TUNNEL BORING MACHINES ARE MASSIVE PIECES OF EQUIPMENT -- TRAIN-SIZED MOBILE FACTORIES DESIGNED TO DIG INTO THE EARTH. COINCIDENTALLY, THEY'RE ALMOST PERFECTLY SHAPED TO FIT ABOARD A ROCKET TO MARS.
Full-scale TBM is way too heavy for the initial colony. Even on Earth, TBMs make economic sense only if you need to bore multi-kilometer long tunnels.I imagine much smaller machines will be used to build first Mars underground habitats. Perhaps these machines will be more versatile, not specialized only for tunneling work.
Something like a roadheader would be more ideal for use on Mars then a TBM since it's much simpler and lighter and you would have more flexibility in the shape of the chambers that can be created.
Quote from: Patchouli on 01/08/2017 06:03 pmSomething like a roadheader would be more ideal for use on Mars then a TBM since it's much simpler and lighter and you would have more flexibility in the shape of the chambers that can be created.So that's interesting - could a roadheader like that one be used for mining purposes, for raw material extraction?Can this thing be used for more than just tunneling?
Roadheaders were initially used for coal mining, so hell-yeah. Tunnels for the O-Train in Ottawa were done using three 135 ton roadheaders, and they were used for parts of the Big Dig..
The cutter above is often used to cut an arched tunnel, like a quonset hut, but there are other heads used for profile cutting such as squaring off. There are vertical versions for boring shafts. The head motors are hydraulic, so power can be whatever you can run the pump with; electric, or an IC using ISRU methalox. Possibly alcohol + GOX using a different ISRU process.
Quote from: docmordrid on 01/12/2017 08:40 amRoadheaders were initially used for coal mining, so hell-yeah. Tunnels for the O-Train in Ottawa were done using three 135 ton roadheaders, and they were used for parts of the Big Dig..Wow, that's a lot of mass to send to the Moon or Mars.I wonder if the thing could be redesigned to shave weight off it?Additionally, making it all-electric power supply would also be required, as well as robotic/tele-operated/semi-autonomous.And for the lunar environment, there's that pesky angular dust which always messes things up.If you had something that big, and were using it all the time, you'd probably be able to expand your interior living space pretty rapidly from tunneling/burrowing.I wonder what the ideal layout would be for a burrow?
Quote from: docmordrid on 01/12/2017 05:56 pmThe cutter above is often used to cut an arched tunnel, like a quonset hut, but there are other heads used for profile cutting such as squaring off. There are vertical versions for boring shafts. The head motors are hydraulic, so power can be whatever you can run the pump with; electric, or an IC using ISRU methalox. Possibly alcohol + GOX using a different ISRU process.Gah, combustible fuels in an engine are just TERRIBLE if you're doing ISRU. They use about an order of magnitude more power (wasting like 90% of the energy) than electric, and since you have to bring along oxygen (and usually want to reclaim the water in the exhaust), usually don't even end up lighter even compared to battery power.I wish that idea would just die.
Just stating the options. I agree with electric, unless you're boring some distance from high power generation. You're not going to carry a reactor or 200 m^2 of panels around. Solid oxide fuel cells maybe...
Cutters work well enough, as long as whatever you're boring through is solid enough to be self supporting.. Otherwise you may need a boring machine with shield and have to erect support ribs/marscrete behind you. At least not too much water to deal with.. depending on where you're going..
If Musk were to use some kind of microwave drill thing to bore tunnels with, perhaps it could also microwave-sinter together the material forming the walls of the tunnel, to make it more self-supporting.
When Elon Musk goes into tunneling, as he is claiming, then I expect some novel method used. I strongly doubt that he would start a company using conventional boring heads. On earth those heads or at least the cutting implements are exchanged very frequently for wear. It would be very advantageous to have a method that reduces need of maintenance. On earth and much more so on Mars.
Well, I was thinking there was the mining/ISRU aspect to this as well. Perhaps a tunneling machine would eventually evolve into a mining machine, which could extract ore and maybe even feed it into a smelter. The article shows a large-sized machine as the current state of the art, but there's no reason that a smaller machine couldn't be used to bore large tunnels, if it had the right technology. I was thinking that microwave boring machine could be small enough and light-weight enough to be transportable to Mars, where it could be used to bore much larger cavities - although using the microwave approach for extracting ore might take some re-thinking (maybe with microwaves you could somehow bore and smelt at the same time?)And at the same time, a microwave-based approach might offer the chance to disrupt the marketplace and take business from the higher-cost established players.
