Author Topic: Airlocks for Mars Colony  (Read 48110 times)

Offline RocketmanUS

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Airlocks for Mars Colony
« on: 01/20/2017 08:32 pm »
This thread is for airlocks for a Mars colony. The air locks are for people, trucks and or equipment. They can be for one person or many people. They can be for small, big trucks, or multiple trucks.

The air pressure on the ISS is at Earth sea level. You can use what ever pressure you like for your airlock concepts. The air mixture in the colony is expected to be primarily nitrogen and oxygen.

Issues on Mars with airlocks-
Lose of some air when door is opened to Mars outside of the airlock.
Dust from Mars getting into colony habitable space.
CO2 getting into habitable area when people or equipment reenter.
How much energy is needed for egress.

Splinter thread from-
Envisioning Amazing Martian Habitats
https://forum.nasaspaceflight.com/index.php?topic=41427.0

Offline Jim

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Re: Airlocks for Mars Colony
« Reply #1 on: 01/21/2017 02:55 am »
And?

Offline RocketmanUS

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Re: Airlocks for Mars Colony
« Reply #2 on: 01/21/2017 06:37 am »
Air pressure in airlock A is at habitat air pressure. Air pressure in airlock B is at Mars atmospheric pressure for that location.
A is ready for people or equipment to enter from hab. B is ready for people or equipment returning from outside.

Person enters airlock A and door closes. Valve opens to airlock B and air flows to B until both have the same pressure ( no energy needed except to open and close valve ).  Valve in A opens and air is pumped into air tank till A is near a vacuum ( saves N2 and O2 ). Valve in A is opened to Mars outside letting in air ( CO2 ) till A has same pressure as out side, valve is closed and door to outside is opened and persons walks out.

When person is ready to reenter A is ready. Person enters and door is closed. Valve is opened and pump takes the air pressure down to near vacuum sending the CO2 back to the outside ( helps keep CO2 out of A and hab ). Valve between A and B is opened and air flows back from B to A till they have the same pressure. Valve is closed and another valve is opened using using a vacuum pump to send the rest of the air from B back to A  ( B is then near vacuum ), valve closes and pump turn off. Then air ( hab air N2/O2 from air tank ) is let back in till it has the same air pressure as hab. A vacuum hose and attachment like from a shop vac is used to vacuum the dust off the persons suit and inside airlock A helping keep dust out of the hab. Door is opened in A to hab and person returns to prep area.

Using two airlocks only half the air pressure is pumped when exiting, the rest is done by high pressure to low pressure flow between the two airlocks. When entering back only half of what is in B needs to be pumped back to A as half air pressure would flow fro high pressure to low , B to A.

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #3 on: 01/21/2017 08:16 pm »
Using two airlocks only half the air pressure is pumped when exiting, the rest is done by high pressure to low pressure flow between the two airlocks. When entering back only half of what is in B needs to be pumped back to A as half air pressure would flow fro high pressure to low , B to A.

As I said in the other thread, you aren't saving any energy, there's no free lunch.

Offline Bob Shaw

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Re: Airlocks for Mars Colony
« Reply #4 on: 01/21/2017 08:26 pm »
I'm not at all sure why you'd need to worry about CO2 from outside getting into the air inside. The mass of any incoming Martian air is minimal compared to the habitat air, and if required then the airlock procedures could simply employ a partial flush cycle to blow away the CO2 as the entry volume is initially pressurised.

Offline Ionmars

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Re: Airlocks for Mars Colony
« Reply #5 on: 01/22/2017 12:10 am »
We don't usually think this way, but co2 above 1 pct is toxic to humans. The long term occupational health level is set to 0.5 pct in the US. So whether or not the co2 in an airlock is a problem will depend on specific circumstances.

First, is the airlock volum significant compared with the indoor space the person will enter. One function of the ECLSS system for the indoor space is to remove co2 from breathable air. So if the indoor volume is 100 times the volume of the airlock, I wouldn't worr about it. But if the indoor space is small, say a small garage for 1 or 2 vehicles then we may have a concern. If the airlock contains Martian air at 96 pct co2 but the pressure is raised 20 times to match the inside air then when the interior door is opened, the amount of co2 entering may be signicant. If the indoor volume were say 10 times airlock volume then it might not take too many airlock openings to reach 1pct.

We can't be sure of operating conditions at all times, so it might be good practice to pump out as much outdoor air as we can before refilling the airlock with indoor air, not co2.

