Yet another Mars architecture

RobertDyck · 2013-11-25 19:54:05

We briefly discussed food in this thread. I looked for pouches of stew on the website of a local outdoors store. They have this brand. It isn't just "canned" in a bag, it's actually freeze dried. You can buy in regular pouches, cans for large quantities for survivalists, or vacuum packed pounches. It's freeze dried, so you have to add boiling water and let it sit to re-hydrate. Intended for backpacking, the vacuum pack has air removed so it won't expand when you hike up a mountain. I think the vacuum pack pouches would be perfect for ISS or Mars. Shelf life is 25 years. They have 21 flavours: stew, spagetti, etc.

http://www.mountainhouse.com/category/MHDL.html

Ps. Commercial-Off-The-Shelf

Last edited by RobertDyck (2013-11-25 19:54:46)

JoshNH4H · 2013-11-25 22:52:20

RGClark wrote:

JoshNH4H wrote:
...The water ice at mid-latitudes in particular is mostly inferred from pictures taken from orbit rather than satellite imagery (which doesn't show water content getting into the 30% range, e.g. unmistakeably water ice as opposed to hydrates) until above 60 degrees latitude.
On Earth, 60 degrees latitude is the approximate location of Oslo and Helsinki. It's not uninhabitable, but it sure is cold; Now, when we're talking about a place where the mean temperature at the equator is significantly below zero; Why in Heinlein's name would you go somewhere less hospitable?
Now, I'll say it again, that the systems needed for atmosphere-based ISRU on Mars can be tested in the proper environment, right here on Earth; there's no need to take this detour to the Moon. As Zubrin says: "If you want to go to Mars, go to Mars."
I don't understand the distinction you are making between "pictures" and satellite imagery. Perhaps you were referring to the instruments that detected high hydrogen amounts from which it was derived indirectly the amounts of water ice. But I think one of the key discoveries of Mars Reconnaissance Orbiter is the finding of large ice deposits within centimeters of the surface at about 40 degrees latitude and above.
This did come from actual imaging. What was found was recent meteor impacts uncovered pure ice beneath just centimeters of soil. Note this was at the latitude of a former lander mission, the Viking 2 landing site. This corresponds to a latitude of New York City on Earth.
I'm actually not opposed to atmospheric ISRU for propellant for the return mission. What is driving my favoring using lunar propellant for Mars missions is that I really, really do not like the 6 to 8 month travel times proposed for Mars missions. Shortening this has required nuclear propulsion which still results in months long travel times. Evidence from ISS missions suggests this will result in at least some of the astronauts being incapacitated for days, in addition to the radiation and eye damage problems now revealed.
Using lunar propellant would allow huge rockets to be used to cut the travel time to weeks.
Bob Clark

The distinction that I was getting at (albeit poorly) was between visible light imagery and hydrogen-finding radar. The first cannot be used to guarantee the presence of Hydrogen, while the latter more or less can.

What's so great, or necessary about cutting the travel time? Spin gravity is perfectly fine and I think we're better off involving as few massive rockets in this mission as possible.

SpaceNut · 2013-11-26 17:15:21

RobertDyck wrote:

We briefly discussed food in this thread. I looked for pouches of stew on the website of a local outdoors store. They have this brand. It isn't just "canned" in a bag, it's actually freeze dried. You can buy in regular pouches, cans for large quantities for survivalists, or vacuum packed pounches. It's freeze dried, so you have to add boiling water and let it sit to re-hydrate. Intended for backpacking, the vacuum pack has air removed so it won't expand when you hike up a mountain. I think the vacuum pack pouches would be perfect for ISS or Mars. Shelf life is 25 years. They have 21 flavours: stew, spagetti, etc.
http://www.mountainhouse.com/category/MHDL.html
Ps. Commercial-Off-The-Shelf

True but on the way out as well as on mars there will be a need for pressure cookers to rise the temperatures to boiling and to keep the food steam from evaporating before it can do its soaking in the open.

