In article ,
Pascal Bourguignon wrote:
Thank you for your comprehensive answer.

You're welcome. I had fun thinking about it.

Indeed, if there's nuclear energy available, it would be simplier to
use artificial light. But storing solar energy is hard and not too
efficient (you need a lot of heavy batteries, or complex
electro-chemical processing), so if natural light can be used at least
half of the time, the better.

If you want to think about this like an engineer, you have to consider
all factors. You may find that building vacuum and meteorite proof
transparent surface structures that require supplemental lighting for
half the month is much more difficult, expensive and unreliable than
having sturdier structures that are artificially lit the whole month
through. After all, if you have to have the spare generating capacity
to provide lighting for half the month (at least - the sun isn't always
high enough in the sky to provide adequate light) you've got it for the
other half as well.

In my example of hydroponic vegetable production in deep mines in
northern Ontario, you have an example of a situation where it's much
cheaper to light a naturally heated (cost-free) area than to heat a
naturally illuminated area on the surface. What's more, it costs to
build a greenhouse, but worked out areas of the mine are already
there. Transportation to the area is time-consuming and expensive
enough that fresh vegetables arrive in poor condition especially in
winter, so it's competitive to raise them locally with free heat even
though electricity for lighting is not very cheap. It's much easier
and cheaper to control environmental factors in the mine than on the
surface, e.g. temperature, day length, light intensity, etc., because
the background environment is constant. (IIRC, the crops are grown at
a depth corresponding to 30C - about 1km underground - while surface
temperatures often go below -40C.)

Conditions on the lunar surface vary drastically from intense heat to
bitter cold over the lunar day/night cycle of 29+ days. You can't
readily dissipate heat by better ventilation as you can in a
terrestrial greenhouse, and shading kind of defeats the purpose. You
don't get conductive or convective cooling of the structure either, and
you'll either have to have movable insulation or expend a lot of energy
to keep your plants from freezing in the lunar night, when your
structure is radiating to unobstructed sky at 3K. At any rate, you'll
need a lot more technology to keep your plants alive in such a
structure than you would in one that has a more constant background.
You'll need heating, cooling, variable amounts of light, protection
from small meteorite strikes, as well as vacuum resistance, not so easy
in a transparent material. When spare parts are fantastically
expensive and may take weeks to obtain even in an emergency, you want
the simplest technology feasible, because it's likely to be the most
robust and easiest to repair. When your air supply depends on your
greenhouse, you don't want to worry about it catastrophically failing
when it gets hit by a pebble, or a bit of caulking cracks.

Overall, you're much further ahead in an underground structure or one
protected from drastic thermal variation and mechanical damage from
small meteorites by a thick layer of regosol, even if you have to light
it. You'll probably be living in exactly the same kind of structure
already, so you'll know how to build and maintain one.

You can generate some of the energy needed for lighting with solar
panels on the surface, but they are only useful for part of the month,
and you'll need another source of energy for the rest of the month.
Your colony is going to need energy for other purposes than growing
plants, so you've got to deal with the problem of intermittent
availability of solar energy anyway.

At any rate, I had fun speculating about all this. Are you planning to
write some science fiction against this background, Pascal? If so,
remember that good writing can carry the reader blindly past a lot of
leaps of faith in science and technology. If you want to correspond
with me by email, take the no-uce and yyz out of my address.

Elie Gendloff wrote:

On the moon, it is either always sunny or always in the dark,

Explain lunar phases.

not 14
hours on and 14 hours off.

Earth days, not hours.

So, what are the results? BRBR

Why don't you try it yourself? I think you would find it very enlightening.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)

One side of the moon is always sunny and one side is always dark. The
moon turns on its axis once for each rotation of the earth, so only
one side is always facing the sun. When it is appoximately between
the earth and the sun, that is a new moon (not visible) because we are
looking at the unilluminated side of the moon. When the earth is
approximately between the sun and the moon we see a full moon because
we are looking at the entire illuminated side of the moon.


On Fri, 03 Sep 2004 17:17:32 -0700, Father Haskell
wrote:

Elie Gendloff wrote:

On the moon, it is either always sunny or always in the dark,

Explain lunar phases.

not 14
hours on and 14 hours off.

