochemistry, as opposed to the
basics numbers related to yield. Also, scientists may have this sort of
basic information about specific cultivars and not publish it, as many
scientists are often loathe to publish useful raw data they collect lest
someone else get a derived publication out of their hard work. :-)
--Paul Fernhout
>
> Zubrin's argument about plants on Mars revolves around the Martian
> atmosphere providing protection from solar flares. This allows
> inflatable greenhouses to work since you don't need shielding.
> Obviously, on the Moon plants in a green house with thin glass would
> be fried in the first solar storm. Marshall Savage gets around this
> by using water for shielding -- which requires a lot of water. You
> also have to worry about things growing in the water and clouding it
> up.
>
> Zubrin says artificial lights won't work because of the power
> requirements. Anybody have good data on power requirements for
> growing things in artificial lights (food crops, not... oh, you know).
>
>> Mike,
>> as always when biological system are concerned things are a little
>> bit more complex than black and white.
>> Yes, plantsgrowth is directly related to the amount of solar energy
>> available, up to a point.
>> For instance no light=no growth. Plants can't live without it. From
>> then on, the more the better, up to the max energy that the plant can
>> use. More than that is wasted, or rather is not used by the plant.
>> Different kind of plants can use a different amount of light.
>> There are places on Earth where there is lots of light but plants
>> can't grow for other reason, like temperature and/or water.
>> In places like deserts reducing the amount of light that reach the
>> soil may infact help vegetation to grow.
>>
>> As for Mars, Mr.. Zubrin is just plane wrong if he says that, for the
>> obvious reason that the moon offers a much better environment
>> already, and is rather closer.
>> Even if there is no water on the Moon, there is plenty of solar
>> energy, and water can be produced out of it. Mars may have water but
>> has very little solar energy, so it's at least as bad as the moon AND
>> it's a quintibazillion miles further away. Mars sucks, sorry.
>>
>> Cheers,
>>
>> Claudio
>>
>> not environmentalists
>>
>> But is what you're saying the same as saying if we take a corn field
>> and reduce the amount of sunlight falling on it to one half or one
>> third normal that it wouldn't have significant consequences for
>> yield?
>>
>> It's just that even Bob Zubrin, who champions Mars as the only place
>> besides Earth where crops can be economically grown, freely admits
>> that plant energetics is directly related to the amount of solar
>> energy available. If crops would grow just as well with 1/2 normal
>> sunlight because they can't really use the otherhalf anyway, I think
>> he'd be shouting that fact from the rooftops.
>>
>> Regards,
>>
>> Mike Combs
>>
> ----------------------
> The International Space Station's (ISS) most important legacy may be
> jump-starting space tourism. Consider: the first space tourist, Dennis
> Tito, was supposed to go to the Soviet era Mir space station. Under
> pressure from NASA, Russia de-orbited the Mir which resulted in Mr.
> Tito going to the ISS instead. Now the Mir was a terrific space
> station, but by the time of Tito's trip it was also old, smelly,
> crowded and probably not all that nice. The ISS was brand new, shiny,
> much more roomy, etc. Mr. Tito came back to Earth with glowing
> accounts of how great space is. Would his experience have been as good
> on Mir?
>
> Al Globus
> CSC at NASA Ames Research Center
> http://www.nas.nasa.gov/~globus/home.html
>
> Views expressed in this email are only my opinions and are not the
> position of any organization I'm familiar with.
>
orbital space colonies with ~150 times the surface area of the Earth in
usable real estate. See http://lifesci3.arc.nasa.gov/SpaceSettlement/
for details.
Al Globus
CSC at NASA Ames Research Center
http://www.nas.nasa.gov/~globus/home.html
Views expressed in this email are only my opinions and are not the
position of any organization I'm familiar with.
>
>> Not.
>>
>> SPS will be built primarily from lunar and/or asteroidal materials.
>>
> While bulk materials can come from extraterrestrial sources, there
> will still be a lot of launch activity getting people and machines up
> there to do the work. If SPS provides economic incentive for orbital
> colonization there will be a lot more launch activity. Current
> launchers do quite a bit of damage -- particularly depositing
> materials in the upper atmosphere, but launches are so infrequent it
> doesn't matter much. If we start thinking about dozens of launches
> (or more) a day, we've got a problem. If we understand that problem
> and work around it in the design stage it will be a lot cheaper to
> deal with.
>
>> The cost of launching from Earth is prohibitive.
>>
>> The quantity of pollution in the atmopshere will hence be negligible.
>>
>> SPS is more benign by far than any other energy source.
>>
> ----------------------
> Space tourism could be our ticket to the stars. Save your pennies,
> suborbital flights for $100,000 may start in 2005! See
> http://www.spaceadventures.com/suborbital for details.
>
> Al Globus
> CSC at NASA Ames Research Center
> http://www.nas.nasa.gov/~globus/home.html
>
> Views expressed in this email are only my opinions and are not the
> position of any organization I'm familiar with.
>
suborbital flights for $100,000 may start in 2005! See
http://www.spaceadventures.com/suborbital for details.