RobertDyck · 2013-11-27 00:10:08

SpaceNut wrote:

True but on the way out as well as on mars there will be a need for pressure cookers to rise the temperatures to boiling and to keep the food steam from evaporating before it can do its soaking in the open.

I trust you're joking. Cooking on Mars will be inside.

I stopped by the store today. They have several more brands: AlpineAire, Backpacker's Pantry, Harvest Foodworks, Natural High, Outdoor Gourmet, Richmoor, Mary Jane's Farm. And others, but these are all rehydratable.

JoshNH4H · 2013-11-27 01:10:14

Perhaps he was referring to the lower air pressure within habitats? I personally tend to favor 40-50 kPa, and I rarely find strenuous disagreement from people around Newmars on that. At 40 kPa, water boils at about 75 C. This is significantly below 100 C, and it might make a difference for cooking purposes.

GW Johnson · 2013-11-27 10:15:17

I would think he was referring to cooking inside a habitat at lower "air" pressure. However, for colonists having babies, I think you will find (if you research it) that something resembling Earth air at near 1 full atmosphere is required for successful pregnancies. This has a major impact on building pressurized structures in which to live.

Whether 0.38 gee is therapeutic enough to stave off microgravity diseases is still an open question, and will be for some time to come, since we did not put a medical centrifuge on ISS. (That seems rather stupid in hindsight, doesn't it?) There is some reason to worry about pregnancies in reduced gee, too, although personally I am less concerned about that risk, than I am having the correct atmosphere to breathe.

Backpacker foods are certainly an improvement upon what NASA has been feeding its astronauts in space, in terms of storage lifetime and palatability. The difference is also the downside: a lot more water is needed for backpacker foods. Once you grit your teeth and do water for life support in sufficient quantities, then better, longer-life food becomes feasible. But, water being very heavy, you don't get to fly a minimalist habitat design off of one big SLS shot.

GW

JoshNH4H · 2013-11-27 12:42:21

GW: What evidence do you have for your claim that (near) 1 full atmosphere is required for successful human pregnancies?

Edit: And how do you compare this evidence with the existence of a permanent human settlement at La Rinconada, Peru, where I calculate the mean pressure to be about 55 kPa. Due to the nature of the town (30,000 people live there, but it's a shantytown, at this point-- Rather like San Francisco in 1849, e.g. the Gold Rush) there's no real record of the miscarriage rate. Due to the extreme poverty (plus the high levels of Mercury and Cyanide in the soil and water) it would be difficult to make any kind of reasonable comparison using those statistics anyway.

By reading up on the information, based in part but not entirely on the use of child labor (for children as young as five, it seems), it sounds like there are some children born there.

I can confirm that the town of Tanggulashan, China seems to have a permanent, self-reproducing population. At 4,500 m above sea level, I would expect the local air pressure to be under about 60 kPa. Because we're on Earth, this means that you'll only get 60% as much oxygen as at sea level, while on Mars they would get the same amount, if not (perhaps) more.

GW Johnson · 2013-11-27 15:55:48

To a certain point, it's not about the pressure. There are acclimatized populations as high as 20,000 feet on Earth. But most folks from nearer sea level do poorly above 10,000 feet. That's why they put oxygen on airplanes. But, there are no populations at all above 20,000 feet. Must be a reason for that! That's air, and it's obvious that 55 KPa is OK in every way for acclimatized populations. Most of us are not so acclimatized. And that shows up in the regional genetics, I might add.

The things I have seen for colony proposals often are custom-composition atmospheres at very low pressure. I know from the MCP spacesuit work in the late 1960's that pure O2 would work just fine for functioning adults at only 180-190 mm Hg. But, composition is important long term, and both pregnancy and child growth are very sensitive to a lot of things that functioning adults are not sensitive to. Composition is one of them, or so I have been led to believe.

You can only go so low with 21% O2 79% N2. Maybe 55-65 Kpa. To go lower, it ain't gonna be air. And that's definitely a problem.

Plus, you're already in trouble trying to cook with boiling water above 10,000 feet.