Explosives work well, but drilling those holes would imo require manpower vs. automation. Drills get frequently stuck badly in holes and can require a frustrated artistry to remove.
Quote from: TripD on 01/14/2017 11:21 pmExplosives work well, but drilling those holes would imo require manpower vs. automation. Drills get frequently stuck badly in holes and can require a frustrated artistry to remove.Explosives are just a form of energy. On Mars they would probably need to be made from atmospheric nitrogen, and in some sense eventually come from solar energy. So might as well use the solar energy directly to drive equipment. Bringing the explosives from Earth would likely be too expensive.
Quote from: lamontagne on 01/14/2017 11:57 pmQuote from: TripD on 01/14/2017 11:21 pmExplosives work well, but drilling those holes would imo require manpower vs. automation. Drills get frequently stuck badly in holes and can require a frustrated artistry to remove.Explosives are just a form of energy. On Mars they would probably need to be made from atmospheric nitrogen, and in some sense eventually come from solar energy. So might as well use the solar energy directly to drive equipment. Bringing the explosives from Earth would likely be too expensive.I was not promoting bringing explosives from earth. I was bringing up the issue of having to drill many holes for any type of explosive. Rocks chip and pin the bit quite frequently. You literally have to outsmart the bit from time to time to retrieve it because shear torque will not work.
It might be better to rely on a cheaper prexisting Tunnel Boring Machine, The Universe, that has already created tunnels on Mars for us! Caves and Lavatubes likely already exist on the surface and a survey of these and their extent with human and robotic assets would be a better starting off goal. Most of these lava tubes are probably not ideal for habitation or not close to useful resources but a few probably are and with an extensive enough survey, these could be discovered.
Mars has significant weather.It sucks that lava tubes tend to be at high altitude where the air is thinner (harder EDL, greater temperature extremes, worse surface radiation, etc etc) and there's less water.
Quote from: Robotbeat on 01/25/2017 08:40 pmMars has significant weather.It sucks that lava tubes tend to be at high altitude where the air is thinner (harder EDL, greater temperature extremes, worse surface radiation, etc etc) and there's less water.Agree with most of the disadvantages, but why is worse surface radiation a problem if you're under 100' of rock?
"Personally, I'd doubt that the Moon has any lava tubes. From the theory of Late Heavy Bombardment which I've heard, the "Mare" areas are all due to impact heating and lava flooding, and not due to volcanic activity."I'm sorry but this is completely false. The idea that the maria were caused by impact heating was promoted by Harold Urey in the 1950s and 1960s, and even he accepted the alternative view promoted by Gene Shoemaker and confirmed by Apollo samples, that the maria are true volcanic lavas. Dating mare basalts shows that volcanism extended at least a billion years after the large basins were formed, and Shoemaker's observation of post-basin but pre-mare craters (Sinus Iridum, Archimedes, Cassini etc.) showed a substantial time gap between impact and lava. Check out Don Wilhelms' book 'To a Rocky Moon' for details.
What if... Radiation just ends up not being a big issue? Then there's not as much reason to be in a lava tube.
Personally, I'd doubt that the Moon has any lava tubes. From the theory of Late Heavy Bombardment which I've heard, the "Mare" areas are all due to impact heating and lava flooding, and not due to volcanic activity.
Quote from: pobermanns on 01/25/2017 08:40 pmPersonally, I'd doubt that the Moon has any lava tubes. From the theory of Late Heavy Bombardment which I've heard, the "Mare" areas are all due to impact heating and lava flooding, and not due to volcanic activity.That sure looks like a good candidate for a lava tube to me...
Personally, I'd doubt that the Moon has any lava tubes. From the theory of Late Heavy Bombardment which I've heard, the "Mare" areas are all due to impact heating and lava flooding, and not due to volcanic activity.However, your suggestion about the lower gravity on Mars might make the necessary difference. Frankly, I can't see how even expert volcanologists can predict this one. Any rock-hounds out there?
