Mars regolith analog

Bill White · 2003-03-31 15:44:27

Because Mars atmosphere is so thin there is very little heat loss to the air. Insulating the floor may be more important. Remember the ground is freezing cold.

Recent findings suggest that vast quantities of ice may exist very close to the surface of Mars, right? If true, the floors of every settlement will need to be well insulated to prevent melting the ground beneath the habitat.

If waste heat is transferred into the regolith, the ground might literally melt away beneath you.

Josh Cryer · 2003-03-31 17:48:26

Hmm, if we're talking about large domes (ones which are actually buried spheres) groundwater shouldn't be an issue, because it seems logical to filter out the water during construction. A cold floor may not be an issue either, because I assume with a large dome most of the interior floor and underground is constructed.

Smaller domes do have the problems you guys were talking about, though.

Hmm, couldn't we take that daily thermal energy (someone noted that there was an overabundence of it) and pipe it with midel into warm underground reserves, keeping the habitats warm at night, and later being able to use it for warming the early cool dome mornings (or heck keeping the dome warm at night)?

Since we're on Mars, it's easier to be cold than it is hot. Perhaps the dome itself should always be overheated a bit. We could always cool the dome with midel which has been cooled dramatically by the outside Martian environemnt.

Bill White · 2003-03-31 20:53:25

Josh, I was responding to this from Space.com

Mars on ice
There is no doubt that Mars is on ice, with huge reservoirs of frozen water hidden just below the planet's surface.
The story of how much ice is sequestered subsurface continues to grow, said William Boynton of the University of Arizona and principal investigator for the Mars Odyssey's Gamma Ray Spectrometer.
Data gleaned by Odyssey has shown tremendous water ice deposits, Boynton said.
"It really is changing the way we think of how the ice formed," Boynton told SPACE.com . The idea that water vapor eked down to depths deep enough and cold enough to condense out does not seem to account for the vast amounts of water ice detected, he said.
There's no telling how deep the ice might extend just below surface on Mars, Boynton said. It could be several hundreds of feet to well over a mile in depth.
"All of a sudden you're starting to talk about a pretty significant amount of water," Boynton said. "It looks like the Viking 2 landing site was actually right on top of this ice. If its robot arm had dug just a little bit deeper they would have found it," he said.

If we build a base just above ice sheets several hundred feet thick, melting that ice seems like a bad idea for the long term prospects of the base, especially if the base was designed to be buried under regolith.

soph · 2003-04-22 19:34:09

Bill, theres an image at spacedaily.com that shows the distribution of water throughout Mars (according to Odyssey readings).

I'm sure that, like Earth, the water distribution on Mars is varied enough that we'd have oceans in some regions (on Mars, the northern basins), and water tables convenient for running water in others. I have said before that the initial base, in my opinion, should be at 0, 0. It's in a very (obviously) central location, and it is in proximity to many interesting and perhaps important geologic features.

In addition, the region is close, but not in dangerous proximity to the areas where estimates have placed oceans in the event of terraformation, which I think is, and should be, inevitable.

I'll see if I can fish up the article for you.

cyclohm · 2003-05-13 21:56:42

I'm late getting back to you guys with a progress report, so if I hope to have not lost your interest.

To give feedback... I don't think aerogel is the answer to my problem, but I don't see why it does not meet the potential for a large habited greenhouse. I want to be able to collapse this into a very small package (at least, compared to the "in use" condition) as mass is not the problem, the fact that I want to be able to deploy this with a minimum of human intervention is. I am hoping to make my model fit inside a box about the size of a computer case when it's collapsed, and have it deploy itself with one command. Thanks to RobertDyck, the Teflon film is what I was thinking of. BGD - I don't mind adding larger greenhouses to the discussion at all.

Anyway, I have done some looking into that Teflon film that RobertDyck suggested. I am excited by the possibility of the Teflon films; they look like they will fit the bill for what I wanted to do. I have also found a shape that will allow me to collapse the greenhouse yet make an "inflatable" structure work. (By work I mean deploy without intervention and still provide a working atmosphere of about 5-psi) know how to describe it here, but when I get a little farther along I will post pictures. I want to test some aspects of my idea but I think I have the first part of the problem in hand. I found an old 12-volt tire inflator to do the pumping of air to actually inflate the structure, but I know that a COTS (commercial of the shelf) pump will never work because of the lubricants. I suppose that it will be okay for my model, as I am using it here on Earth, but will not work for a Mars flight. I am just accepting the limitation for now, as if this was going to Mars I know there are pumps available. I still don't know how to simulate the Martian pressure, but am willing to settle with substitution of CO2 until I get further along.

