Aerogel - don't build - your greenhouse w/o it

BWhite · 2005-05-05 22:51:09

http://www.supersky.com/nanocatalog/nan … og.pdf]Its almost off the shelf - - today!

Sandwich it between high performance plastic and there you go!

srmeaney · 2005-05-05 22:56:12

Is it something we can fill a space between the internal wall and exterior armor? Spacehab was looking at something along those lines for reducing spacehab module weight, and yet getting better armor.

BWhite · 2005-05-06 09:43:22

Is it something we can fill a space between the internal wall and exterior armor? Spacehab was looking at something along those lines for reducing spacehab module weight, and yet getting better armor.

I believe the anser is yes. Areogel would be terrific as thermal insulation for a habitat on the Moon or Mars.

Today, aerogel is being sewn into parkas for use at the South Pole and the initial reports are very favorable.

Shaun Barrett · 2005-05-06 19:46:26

Interesting product.
I note that it has countless small bubbles of air in it - in fact, it's 95% air and only 5% heat-conducting mass.
I assume the air bubbles are at sea-level atmospheric pressure(?). If so, off-the-shelf Nanogel panelling probably wouldn't be suitable for greenhouses on the Moon or Mars, at least not in large sections, because the internal pressure would blow the polycarbonate external sheeting apart.

It may well be possible, though, to manufacture the same product in 'Moon-rated' or 'Mars-rated' form. This would likely be achieved more easily in-situ, where the internal pressure of the panels would automatically match the external pressure.

Rxke · 2005-05-07 03:14:43

Been wondering about that, too.
Any material (would be) scientist around who can shed some light on this?
It's probably a non- issue, otherwise we would have heard about it before?

I'd love to get my hands on a small batch of cheap aerogel, to measure temps of electronics/batteries inside aerogel-insulated little robots in my deep-freezer

maxie · 2005-05-11 00:27:38

I think aerogel cracks very easy under some small mechanical pressure (like some wind hitting the greenhouse for a few weeks?)... I least this is what I remember...

dicktice · 2005-05-11 08:37:03

Shaun: Space-rated aerogel obviously will have to be composed of vacuum bubbles. :;):

BWhite · 2005-05-11 09:02:34

I think aerogel cracks very easy under some small mechanical pressure (like some wind hitting the greenhouse for a few weeks?)... I least this is what I remember...

That is why sandwich structures are good. Put a layer of aerogel in between layers of ballistic glass, with clear plastic films to bind them together.

GLASS
(film)
AEROGEL
(film)
GLASS

Possibly better than thermopane (vacuum between glass) and easier to fabricate than thermopane windows.

Also, sew panels of the stuff into kevlar pockets in an inflatable hab. By overlapping aerogel panels as part of an intricate Transhab-like structure you can protect the aerogel while still getting the thermal and acoustic insulation.

Aerogel is also a terrific acoustic insulator - - aerogel sandwiched between thin plastic sheets might make excellent ultra-light interior walls that provide increased privacy for personal spaces.

NOT hearing crewmates snore (or worse) will be good for morale. :;):

Edited By BWhite on 1115823823

karov · 2005-05-15 10:07:05

Shaun: Space-rated aerogel obviously will have to be composed of vacuum bubbles. :;):

http://en.wikipedia.org/wiki/Aerogel

Yes, the highly dendritic structure ( actually a 3D mesh made from tiny SiO2, quarz rods), perhaps would allow to be composed "vacuumgel". Using for the nano-rods material with greater compression strenght, and more precise arangement of the nano-mesh will give us material with the border characteristics in the all "records". Bigger strenght, lower specific weight, etc. than the aerogel.

BTW, the aerogel itself is quite strong structure: "Aerogel can support 2000 times its own weight without collapsing." from the quoted article.

dicktice · 2005-05-15 11:14:08

Let's see: If Aerogell weighs practically nothing, it should therefore be able to support 2000 times practically nothing. :hm:

karov · 2005-05-29 10:21:48

http://www.space.com/businesstechnology … 00302.html

This is the "carbogel"!

RobertDyck · 2005-05-29 11:19:38

Actually, you don't need aerogel. Yes, Mars gets very cold at night but the air is very thin. Thin air conducts heat very slowly. I asked one aerospace engineer to produce a thermodynamic spreadsheet for me. The result was a single layer inflatable greenhouse got too cold at night and too hot in the day. I asked for a more sophisticated model, but she didn't have the interest. You can just apply a spectrally selective coating, commercially sold by the brand name "Heat Mirror" or "low-e" which will transmit visible light but reflect UV and much of IR. If you want the exact spectral response look http://www.pnl.gov/fta/13_glazings/imag … 3.jpg]here, I'm talking about line number 5. Then use two layers of inflatable material with argon gas in the gap. Argon can be harvested from Mars atmosphere. Finally use an aluminized mylar curtain to keep heat in at night, but open during the day to let light in.