GW

RobertDyck · 2013-11-27 16:54:40

Did a quick Google for pregnancy problems from air pressure. They say fluctuations can cause the membrane to burst prematurely. That's fluctuation, not steady pressure.

I worked on the Mars Homestead Project, Phase 1: Hillside Settlement. They guys said they expected roughly 0.6 atmosphere pressure in the hab, but didn't have anything to back that up. So I looked into it. For zero pre-breathe time when decompressing, such as going outside in a spacesuit, the maximum partial pressure of nitrogen in the hab to total pressure in the suit is 1:1.2. That's based on a lot of work done by medical professionals studying the Bends for divers. For Apollo, NASA made suit pressure 3.3 psi pure oxygen so 10% pressure loss due to a slow leak would only reduce O2 down to what they were used to in the spacecraft or Skylab. But lower suit pressure results in more dexterity, so I calculate for 3.0 psi pure oxygen in a suit, and hab with 2.7 psi partial pressure O2. After all, Mars astronauts will have 6 months transit to acclimate before landing, and 2.7 psi partial pressure O2 is higher than Boulder, Colorado. According to the NOAA website, today's pressure at Boulder, Muni airport, is 12.412 psi. Multiplying by 20.9% O2, that gives 2.54 psi partial pressure O2. Using the 1:1.2 ratio and 3.0 psi suit pressure, that means 3.6 psi partial pressure N2 in the hab. And I also used a tri-gas mix: O2/N2/Ar. And made the ratio of N2:Ar match the ratio in Mars atmosphere. That way you can make diluent gas by taking Mars atmosphere and removing CO2. I have a whole paper on that. Using Mars atmosphere as measured by Viking 2 lander, N2=2.7% and Ar=1.6%, so this would give the habitat 2.133 psi Ar. Adding that together is 8.433 psi total pressure = 58.16 kPa.

Zero prebreathe time is important for Mars. Just get in a spacesuit, cycle the airlock. You could recalculate with newer measurements of N2 & Ar, but Ar can't be too high. There's a limit to Ar as well for zero prebreathe.

This calculated hab pressure appears to agree with what both of you are saying.

JoshNH4H · 2013-11-27 23:48:54

GW-

If that were true, I would be most surprised that a study had been done at all. Where did you hear that?

GW Johnson · 2013-11-28 10:22:09

Hi Josh:

To answer your question, I don't remember now where I read about pregnancy risks vs "air" composition and pressure. It was about the time I first started looking into MCP suits and found that old flight surgeon's page about his late 1960's experiments. It was people like him (not him specifically) voicing concerns. But it makes sense, because all sorts of seemingly-trivial insults can induce abortions and miscarriages.

The numbers I have based on populations living at altitudes agree quite closely with your 55 Kpa figure for something resembling Earthly air. I had not heard of the 1.2 ratio governing nitrogen for getting into a spacesuit without pre-breathing O2, but that neatly explains the older 1/3 of an atmosphere O2 relative to 1 full atmosphere of air. That 1/3 of an atmosphere compression is what has been holding back MCP suits.

I ran some quick numbers on 55 Kpa in the hab air. 0.543 atm total for 0.114 atm O2 and 0.429 atm for N2 (excluding argon, call it "synthetic air if you like). Using the 1.2 ratio rule, the pure O2 suit has to be at least 0.357 atm, just about the old NASA compression requirement. That's 36.2 Kpa, or 271 mm Hg, which is beyond what MCP can achieve (200+---ish mm).

The old experiments say 190 mm Hg worked, and my altitude-equivalent numbers say 170 mm Hg would work, even accounting for water vapor displacement in the lungs. None of those are compatible with the 1.2 rule using 55 Kpa air in the hab. You would have to use a higher oxygen/nitrogen ratio in the hab to match an MCP suit and the 1.2 rule, and the doctors start screaming about high oxygen during pregnancy. 0.243 atm O2 and 0.300 atm N2 for 0.543 total pressure, or 45% O2-55%N2 mix at 55 Kpa. That's just about like the hospital 40% O2 that the doctors warn about.