I have also decided to use the National Semiconductor LM34 temperature sensors for now, and am looking for pressure and humidity sensors as well. There is a slew of them available, it's just a matter of choosing one I can both afford and interface to the 68HC11 board that I am planning on using. I have also pulled some computer fans from my scrap box to use for circulation, but need to come up with a way to provide cooling. I think cooling will be more of an issue on Earth, but it still may become an issue.

My power source is going to be a 12-volt lead acid battery for now. Gel Cells are easy to obtain and reliable, but I really want to use a solid oxide fuel cell. I think a real Mars application would have access to this technology, and the waste heat could be used for many things, not to mention keeping a greenhouse warm. I will probably go back to this when I can, I want to get a greenhouse proper built before the end of the summer and will work out the energy details later. (I am planning on using the waste heat to pre-process regolith for water, conversion to growing media, etc.) I know this may be a mistake, but I have to start somewhere, and once I have a physical size etc down, I can start to determine what else I will need.

Two problems have crept up in the tomatoes that I am growing. Now that I have flowers, I have no carriers to pollinate indoors. I don't know how to solve this problem in a small greenhouse on Mars, currently I am using a hobby paintbrush and brushing all the blossoms a couple of times. Not very effective, I am only getting 1 or 2 tomatoes for every 10 or 12 blossoms. I have yet to have managed to get one to ripen, but I suspect that will be happening soon. So, I either have to include pollinating insects (which makes it necessary to scale the project up tremendously) or figure out a way to pollinate without them. Also, my light levels indoors are too low. 80 watts is just not enough, my plants are only marginally healthy, they are skinny and taller than they should be. This can be corrected, but the power bill is already much larger than I want it to be, so I am thinking about spending some time building a few solar panels. I want to include solar power for now into the project, but I want to make sure that I can provide enough artificial light to keep the plants in ALIVE with the solar panels. I know that the energy requirements for HEALTHY plants are too great to provide with practical solar panels, but if I can find a "keep alive" stage where the additional light is just enough, I may be able to reach the stage where the additional light is enough to simulate a summer daylight light cycle this December without supporting small countries with my power bill.

More later, (hopefully before next month) I have to work on midterms.

RobS · 2003-05-18 23:22:31

I have a question about the mass of a Mars greenhouse. How much would it be? Let us assume the greenhouse is 20 meters long and 6 meters in diameter. It would have an interior volume of 564 cubic meters, an exterior surface area of 436 square meters (including two 28 square meter caps) and a flat surface area receiving sunlight of 6 x 20 = 120 square meters. Based on biosphere 2 data, this could feed 1 person, maybe 2 with a lot of efficient planting.

I gather 436 square meters of 2 mm thick Tefzel or Teflon FEP wouldn't weigh much; but how much? A few hundred kilograms? If its density were the same as water, its mass would be about 1 kg per square meter for every 1 mm of thickness.

What else do we need? A few air circulation fans and motors? An electric heater? A nighttime insulation blanket and electrical motors to deploy it? A water tank? About 60 meters of irrigation hoses? Some sort of fancy air filter to remove nitrogen oxides, methane, ozone, and other waste gasses that could build up? An oxygen tank? A CO2 tank? A nitrogen tank? Pots and trays to plant in (they could get heavy)? An ammonia manufacturing unit for making nitrogen fertilizer (I think a Sabatier reactor may be adaptable for this)? Phosphates and a few other nutrients imported from Earth? Martian soil (if we use 20 centimeters of it at a density of twice that of water, the astronauts will have to haul in 400 kg per square meter, or about 50 tonnes of it)?

You get the idea. I wonder whether a greenhouse of this size could be made from, say, 4 or 5 tonnes of stuff hauled from Earth? Or possibly, if the pots and trays were made from simple Martian plastic, we might save mass hauling a small plastic making unit to Mars instead of the pots and trays.