Frankly, I would not put too much credence into suggestions of a late bombardment* seeing how the idea is caused by a statistical error [ http://www.pnas.org/content/113/39/10802 ], and further is not consistent with basic planetary physics and especially chemistry of the Tellus-Theia collision
And not surprisingly then it just doesn't fit with our biological record [ibid]. An extraordinary hypothesis needs extraordinary evidence, and in retrospect this hypothesis lacks that. (It would not be the first time... * If you want to satisfy the generic Nice model there are many observations that place the equivalent mechanisms in the natural early bombardment. Which planetary orbit changes is consistent with what we see in other systems.
Quote from: Phil Stooke on 01/25/2017 08:59 pm"Personally, I'd doubt that the Moon has any lava tubes. From the theory of Late Heavy Bombardment which I've heard, the "Mare" areas are all due to impact heating and lava flooding, and not due to volcanic activity."I'm sorry but this is completely false. The idea that the maria were caused by impact heating was promoted by Harold Urey in the 1950s and 1960s, and even he accepted the alternative view promoted by Gene Shoemaker and confirmed by Apollo samples, that the maria are true volcanic lavas. Dating mare basalts shows that volcanism extended at least a billion years after the large basins were formed, and Shoemaker's observation of post-basin but pre-mare craters (Sinus Iridum, Archimedes, Cassini etc.) showed a substantial time gap between impact and lava. Check out Don Wilhelms' book 'To a Rocky Moon' for details.Well, if that's all true, then I tip my hat to an expert - which I personally ain't.
Quote from: Darkseraph on 01/08/2017 05:46 pmIt might be better to rely on a cheaper prexisting Tunnel Boring Machine, The Universe, that has already created tunnels on Mars for us! Caves and Lavatubes likely already exist on the surface and a survey of these and their extent with human and robotic assets would be a better starting off goal. Most of these lava tubes are probably not ideal for habitation or not close to useful resources but a few probably are and with an extensive enough survey, these could be discovered. I recently visited a lava tube, on Lanzarote Island (part of the Canary Islands). I'm not a geologist, so this was all-new for me. In case y'all have never seen one, here's my report on that.The tunnel starts from near sea level on the east side of the island, and goes uphill about 7 KM toward the summit of "La Corona". Our tour only went a about half a KM into it, starting at "Cueva de los Verdes", but I've seen a cross-section map that shows that it's continuous for most of the way. As shown on the JPG, another attraction, "Jameos del Agua", was a non-continuous but additional section, right on the Atlantic.The graphics that I've seen some members here post, about having multiple, half-cylinder pressure habitats within a lava tube, wouldn't have worked in the one that I visited. It wasn't wide or high enough. I didn't take any measurements, but I'd estimate that the widest point that I saw was 50-60 feet, and the highest about 40 feet. And at that widest point, the ceiling was only 20 feet. Many sections were much tighter, including places where we had to stoop to pass thru, although I'm sure that with explosives or other equipment these could have been expanded. There was one section where there were actually two levels, so perhaps such an area could have supported a structure of 100 foot in height. Some areas had strangely smooth walls, but most of the ceilings were very jagged. In many places the floor was relatively flat, but still with fist-sized or bowling-ball-sized rocks all over. Rock in-falls were common, but again, I'm sure that these could be cleared with time and effort. I would estimate that we were about 100 feet underground for most of the tour.Again, I'm no expert on this, so I defer to any of you who are.