Question: why does everybody in the hab have to breathe the same "air" that EVA astronauts breathe? Is that assumption not driving us into an impossibility here?

GW

RobertDyck · 2013-11-28 11:34:55

GW Johnson wrote:

Question: why does everybody in the hab have to breathe the same "air" that EVA astronauts breathe? Is that assumption not driving us into an impossibility here?

They don't. Suits use pure oxygen, with some humidity and whatever CO2 the astronaut exhales. That's what reduces pressure. It was used for Apollo suits, and I'm arguing for Mars suits. The EMU used for the Shuttle and ISS uses higher pressure, with some N2, but not as much N2 as the Shuttle or ISS. The Shuttle flew such short missions that they didn't think putting astronauts through decompression was worth it. Ironically, any astronaut that went out had to prebreathe O2 in order to purge N2 before going through decompression. Wikipedia says they decompressed the whole Shuttle to 10.2 psi prior to EVA, in order to reduce prebreathe time. ISS also uses sea level pressure, so the same as KSC. EMU uses 4.3 psi.

Or are you asking astronauts who are about to debark to be isolated in reduced pressure environment? I don't think that's practical. The hab is small to start with.

And it's not impossible. Apollo and Skylab used 5.0 psi with 60% O2 / 40% N2. That works fine. No drying of lungs. No prebreathe for EVA. We're talking about higher pressure. And you don't need 3.0 psi partial pressure O2. That's sea level. As I said, Boulder Colorado has 2.54 psi partial pressure O2.

SpaceNut · 2013-11-28 13:22:42

Wishing all a happy Thanksgiving Day.

Mine will be with family, making the meal hopefully with a little help and enjoying the Macy thanksgiving day Parade on TV being shown by the networks on the cable provider.

My meal will be sort of traditional but I can not say that for Irradiated Turkey, Thermostabilized Yams: Thanksgiving Dinner in Space to feed two Americans currently living on the International Space Station amoung the six people that have been there for a short while.

Sure, you can do a lot of things to space food to make it less space-food-y: You can spice it and sweeten it and try to make it simulate, as much as possible, its Earth-bound counterparts. Ultimately, though, the foodstuffs you're consuming are still desiccated/rehydrated/irradiated/thermostabilized. Which is all compounded by the fact that your taste buds are sort of shot by the whole microgravity thing, anyway.

Here, per NASA, are the dishes that will grace the only Thanksgiving table whose crazy tablescape is space.
Turkey
Technically, it's "irradiated smoked turkey." It comes in a sealed foil pouch.According to the AP, the foodstuff that results "resembles sliced deli meat," except it's "stiffer."
That's in part because the turkey "functions just like a canned product," NASA food scientist Vicki Kloeris said in an interview this morning. It has "about a three-year shelf life." The turkey the astronauts will be feasting on this time around was produced "probably about two years ago."
Stuffing
The good: It's cornbread stuffing! The former ISS astronaut Tom Marshburn said it was his favorite dish of all the Thanksgiving offerings! The bad: It "has a broth-heavy, institutional flavor." Also, it comes in a foil pouch.
Potatoes
The good: "homestyle"! The bad: They're rehydrated. (And also, they come in a foil pouch.)
Yams
The good: they're candied! The bad: They're thermostabilized. And also,apparently, "bland inside."
Green beans
They're freeze-dried. And foil-packed. And also "taste like they've been microwaved to death." (Or, as Marshburn puts it, understatedly: "It's not quite like fresh steamed green beans.")
Cranberries
These are, as they often would be on Earth, canned. And, as jelly, they come in hotel-style little jam packs.
Pie
Well, modified pie: cobbler. In this case, cherry-blueberry cobbler. Which comes, Kloeris says, with "a little bit of crust in there." (That said: "It's not quite the same as having a slice of pice.") It comes in a, yep, foil pouch.

The meal sounds sort of ok but it would seem we have a long ways to go for this being for Mars....