-- Rob S

RobertDyck · 2003-05-20 13:31:21

I have a question about the mass of a Mars greenhouse. How much would it be? Let us assume the greenhouse is 20 meters long and 6 meters in diameter. It would have an interior volume of 564 cubic meters, an exterior surface area of 436 square meters (including two 28 square meter caps) and a flat surface area receiving sunlight of 6 x 20 = 120 square meters. ...
I gather 436 square meters of 2 mm thick Tefzel or Teflon FEP wouldn't weigh much; but how much?

According to Dupont Teflon FEP film of 2 mil thickness (0.050 mm) has an area factor of 9 m^2/kg. That means 436 m^2 would mass 48.44 kg. You probably want to add a little mass for fibre reinforcement to make the film rip-stop, and to hold a non-cylindrical shape. A squashed cylinder can provide more usable space than a pure cylinder, but it must be tied down to squash it.

Bill White · 2003-05-20 19:30:18

. . . Also, my light levels indoors are too low. 80 watts is just not enough, my plants are only marginally healthy, they are skinny and taller than they should be. This can be corrected, but the power bill is already much larger than I want it to be, so I am thinking about spending some time building a few solar panels.

Well done!

I applaud your actually doing this project.

Here is an idea about light levels that may not be practicable but what do you think about this?

What if (on Mars) you added inflatable reflectors (mylar balloons with shiny silver surfaces) and concentrated sunlight into light tubes for funneling into the greenhouse? If shipped deflated, mylar balloons would be very lightweight and compact and could be inflated with Mars C02 into a rigid shape.

Spread large numbers of parabolic shaped balloons on the surface all around your greenhouse and channel the light through mylar light tubes into the greenhouse. Ring the entire settlement with a "fence" of mylar to reflect light towards the greenhouses.

A cheap home demo test could be done in a backyard with a plywood box. Stick a light meter inside the box and attempt to channel sunlight into the box with parabolic mylar reflectors fashioned from PartyCity children's balloons - the silver mylar variety. Fashion the box to allow only (mostly)reflected light into the box - but if you measure the light levels before setting up the mylar you would at least know how much more you are getting by reflection.

Artificial light will remain essential back up (dust storms!) yet harvesting as much sunlight as possible might avoid the need to send additional nuclear reactors for artificial light to grow plants. Lets see - what would be cheaper? Yet another nuke reactor or 500 kilos of mylar party ballons?

cyclohm · 2003-06-10 00:43:58

Well, there has been at least a small setback, I lost my tomatoes. They started looking kind of wilted and stringy, then started loosing their leaves. Finally, I gave up, turned off the grow lights and set them outside. They seem to be doing nothing, I probably shocked them even more by putting them outside without a proper hardening off, but I think that either my lighting or watering was off too much, and figured that it would be best to try again.

I'm having problems obtaining samples of tefzel film, seems like every "distributor" wants to sell me several hundred feet on rolls but not just a few feet. I'm thinking that I may just buy some and offer the rest for sale, but I have been trying to get in contact with someone at DuPont directly to obtain what I need. Of course, I was not smart enough to approach this like I would at work and ask for a sample

I have come up with several circuits for monitoring temp, liquid water, pressure and light levels, but am still trying to figure out humidity. I have a "humidity" sensor that I obtained as an engineering sample, but I only have the one, and small quantities are not readily available. It also wants a serial data stream, which means that I would have to bit-bang a digital port into a serial interface. I hope to layout and build the sensor subassemblies (including the circuits that are necessary to convert the output voltages/currents to 0-5 volt so I can read them with the 'HC11's onboard A/D converters over the summer, so that in October I can set up a greenhouse and try this out over the winter.

Bill White - I like the mylar idea, but I was thinking about using those space blankets, so I had large surfaces to work with and could shape them over a frame. Also, I can get the space blankets for a few bucks from the drugstore.

Instead of a nuclear reactor, how about something like a solid oxide fuel cell? The operating temp is about 800? C from what I have read, which means there would be waste heat to use, and you could use methane as a hydrogen donor gas, which puts it within the class of "cheap to fuel on Mars"

Finals are over next week, I plan on increasing the amount of time I put into this - incuding putting pictures up on a webpage so I can share what I have done!

cyclohm · 2003-06-10 00:51:27

One other thing I need to ask of the experts who frequent this arena.

How do you measure the quantity of light? Do you break it down by spectrum/wavelength? Intensity? Some combination of the two? The one reference (Plant growth chamber handbook) I have says "use your calibrated light meter" but what is it calibrated to? Anybody know?