Quote from: pobermanns on 01/25/2017 08:15 pmQuote from: Darkseraph on 01/08/2017 05:46 pmIt might be better to rely on a cheaper prexisting Tunnel Boring Machine, The Universe, that has already created tunnels on Mars for us! Caves and Lavatubes likely already exist on the surface and a survey of these and their extent with human and robotic assets would be a better starting off goal. Most of these lava tubes are probably not ideal for habitation or not close to useful resources but a few probably are and with an extensive enough survey, these could be discovered. I recently visited a lava tube, on Lanzarote Island (part of the Canary Islands). I'm not a geologist, so this was all-new for me. In case y'all have never seen one, here's my report on that.The tunnel starts from near sea level on the east side of the island, and goes uphill about 7 KM toward the summit of "La Corona". Our tour only went a about half a KM into it, starting at "Cueva de los Verdes", but I've seen a cross-section map that shows that it's continuous for most of the way. As shown on the JPG, another attraction, "Jameos del Agua", was a non-continuous but additional section, right on the Atlantic.The graphics that I've seen some members here post, about having multiple, half-cylinder pressure habitats within a lava tube, wouldn't have worked in the one that I visited. It wasn't wide or high enough. I didn't take any measurements, but I'd estimate that the widest point that I saw was 50-60 feet, and the highest about 40 feet. And at that widest point, the ceiling was only 20 feet. Many sections were much tighter, including places where we had to stoop to pass thru, although I'm sure that with explosives or other equipment these could have been expanded. There was one section where there were actually two levels, so perhaps such an area could have supported a structure of 100 foot in height. Some areas had strangely smooth walls, but most of the ceilings were very jagged. In many places the floor was relatively flat, but still with fist-sized or bowling-ball-sized rocks all over. Rock in-falls were common, but again, I'm sure that these could be cleared with time and effort. I would estimate that we were about 100 feet underground for most of the tour.Again, I'm no expert on this, so I defer to any of you who are.40 feet wide and 20 feet high for several kilometers could house a pretty significant base. You don't need a blowup structure inside except to start off with. Seal the ends then pressurize.
You want a glassified tunnel surface to prevent zillions of small air leaks and act as its own pressure vessel. Glass forced into cracks also acts as anchors to provide mechanical support for the walls and ceilings
I would think that a better idea would be to have a whole bunch of relatively small modules, which could be linked together, ad hoc. That would allow the arriving astronauts to set things up as the physical dimension limits allowed, and yet still use the lava tube for protection.
Quote from: pobermanns on 01/26/2017 08:50 pmQuote from: sghill on 01/26/2017 01:17 pmYou want a glassified tunnel surface to prevent zillions of small air leaks and act as its own pressure vessel. Glass forced into cracks also acts as anchors to provide mechanical support for the walls and ceilingsI'm uploading a few pix from my trip to the two sites on Lanzarote. Perhaps you all will find these instructive. The first 6 are from the long tube, which extends most of the way to the summit. The last one is from the place on the Atlantic, which is non-continuous with the rest of the lava tube. It is has cave-ins on both ends, with a shallow pond of collected rainwater inside of it.Gorgeous photos. They illustrate perfectly why lava tubes won't be used IMHO. You'd have no idea about the mechanical strength and stability of the tube, and their wildly varying shapes and ragged edges would force you to tunnel through the tunnel to get some sort of standardized diameter- which you would then have to reinforce.All of this would be done in a hard vacuum over months or years with materials brought from Earth, and they'd be small tools too because of shipping constraints.So much safer, cheaper, and easier to use an electric TBM or welding subterrene and make a new tunnel, then only ship an airlock door, which you mount to the sealed walls. You're already going to have to send up a huge powerplant, so it's not your limiting constraint. The ITS diameter and mass to Mars is your limiting constraint.And I haven't even broached the subject of longevity. A glassified tunnel would exist for eons. Anything less will not. If we're serious about colonizing Mars with anything less than complete terraforming, then we need to think on the time scales of civilizations, not decades.
Quote from: sghill on 01/26/2017 01:17 pmYou want a glassified tunnel surface to prevent zillions of small air leaks and act as its own pressure vessel. Glass forced into cracks also acts as anchors to provide mechanical support for the walls and ceilingsI'm uploading a few pix from my trip to the two sites on Lanzarote. Perhaps you all will find these instructive. The first 6 are from the long tube, which extends most of the way to the summit. The last one is from the place on the Atlantic, which is non-continuous with the rest of the lava tube. It is has cave-ins on both ends, with a shallow pond of collected rainwater inside of it.
I think trying to make them air tight might not be worth it. Probably just using it as extra shelter from radiation and temperature swings. Maybe if you find a big one that is strong, you can pressurize it to 1-2psi with outside air (in case it's leaky) as a double layer of safety for the habs. That'd mean a positive-pressure oxygen mask and/or helmet would work but you could have far better dexterity since the limbs wouldn't need to be pressurized.