Earth days, not hours.

Excuse me, but only one side of the moon always faces the sun. See:
http://www.astro.umd.edu/education/a...on/phases.html
But that would be good for growing plants because they could
photosynthesize constantly. Solar collectors would also be very
efficient on the moon - no clouds, constant radiation.




On 3 Sep 2004 17:22:49 GMT, wrote:

In article ,
Pascal Bourguignon wrote:
Thank you for your comprehensive answer.

You're welcome. I had fun thinking about it.

Indeed, if there's nuclear energy available, it would be simplier to
use artificial light. But storing solar energy is hard and not too
efficient (you need a lot of heavy batteries, or complex
electro-chemical processing), so if natural light can be used at least
half of the time, the better.

If you want to think about this like an engineer, you have to consider
all factors. You may find that building vacuum and meteorite proof
transparent surface structures that require supplemental lighting for
half the month is much more difficult, expensive and unreliable than
having sturdier structures that are artificially lit the whole month
through. After all, if you have to have the spare generating capacity
to provide lighting for half the month (at least - the sun isn't always
high enough in the sky to provide adequate light) you've got it for the
other half as well.

In my example of hydroponic vegetable production in deep mines in
northern Ontario, you have an example of a situation where it's much
cheaper to light a naturally heated (cost-free) area than to heat a
naturally illuminated area on the surface. What's more, it costs to
build a greenhouse, but worked out areas of the mine are already
there. Transportation to the area is time-consuming and expensive
enough that fresh vegetables arrive in poor condition especially in
winter, so it's competitive to raise them locally with free heat even
though electricity for lighting is not very cheap. It's much easier
and cheaper to control environmental factors in the mine than on the
surface, e.g. temperature, day length, light intensity, etc., because
the background environment is constant. (IIRC, the crops are grown at
a depth corresponding to 30C - about 1km underground - while surface
temperatures often go below -40C.)

Conditions on the lunar surface vary drastically from intense heat to
bitter cold over the lunar day/night cycle of 29+ days. You can't
readily dissipate heat by better ventilation as you can in a
terrestrial greenhouse, and shading kind of defeats the purpose. You
don't get conductive or convective cooling of the structure either, and
you'll either have to have movable insulation or expend a lot of energy
to keep your plants from freezing in the lunar night, when your
structure is radiating to unobstructed sky at 3K. At any rate, you'll
need a lot more technology to keep your plants alive in such a
structure than you would in one that has a more constant background.
You'll need heating, cooling, variable amounts of light, protection
from small meteorite strikes, as well as vacuum resistance, not so easy
in a transparent material. When spare parts are fantastically
expensive and may take weeks to obtain even in an emergency, you want
the simplest technology feasible, because it's likely to be the most
robust and easiest to repair. When your air supply depends on your
greenhouse, you don't want to worry about it catastrophically failing
when it gets hit by a pebble, or a bit of caulking cracks.

Overall, you're much further ahead in an underground structure or one
protected from drastic thermal variation and mechanical damage from
small meteorites by a thick layer of regosol, even if you have to light
it. You'll probably be living in exactly the same kind of structure
already, so you'll know how to build and maintain one.

You can generate some of the energy needed for lighting with solar
panels on the surface, but they are only useful for part of the month,
and you'll need another source of energy for the rest of the month.
Your colony is going to need energy for other purposes than growing
plants, so you've got to deal with the problem of intermittent
availability of solar energy anyway.

At any rate, I had fun speculating about all this. Are you planning to
write some science fiction against this background, Pascal? If so,
remember that good writing can carry the reader blindly past a lot of
leaps of faith in science and technology. If you want to correspond
with me by email, take the no-uce and yyz out of my address.