RobertDyck · 2003-06-10 06:28:01

A "calibrated light meter" measures light intensity. Photographers use a handheld light meter to measure light intensity. It would be nice to measure light intensity for different colors, but that is only applicable if you are using colored lights. If you are using full spectrum grow lights, then the intensity of each color is not important. Light intensity could be measured in Lux (Lx) which is Lumens per square metre (lm/m^2) if using metric, or foot-candles if using the old English measurement system. Lux is also known as Luminous flux.

RobS · 2003-06-12 18:54:02

I have another wuestin about domes. In Mars Direct, Zubrin refers to the idea of making domes out of kevlar, but he doesn't give any background, such as: is it transparent? Is it stable in UV? Does it degrade slowly? Are there other plastics that might be better? Are there combinations that are better? I was wondering whether anyone had thought about these matters.

Zubrin also says a kevlar "dome" should be covered by a plexiglass structure, I guess for protection. Any idea why that is necessary? Couldn't a simple, thin, cheap, ultraviolet-impervious plastic sheet plus a wall of rocks around the dome to keep vehicles away do the same thing?

-- Robert Stockman

RobertDyck · 2003-06-12 19:47:02

As far as I can discover, Kevlar is a fibre, not a film. There are films reinforced with Kevlar fibre, but not pure Kevlar film. Kevlar has the great advantage that the strength to weight ratio is six times as high as steel. Something made with Kevlar is thicker than steel, but for a given weight it is much stronger. Its features include High Tensile Strength at Low Weight, Low Elongation to Break High Modulus (Structural Rigidity), Low Electrical Conductivity, High Chemical Resistance, Low Thermal Shrinkage, High Toughness (Work-To-Break), Excellent Dimensional Stability, High Cut Resistance, and Flame Resistant (Self-Extinguishing). However, it is opaque. All these wonderful benefits are not applicable to a transparent structure.

I had suggested the ideal would be Teflon FEP film reinforced with fibre glass. The glass fibres should be oriented to create a "rip stop" matrix. The glass fibres would tend to diffuse the light, making it translucent rather than transparent, but that may be beneficial for a greenhouse. However, pure Teflon FEP film is available off-the-shelf today. Tefzel is also available off-the-shelf and it is both stronger and lighter for a given thickness. It is also more gas impermeable; however it is more susceptible to UV damage. For Mars I suggest an outer layer of Teflon FEP with a spectrally selective coating, and an inner layer of Tefzel. The greater gas impermeability would keep greenhouse atmosphere in. The inter-layer gap could be filled with argon gas. The large molecule size of argon would have greater impermeability through Teflon FEP. Argon has low heat conductivity so it would help keep heat in, and argon is a constituent of Mars atmosphere.

Enyo · 2003-10-22 15:27:25

P.S. I should clarify something about the GCMS. It was designed to detect organic material - NOT life. The fact that it detected no organic material was taken to mean that no bacteria, alive or dead, were present in the regolith, although the Labeled Release experimental data were strongly indicative of actively metabolising microorganisms. The problem was simply that you would need at least 10,000,000 bacteria in the soil (alive or not) for the GCMS to detect organic material. The LR device is capable of detecting the metabolic products of as little as 50 organisms! Thus, in a harsh environment like Mars, where the population of microorganisms could well be small (as in Antarctic soils), the GCMS was too insensitive to detect the amounts of organic material involved.

The problem is that the LR producted a sudden spike of activity with just as sudden a drop. Nothing like the bell curve you would think life would produce. It has also been discredited by others work...

Maybe Beagle II will answer this question.

Shaun Barrett · 2003-10-24 07:57:07

Hi Enyo!
I'm not sure what data you're referring to.
What I'm talking about is a graph produced from the actual results of the Viking Labeled Release experiment (LR), performed on Mars.
There is no 'sudden spike of activity with just as sudden a drop' in the graph, unless I'm mistaking what you mean.

For a look at the graph I refer to, see this site.
As well as the kind of curve which would be expected if there were living microbes in the Martian soil, a Dr. Joseph Miller, circadian biologist and neuroscientist from Texas Tech University, was surprised to see oscillations in the curve. He noted that these oscillations had a period of one Martian Sol and speculated that they might represent circadian rhythms of the putative microbes.
However, since the article I've linked is some years old now, and since no startling news has been announced confirming the circadian rhythm hypothesis, I assume the hypothesis was never substantiated.