If we are employing  a double lock system as suggested here, we would be using indoor air from airlock 1 to refill airlock 2, etc. This would be a good way to conserve indoor air, which is expensive to create on Mars.

Offline RocketmanUS

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Re: Airlocks for Mars Colony
« Reply #6 on: 01/22/2017 02:12 am »
Using two airlocks only half the air pressure is pumped when exiting, the rest is done by high pressure to low pressure flow between the two airlocks. When entering back only half of what is in B needs to be pumped back to A as half air pressure would flow fro high pressure to low , B to A.

As I said in the other thread, you aren't saving any energy, there's no free lunch.
Have two identical containers connected at their base with a valve in between the two. Have one on the left filled to its top with water. The one on the right is empty. Open the valve, the water will flow to the other container till the water is at the same level in both, no pumping needed. Now if you want the rest of the water in the right side container to be in the left side container then a pump is needed. We don't need to pump all the water from one side to the other , just half of it. It should be the same for the two airlocks except we are dealing with air pressure.

So how does this not save energy in not having to pump all the air out of airlock A into B as some of it will flow to B until the two airlocks have the same pressure?

Offline john smith 19

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Re: Airlocks for Mars Colony
« Reply #7 on: 01/22/2017 09:13 am »
Using two airlocks only half the air pressure is pumped when exiting, the rest is done by high pressure to low pressure flow between the two airlocks. When entering back only half of what is in B needs to be pumped back to A as half air pressure would flow fro high pressure to low , B to A.
You do realize that using B to pressurize A on the return leg will pressurize it not to (Phab-Pmars/2) but ((Phab-Pmars/2)/2) IE 1/4 of hab pressure, not 1/2 of hab pressure right? That leaves you with 3/4 of the Phab pressure to make up from the gas you pumped out of the lock on exit and storage or by pumping it back into A from B and the rest from storage.

At best you can schedule some of the pumping energy needed to pressurize and de pressurize the locks. You also have a lowish pressure differential (but high volume) air pump between chambers.
It's easy to depreussurize a lock on Mars, you just vent it. However given Mars Patm is 1/160 of Earth conserving that atmosphere on a long term basis is likely to be important.

Likewise it's easy to pressurize a chamber if you have a much higher pressure storage tank.

The benefits of a low pressure differential pump are cancelled by the high volume it's going to pump. You will still need a high pressure pump to keep the main habitat reserve tanks pressurized in any case.
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Offline Ionmars

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Re: Airlocks for Mars Colony
« Reply #8 on: 01/22/2017 09:29 am »

You do realize that using B to pressurize A on the return leg will pressurize it not to (Phab-Pmars/2) but ((Phab-Pmars/2)/2) IE 1/4 of hab pressure, not 1/2 of hab pressure right? That leaves you with 3/4 of the Phab pressure to make up from the gas you pumped out of the lock on exit and storage or by pumping it back into A from B and the rest from storage.

At best you can schedule some of the pumping energy needed to pressurize and de pressurize the locks. You also have a lowish pressure differential (but high volume) air pump between chambers.
It's easy to depreussurize a lock on Mars, you just vent it. However given Mars Patm is 1/160 of Earth conserving that atmosphere on a long term basis is likely to be important.

Likewise it's easy to pressurize a chamber if you have a much higher pressure storage tank.

The benefits of a low pressure differential pump are cancelled by the high volume it's going to pump. You will still need a high pressure pump to keep the main habitat reserve tanks pressurized in any case.
Very good reminder of basic principles. We'll need high pressure pumps somewhere in the system. And if we can save a little energy here and there it will add up over many uses of the airlock(s).

Offline darkenfast

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Re: Airlocks for Mars Colony
« Reply #9 on: 01/22/2017 10:05 am »
Regarding dust: how about a liquid "car-wash" type sprayer to get the dust off after the pressure is sufficiently high.  The liquid would be filtered and recycled.  Followed by a drying cycle, prior to cracking seals or rings.  Some of the Apollo suits were filthy after use on the Moon, and I'm not sure how healthy Martian dust is.   Obviously, the suits would have to be designed for this from the beginning.  The liquid doesn't have to be water, of course, but I have no idea what might be better.   
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Offline AncientU

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Re: Airlocks for Mars Colony
« Reply #10 on: 01/22/2017 10:51 am »
Dust removal should be done before entering the airlock, say in an anteroom, preferably by robotically articulated arm CO2 sprayers (like Co2 fire extinguishers held by robots). We clean observatory mirrors with such a 'snow' blast and solids instantly dissipate... Almost free as only a multi-stage compressor is needed using unprocessed Mars atmosphere -- and robots, of course.  Robots should have capability to determine size and position of objects/people in the anteroom and should do a thorough top-down spray cleaning and finish with soles/wheels as objects/people move into airlock.  Anteroom will be cleaned of accumulated dust and debris by robots as needed.