Were you using pure oxygen in your positive pressure device?The Apollo suits were 3.5psi, without positive pressure breathing. They used pure O2.Some people climb Everest without oxygen. That's a partial pressure of just 1psi oxygen. Twice that is adaptable for pure oxygen, and if you add another 1psi of positive pressure (or some other method like blood doping), I think performance should be more than acceptable.
Except you adapt fairly quickly to higher altitudes, but it still takes weeks or months, you shouldn't compare your experience of just going from sea level to low pressure in minutes or hours. People who live at high altitudes have adapted to this. On Mars, you'll likely have lower pressures, so it'll be like living in Breckenridge or Aspen at 10000ft, then going hiking or skiing at 13000-14000ft.
So is .2 atm @ 100% o2 the same as 1 atm @ 20% o2?
It's not perfect adaption. As you go higher and higher, it's harder and harder. But this is the reason why people who attempt Mount Everest stay at the base camp for a while before starting the real climb. You have to give your body time to adapt. And you don't have to be born some place to take advantage of it. Merely living there a while can do it.Over the longer term, many generations, you get actual genetic adaptations. The Tibetans are a classic example, who adapted to the high altitudes (15000 ft... The average altitude of the whole country is higher than any peak in Colorado) after splitting off from their low altitude cousins just 2750 years ago. Gene therapy can probably accelerate this and help regular people adapt, too. And so there's a long-term reason to make your habs low-pressure: to develop adaptations (natural and artificial) to prepare Martians for the early days of terraforming when pressures will be very low.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.
Quote from: rsdavis9 on 01/27/2017 06:30 pmSo is .2 atm @ 100% o2 the same as 1 atm @ 20% o2?Referencing the Navy Flight Surgeons Manual ( http://www.med.navy.mil/sites/nmotc/nami/academics/Documents/FlightSurgeonsManual.pdf), 33,700 feet MSL yields the same blood O2 saturation level, when on 100% O2, as when breathing normally at sea level. That's about 4 psis. I don't know what the partial pressure of oxygen would be at .2 ATM, nor that the equivalent altitude would be, but I'm sure that a full-pressure suit would be mandatory.
Quote from: Robotbeat on 01/27/2017 06:48 pmIt's not perfect adaption. As you go higher and higher, it's harder and harder. But this is the reason why people who attempt Mount Everest stay at the base camp for a while before starting the real climb. You have to give your body time to adapt. And you don't have to be born some place to take advantage of it. Merely living there a while can do it.Over the longer term, many generations, you get actual genetic adaptations. The Tibetans are a classic example, who adapted to the high altitudes (15000 ft... The average altitude of the whole country is higher than any peak in Colorado) after splitting off from their low altitude cousins just 2750 years ago. Gene therapy can probably accelerate this and help regular people adapt, too. And so there's a long-term reason to make your habs low-pressure: to develop adaptations (natural and artificial) to prepare Martians for the early days of terraforming when pressures will be very low.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. I have respected your opinions on many previous posts, but in this case I think that you are wrong. Personal experience tells me that these are dangerous assumptions.
It would not be the first time I've been wrong.
Quote from: pobermanns on 01/27/2017 07:14 pmQuote from: rsdavis9 on 01/27/2017 06:30 pmSo is .2 atm @ 100% o2 the same as 1 atm @ 20% o2?Referencing the Navy Flight Surgeons Manual ( http://www.med.navy.mil/sites/nmotc/nami/academics/Documents/FlightSurgeonsManual.pdf), 33,700 feet MSL yields the same blood O2 saturation level, when on 100% O2, as when breathing normally at sea level. That's about 4 psis. I don't know what the partial pressure of oxygen would be at .2 ATM, nor that the equivalent altitude would be, but I'm sure that a full-pressure suit would be mandatory.0.2 atm is 20 kPa or 2.9 psi. It's the standard air pressure at 41,000 feet, and a full pressure suit is not critical, according to page 1-21 of that manual.