You may notice one thing not on the menu above: gravy. Which is, along with apple pie (the crust doesn't work in space), something of a white whale for space-food science. So far, Kloeris notes, NASA scientists haven't been able to get the ultimate Thanksgiving sauce into space-ready form. The result, for the menu above? "We have no gravy, unfortunately."

JoshNH4H · 2013-11-29 20:03:55

I was just wondering what food would be like on Mars, specifically because the population would be pretty close to vegetarian, because of the high price of eating meat.

Would there still be a harvest festival when food can be grown inside, in greenhouses? I wonder. Yield would be lower in the winter but I wouldn't expect farming to stop entirely. How do you think diet would vary during the year? When would the optimal "Thanksgiving" time be?

RobertDyck · 2013-11-29 21:35:25

Mars has gravity, so the problems SpaceNut reported for ISS wouldn't happen. We in western countries have plenty of food, but the tradition of Thanksgiving continues. Based on European harvest festivals, so they have something similar. In Canada it's the second Monday of October, because harvest is around then. Snow comes in early November, right now it's winter with snow and ice. Driving is hazardous. Mars has an elliptical orbit, so an ambient light greenhouse will have some "season". Even a heated greenhouse near the equator, which is where I expect human habitation. But the Martian year is 686.98 Earth days, or 668.59 solar days (sols). Would settlers create new traditions and new festivals, or adhere to Earth holidays? Don't know. But I have a long-winded discussion about food under the Life Support topic, here: Crops.

Terraformer · 2013-11-30 05:21:34

Would they have Tilapia on their holidays? Or maybe kill some of the chickens? They will have chickens, surely, going without eggs is going a bit too far...

RobertDyck · 2013-11-30 09:08:15

I'm trying to create an entire vegan diet. For one thing, how do you get chickens to Mars? In "Life Support Systems", in the discussion Livestock, we discuss cattle and chickens.

I suggested bringing calves just barely weaned from milk, in hibernation. One researcher has succeeded in putting deer, elk, and moose in hibernation. The catch is 10% of the animals die when you try to revive them; and of those that do survive, 30% suffer permanent brain damage. They become lethargic: do nothing but stand around eat, shit, and sleep. Obviously something we can't do to astronauts, but can with livestock. Dead calves would be veal; they wouldn't be force-fed, so would taste more like beef than veal, but I'm sure settlers would enjoy the feast. And animals with brain damage would be easier to handle, they would be there for milk and meat anyway. The reason for hibernation is so animals don't freak-out in the spacecraft. You don't want a panicking animal when you're trying to navigate in zero-G. Even a spacecraft that uses rotation will be in free-fall before the rotation can begin. And hibernation reduces oxygen consumption to 10%, and the animal won't eat, drink, or shit, making transit vehicle life support a lot easier.

For chickens, I suggested sending fertilized eggs. Same reason: don't have to deal with awake animals during transit. My idea was a refrigerator that could become an incubator upon landing. But as you'll read, further study showed a problem. Fertilized eggs can't be refrigerated as cold as a kitchen fridge, and only for about 6 weeks. But it takes 6 months to get to Mars. One possibility is to freeze the fertilized egg in liquid nitrogen, then thaw on Mars. Human embryos can be frozen in liquid nitrogen, when they're still very small, as part of in-vitro fertilization treatment. So chicken embryos can too. The question is whether the liquid of an egg would create ice crystals during freezing that kill the embryo. Would we have to surgically remove the embryo from the egg, and re-insert after thawing? One member who has a chicken farm offered to try to freeze whole fertilized eggs. But his neighbour who he calls an expert had moved away. The experiment was not conducted.

GW Johnson · 2013-11-30 10:39:41

Re post 187 above: a transit vehicle needs to fairly spacious, or the crew won't arrive in good mental condition. There should be enough space for a prep room adjacent to the airlock, in which the astronauts can prep and dress at reduced pressure/enriched oxygen relative to the rest of the hab. That's the N2 blowoff needed before going into a pure O2 suit at 20 to 35% of an atmosphere breathing pressure. The rest of the hab could be 21-25% O2 at about 0.7 to 1 atm total pressure. Doesn't have to be Earth air in composition, but if it's close, fire dangers are reduced, and so are hazards to pregnancies. It certainly need not be full sea level pressure, either. Could be as low as 0.5-0.6 atm. (The pregnancy thing applies more to a base or colony, but all the air composition and pressure considerations still apply to base or transit vehicle).

