I just realized this, it makes me wonder if any other Scientist ever has bothered to realize this because it seems to me it WILL be a big deal.

Mars can not sustain plant-growth because the light reaching the surface is not white light, it is red light. Pinkish really, but that is only a PORTION of the visible spectrum. A lot of the light's energy is being diffused and absorbed.

I remembered this when I was looking at some diagram talking about how to terraform mars, and it showed the light beams and the "green house effect".

Something made me remember that long ago High School experiment, where you grow 4 plants. One exposed to white light. One exposed to green tinted light only. One exposed to red tinted light and one to blue tinted light.

The green exposure no plant growth occured, the blue exposure very little, the red was moderate, and the white light well you get the picture.

In an environment as harsh as Mars, even if we could make it "moderately" adaptable, we could not rely on plants to do the rest because they will not grow well under that red sun. The only way they would grow is if they are especially taken care of which defeates the purpose of terraforming.

Thus, add this to the list of terraforming problems on Mars.

And why does only red light get through? Please explain
I've never heard of this before
I would assume light/electro-magnetic rays of most nearly all of the spectrum would be getting through, as Mars has no, virtually no, atmosphere

pssst...FreeMason, I believe your premise is wrong.

Can you please explain what is out there diffracting all light but red? And why there is apparently enough of other colors for us to see other colors in the pics? For instance, there appears to be white objects - that would be indicative ALL light colors getting through, right? And there appears to be some black objects, again indicative of all light colors getting through. We apparently have some green light - which is indicative of at least blue and yellow light getting through.

Mars has almost no atmosphere but that wouldn't matter anyways considering it's mostly CO2 which is a transparent gas.

Mars's atmosphere is however chock-full of dust. Chock-full by earth standards, it obviously does not impead visibility too much, that we can recognize.

However if you could remove the dust from Mars's atmosphere, the surface would not look so similar to earth, it would be absolutely alien. Even when the sun is out the sky would be black, the horizon a faint tinge of scattered light.

Instead because of all that dust, Mars looks like it has an earth-like albeit pink atmosphere. In reality it doesn't, it has dust that's been aerosolized.

The problem even gets worse...

I forgot to even consider the fact that less light even reaches Mars because of its distance from the Sun.

That light is then absorbed by the dust and reflected in the reddish-pinkish hue, putting it at around the 7x10^-7 m part of the spectrum. Relatively low energy.

So the lower energy reaching Mars, and then the lowered energy by the dust in the atmosphere creates what I think is a problem.

Of course our solar panels seem to work fine on Mars, but that's a bit different, I don't know if they made them especially to release electrons at that part of the spectrum or what.

But then a plant consumes a bit more energy than that little robot does (versus surface area).

Either-way...short question long answer.

But there are plants that require far less solar energy than the solar cells. There are plants that need almost no solar energy. Algaes, funguses, etc. And that is exactly what is targeted in terraforming activities.

In addition, I would offer that there are only two things that the dust in the atmosphere can do: forward scatter, or backscatter.

Back scatter must not be all that great since Mars isn't WAY bright. And, since you state (without me checking on the validity) the dust is "aerosolized", which would mean extremely fine particles. If it is extremely fine, then it will have a characteristic dimension less than the wavelength of the light hitting it and will forward-scatter.

It will NOT absorb, or we would be getting extremely low-light pics and I don't believe the solar cells would be working very well. There is apparently plenty of light striking the surface for many types of low-solar-energy-requiring plants.

[edit on 6-15-2004 by Valhall]

Valhall the color you see in the pictures is never in "true" color and the best approximations are generally redder than most. That one picture I devoted a thread to I think is a close approximation, I honestly don't know because it didn't say and I've never been to Mars to be able to compare. Viking's pictures revealed a bit more red surface but it was stated that sometimes they had too much red filter.

But either way, of course some white light is getting through, the atmosphere is not opaque to all but red, but the point is, that so much of it is absorbed that there must be a significant loss in the energy that plants can absorb.

"But there are plants that require far less solar energy than the solar cells. There are plants that need almost no solar energy. Algaes, funguses, etc. And that is exactly what is targeted in terraforming activities."

Algaes require too much water - lichen would be better? And fungi are anerobic if I'm not mistaken?

"In addition, I would offer that there are only two things that the dust in the atmosphere can do: forward scatter, or backscatter."

The dust is not 100% reflective, it absorbs light the same way your clothes do to make it the colors it is. Our atmosphere scatters light, breaking it so that the blue is more visible but on Mars it has an actual physical obstruction much more similar to when our volcanos go off and put dust into our atmosphere.

"It will NOT absorb, or we would be getting extremely low-light pics and I don't believe the solar cells would be working very well. There is apparently plenty of light striking the surface for many types of low-solar-energy-requiring plants."

I don't agree so since your examples seem unviable, I'm not sure if lichen produce oxygen or carbon-dioxide.

And I don't see how you figure that the dust is not absorbing light, it does not scatter the light into the red spectrum it is reflecting that light absorbing the other colors. Just as a red sweater does.

How much this changes the energy levels reaching the surface ... well I don't have figures on those.

No, forward scattering is not Rayleigh scattering. Rayleigh scattering is a form of forward scattering. It's not a two-way statement.

CLARIFICATION:

RAYLEIGH SCATTERING IS NECESSARILY FORWARD SCATTERING, FORWARD SCATTERING IS NOT NECESSARILY RAYLEIGH SCATTERING.

that should clarify what I mean.

[edit on 6-15-2004 by Valhall]