Quote from: envy887 on 01/27/2017 07:38 pmQuote from: pobermanns on 01/27/2017 07:14 pmQuote from: rsdavis9 on 01/27/2017 06:30 pmSo is .2 atm @ 100% o2 the same as 1 atm @ 20% o2?Referencing the Navy Flight Surgeons Manual ( http://www.med.navy.mil/sites/nmotc/nami/academics/Documents/FlightSurgeonsManual.pdf), 33,700 feet MSL yields the same blood O2 saturation level, when on 100% O2, as when breathing normally at sea level. That's about 4 psis. I don't know what the partial pressure of oxygen would be at .2 ATM, nor that the equivalent altitude would be, but I'm sure that a full-pressure suit would be mandatory.0.2 atm is 20 kPa or 2.9 psi. It's the standard air pressure at 41,000 feet, and a full pressure suit is not critical, according to page 1-21 of that manual.Thanks for finding that. And you're quite right. I guess that laziness prevented me from seeing the same thing. Or, since it's 10:30 PM here and I'm already thru a few great German Biers, I'm a little distracted.
Quote from: pobermanns on 01/27/2017 08:38 pmQuote from: envy887 on 01/27/2017 07:38 pmQuote from: pobermanns on 01/27/2017 07:14 pmQuote from: rsdavis9 on 01/27/2017 06:30 pmSo is .2 atm @ 100% o2 the same as 1 atm @ 20% o2?Referencing the Navy Flight Surgeons Manual ( http://www.med.navy.mil/sites/nmotc/nami/academics/Documents/FlightSurgeonsManual.pdf), 33,700 feet MSL yields the same blood O2 saturation level, when on 100% O2, as when breathing normally at sea level. That's about 4 psis. I don't know what the partial pressure of oxygen would be at .2 ATM, nor that the equivalent altitude would be, but I'm sure that a full-pressure suit would be mandatory.0.2 atm is 20 kPa or 2.9 psi. It's the standard air pressure at 41,000 feet, and a full pressure suit is not critical, according to page 1-21 of that manual.Thanks for finding that. And you're quite right. I guess that laziness prevented me from seeing the same thing. Or, since it's 10:30 PM here and I'm already thru a few great German Biers, I'm a little distracted.HEY wait a second. We have MUCH better beer here in NH.
Es tut mir leid, aber die deutsche Biere sind die Beste der Welt! Mein Großvater war ein Deutscher, und das hat er mir als Kind erzählt!............@guckyfan - maybe you can double-check my German? Thanks.
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.
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.
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.
Except you adapt fairly quickly to higher altitudes, but it still takes weeks or months, you shouldn't compare your experience of just going from sea level to low pressure in minutes or hours. People who live at high altitudes have adapted to this. On Mars, you'll likely have lower pressures, so it'll be like living in Breckenridge or Leadville at 10000ft, then going hiking or skiing at 13000-14000ft.
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.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.-----------------------------------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.
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.
Why?
People go to high altitudes without such preselection.
Also, there are countermeasures available for those who'd want to stay.
No, simpler ones. Anyway, basically everyone who doesn't have a profound health problem can adapt to high altitude.Again, this is the bias of ignorance of people who have not spent much time at high altitudes, manifesting in fear.
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.
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.
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.
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.
Low landers can adapt to living and working at altitude given time and patience (a few weeks)
I have to admit I don't really understand why the air pressure is such an issue. We need to design in safety factors anyway, so why not design for full pressure, and over time optimise for lower pressure if it turns out to be useful or beneficial? Creating the atmospheres for habitats will not be a major energy drain on the colony, compared to fuel and food production.Yes, lower pressure would allow for less massive habitats, but using in situ resources is that an issue? What construction problems does a 30% lower pressure solve, or even 50% lower? Isn't radiation protection more massive than whatever structural element is used anyway?
what was the pressure limit for no prebreathing? I know it is up thread someplace.
If you are going to design for a civilization and not an outpost, then you need to be at 9 psi or higher. Why? Because we literally have thousands of examples of towns and cities here on Earth where the cutoff is at 9 psi. People just don't breed and live at lower pressures. It's ok temporarily, but not for living.
But just for personal interest, if 9psi is reasonable on earth, then about what would you end up with if you kept the same partial pressure of oxygen while lowering the total pressure.. to exactly the point where the fire risk rises to again equal earth sealevel?
I wonder if a higher O2 PP will help increase tolerance of relatively high CO2. It seems to me CO2 scrubbing will be an ongoing concern, and if tolerance for it can be increased it can mitigate some risk.