GW

RobertDyck · 2013-11-30 11:28:51

GW Johnson wrote:

Doesn't have to be Earth air in composition, but if it's close, fire dangers are reduced

This one point isn't right. Adding diluent gas does not reduce fire. Combustion is directly proportional to partial pressure of oxygen. Percentage of oxygen is irrelevant. Nitrogen is irrelevant. Any other diluent is irrelevant. You're a jet engine engineer; you have to worry about all the subtle effects of diluent gas in the extreme environment of a jet engine. But a house fire or fire in a habitat or spacecraft, diluent gas would have such little effect as to be irrelevant.

Some people look at the Apollo 1 fire and thing that was due to pure oxygen. It wasn't, it was due to 17 psi partial pressure O2. The ignition source was due to bare electrical wires, and they added so much Velcro that it violated safety rules. (Originally that test had some other designation, but a Congressman posthumously named it "Apollo 1" due to loss of life.) I saw a video demonstration: Velcro in normal air with a match, it smouldered but did not burn. Velcro in 3.0 psi pure oxygen, also smouldered but did not burn. The second test was exactly the same as the first. Then 17 psi pure oxygen: the Velcro ignited like the head of a match.

We do need habitat pressure higher than 3.0 psi, but that's to avoid drying lung tissue. At extremely low pressure, lung tissue will dry out. That can be mitigated somewhat with high humidity, and spacesuits will get humidity simply by recycling breath. But for safety the habitat needs higher pressure. But the reason is lungs, not fire.

GW Johnson · 2013-11-30 18:20:31

I'm sorry, I have to both agree and disagree simultaneously with RobertDyck. Partial pressure of oxygen (or any other constituent) is the product of total pressure and percent (by volume, same thing as mole fraction) of the oxygen (or other component). Those two must both be considered to find the partial pressure of the component. No way around that. And that's where I disagree with him. It's just not one number.

As for partial pressure of O2 for breathing purposes, that's what drives osmosis across the alveoli. There is a displacement effect for both water vapor and for CO2, but the CO2 is essentially neglectible, because the numbers are so small. The water vapor pressure is not, because it is always 100% humidity inside the alveoli, and the equilibrium vapor pressure of water is significant at body temperatures. At human body temperature (37 C), the equilibrium partial pressure of the water vapor displacement is 47 mm Hg, regardless of the partial pressures of all the other constituents. And there's no way around that, either.

The net effect of that is that lower total pressure dry atmospheres must have higher percentage O2 content, just to get the same partial pressure of O2 inside the lungs, by that 47 mm Hg. No way around that.

The 17 psi partial pressure of O2 in the Apollo-1 (old name Apollo-204) fire was also the total pressure of the dry atmosphere being used in the capsule, because it was straight dry O2, no other components. That's 879 mm Hg oxygen partial pressure which also equals the total dry atmosphere pressure. Inside the wet lungs, there was essentially 47 mm Hg water vapor pressure and 832 mm Hg oxygen partial pressure. Those two add to 879.

That's where I agree with RobertDyck: at either 879 mm Hg in the capsule, or 832 mm Hg inside the lungs, there was more than enough oxygen to make almost anything "ordinarily flammable in air" into something almost explosive, which is typical of any oxygen-enriched atmospheres with total pressures anywhere near 1 atm.

Chemical combustion reaction global rates are more-or-less proportional to oxygen and fuel partial pressures raised to some exponent that typically falls between about 0.2 and 1.5. (Depends upon what global reaction rate model you want to use to use as an approximation for something fundamentally more complicated.)

So, yes, fire is a serious concern, including atmospheres like 0.5 atm at 60-40 O2-N2, which is an O2 partial pressure of 0.3 atm, richer in O2 than sea level air. It ain't just lungs drying out.