This will depend on exact circumstances, but put like that plants will grow
as much in a day no matter how long it lasts (24 hours or a month)

Yes, but. It depends on the plant's metabolism, doesn't it? Many of my orchids
are CAM (I know, we lost the original questioner by now). I have my lights on
18 hours a day. When I went to 19 hours, my Cattleyas exhibited black shoots,
which for them is a sign of sleep deprivation. It's been 18 hours ever since. I
am not about to experiment with lengthening the night period at the same time.
It wouldn't buy the result I'm looking for anyway, which is maximum total light
exposure.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)

In article , Elie Gendloff
writes
Excuse me, but only one side of the moon always faces the sun. See:
http://www.astro.umd.edu/education/a...on/phases.html

That turns out not to be the case; the moon is tide-locked to the Earth,
not to the Sun.

But that would be good for growing plants because they could
photosynthesize constantly. Solar collectors would also be very
efficient on the moon - no clouds, constant radiation.


--
Stewart Robert Hinsley

In article ,
Elie Gendloff wrote:
Excuse me, but only one side of the moon always faces the sun. See:
http://www.astro.umd.edu/education/a...on/phases.html

Excuse me, but have you ever looked at the moon?

The moon is tidally locked to the earth, not the sun. One side of the
moon always faces the *earth*, which is why the same features of the lunar
disk are visible from earth regardless of lunar phase. The moon circles
the earth in about a month, during which the visible surface undergoes a
complete cycle of phases. I.e. Any point on the lunar surface experiences
half a month of constant light and half a month of constant darkness. (This
isn't entirely true at the poles, but the generalization is close enough.)

But that would be good for growing plants because they could
photosynthesize constantly. Solar collectors would also be very
efficient on the moon - no clouds, constant radiation.

Constant light is not always good for plants, and indeed may prevent
them from flowering, which is a problem if your crop is fruits or
seeds. It may also cause premature flowering which is a problem if
your crop is leaves or stems. And because most plants are adapted to a
day-night cycle on the order of 24 hours, you can't expect twice as
much photosynthesis from 24 hours of continuous light as from 12 hours
in all species.

Elie Gendloff schreef
One side of the moon is always sunny and one side is always dark. The
moon turns on its axis once for each rotation of the earth, so only
one side is always facing the sun.

******
No, one side is always facing the earth.
The reason why there is much excitement about the far side of the moon
******

When it is appoximately between
the earth and the sun, that is a new moon (not visible) because we are
looking at the unilluminated side of the moon.

* * *
We are still looking at the same side of the moon, which happens to be
unilluminated at that moment
* * *

When the earth is
approximately between the sun and the moon we see a full moon because
we are looking at the entire illuminated side of the moon.

******
Still the same side of the moon

Iris Cohen schreef
Yes, but. It depends on the plant's metabolism, doesn't it?

* * *
Among other things. There is also quite a bit of variation in what is a
"natural schedule of watering", "natural" being tied to the nature of the
person involved.
PvR

On Thu, 02 Sep 2004 20:13:18 +0000, Pascal Bourguignon wrote:

"Gordon Couger" writes:

"Pascal Bourguignon" wrote in message
...

Has the experiment of growing plants under the light conditions of the
Moon surface ever been done? What would happen if you tried to grow
normal plants with lights on for 14 days and off for 14 days?

The ultraviolet light in the sun light on the moon would kill most
plants.

I assume that UV filters would be integrated to the green-house...


Some will adapt to the 14 day of sun an night but most higher plants
would not do well. Lichens would do fine. They might even stand the UV.

What about genetic modifications to help tomatoes and potatoes adapt to
that schedule?


It would seem to be alot of work to modify plants to produce on an alien
enviroment. It would seem to me that the major benifts of plant growth in
space would be for the recycling of co2 and waste water. We would be
looking at the most cost effective way for living on the moon and growing
our own food on the moon would very likely not be cost effective (IMHO).

It seems the best set up would be a system where the green house was
shaded every 12 to 14 hours to give the plants a dark photo period. During
the dark period on the moon, they would suppliment the light photo period
with good old lights. Hid or even sulpher (why not we're on the moon
eh..?) lights running off a battery bank or fuel cell.

Elie Gendloff writes:

One side of the moon is always sunny and one side is always dark. The
moon turns on its axis once for each rotation of the earth, so only
one side is always facing the sun. When it is appoximately between
the earth and the sun, that is a new moon (not visible) because we are
looking at the unilluminated side of the moon. When the earth is
approximately between the sun and the moon we see a full moon because
we are looking at the entire illuminated side of the moon.