I've heard a number of greenhouse researchers claim there isn't a suitable material for an inflatable greenhouse. But there is: Kel-F technically known as http://www.boedeker.com/pctfe_p.htm]Pol … roEthylene or the acronym PCTFE. It does not off-gas ethylene or any other contaminants, service temperature is -240°C to +204°C (Mars is -111°C to just above zero), it's the most impermeable to oxygen and nitrogen of any polymer, regolith won't corrode it, and it's more UV resistant than Teflon FEP which has already been used on satellites in Earth orbit. Only molten alkali metals, gaseous fluorine, and certain complex halogenated compounds such as chlorine will react with it. If regolith in contact with the greenhouse is molten, you have a more serious problem then greenhouse corrosion. It's not quite as strong as Tefzel film, which is usually used on Earth; tensile strength of Tefzel is 6000psi while Kel-F is 5300psi. And it's a little heavier, density is 2.13g/cm^3 while Tefzel is 1.73-1.77g/cm^3. But Tefzel isn't as impermeable, Tefzel degrades more quickly from UV, and most importantly Tefzel will become brittle and break at -100°C. You have to use a material that's reliable.

The outstanding question is actually the floor. Mars atmosphere is so thin and the ground so cold that the greenhouse will loose more heat to the ground than to air. How do you insulate the floor with something strong enough to walk on and light enough to bring from Earth?

Shaun Barrett · 2005-05-29 17:56:44

RobertD:-

If regolith in contact with the greenhouse is molten, you have a more serious problem then greenhouse corrosion.

:laugh: Good point!
I'm not surewhat pressure you want in this PCTFE greenhouse, but presumably it'll have to be cylindrical(?) with the lower 1/3rd or so below the level of the surrounding ground(?)

RobertDyck · 2005-05-29 20:02:08

If you look at http://www.marssociety.org/images/full/ … 1.jpg]this picture by Robert Murray, it shows a non-cylindrical greenhouse. It's squished down by 4 straps across and 1 down its length. This idea of straps was proposed by Penny Boston in one of the Case for Mars papers before the Mars Society. A two layer greenhouse would inflate the gap with pressure more than Mars ambient but less than greenhouse interior so that both layers are supported by pressure. Both layers would require squish-down straps, but the outer layer could be formed with straps for the inner layer passing through near the ground and sealed in place. Tugging on the straps would just slightly deform the lower edge of the outer layer. Penny's paper included regolith inside to weight down the floor; you don't need to extend the cylinder into the ground because soil (regolith) is heavy. With regolith inside and out, and the gap between layers will be completely squished under the floor so both layers press against each other.

Hmm. One technique to insulate homes on Earth is to partially burry them. Soil becomes temperature stable after a certain depth. But they use boards of styrofoam insulation buried in a skirt around the house to ensure heat doesn't conduct to frozen ground. Could you dig a trench around the greenhouse and fill it with air bags like those used for packaging, not bubble wrap but air bags several inches on a side. Fill on-site with Mars air. Would ground beneath the greenhouse remain temperature stable? Could you heat it with sunlight alone, controlled with the aluminized mylar curtain?

RobS · 2005-05-30 00:23:13

You might be able to reuse the landing parachutes to provide some insulation to the floor of the greenhouse.

-- RobS

RobertDyck · 2005-05-30 02:33:18

Pressure: the greenhouse guys at Guelph University found Arabidopsis and lettuce can grow in pressure as low as 10kPa (1.45psi) as long as it has plenty of water. That's so low that humans can't breathe. Partial pressure of oxygen on Earth at sea level is 3.0psi so pure oxygen at 3.0psi is easy. A healthy strong individual such as a fighter pilot (Airforce study) who has spent a few weeks of high altitude training can breathe 2.5psi pure oxygen. Acclimated pilots can take 2.0psi pure oxygen up to 30 minutes before passing out. However, at low pressure lungs dry out, extended exposure can dry lungs tissue so it cracks and bleeds. Short duration of 3.0psi pure oxygen such as an EVA in a space suit is fine, but you want higher pressure in the habitat. Skylab and Apollo used 5.0psi with 60% O2 and 40% N2. That creates 3.0psi partial pressure O2 in the habitat, but Apollo suits used 3.2psi in case of a leak. I would recommend 2.7psi partial pressure O2 in the hab with 60%/40% O2/N2 and 3.0psi pure oxygen in suits. That reduces suit pressure which makes joints easier to move. Astronauts have 6 months to under go high altitude training during transit to Mars, that's 4 times as long as full duration high altitude training. That makes habitat pressure 4.5psi or 31.0kPa. Effective operation requires greenhouse to be the same as the hab. Guelph University experiments show lettuce can handle that. Wheat requires as much partial pressure as humans; since lettuce can take much less I would recommend not growing wheat. Grow potatoes, tomatoes, lettuce and fresh vegetables that grow quickly.

