How about looking at some numbers?Sea level pressure is 14.7 psi with 21% O2. That yields an O2 partial pressure of 3.1 psi.Airliner cabins are pressurized at levels between 6000 ft and 8000 ft. This effective altitude is used because almost everyone can handle it without medical issues.Using the high end of 8000 ft, air pressure is 76% of sea level, resulting in an O2 partial pressure of 2.4 psi.Quote from: Coastal Ron on 01/28/2017 07:10 pmNASA is incorporating that into their HI-SEAS (Hawai’i Space Exploration Analog and Simulation) Mars simulation on Hawaii's Mauna Loa, located at an altitude of only 8,200 feet.So, NASA is already thinking about this, having the test at 8200 ft.Quote from: clongton on 01/28/2017 06:18 pmWhen I visit my relatives in Denver it takes me 1 to 1-1/2 days before my high altitude headaches go away, but I remain short of breath for a good week or more. They tell me that it took them almost a full year after they moved there before they were fully comfortable with the lower pressure and able to always breath easy like they used to in Connecticut before the move without shortness of breath.Adaption can take awhile. . .Quote from: MickQ on 01/28/2017 06:44 amOnce ITS goes thru TMI there will be 3+ months for pressure and O2 levels to be adjusted from Earth norm toMars norm, whatever that turns out to be. Should be time enough to adapt.That will be enough time for most people. Others may need to stay at an 8000 ft facility before launch.Now remember that 2.4 psi O2 partial pressure I was talking about? In an 8 psi habitat that would be 30% O2. Slight increase in fire risk, so hab designers need to take that into consideration. An advantage of 8 psi with 30% O2 is someone can go straight to a spacesuit without prebreathing. Good for anyone who needs to work outside.Speaking about spacesuits, they are at 4.7 psi with 100% O2 for a good reason. You don't really want to go lower pressure than that because you need to work, not be fatigued and just getting by.Now how does this relate to the actual topic of this thread? Well, habs can be at 8 psi with 30% O2, the interior of the lava tube or tunnel can be at 4.7 psi with 100% inert gas (no fire risk at all) and anyone having to work exposed in the pressurized lava tube will only need an oxygen mask.If everybody isn't comfortable at 8 psi, then the main habs can be at a more Earth-like atmosphere and only work areas with airlocks can be at 8 psi.Check out www.altitude.org for information on going above 8000 ft.
NASA is incorporating that into their HI-SEAS (Hawai’i Space Exploration Analog and Simulation) Mars simulation on Hawaii's Mauna Loa, located at an altitude of only 8,200 feet.
When I visit my relatives in Denver it takes me 1 to 1-1/2 days before my high altitude headaches go away, but I remain short of breath for a good week or more. They tell me that it took them almost a full year after they moved there before they were fully comfortable with the lower pressure and able to always breath easy like they used to in Connecticut before the move without shortness of breath.
Once ITS goes thru TMI there will be 3+ months for pressure and O2 levels to be adjusted from Earth norm toMars norm, whatever that turns out to be. Should be time enough to adapt.
FWIW there are ways to minimize the impact on altitude disruption. When going to high altitude, one can increase red meat consumption to allow for greater red blood cell demand to carry oxygen. Conversely, when losing the adaptation, one steers clear of iron bearing items in ones diet to allow for the liver to absorb the load of too much hemoglobin breaking down.
When I've been at extreme altitudes, primary concern is hypoxia - it sneaks up on you in peculiar ways. To train you for it, you're conditioned in a hyperbaric chamber for considerable time with a few others in somewhat humorous circumstance. Even then, when returning from a mission almost landed on the road next to the runway instead of the runway. The adjacent power/telephone poles were a dead giveaway …
Many have nitrogen bubbles in bones/cartilage, so at altitude you get strange aches in weird places. A particular favorite is quite literally a pain in the tailbone (coccyx). I have decades old shrapnel wounds that have had trapped gas pockets that took awhile to find and "pop", would reliably give "charlie horse" in a muscle above 50,000 ft.
There are many who have vision problems at altitude, and it may take a day or two before they show up. Have to chase that one down, but I think it has something to do with vitreous humor pressure.And, decades back, watched many fall out of the AF academy because of sinus problems/allergies and altitude. They did not want to do be at the bottom of a silo or fly a desk.
Curious! But don't understand the last part about avoiding iron-bearing foods. Why?
Now remember that 2.4 psi O2 partial pressure I was talking about? In an 8 psi habitat that would be 30% O2. Slight increase in fire risk, so hab designers need to take that into consideration.
the interior of the lava tube or tunnel can be at 4.7 psi with 100% inert gas (no fire risk at all) and anyone having to work exposed in the pressurized lava tube will only need an oxygen mask.