You have problems with maths, don't you?
There's quite a difference between:

There is a face, such as for all time, the face is under the sun.
and: For all time, there is a face, such as the face is under the sun.


--
__Pascal Bourguignon__ http://www.informatimago.com/

Our enemies are innovative and resourceful, and so are we. They never
stop thinking about new ways to harm our country and our people, and
neither do we.

Don't be a smartass, Pascal. You are your own worst enemy, dude.

Your original question has got to be one of the stupidest yet asked in this
newsgroup and that is saying a lot!

Your original premise is flawed beyond belief and you have no right
criticizing other that point out that fact.

If you knew anything at all about plants, you would have know that most
plants have their life cycles intimately correlated with the yearly cycles
of day verses night length and light quality and would never be able to
adapt to growing on the moon under any conditions.

Name the particular species you have in mind or just shut up. Such plants
would need to be able to germinate from seed, grow, flower and fruit
regardless of the day length and not require any daily dark period for
metabolism. You might have no choice but to limit yourself to algae such as
Chlorella.

Someone suggested lichens but they are highly specialized symbiotic
organisms even more specialized than green plants and they would not survive
under your conditions.


"Pascal Bourguignon" wrote in message
...
Elie Gendloff writes:

One side of the moon is always sunny and one side is always dark. The
moon turns on its axis once for each rotation of the earth, so only
one side is always facing the sun. When it is appoximately between
the earth and the sun, that is a new moon (not visible) because we are
looking at the unilluminated side of the moon. When the earth is
approximately between the sun and the moon we see a full moon because
we are looking at the entire illuminated side of the moon.

You have problems with maths, don't you?
There's quite a difference between:

There is a face, such as for all time, the face is under the sun.
and: For all time, there is a face, such as the face is under the sun.


--
__Pascal Bourguignon__ http://www.informatimago.com/

Our enemies are innovative and resourceful, and so are we. They never
stop thinking about new ways to harm our country and our people, and
neither do we.

Elie Gendloff wrote:

One side of the moon is always sunny and one side is always dark. The
moon turns on its axis once for each rotation of the earth, so only
one side is always facing the sun.

Go out and *look* at the moon for several consecutive days or nights.
Pay CLOSE attention to the terminator.

When it is appoximately between
the earth and the sun, that is a new moon (not visible) because we are
looking at the unilluminated side of the moon. When the earth is
approximately between the sun and the moon we see a full moon because
we are looking at the entire illuminated side of the moon.

On Fri, 03 Sep 2004 17:17:32 -0700, Father Haskell
wrote:

Elie Gendloff wrote:

On the moon, it is either always sunny or always in the dark,

Explain lunar phases.

not 14
hours on and 14 hours off.

Earth days, not hours.

I looked this up again.....You are right, I was wrong. Now I know
everything.

On 4 Sep 2004 14:45:45 GMT, wrote:

In article ,
Elie Gendloff wrote:
Excuse me, but only one side of the moon always faces the sun. See:
http://www.astro.umd.edu/education/a...on/phases.html

Excuse me, but have you ever looked at the moon?

The moon is tidally locked to the earth, not the sun. One side of the
moon always faces the *earth*, which is why the same features of the lunar
disk are visible from earth regardless of lunar phase. The moon circles
the earth in about a month, during which the visible surface undergoes a
complete cycle of phases. I.e. Any point on the lunar surface experiences
half a month of constant light and half a month of constant darkness. (This
isn't entirely true at the poles, but the generalization is close enough.)

But that would be good for growing plants because they could
photosynthesize constantly. Solar collectors would also be very
efficient on the moon - no clouds, constant radiation.

Constant light is not always good for plants, and indeed may prevent
them from flowering, which is a problem if your crop is fruits or
seeds. It may also cause premature flowering which is a problem if
your crop is leaves or stems. And because most plants are adapted to a
day-night cycle on the order of 24 hours, you can't expect twice as
much photosynthesis from 24 hours of continuous light as from 12 hours
in all species.