Hand held vacuums won't work in low (Martian atmosphere) pressure; they are too slow and inefficient even in Earth conditions with an assistant doing the vacuuming.  Impossible to self-clean those hard to reach areas.
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Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #11 on: 01/22/2017 12:06 pm »
Dust removal should be done before entering the airlock, say in an anteroom, preferably by robotically articulated arm CO2 sprayers [...]
Hand held vacuums won't work in low (Martian atmosphere) pressure; they are too slow and inefficient even in Earth conditions with an assistant doing the vacuuming.  Impossible to self-clean those hard to reach areas.

There's a big gap between "handheld vacuums" and "robotic arms spraying CO₂ snow".

Hand-held pressurised CO₂ "air"-hoses, fixed frame CO₂ "air curtains"/"air blades", hand-held brush-hose combinations (such as you use to clean your car, but with CO₂ instead of water), etc.

Regarding dust: how about a liquid "car-wash" type sprayer to get the dust off after the pressure is sufficiently high.  The liquid would be filtered and recycled.

I don't think you would use water for cleaning, since you then have to design every component to be water-proof. (Not just pressure vessels (which should be okay, obviously) but every support system around the pressure vessel.)

And if you're going to that much trouble, you might as well go all the way to a wet-lock and get rid of the airlock entirely
« Last Edit: 01/22/2017 12:07 pm by Paul451 »

Offline AncientU

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Re: Airlocks for Mars Colony
« Reply #12 on: 01/22/2017 02:01 pm »
Dust removal should be done before entering the airlock, say in an anteroom, preferably by robotically articulated arm CO2 sprayers [...]
Hand held vacuums won't work in low (Martian atmosphere) pressure; they are too slow and inefficient even in Earth conditions with an assistant doing the vacuuming.  Impossible to self-clean those hard to reach areas.

There's a big gap between "handheld vacuums" and "robotic arms spraying CO₂ snow".

Hand-held pressurised CO₂ "air"-hoses, fixed frame CO₂ "air curtains"/"air blades", hand-held brush-hose combinations (such as you use to clean your car, but with CO₂ instead of water), etc.


Robotics will be a fact of life on Mars. 
 -- Mass delivered to Mars is order of magnitude same for person or robot
 -- Consumables needed for robot near zero
 -- Stay time in Martian atmosphere, radiation environment essentially unlimited for robot
 -- Intelligence/speed for single, repetitive functions much superior for robots (assembly line type operations such as at auto assembly plant)

Unique situation analyses are human strengths... human time wasted doing routine tasks (vacuuming, manually spraying, etc.) will need to be minimized.

Robots will outnumber people, possibly permanently...

Remember, this is a Silicon Valley mindset, not evenly vaguely similar to Beltway behavior.  Compare ITS and its timeline and ultimate goals versus SLS/Orion, their timeline, and ultimate goals (if any can be discerned)

Here's an article on robots in the Gigafactory... gives an idea of the possibilities.
https://electrek.co/2016/07/31/tesla-gigafactory-robots-machines-battery-factory/
« Last Edit: 01/22/2017 02:34 pm by AncientU »
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Offline JazzFan

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Re: Airlocks for Mars Colony
« Reply #13 on: 01/22/2017 02:37 pm »
Maybe the airlock can serve an additional purpose than on orbital stations, such as ISS.  The use of an outer window on the airlock could be an additional observation vantage and control point for Mars surface operations.  Kind of like flight control stations on naval vessels for air operations. 

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Re: Airlocks for Mars Colony
« Reply #14 on: 01/22/2017 03:11 pm »
If you count cars, trucks, lawn mowers, vacuum cleaners, drones, CNC machines, and 3D printers as robots, robots outnumber humans in the US, too.
« Last Edit: 01/22/2017 03:38 pm by Robotbeat »
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Re: Airlocks for Mars Colony
« Reply #15 on: 01/22/2017 03:35 pm »
The goal here, for daily use, is to move humans between surface suits and inside living/working areas.  Maintenance can be handled differently.