Al Globus
CSC at NASA Ames Research Center
http://www.nas.nasa.gov/~globus/home.html
Views expressed in this email are only my opinions and are not the
position of any organization I'm familiar with.
Martian atmosphere? IIRC that's about 1% of earth...doubt that would shield
much, and even if it does, than a earth like atmosphere inside an inflatable
greenhouse would protect as much as 100 times as an equivalent amount of
Martian atmosphere. Plants developed on earth when the atmosphere was much
denser and rich in Co2 than it is now, so all plants can use a much greater
amount of it than it is present today in the air (this is why commercial
greenhouses use co2 generators to get accelerated growth rates), so it is
certainly possible to grow plants in a much denser atmosphere than earth
one. Add the two things together and you probably need only sixty-seventy
meters of dense greenhouse air to have the same protection given by 10000
meters of Martian atmosphere.
But the point is moot IMHO, because the whole idea of inflatable greenhouses
seems something straight out of a sixties movie to me... :) why inflatable?
If you want to build greenhouses on the moon, or in orbit using moon
materials, you got abundance of raw materials to make glass. I'm pretty sure
that would be enormously cheaper than any flexible transparent cover that
can hardly be manufactured with local raw material... glass can be made
cheaply and used as building material itself, can be meters thick, and still
let pass plenty of light while providing an efficient shielding from
micrometeorites as well as radiations. Can be easily manufactured and as
easily maintained, replacing any damaged slab and re-melting it to produce
spares. It can be made including an amount of impurities that helps shield
radiations. This assuming you want to "build" greenhouses which is a daft
idea in itself, always IMHO, because would be much better dig them instead.
Then you'll have a really nice solid rock and lunar concrete shielding all
around, and all you need is a mean to get light in. This can be better
achieved with large mirrors that reflect the light down through apposite
"windows", and both these components can be made so that the mirror coat
will reflect only a minimum of radiation if any at all and the window itself
shield from the rest.
Using water for shielding is another nonsense as far as I can tell because
to begin with how you keep it liquid, without using even more power to heat
it than it would be required to generate artificial light? Incidentally
solid and even better underground greenhouse would also be much more
efficient at thermal insulation, how exactly an inflatable greenhouse is
supposed to keep 30 or 40 C^ inside when the outside temperature goes down
near the absolute zero? And what happens if it's pierced by an accident?
Kaboom.
Even for orbital structures I would imagine a very thick walled box of
concrete with an as much thick transparent wall at the end facing away from
the sun, and a mirror to reflect the light in, is a much cheaper, safer,
easier to maintain, flexible and solid design than any inflatable
transparent structure, which are not very reliable even on earth, go figure
in space... ;)
IIRC Zubrin "plan" was based on the existence of hot pools of water
underground on Mars, which is like to say if the planet is habitable we can
inhabit it. Great. AFAIK though, there are no such pools, and Mars remain a
frozen airless hellish inhabitable ball of rock. For all we know there may
not be water at all either, as the recent about-face about water on the moon
shows. If we can't tell for sure if it's water what we see on the moon I
tend to be cautious about it existing on mars. Polar caps are mostly frozen
Co2 anyway if I'm not grossly mistaken.
Bottom line, there is no need to travel all the way to Mars to find
unbelievably cold, low gravity, un-pressurized sterile mountains of dust,
there is plenty much closer. Anything you could maybe theoretically possibly
if maybe perhaps do on mars you can at least as probably do it on the moon,
and for sure it would be a lot cheaper and safer. Probably a thousand times
cheaper and safer.
As for "terraforming" a planet, apart the immense scale of the project that
makes it as realistic and probable a possibility as that you win the lottery
without playing, for the pure pleasure of the speculation why mars? Why not
Venus? At least it has an atmosphere, and is able to retain it. You "only"
need to break the greenhouse effect to cool it down, and then clean up some
sulphuric acid, a kids game... :)
Beside we could colonize Venus as it is, without terraforming it. Venus is
usually thought as impossibly inhospitable, but conditions in the atmosphere
at an altitude of around 50 kilometres are relatively mild: the temperature
is about 70 C, with a pressure of about 1 atmosphere. A paradise compared
to Mars, even without considering that there is water (albeit admittedly in
the unpleasant form of sulphuric acid), plenty of metal and life essential
gases (apart oxygen) and that the gravity is nearly the same as earth. There
have been already interesting ideas about colonising Venus using aerostatic
habitats, since the atmosphere is so dense, breathable air is a lifting gas
on Venus, so a shell of some kind full of breathing air and with a ballast
of soil would elegantly float at the right height. It won't even need to be
particularly strong as at the right height the pressure is conveniently
balanced at about 1 bar.
Access to the surface is relatively simple from an aerostatic base, since
the thick atmosphere allows flight by airplanes and balloons.
IIRC Venus is also closer, in terms of flight time, to the asteroid belt
than either the Earth or Mars, so makes a better starting point even for
asteroid mining operations.
to live there, although admittedly the polar caps may make a great ski
resort one day... :)
Cheers,
Claudio