Quote from: Jcc on 02/04/2017 02:28 pmI wonder if a higher O2 PP will help increase tolerance of relatively high CO2.[...] However, what leads you to believe that higher O2 would combat CO2 toxicity?
I wonder if a higher O2 PP will help increase tolerance of relatively high CO2.
When he first outlined his plans for Mars, he talked about people living in geodesic domes on the Martian surface. But he was probably called out on that part, by skeptics who didn't feel the dome idea could work (pressure forces, etc). So because of this, he's probably now shifting to the tunnel idea
Also to keep radiation exposure to within acceptable limits, time spent in domes on the surface should be controlled, although valuable for aesthetic and psychological reasons.
We have a rover on Mars (MSL) which includes an instrument capable of measuring the biological equivalent of the radiation received, not just raw radiation level.
Quote from: sanman on 02/05/2017 09:21 pmWhen he first outlined his plans for Mars, he talked about people living in geodesic domes on the Martian surface. But he was probably called out on that part, by skeptics who didn't feel the dome idea could work (pressure forces, etc). So because of this, he's probably now shifting to the tunnel idea Just to be pedantic, he originally said people live in domes, industry in tunnels. So there's nothing inconsistent with his original statements in his pursuing tunnelling technology.
But I am sure that Elon Musk sees at least one such dome with green plants as indispensible for the colony from the early days on. If only people know it is there and they can go and spend some time between plants and see the outside, if they want to.
Quote from: Robotbeat on 02/07/2017 01:45 amWe have a rover on Mars (MSL) which includes an instrument capable of measuring the biological equivalent of the radiation received, not just raw radiation level.No we don't. The only instrument capable of measuring the biologic impact would be a living organism. Once a sufficiently large number of living organisms have been exposed to the radiation and effects determined we can then apply that info to the readings of radiation measuring devices. The relation is presently only based on assumptions.
Accelerated or burst exposure to radiation will not give a sufficiently accurate biologic response. But that is what we can do on earth. We don't have affordable radiation sources that can provide constant low simulations of cosmic background radiation.
Yes I believe we have them. They are called airplanes. And the test subjects are called pilots and flight attendees. They might not operate at the same radiation level as there would be on Mars, but that a start with a large sample size. The other experiment using astronauts has probably a too small sample size and time of exposure for a statically significant conclusion. Before you name the missing magnetic field of Mars, I think that is only applicable for solar flare radiation but irrelevant for cosmic radiation. Not 100% sure though.
Something tells me that making a dome that gives equal protection, while being transparent enough to see the outside, and perhaps color matched to not look too Orangeto th einhabitants inside, is going to be a tricky piece of materials and structural engineering.
Just a reminder.To give the equivalent protection that Earth's atmosphere provides people at Sea Level takes about 3m of Martian Regolith. Something tells me that making a dome that gives equal protection, while being transparent enough to see the outside, and perhaps color matched to not look too Orangeto th einhabitants inside, is going to be a tricky piece of materials and structural engineering. Plants seem to be more tolerant of lower pressures and higher radiation, so slightly pressurized "green houses" seem to be the way to go to grow food without the huge cost of artificial light while staying underground (or burrowed into a cliff face) seems to be the way to go for humans.
Elon Musk mentioning a geodesic dome suggests a different approach. Build the dome to just contain pressure and be transparent. Think the panorama window in ITS. Build structures with radiation shielding inside. Those can have windows and a shielded porch to look at the plants and going outside for an hour or two a day would be OK in your radiation budget unless you are pregnant or an infant.
Quote from: john smith 19 on 03/04/2017 08:36 amJust a reminder.To give the equivalent protection that Earth's atmosphere provides people at Sea Level takes about 3m of Martian Regolith. Something tells me that making a dome that gives equal protection, while being transparent enough to see the outside, and perhaps color matched to not look too Orangeto th einhabitants inside, is going to be a tricky piece of materials and structural engineering. Plants seem to be more tolerant of lower pressures and higher radiation, so slightly pressurized "green houses" seem to be the way to go to grow food without the huge cost of artificial light while staying underground (or burrowed into a cliff face) seems to be the way to go for humans. Mars has quite a few magnetic anomalies, especially in the south, which will provide some protection.As for the radiation protection - ice. Sandwich between two sheets of glass, and the internal pressure will counteract the weight, there have been plenty of threads on this, and papers on the net.The sky colour won't be a problem. Human eyes adapt very quickly to coloured lighting conditions. Indoor lights are very different to natural "white" sunlight, yet white things still look white to you.If you look at the exposed rocks from one of the rover pictures, they often look slightly blue - they aren't. They're a grey colour, as you'd find on the Moon or Earth, your eye is just auto-balancing against the ochre-orange of Mars.