NASA already has surface suit concepts where humans will access the suit through a hatch on the back of the suit.  Which means the amount of area that needs to be cleaned for human-transfer operations is just the hatch on the back, which likely won't be as dirty as the feet and hands of the suit.  Also there could be a cover on the "hatch" so that it stays clean during surface operations, also reducing the amount of cleaning required when "docking".

But if you want to reduce the amount of air lost when leaving a station, then one way would be to have a "balloon" inflate inside the airlock to force out as much station air as possible, then retract when suited worker is ready to leave the lock.  That should require less energy than trying to evacuate the entire lock.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

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Re: Airlocks for Mars Colony
« Reply #16 on: 01/22/2017 04:12 pm »
I bet suit ports as we have now will not be the most common type of suit used. Too cumbersome.
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Offline Ionmars

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Re: Airlocks for Mars Colony
« Reply #17 on: 01/22/2017 05:15 pm »
I bet suit ports as we have now will not be the most common type of suit used. Too cumbersome.
A suitport is not really a type of suit, but an alternative to an airlock. Here is Wikipedisa's definition: "A suitport or suitlock is an alternative technology to an airlock, designed for use in hazardous environments and in human spaceflight, especially planetary surface exploration. Suitports present advantages over traditional airlocks in terms of mass, volume, and ability to mitigate contamination by—and of—the local environment." See diagram.

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Re: Airlocks for Mars Colony
« Reply #18 on: 01/22/2017 05:25 pm »
I bet suit ports as we have now will not be the most common type of suit used. Too cumbersome.

Certainly we don't know why humans will be venturing out onto the surface of Mars to do, so everything is pretty speculative at this point.  So I think suitports could be what is initially used until the requirements for EVA suits are better understood.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

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Re: Airlocks for Mars Colony
« Reply #19 on: 01/22/2017 05:28 pm »
I bet the opposite. We'll use the suits SpaceX is developing for Mars first. SpaceX is not developing a suit port.
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Offline DusanC

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Re: Airlocks for Mars Colony
« Reply #20 on: 01/22/2017 05:50 pm »
I bet the opposite. We'll use the suits SpaceX is developing for Mars first. SpaceX is not developing a suit port.

SpaceX is not developing a suit port for travel to ISS.

We don't know what are they developing for Mars.

IMHO suit port is much better than airlock for Mars.

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #21 on: 01/22/2017 05:55 pm »
Dust removal should be done before entering the airlock, say in an anteroom, preferably by robotically articulated arm CO2 sprayers [...]
Hand held vacuums won't work in low (Martian atmosphere) pressure; they are too slow and inefficient even in Earth conditions with an assistant doing the vacuuming.  Impossible to self-clean those hard to reach areas.

There's a big gap between "handheld vacuums" and "robotic arms spraying CO₂ snow".

Hand-held pressurised CO₂ "air"-hoses, fixed frame CO₂ "air curtains"/"air blades", hand-held brush-hose combinations (such as you use to clean your car, but with CO₂ instead of water), etc.

Regarding dust: how about a liquid "car-wash" type sprayer to get the dust off after the pressure is sufficiently high.  The liquid would be filtered and recycled.

I don't think you would use water for cleaning, since you then have to design every component to be water-proof. (Not just pressure vessels (which should be okay, obviously) but every support system around the pressure vessel.)

And if you're going to that much trouble, you might as well go all the way to a wet-lock and get rid of the airlock entirely
Water tolerant is not water proof. All trucks on Earth are water tolerant.
http://www.kkewash.com/Specialised-Mining-Vehicle-Wash-Equipment/Mining-Equipment-Truck-Wash-System.html

I actually spec'ed some of these for mining garages.  There are not that complex.

« Last Edit: 01/22/2017 06:04 pm by lamontagne »

Offline AncientU

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Re: Airlocks for Mars Colony
« Reply #22 on: 01/22/2017 06:48 pm »
The goal here, for daily use, is to move humans between surface suits and inside living/working areas.  Maintenance can be handled differently.

NASA already has surface suit concepts where humans will access the suit through a hatch on the back of the suit.  Which means the amount of area that needs to be cleaned for human-transfer operations is just the hatch on the back, which likely won't be as dirty as the feet and hands of the suit.  Also there could be a cover on the "hatch" so that it stays clean during surface operations, also reducing the amount of cleaning required when "docking".

