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View Full Version : Discussion: Getting a Greenhouse to Work on Mars



Fraser
2004-Feb-25, 05:00 PM
SUMMARY: One key to the long-term exploration of Mars will be figuring out how to get plants to grow there in greenhouses - they're natural factories for air and food. Since they evolved on Earth, they have no mechanism for surviving in low pressures, which would be a requirement for off-planet greenhouses; they think they're drying out even when there's plenty of water. One solution might be to biochemically adjust levels of hormones that initiate the drought instinct.

What do you think about this story? Post your comments below.

Duane
2004-Feb-25, 07:39 PM
Another solution might be to pressurize the greenhouse domes.

steva
2004-Feb-25, 08:18 PM
One possibility to raise Mars's temperature is to make it have a denser atmosphere. Having a denser atmosphere, de CO2 that exists on it's surface may do its job and rise the temperature on Mars.

Littlemews
2004-Feb-25, 08:23 PM
Methane is also a good explanation that cause the temperature raise on Mars...

John LaCour
2004-Feb-26, 03:31 PM
Originally posted by Duane@Feb 25 2004, 07:39 PM
Another solution might be to prossurize the greenhouse domes.
Because of the low atmospheric pressure on Mars you would have to make a strong structure to have the interior of the greenhouses at Earth pressure. By growing the plants in a low pressure atmosphere, you can make a simpler, and lighter, greenhouse.

Nick4
2004-Feb-26, 08:17 PM
How hard would it be to pressurize the greenhous?

Duane
2004-Feb-26, 08:39 PM
Actually, now that I have actually taken the time to read the whole article, I have to say my rather flippant comment looks exactly like that--flippant. Absolutely John, the lower the pressure needed in the domes, the lower the cost to ship and build them.

Kind of neat the way they are manipulating the genes of the plants to allow their survival in such a low pressure enviroment to be considered.

neil price
2004-Feb-27, 04:53 AM
Sounds like some very appropriate locations to go mad with biotechnology!!
Sure, Genetically engineer away! I think it will be neccesary. Do these green houses also support humans ? Wouldn't it be more comfortable for plants and humans alike to get conditions as close to those on earth as possible ? Worth the weight in Oxygen I think.

John LaCour
2004-Feb-27, 05:47 PM
Originally posted by neil price@Feb 27 2004, 04:53 AM
Do these green houses also support humans ? Wouldn't it be more comfortable for plants and humans alike to get conditions as close to those on earth as possible ? Worth the weight in Oxygen I think.
At 10% atmosphere it would not be able to support a human, not without a suit and helmet. The whole point of this is to reduce the necessary structural support that a one Earth atmosphere greenhouse would require on the Moon or Mars were there is little to no atmosphere, and therefore reduce the overall weight. If its light weight, then we can ship more of these, or larger ones, to provide food and to help process breathable air.

Victoria
2004-Feb-29, 12:27 AM
Now this is refreshing. :) I am pleased to learn of hormonal changes made to balance one's nursery. :P

Tom Wray
2004-Feb-29, 01:27 AM
First off, forget about conventional greenhouses. Forget about the Biosphere II design. Remember, there is radiation to consider, so you need several feet of soil to protect the spaces that humans will live and work in(like the greenhouse). Also, the all-glass designs we're accustomed to since Victorian times can only maintain a tolerabletemperature(ie-not too hot) with venting, and you woudn't want to vent to a 4 millibar outside pressure on Mars.

Also, in the icy cold of space and the surface of Mars, a thin-skinned glass or plastic greenhouse will get too cold.

So, you should inflate a thin structure(airbag) to standard Earth pressure and then cover it with Martian soil(the soilwon't weigh as much-lower Martian gravity), pump in the air( I saw a paper at the Case for Mars III conference in Boulder, Co. in 1986 or '87...(Hey! am I getting that old?)..where the researcher pumped the plant test chambers with pure CO2(close to Mars) and the plants did just fine. Then the plants produce Oxygen which we don't need to haul from Earth.

Oh, but how will the light come in through the several feet of soil you might think? A nifty invention by a Japanese company a few years back is the Himawara(Sunflower) system. You concentrate light(they used lenses but you could just as easily use a foil reflector-also lightweight) into a fiber optic line at a 10,000 to 1 ratio, or a 1 meter square area into a 1 centimeter square area fiber bundle(focused to eliminate the harmful ultraviolet rays), pass the fiber through your radiation shield(soil roof/kiva) and lens diffuse it back inside the plant room. Cozy, warm and very lightweight. I hear that folks can use the Sunflower system and get a nice non-burning tan while lounging indoors. B)

Duane
2004-Mar-01, 05:23 PM
Intesting concept from Himawara Corp. (http://www.ornl.gov/sci/hybridlighting/index.htm) Their website says the concept of hybrid lighting systems originated with Jeff Muhs, who is working with industry and universities to see if the concept can be adapted for use.

A brief summation: sunlight is collected by a collector (basically a converted satilite dish) and focused into an array of optical fibers. The light is then used by "hybrid" light fixtures, which converts part of the spectrum into light, and the rest of the spectrum (mostly infrared radiation) into heat and electricity.

The heat and electricity is used to both heat the building that has been adapted to use the system, and to supplement the electricity used in the building.