Nevertheless, the simplest explanation for the LR results, in my view, is still that living microbes in the Martian regolith responded to the LR nutrient solution by metabolising.
This and other lines of evidence lead me to the conclusion that there is life on Mars. I'm almost positive about it but can't prove a thing!!

Enyo · 2003-11-15 03:06:15

You are right I was looking at a different graph. The webpage you mention is from Spacedaily and is written by Barry DiGregorio a non-scientist with the agenda of never in a hundred years having humans visit mars! I think he is not worthy of reading. I don't know if there is life on Mars, but I wouldn't accept Barry's views as fact. He is a hack!

Try: Life Pinned on Viking Horns?at Astrobiology Magazine

Rxke · 2003-11-15 03:48:51

One other thing I need to ask of the experts who frequent this arena.
How do you measure the quantity of light? Do you break it down by spectrum/wavelength? Intensity? Some combination of the two? The one reference (Plant growth chamber handbook) I have says "use your calibrated light meter" but what is it calibrated to? Anybody know?

Cyclohm, there are devices on the market, mainly for use in musea, that measure relative humidity, temp, lightlevel (ambient and direct) (in visible/UV) in one handy enclosure Some of these have serial ports, so you can download/monitor their outputs. I've worked with some of them, and they're lightweight and very precise... They are pre-calibrated, and you can let them re-calibrate by service personnel... Stupid of me (or my fried harddisk), but i can't find the specs, not even the manufacturer, but there are several on the market... maybe you could ask your local museum?

I'm afraid these thingies are quite expensive, though, being 'reference' measurin devices...

All the luck with your project!

Shaun Barrett · 2003-11-20 07:55:00

Thanks Enyo!
I'm aware of Barry DiGregorio's shortcomings as a writer but I was unaware of his 'agenda'. I'm still not sure what you mean about the 'no humans on Mars in a hundred years' (?).
???

In any event, my intention was simply to show you the graph I've been referring to. The article it appears in wasn't central to my post and the possibility of a circadian rhythm, though intriguing, has never been a salient feature of the Labeled Release debate.

I read the Astrobiology Magazine link you provided, thank you. The discussion of the three main experiments is familiar to me and I realise there is a degree of ambiguity in the results. If there were not, of course, we wouldn't be talking about the possibility of life on Mars!
What caught my attention was the reference to Dr Gerald Soffen's confidence in the capabilities of the Gas Chromatograph Mass Spectrometer (GCMS). This is a major bone of contention, since the failure of the GCMS to detect any organic compounds in the Martian soil, even down to the parts-per-billion level, was the single biggest factor leading to the final conclusion that none of the experiments had detected living organisms.
As I understand it, identical GCMSs have consistently failed to detect small reproducing populations of micro-organisms in Antarctic soils. This is not surprising when you consider that the GCMS would need millions of bacteria per gram of soil in order to give a positive reading, while the depleted Antarctic soil contains far fewer organisms than that. The same soils, tested using a duplicate of the Viking Labeled Release experiment, produced a positive result quite similar to the data recorded on Mars. Again, this is not very surprising given the extraordinary sensitivity of the technique, which can detect as few as 50 bacteria per gram of soil.
It seems difficult to believe Dr Soffen could have had any real confidence in an instrument like the GCMS on Mars, given its subsequent demonstrated inability to find carbon compounds in soils known to contain living organisms here on Earth!
This kind of statement seems patently unscientific to my mind and raises questions about the motives of the person making it. I'm inclined to suspect that Barry DiGregorio may not be the only one with an 'agenda'.
???

SpaceNut · 2016-12-29 11:02:25

Bump
Fix conversion artifacts and shifting for topic posts.

So what does a simulant look like...

Looks over processed to what we would be using on Mars...
http://geology.com/stories/13/rocks-on-mars/

http://geology.com/stories/13/rocks-on- … rop-lg.jpg

Here are some Nasa simulant links...

http://physics.ksc.nasa.gov/Publication … 0Gross.pdf
Particle Charging Experiments in a Low Pressure Environment

http://www.lpi.usra.edu/meetings/LPSC98/pdf/1690.pdf
This lists typical table of compositions

SpaceNut · 2021-11-21 10:07:54

soil by another name...

So does the analog material have the balance of these nitrogen, phosphorus, potassium, calcium, magnesium, iron, zinc, copper, nickel, boron, molybdenum, to promote plant growth?

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