But if you want to reduce the amount of air lost when leaving a station, then one way would be to have a "balloon" inflate inside the airlock to force out as much station air as possible, then retract when suited worker is ready to leave the lock.  That should require less energy than trying to evacuate the entire lock.

Someone above mentioned 'no free lunch'... how do you retract without pumping?  Suggest you save the balloon for something more useful.
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Re: Airlocks for Mars Colony
« Reply #23 on: 01/22/2017 08:17 pm »
We don't usually think this way, but co2 above 1 pct is toxic to humans. The long term occupational health level is set to 0.5 pct in the US. So whether or not the co2 in an airlock is a problem will depend on specific circumstances.

First, is the airlock volum significant compared with the indoor space the person will enter. One function of the ECLSS system for the indoor space is to remove co2 from breathable air. So if the indoor volume is 100 times the volume of the airlock, I wouldn't worr about it. But if the indoor space is small, say a small garage for 1 or 2 vehicles then we may have a concern. If the airlock contains Martian air at 96 pct co2 but the pressure is raised 20 times to match the inside air then when the interior door is opened, the amount of co2 entering may be signicant. If the indoor volume were say 10 times airlock volume then it might not take too many airlock openings to reach 1pct.

We can't be sure of operating conditions at all times, so it might be good practice to pump out as much outdoor air as we can before refilling the airlock with indoor air, not co2.

If we are employing  a double lock system as suggested here, we would be using indoor air from airlock 1 to refill airlock 2, etc. This would be a good way to conserve indoor air, which is expensive to create on Mars.

CO2 will be removed by the absorbers
Apologies in advance for any lack of civility - it's unintended

Online Dalhousie

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Re: Airlocks for Mars Colony
« Reply #24 on: 01/22/2017 08:22 pm »

Robots will outnumber people, possibly permanently...


People and robots are not comparable, alternative, or interchangeable regardless of the hype and SF movies.  Robots are just tools. You might as well say that people are outnumbered by home appliances or workers outnumbered by power tools. 
Apologies in advance for any lack of civility - it's unintended

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #25 on: 01/22/2017 08:32 pm »
Re: Suitport type spacesuits.

The other advantage of this design is that it's donnable by one person alone. (The Russian Orlon suits also have the same type of hinged-hatch entry, even though they aren't intended to be used in a suitport.) So the design is also useful even when you are using a mundane airlock.

However, all conventional suits are wrong for Mars. They are too top heavy, the PLSS needs to be completely redesigned. And they are way too high maintenance even when being used in a clean vacuum. None will cope with daily use of being regularly ground against sharp dust, rocks, etc.

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Re: Airlocks for Mars Colony
« Reply #26 on: 01/22/2017 08:46 pm »
I bet the opposite. We'll use the suits SpaceX is developing for Mars first. SpaceX is not developing a suit port.

SpaceX is not developing a suit port for travel to ISS.

We don't know what are they developing for Mars.

IMHO suit port is much better than airlock for Mars.
Do you see a suit port suit in SpaceX's ITS video? I sure don't. I see something much more akin to the SpaceX commercial crew suits. Definitely don't see a big port on the back of them:

SpaceX's spacesuits have a major design requirement that suitports simply can't meet: they MUST look badass.
« Last Edit: 01/22/2017 08:56 pm by Robotbeat »
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Re: Airlocks for Mars Colony
« Reply #27 on: 01/22/2017 11:51 pm »
Someone above mentioned 'no free lunch'... how do you retract without pumping?  Suggest you save the balloon for something more useful.

I'm figuring that air loss is more important than power, but no doubt there is a balance to be struck.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #28 on: 01/23/2017 12:15 am »
Someone above mentioned 'no free lunch'... how do you retract without pumping?  Suggest you save the balloon for something more useful.

I'm figuring that air loss is more important than power, but no doubt there is a balance to be struck.
Air loss is power.  Atmosphere in a Martian habitat is just a form of energy storage  :-)  It would cost about 250$ per vehicle airlock cycle to vacuum the lock atmosphere. The cost of the atmosphere, mostly oxygen and nitrogen is, perhaps about 20 or more times that value.  There is a compression page in the joined spreadsheet.  Compression or pumping are the same work.

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Re: Airlocks for Mars Colony
« Reply #29 on: 01/23/2017 12:22 am »
So we can halve that cost if we halve the pressure... Just saying. :D

(Side note)
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Offline Nibb31

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Re: Airlocks for Mars Colony
« Reply #30 on: 01/23/2017 09:03 am »
Remember that Mars dust has a high concentration of perchlorate salts, which are highly toxic. Fighting perchlorate contamination will be one of the toughest tasks a Mars expedition is going to be faced with.