And there's doctors that cry out about damaging effects to the fetus if the O2 percentage is too high, even if total pressure is somewhat lower. That seems to be a partial pressure thing, but no one knows for sure. And THAT is my point. Until we do know, then 21% O2, 79% N2, at 0.6 to 1 atm total pressure, seems to be the "safe prescription" if pregnancy is involved, and with respect to fire dangers as well. Until we know better, there is no way around THAT.

As for EVA suits, I have posted some stuff on what is really needed, ignoring the N2-blow-off decompression effect. Based on partial pressure of O2 inside the wet lungs, with water vapor displacement effects included, I get a minimum compression or breathing pressure of 20 to 25% of an atmosphere, if you feed pure, dry O2 to the breathing helmet. I posted that analysis long ago over at "exrocketman", in an article dated 1-21-2011. I intended it as a design requirement for MCP suits, but it applies to gas balloon suits, too.

GW

JoshNH4H · 2013-11-30 19:49:57

With regards to atmospheres, Midoshi made a wonderful series of posts in the "Minimal Martian Terraformed Atmospheres" thread. It was lost in the crash but he has reposted it here. I cannot recommend it more highly. It covers exactly what we've been discussing regarding atmospheres in a clear, well-cited, and detailed format.

The thread also covered Nitrogen and Flammability issues, but he doesn't seem to have reproduced them there.

Terraformer · 2013-12-01 04:04:36

Well, testing the effects of pressure and oxygen content on developing fetus' doesn't appear to be a particularly difficult or expensive experiment to perform. Try it with mice first, and then move up to something like sheep, or perhaps pigs.

Also, we probably have a lot of the data from people living at high altitudes. How do their infant mortality rates compare, how many miscarriages etc?

Tom Kalbfus · 2013-12-01 07:15:36

RobertDyck wrote:

I'm trying to create an entire vegan diet. For one thing, how do you get chickens to Mars? In "Life Support Systems", in the discussion Livestock, we discuss cattle and chickens.
I suggested bringing calves just barely weaned from milk, in hibernation. One researcher has succeeded in putting deer, elk, and moose in hibernation. The catch is 10% of the animals die when you try to revive them; and of those that do survive, 30% suffer permanent brain damage. They become lethargic: do nothing but stand around eat, shit, and sleep. Obviously something we can't do to astronauts, but can with livestock. Dead calves would be veal; they wouldn't be force-fed, so would taste more like beef than veal, but I'm sure settlers would enjoy the feast. And animals with brain damage would be easier to handle, they would be there for milk and meat anyway. The reason for hibernation is so animals don't freak-out in the spacecraft. You don't want a panicking animal when you're trying to navigate in zero-G. Even a spacecraft that uses rotation will be in free-fall before the rotation can begin. And hibernation reduces oxygen consumption to 10%, and the animal won't eat, drink, or shit, making transit vehicle life support a lot easier.
For chickens, I suggested sending fertilized eggs. Same reason: don't have to deal with awake animals during transit. My idea was a refrigerator that could become an incubator upon landing. But as you'll read, further study showed a problem. Fertilized eggs can't be refrigerated as cold as a kitchen fridge, and only for about 6 weeks. But it takes 6 months to get to Mars. One possibility is to freeze the fertilized egg in liquid nitrogen, then thaw on Mars. Human embryos can be frozen in liquid nitrogen, when they're still very small, as part of in-vitro fertilization treatment. So chicken embryos can too. The question is whether the liquid of an egg would create ice crystals during freezing that kill the embryo. Would we have to surgically remove the embryo from the egg, and re-insert after thawing? One member who has a chicken farm offered to try to freeze whole fertilized eggs. But his neighbour who he calls an expert had moved away. The experiment was not conducted.