Quote from: pobermanns on 01/28/2017 11:07 pmCurious! But don't understand the last part about avoiding iron-bearing foods. Why?I interpreted it as trying to reduce the load on the liver, while it's removing excess haemoglobin.Quote from: RonM on 01/28/2017 10:30 pmNow remember that 2.4 psi O2 partial pressure I was talking about? In an 8 psi habitat that would be 30% O2. Slight increase in fire risk, so hab designers need to take that into consideration.No. You can't expect a whole colony to be like a vehicle/lander. You have to assume that you can't control the materials that closely. Hence, any increased fire risk is unacceptable.IMO, even the baseline fire risk of Earth at sea-level is unacceptable in a closed atmosphere. That's why I've suggested higher total pressure (right back to 14-15psi) but the lowest O₂ levels we can get away with, without making people lethargic/clumsy when doing heavy work or complex mental tasks, say 2-2.25psi. Keep the oxygen fraction below 15%. Reduce the fire risk, not debate how much we can increase it.Remember, you're going to be doing stuff that would never be allowed in a more conventional NASA moon/Mars mission. Welding, grinding, fabbing, moulding, lubing, etc. Fumes and sparks and hydrocarbons and random materials and machinery. And those are precisely the areas where the workers themselves will need the most oxygen for breathing (coz they're working). And if you aren't running the workshop/machine-room/repair areas at reduced pressure, what's the point of doing it through the rest of the hab?Quote from: RonM on 01/28/2017 10:30 pmthe interior of the lava tube or tunnel can be at 4.7 psi with 100% inert gas (no fire risk at all) and anyone having to work exposed in the pressurized lava tube will only need an oxygen mask.Although it's worth remembering that even with nitrogen, the effects of losing oxygen are quick and deceptive. (Faster than holding your breath. Biology is weird.) You will still need to treat every trip into a non-oxygenated area like a deep dive or cave dive. With buddy-systems and checklists and safety-areas and people "up top" ready to call in a rescue if you don't check in on cue. (And pure CO₂ doesn't have to leak much around your mask before you're symptomatic.)
Reply to myself.... Highest town in the US is about 3000m so it is possible to live higher for us sea level dwellers.
Quote from: RonM on 01/28/2017 10:30 pmNow remember that 2.4 psi O2 partial pressure I was talking about? In an 8 psi habitat that would be 30% O2. Slight increase in fire risk, so hab designers need to take that into consideration.No. You can't expect a whole colony to be like a vehicle/lander. You have to assume that you can't control the materials that closely. Hence, any increased fire risk is unacceptable.IMO, even the baseline fire risk of Earth at sea-level is unacceptable in a closed atmosphere. That's why I've suggested higher total pressure (right back to 14-15psi) but the lowest O₂ levels we can get away with, without making people lethargic/clumsy when doing heavy work or complex mental tasks, say 2-2.25psi. Keep the oxygen fraction below 15%. Reduce the fire risk, not debate how much we can increase it.Remember, you're going to be doing stuff that would never be allowed in a more conventional NASA moon/Mars mission. Welding, grinding, fabbing, moulding, lubing, etc. Fumes and sparks and hydrocarbons and random materials and machinery. And those are precisely the areas where the workers themselves will need the most oxygen for breathing (coz they're working). And if you aren't running the workshop/machine-room/repair areas at reduced pressure, what's the point of doing it through the rest of the hab?
Quote from: RonM on 01/28/2017 10:30 pmthe interior of the lava tube or tunnel can be at 4.7 psi with 100% inert gas (no fire risk at all) and anyone having to work exposed in the pressurized lava tube will only need an oxygen mask.Although it's worth remembering that even with nitrogen, the effects of losing oxygen are quick and deceptive. (Faster than holding your breath. Biology is weird.) You will still need to treat every trip into a non-oxygenated area like a deep dive or cave dive. With buddy-systems and checklists and safety-areas and people "up top" ready to call in a rescue if you don't check in on cue. (And pure CO₂ doesn't have to leak much around your mask before you're symptomatic.)
Quote from: Space Ghost 1962 on 01/28/2017 10:49 pmConversely, when losing the adaptation, one steers clear of iron bearing items in ones diet to allow for the liver to absorb the load of too much hemoglobin breaking down. Curious! But don't understand the last part about avoiding iron-bearing foods. Why?
Conversely, when losing the adaptation, one steers clear of iron bearing items in ones diet to allow for the liver to absorb the load of too much hemoglobin breaking down.