I can see only two ways of prevent Martian dust from contaminating the atmosphere of the hab:
- Either an extensive washdown of anything coming inside, which will consume a lot of water.
- Or suit ports.

Even if suitports are used for most EVAs, there still needs to be an airlock to bring suits and equipment inside for maintenance.

Offline guckyfan

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Re: Airlocks for Mars Colony
« Reply #31 on: 01/23/2017 10:01 am »
Even if suitports are used for most EVAs, there still needs to be an airlock to bring suits and equipment inside for maintenance.

I expect workshops for maintenance of suits and vehicles completely separate from the living quarters. Maybe with a pressurized path but separated by their own airlocks. That would reduce contamination significantly.

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #32 on: 01/23/2017 11:05 am »
I expect workshops for maintenance of suits and vehicles completely separate from the living quarters. Maybe with a pressurized path but separated by their own airlocks. That would reduce contamination significantly.

That's what I was trying to get at with my sketch of separate chambers bracketing the airlocks. The idea that you have an outside, unpressurised by enclosed area you can do things like brush or blow dust off of vehicles, and which has a floor that is not regolith & dust. Then the airlocks. Then another area which is at habitat pressure, but is still separated from the main habitat because you assume it will end up with a lot of dust.

Since you have an area you assume is dusty, that seemed to me to be a logical place put your main machine-shop. Dust, fumes, etc, just adds to the mess. And logically, the airflow is from habitat, to low-dust workshop/prep-area, to high-dust workshop/prep-area, to air filtration plant, then to the air-conversion system (mechanical or biological), then probably through the agricultural areas, then back to the habitat.

(Edit: In my sketch, the "low-dust area" in the pressurised bay effectively serves the role of non-pressurised airlocks. Since air is always flowing in that direction.)
« Last Edit: 01/23/2017 11:09 am by Paul451 »

Online Robotbeat

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Re: Airlocks for Mars Colony
« Reply #33 on: 01/23/2017 11:39 am »
Remember that Mars dust has a high concentration of perchlorate salts, which are highly toxic. Fighting perchlorate contamination will be one of the toughest tasks a Mars expedition is going to be faced with.

I can see only two ways of prevent Martian dust from contaminating the atmosphere of the hab:
- Either an extensive washdown of anything coming inside, which will consume a lot of water.
- Or suit ports.

Even if suitports are used for most EVAs, there still needs to be an airlock to bring suits and equipment inside for maintenance.
Maybe. Or maybe perchlorates are overblown.
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Offline pobermanns

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Re: Airlocks for Mars Colony
« Reply #34 on: 01/23/2017 09:42 pm »
The idea that you have an outside, unpressurised by enclosed area you can do things like brush or blow dust off of vehicles, and which has a floor that is not regolith & dust.

I like the whole scheme for incremental regions. But for the outer, unpressurized area, would it be helpful to have filtered and (slightly) pressurized ambient Martian air flow into that area, so that it would help keep any new dust from coming in?
« Last Edit: 01/23/2017 09:44 pm by pobermanns »

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #35 on: 01/23/2017 10:21 pm »
The idea that you have an outside, unpressurised by enclosed area you can do things like brush or blow dust off of vehicles, and which has a floor that is not regolith & dust.
I like the whole scheme for incremental regions. But for the outer, unpressurized area, would it be helpful to have filtered and (slightly) pressurized ambient Martian air flow into that area, so that it would help keep any new dust from coming in?

Then you either need another airlock, or continuous over-pressure. Which seems a waste. The outside area is just about creating a stable, protected prep and storage area. Based on the similar unpressurised structure on the ISS "Quest" airlock. But scaled up, in this case, for vehicles.

Offline Oersted

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Re: Airlocks for Mars Colony
« Reply #36 on: 01/24/2017 10:36 am »
Regarding the "outside area" I think it doesn't really need to be outside the hill-side. Just let it be the first big room in the tunnel system and then have the airlock a bit further inside the hill. That way it won't be necessary to build a hall outside and expend invaluable material on unnecessary walls. It would probably also improve the airtightness of the airlocked zone that it only begins well inside the regolith.
« Last Edit: 01/24/2017 10:42 am by Oersted »

Offline Unobscured Vision

Re: Airlocks for Mars Colony
« Reply #37 on: 01/24/2017 11:20 am »
Are we talking a very large Hab that we've buried with regolith, or an actual "we've tunneled our way into a hillside" kind of idea? I just need some context.  ;)
Yep ... just ... yep.