Chickens are small, I don't see what the big deal is, You could bring them to Mars the same way we would bring humans. Also Zubrin suggested that we separate the hab from the engine in transit and attach the two with tethers, there is 200 meters separating the engine from the hab, and we rotate both for gravity while in transit to Mars, now that seems like a whole lot less challenging technically than trying to come up with a hibernation scheme for chickens. Centrifuges we know how to do, its just that NASA has been too "chicken" to try them, though I believe one Gemini Mission involving Neal Armstrong did accidentally get involved with a spinning Gemini capsule, and we found out that the astronauts got pressed into their seats and centrifugal force works in space as well as on Earth, so the matter has been cleared up.

GW Johnson · 2013-12-01 10:16:27

Re Terraformer in post 197 (hey I'm agreeing with you!): Miscarriages are not (anecdotally) noticeably higher in Boulder CO or even in the Andes. There is acclimatization, including genetic changes, associated with the higher populations (15-20,000 feet above MSL). But, the fact that the Ptot is way lower up there while the percentage (20.9% O2) is unchanged means it is partial pressure of O2 that is far lower up there.

That in itself tells you that partial pressure is NOT the entire story as regards human health. The real world is almost always more complicated than what we can write down in simple science equations. Midoshi's recovered post is quite good, but I'd bet we'd better consult some medical schools about this before deciding upon an atmosphere for colonists who can have babies. And we'd better do the research. Time is short, the smartest thing to do is to plant a base on that first mission. The commercial guys will follow ("if you build it, they will come").

GW

JoshNH4H · 2013-12-01 15:40:42

I'm not disagreeing, and it's very reasonable to suggest that more study is needed before we can confidently say that these things will not be problematic. What midoshi was trying to do, I think, was to give us an idea of what reasonable atmospheric parameters are, pending more study.

Fortunately, these are the kinds of studies that can be done on Earth, for relatively small amounts of money (Admittedly, to experiment with low pressure you do need to build a pressure chamber, plus you have to pay your human volunteers. Typically they will be more than glad to work for a few hundred dollars per week.

What I'm saying is that a research grant of a few million dollars or less should be sufficient to explore the biology of different atmospheres on humans, as well as its effect upon animals in a wider variety of circumstances.

In terms of nitrogen narcosis, why don't we reduce the nitrogen in the hab to low levels and replace it with Argon?

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#176 2013-11-25 19:54:05

Re: Yet another Mars architecture

#177 2013-11-25 22:52:20

Re: Yet another Mars architecture

#178 2013-11-26 17:15:21

Re: Yet another Mars architecture

#179 2013-11-27 00:10:08

Re: Yet another Mars architecture

#180 2013-11-27 01:10:14

Re: Yet another Mars architecture

#181 2013-11-27 10:15:17

Re: Yet another Mars architecture

#182 2013-11-27 12:42:21

Re: Yet another Mars architecture

#183 2013-11-27 15:55:48

Re: Yet another Mars architecture

#184 2013-11-27 16:54:40

Re: Yet another Mars architecture

#185 2013-11-27 23:48:54

Re: Yet another Mars architecture

#186 2013-11-28 10:22:09

Re: Yet another Mars architecture

#187 2013-11-28 11:34:55

Re: Yet another Mars architecture

#188 2013-11-28 13:22:42

Re: Yet another Mars architecture

#189 2013-11-29 20:03:55

Re: Yet another Mars architecture

#190 2013-11-29 21:35:25

Re: Yet another Mars architecture

#191 2013-11-30 05:21:34

Re: Yet another Mars architecture

#192 2013-11-30 09:08:15

Re: Yet another Mars architecture

#193 2013-11-30 10:39:41

Re: Yet another Mars architecture

#194 2013-11-30 11:28:51

Re: Yet another Mars architecture

#195 2013-11-30 18:20:31

Re: Yet another Mars architecture

#196 2013-11-30 19:49:57

Re: Yet another Mars architecture

#197 2013-12-01 04:04:36

Re: Yet another Mars architecture

#198 2013-12-01 07:15:36

Re: Yet another Mars architecture

#199 2013-12-01 10:16:27

Re: Yet another Mars architecture

#200 2013-12-01 15:40:42

Re: Yet another Mars architecture

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