The company suggests that this use of solar energy could half or even quarter the cost of using solar energy, and the amount of energy generated is double what current solar energy arrays produce. As a plus, the system automatically adjusts to the amount of sunlight available, dimming the lights when sunlight is strong, brightening when not.

I can't find anything suggesting the system is being looked at for off-world use, but it seems like it should be.

Tom2Mars
2004-Mar-02, 08:23 AM
Thanks for finding that Himawara link Duane, I hadn't looked at their stuff for awhile. Another way to reduce the costs of solar energy is to simply not need it. Especially if the goal is to develop and refine technology for use off planet.

Building more efficient houses would require fewer solar panels, batteries & inverter capacity. I have copies of the National Passive Solar Home Awards from the 70's(Carter administration) and many homes in the design competition were achieving 70% to 80% efficiency improvement over conventional use. It is amazing what is not being considered for use off-planet.

Fun fact- Do you know that one of the earliest uses of passive solar in the U.S. was by the Anasazi Indians in the Chaco Canyon area(S.W. U.S.) dating back, I believe, 700 to 1400 years. In the cliff dwellings(summer shade, winter-direct collection)(sim. to Paolo Soleri's apses in Arcosanti), there were white painted areas on the cliff wall above the structures. There were holes in the roofs under the painted areas. Turns out that in the winter, the sunlight would reflect off the white paint and go through the hole, warming the interior mass, the heat being released back at night.

So much can be done to prepare for Mars, while simultaneously bringing down the cost.

Tom2Mars
2004-Mar-02, 08:26 AM
Thanks for finding that Himawara link Duane, I hadn't looked at their stuff for awhile. Another way to reduce the costs of solar energy is to simply not need it. Especially if the goal is to develop and refine technology for use off planet.

Building more efficient houses would require fewer solar panels, batteries & inverter capacity. I have copies of the National Passive Solar Home Awards from the 70's(Carter administration) and many homes in the design competition were achieving 70% to 80% efficiency improvement over conventional use. It is amazing what is not being considered for use off-planet.

Fun fact- Do you know that one of the earliest uses of passive solar in the U.S. was by the Anasazi Indians in the Chaco Canyon area(S.W. U.S.) dating back, I believe, 700 to 1400 years. In the cliff dwellings(summer shade, winter-direct collection)(sim. to Paolo Soleri's apses in Arcosanti), there were white painted areas on the cliff wall above the structures. There were holes in the roofs under the painted areas. Turns out that in the winter, the sunlight would reflect off the white paint and go through the hole, warming the interior mass, the heat being released back at night.

So much can be done to prepare for Mars, while simultaneously bringing down the cost.

Victoria
2004-Mar-02, 02:21 PM
I've seen some pretty cool and energy efficient homes and the recycables used to live is extrodinary and creative. Aluminum and rubber are big supplies though with the surface temp. on Mars, I'm not so sure rubber or plastic would be a beneficial alternative. Fiber optics seem to be good for a variety of uses. B)

Tom2Mars
2004-Mar-02, 03:47 PM
That's true about the plastic use Victoria. I guess there is much more U.V. at the surface of Mars. I had made some small greenhouse tests years ago, the plastic used to last a couple of years. I used some recently and it started falling apart in 4 months. Now, either the U.V. level shot up, or the manufacturers of the plastic have backed-off on some chemical going into the mix at the factory to save some money.

Also, it would be good to implement designs at Mars using materials available at Mars. Fiber optic glass can come from silicates. Plastic can be made from hydrocarbons, but we will want to hoard those, I'm sure.

Spacemad
2004-Mar-02, 08:46 PM
I really think we should forget about building greenhouses (as we conventionally understand them, i.e.: structures of glass) & think about building biospheres, probably underground, where plants could be grown in an environment adapted to them & their necessities, (though just how we will circumvent the lack of gravity defies me at present, though don´t plants grow on the ISS with almost complete absence of gravity?). They will be provided with artificial lighting ,again adapted to their necessities - even of different species.

They are carrying out experiments on plant growth & vegetable yield right now on the ISS. Without doubt they will continue to do even more experiments with plant growth in the coming years as NASA prepares to comply with President Bush´s mandate of returning to the Moon & press onward with the exploration of Mars.

I have read several pages on the experiments that NASA is holding - or has held in the past - & find they make excellent reading for someone like me interested in the growing of plants as well as Space - especially human exploration/explotation thereof.

Tom2Mars
2004-Mar-03, 02:33 AM
I'm in definite agreement with you about not using conventional glass greenhouses Spacemad. Soil covered or underground is the way to go, mostly because of the higher radiation environment at Mars. And the structures would have better thermal characterists too.

The gravity at Mars shouldn't be a problem though. At 38% of Earth's, most research articles I had seen predict taller plants which could support larger fruit. Ray Bradbury imagined taller beings.

One of the papers I gave describes a 500 ft. diameter space station which will provide artificial gravity in the range of 1/10th G to 1/2 G, with zero-G available in the central hub. This makes it possible to test out the effects of Lunar and Mars base concepts in low-Earth orbit.[I]

We could learn what the effects would be on plants before making the long trip to Mars.

Tom2Mars
2004-Mar-03, 02:38 AM
addendum to Spacemad...

I was only mentioning my recent experience with plastic in a greenhouse as a slight to the plastics industry to confirm to Victoria that I was in agreement with her questioning the use of rubber/plastics for martian structures.