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #38 on: 01/24/2017 11:54 am »
The idea that you have an outside, unpressurised by enclosed area you can do things like brush or blow dust off of vehicles, and which has a floor that is not regolith & dust.
I like the whole scheme for incremental regions. But for the outer, unpressurized area, would it be helpful to have filtered and (slightly) pressurized ambient Martian air flow into that area, so that it would help keep any new dust from coming in?

Then you either need another airlock, or continuous over-pressure. Which seems a waste. The outside area is just about creating a stable, protected prep and storage area. Based on the similar unpressurised structure on the ISS "Quest" airlock. But scaled up, in this case, for vehicles.
A problem that may happen with the external structure is that it will itself become dirty and contaminated, and might create a local atmosphere that is worse than the outdoors.  That may be why I prefer the semi open version.  Or perhaps it's just obstructionism ;-)

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #39 on: 01/24/2017 07:09 pm »
Are we talking a very large Hab that we've buried with regolith, or an actual "we've tunneled our way into a hillside" kind of idea? I just need some context.

The topic came up in the Amazing Habitats thread in relation to underground/hill-tunnel habitats. But it shouldn't matter in this context. The principle applies to any airlock, suitport, vehicle docking port, or storage area.

The ISS has such an unpressurised but enclosed room outside the Quest module's airlock, enabling mission preparation, with an umbilical to extend PLSS lifespan. (I don't know whether it also allows PLSS recharging without necessitating passing back through the airlock, but it seems like a logical addition.)

Hence, even for a limited flag'n'footprints mission, having an unpressurised enclosed area outside the airlock makes sense. (It doesn't have to be big, the Quest extension seems to only fit one astronaut at a time (or at least I can't find images with two.)) Even suitlock proposals typically have a closable soft-cover. But for a permanent colony, the possible secondary uses make me think it would be better to make it as large as reasonably possible.

[edit: apparently not.]



Quest module.

Being berthed.



(The airlock-proper is the larger disc-shaped section, called the "equipment lock". The unpressurised extension is the long, narrow cylinder sticking out, called the "crew lock". Which seems backwards to me.)

Berthed.



Giving birth...





[Amusingly (or horrifyingly, depending on how much these people scare you), I noticed that this image with the flimsy outer cover on the unpressurised extension is used on... certain websites... to prove that NASA is faking the whole having-a-space-station thing. You know, coz you can't orbit a flat Earth.]

And a view inside the extension (crew lock).





Suitports enclosures.

Open. (The idea is that you close the cover before you open the back-plate and return to the vehicle.)



Concept. (Individual covers. one open, two closed.)

« Last Edit: 01/25/2017 02:51 am by Paul451 »

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #40 on: 01/24/2017 07:44 pm »
Regarding the "outside area" I think it doesn't really need to be outside the hill-side. Just let it be the first big room in the tunnel system and then have the airlock a bit further inside the hill. That way it won't be necessary to build a hall outside and expend invaluable material on unnecessary walls.

Being unpressurised and without significant loading from wind, the walls can the flimsy and the frame can be light. Or it can be made of sintered bricks (which are horribly porous and structurally weak), arched or domed. (Finally a dome makes sense on Mars.)

I suspect that it would use up fewer resources than "digging a sodding great hole in the rock" just for an unpressurised box. But if you are digging deep into rock for the habitat, and need to dig in a certain way before you reach suitable structural rock, then yes you might use that entry volume for the airlock extension. Although you'd still need support walls, which will be stronger (therefore more resource demanding) than a structure that's not holding up semi-consolidated regolith or weak fractured rock.

(I need a better name. Porch/veranda/etc doesn't really capture that it's enclosed. Shed/carport doesn't specify that it's attached. And then, of course, I'm suggesting another inside area which is pressurised, and that needs another name.)

A problem that may happen with the external structure is that it will itself become dirty and contaminated

The only source of permanent contamination are fluids in the vehicles and equipment. And that would affect any maintenance area.

Everything else is just regolith dust and CO₂, which are obviously present in an unenclosed area.

and might create a local atmosphere that is worse than the outdoors.

How? It's not meant to be airtight, by definition. And without wind, the air won't hold any significant quantities of dust.