::Edit:: Bursting strength (Mullen) of Teflon FEP 1mil film at 25°C is 11psi, and tensile strength is 3000psi. Tensile Strength of Kel-F is 5300psi so 2mil film should burst at 38.8667psi. That's 8.6 times as great as the pressure I'm recommending. Temperature will affect strength and overdesign permits bumping and rubbing.

srmeaney · 2005-05-30 04:04:54

The big one is, can Aerogel be used as sandwich fill for a Bubble. Blow a bubble in space and line it with aerogel interlocking tiles and blow a second bubble on the inside? All of this would be useful if we could include a tourist access zone as part of the ISS from which we could expand the next Space Station.

Josh Cryer · 2005-06-22 09:11:56

I got some blue aerogel on ebay, it's really fascinating stuff. The problem with it, though, is that it's extremely fragile. While you hold it, it feels like almost nothing, but it has a sort of porous feel to it. You could crumble it in your hands if you wanted to (although I wouldn't recommend that, as it's essentially glass in a porous form). I would think that those jackets with aerogel inside would be quite ineffective as soon as someone gave you a big barehug, unless they've created some sort of netting or something to minimize crumbling.

I could see using it in greenhouses, but only if it didn't decrease the light too appreciably, it's something that we need on Mars. Certainly producing it is quite simple, I had for a brief moment considered starting an aerogel producing company, sell it as insluation for attics. It would be quite ideal. Just never went far with it.

CanalBuilder · 2005-06-22 10:40:26

I read that aerogel has a low refractive index. Ideal for letting in the essential visible and infra-red radiation. This leaves the problem of cosmic rays. How effective would a substance that is effectively not there be at stopping these fast particles?

[Later]

Been thinking about the atmosphere in the greenhouse.

Pressure: the greenhouse guys at Guelph University found Arabidopsis and lettuce can grow in pressure as low as 10kPa (1.45psi) as long as it has plenty of water.

The gas that plants need to grow is carbon dioxide. There's plenty of that available for free on Mars. Perhaps the partial pressure of carbon dioxide could be increased in the greenhouses. As the gas is not poisonous to humans per se, it would be safe to work in this higher pressure environment as long as the partial pressure of oxygen was maintained.

Perhaps this denser atmosphere could be used throughout the entire base. It would increase the boiling point of water (but it still won't be high enough to make a decent cup of tea), and would, I suspect, make the explorers feel more comfortable. Plants could then be grown throughout the complex, releasing oxygen and moisture into the atmosphere, and helping to remove pollutants. I know NASA has done research on the beneficial effects of house-plants. It's amazing what they research.

Mace · 2005-07-17 17:16:14

Why can't we use something cheap and semi-strong? I suggest styrofoam. It keeps heat off pretty well and after all, how good do we need to insolate the Mars colony? We don't want it to overheat and it will be full of heat emitting people and heat emitting machines. The very light-bulb in my room burns my hand if I touch it after it was on. In a closed environment were no heat can get out, it will roast me.

clark · 2005-07-17 17:34:40

Many have pointed out that if heat is not properly dealth with in a controlled manner, the base may end up meltinf the martian permafrost.

Mars is a giant frozen slushball afterall...

Mace · 2005-07-17 17:46:48

What would happen if it did melt? Surely there are areas on Mars that has stable building ground.

noosfractal · 2005-10-30 01:45:37

Been wondering about [suitability of aerogel full of 1.0 bar air for Mars], too.

Apparently aerogel is even more awesome when it is full of vacuum. Wait, that doesn't make sense, does it. Well, anyway, you know what I mean.

I'd love to get my hands on a small batch of cheap aerogel, to measure temps of electronics/batteries inside aerogel-insulated little robots in my deep-freezer

These guys will send you some to play with for $25 - proceeds to SpaceGen. I'm going to get some as Christmas presents

http://homepages.cae.wisc.edu/~aerogel/outreach.html
.

SpaceNut · 2015-09-21 20:19:41

Fixed shifting after finding the topic contained information for the floor of the greenhouse.....

SpaceNut · 2020-01-26 19:10:45

BWhite's post 8 conatins the format of use for aerogel but with glass not plastics...

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Re: Aerogel - don't build - your greenhouse w/o it

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Re: Aerogel - don't build - your greenhouse w/o it

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Re: Aerogel - don't build - your greenhouse w/o it

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