Quote from: guckyfan on 03/04/2017 08:47 amElon Musk mentioning a geodesic dome suggests a different approach. Build the dome to just contain pressure and be transparent. Think the panorama window in ITS. Build structures with radiation shielding inside. Those can have windows and a shielded porch to look at the plants and going outside for an hour or two a day would be OK in your radiation budget unless you are pregnant or an infant.Elon musks' actual words (Reddit AMA):"Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space."- The "huge amount of pressurized space" of his base on Mars will obviously be subterranean.
Just a reminder.To give the equivalent protection that Earth's atmosphere provides people at Sea Level takes about 3m of Martian Regolith.
Thinking of my adolescent son, playing in front of his computer, I don't think he sees natural light more than a few minutes every week
Literacy in general is a risk factor in nearsightedness. Reading books.
So, what you are saying is that the Mars colonists living in tunnels and caves for the first couple of generations will become a race of blind moles?
Quote from: Robotbeat on 03/05/2017 03:17 amLiteracy in general is a risk factor in nearsightedness. Reading books.No, that's what the new research tested. It's not books or TV or video-games. (Or close work in general.) It's that kids who preferred those activities tended to spend less time in the sun. Once you correct for that, the link with reading/education, or other activities is eliminated.
But how much of Earth's atmosphere is needed for adequate radiation shielding? After all, people live quite happily in Nepal and Tibet, which have approximately only 30% of the atmospheric pressure at sea level (ref).Also, Mars does have an atmosphere, which provides some shielding, and the Solar radiation flux is less.
(The Sydney Myopia Study tracked 4000 school-age children from 55 schools. The only statistically significant link was time spent outdoors. Follow-up animal studies showed the that light levels alone can alter eye elongation (the cause of myopia.) It seems to be related to dopamine levels in the eye, which is related to switching between rod and cone dominated vision. Block the dopamine pathway (yet further follow-up research) and you not only induce 100% myopia in the animals, but eliminate the protective effect of light exposure. In a school trial in Sydney, they added 50 minutes of additional sun exposure to the school day, and saw a 25% reduction in myopia. In Taiwan, researchers were able to convince authorities to add 100 minutes of extra sun exposure to school days, and saw a 50% reduction in myopia.)
Given Mars is so much farther away from the Sun it already starts out with a lower solar level than Earth. Multiply by lack of regular exposure and the long term effects could be severe.Unless people are prepared to look at "anti-myopia" pills.
Quote from: Paul451 on 03/05/2017 03:45 amThe Sydney Myopia Study tracked 4000 school-age children from 55 schools. The only statistically significant link was time spent outdoors. Follow-up animal studies showed the that light levels alone can alter eye elongation (the cause of myopia.) It seems to be related to dopamine levels in the eye, which is related to switching between rod and cone dominated vision. [...] This is very exciting, suggesting myopia can be radically reduced in developed countries.
The Sydney Myopia Study tracked 4000 school-age children from 55 schools. The only statistically significant link was time spent outdoors. Follow-up animal studies showed the that light levels alone can alter eye elongation (the cause of myopia.) It seems to be related to dopamine levels in the eye, which is related to switching between rod and cone dominated vision. [...]
Given Mars is so much farther away from the Sun it already starts out with a lower solar level than Earth.
Or have brighter indoor lighting?
Quote from: gospacex on 03/07/2017 02:32 pmOr have brighter indoor lighting?If you are currently in a brightly lit room, the lighting level will be around 1000 lux. We need 30-40,000 lux. So multiply the number of lights in your room by 40-fold over the same area. Then, even allowing for LED efficiencies, think about the power consumed, the heat released, and the annoyance of working on anything with a screen. It seems unlikely anywhere outside a grow-chamber (indoor greenhouse).