Quote from: clongton on 01/28/2017 06:18 pmQuote from: Robotbeat on 01/27/2017 06:48 pmI can tell a lot of people have misconceptions about high altitudes. Maybe we have people who live in Denver (Lockheed, etc) design the habs so we don't get this low lander bias in the design. When I visit my relatives in Denver it takes me 1 to 1-1/2 days before my high altitude headaches go away, but I remain short of breath for a good week or more. They tell me that it took them almost a full year after they moved there before they were fully comfortable with the lower pressure and able to always breath easy like they used to in Connecticut before the move without shortness of breath.I think low pressure acclimation here on Earth for altitude changes is something that is not completely understood, or at least not predictable without actually experiencing it.For instance, I've done a lot of backcountry backpacking, mostly at altitudes between 7-12,000 feet, and once even to 14,000. I live along the coast (but you knew that) and I've never had altitude sickness. At most we would acclimate for one night before doing our backpacking trips. And this is while humping 50 lb loads on our backs while climbing sometimes aggressively vertical trails.But one of my backpacking buddies was concerned about altitude sickness, and his doctor prescribed him something for our 14,000 foot trip - which apparently helped (or at least didn't hurt).So maybe one way to know ahead of time if someone is going to being able to acclimate quickly or not is to send them to a high altitude camp for a couple of weeks of strenuous work? Cheaper than taking the trip to Mars and finding out that low pressure is an issue.NASA is incorporating that into their HI-SEAS (Hawai’i Space Exploration Analog and Simulation) Mars simulation on Hawaii's Mauna Loa, located at an altitude of only 8,200 feet.
Quote from: Robotbeat on 01/27/2017 06:48 pmI can tell a lot of people have misconceptions about high altitudes. Maybe we have people who live in Denver (Lockheed, etc) design the habs so we don't get this low lander bias in the design. When I visit my relatives in Denver it takes me 1 to 1-1/2 days before my high altitude headaches go away, but I remain short of breath for a good week or more. They tell me that it took them almost a full year after they moved there before they were fully comfortable with the lower pressure and able to always breath easy like they used to in Connecticut before the move without shortness of breath.
I can tell a lot of people have misconceptions about high altitudes. Maybe we have people who live in Denver (Lockheed, etc) design the habs so we don't get this low lander bias in the design.
Remember, you're going to be doing stuff that would never be allowed in a more conventional NASA moon/Mars mission. Welding, grinding, fabbing, moulding, lubing, etc. Fumes and ...
There are many engineering tradeoffs to consider. It will depend on what the colony can produce. A Mars research base could easily be designed with flame resistant materials,
We can discuss the options, but without actually designing all the colony systems we can't definitely say which option is best.
Quote from: Paul451 on 01/29/2017 12:03 amQuote from: RonM on 01/28/2017 10:30 pmthe interior of the lava tube or tunnel can be at 4.7 psi with 100% inert gas[wah, wah, inert can be bad too]Maybe it's not a good idea to pressurize the lava tube. Might be better to use a spacesuit anyway.
Quote from: RonM on 01/28/2017 10:30 pmthe interior of the lava tube or tunnel can be at 4.7 psi with 100% inert gas[wah, wah, inert can be bad too]
the interior of the lava tube or tunnel can be at 4.7 psi with 100% inert gas
Quote from: Paul451 on 01/29/2017 12:03 amRemember, you're going to be doing stuff that would never be allowed in a more conventional NASA moon/Mars mission. Welding, grinding, fabbing, moulding, lubing, etc. Fumes and ...As an aside it's worth noting that an additional angle to this is the normal outgassing of very commonly used solvents and lubricants that can contaminate the atmosphere in close loop systems. Used normally on earth they are simply absorbed into the air and dissipated with no harmful effects. In closed loop systems, like submarines for instance, studies have demonstrated the O2% of the breathable air and the ambient pressure both, individually and in conjunction with each other, affects the outgassing process. So it's not just a matter of how much oxygen is available to breath. Naturally produced outgassing of the materials we use everyday that are health harmful need to part of the equation of determining the pressure/O2 mix ratio. And because we don't have a planet's whole atmosphere readily available to dissipate them into, removal of those contaminates may be harder than one would normally expect before they can be vented into the Martian air.
Well the highest inhabited village in Europe is Ushguli at about 2100m (7000'). Populations live higher than that, and in large numbers, but they are genetically adapted to the altitude.If you are thinking of having permanent populations of physiologically adapted I'd suggest that as an upper limit for now.