It's a "shed". Except that by being on Mars, it doesn't have to handle significant winds, so it can be a very light structure. It's just a way to keep the wind-borne dust out, provide a stable floor to work on, protect against sun, provide consistent work lighting, and allow you to run conduit around the walls with at least power to vehicle recharge stations and power tools (and maybe air & water lines too). Given such an area, it also seems like the logical spot to also service equipment from outside that needs to be repaired, which gives you a protected area to do fiddly work without losing parts or getting them full of dust. And that also suggests it as an area for the storage of bulk items used outside. Like spools of steel/fibre cable, power cables, large structural elements, spare vehicle parts, down to nuts and bolts and connectors. Or anything unloaded from the incoming ships, but still waiting to be assembled/deployed.

(OTOH, IMO there's no real advantage to having stand-alone roofed area, far from the airlocks, as your main vehicle storage area. You need another vehicle or an EVA to get from the habitat airlock to the vehicle shed, and when you're done for the day, you need another vehicle or EVA to get back to the habitat again. If you want to recharge the air and water supply, or drain the waste-water, you need to transport the fluids to/from the habitat or have a secondary fluid/gas processing plant at the shed. Similarly you can't easily share power with the hab. And what does it gain?

Exception: You might have a simple sun-shade at a common off-site area that needs a lot of maintenance - such as the ISRU plant, the launch/landing pads, etc. Solar panels as the roof to allow recharging the vehicle while the crew are off EVAing. But that's only when you are using vehicles to travel to an area each day, then exiting for on-foot EVA. The vehicles return to the habitat at the end of each shift.)

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #41 on: 01/24/2017 08:25 pm »
Should this thread be moved from the SpaceX Mars section back to the general Missions To Mars (HSF) section?



Feeling a bit guilty for hijacking the thread.

So here's another airlock concept that was discussed in other threads.

The Wetlock or Moon-pool.



Image courtesy of MeekGee. (KelvinZero is another strong proponent.)

MeekGee suggests an ice-layer at the end (kept thin enough to walk or drive through, but which reduces evaporation). KelvinZero has wondered about using another liquid with a very low evaporation, or having a low-evaporation layer floating on the water. I've suggested a low pressure airlock at the outer-end, just enough pressure to reduce boil-off at the target temperature, and high enough humidity to eliminate further evaporation.

And many of us have mentioned the complication of buoyancy.

Offline Lar

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Re: Airlocks for Mars Colony
« Reply #42 on: 01/24/2017 08:31 pm »
Should this thread be moved from the SpaceX Mars section back to the general Missions To Mars (HSF) section?
Moved. Doing a report to mod is another good way to ask for same, actually better... (2 years from now when someone's coming up to speed, they won't care about this housekeeping stuff)

If there is another one that should have moved (I forget now) report to mod or PM me...
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Offline Ionmars

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Re: Airlocks for Mars Colony
« Reply #43 on: 01/24/2017 09:01 pm »
For the outdoor foyer to the airlock:
Maybe there is finally a practical use for an iRobot Roomba.
Or would it even work in very low air pressure? Maybe a rotary dust brush like a Bissel Sweeper, electrified.
(I know my proper role in the Earthly Martian household!) :)
« Last Edit: 01/24/2017 09:02 pm by Ionmars »

Offline Jim

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Re: Airlocks for Mars Colony
« Reply #44 on: 01/25/2017 01:42 am »

(The airlock-proper is the larger disc-shaped section, called the "equipment lock". The unpressurised extension is the long, narrow cylinder sticking out, called the "crew lock". Which seems backwards to me.)


Wrong.  The long, narrow cylinder is the "airlock".  It is the part where the crew (two of them at the same time) enters and exits the station.  It is the only part that is depressurized and repressurised, hence crew lock.   The "equipment lock" is where the EVA suits and tools are stored and maintained.  It is where the crew does there pre breathe campout.

There is no "unpressurised but enclosed room".  There is no "umbilical to extend PLSS lifespan" on the exterior.  Just like the shuttle (in fact the crew lock is based on the shuttle airlock), the crew is on umbilical until the airlock is depressurized and goes back on umbilical while the airlock is depressurized.

Two crew in the crew lock (who else would have taken the photo of one of the crew)
« Last Edit: 01/25/2017 01:50 am by Jim »

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #45 on: 08/23/2019 12:39 pm »
This is a spin-off thread from the Amazing Martina habitats thread.

The existing docking and berthing ports may not be adequate for use on the surface of Mars.  The docking ports are very small, and the berthing cargo port, although wide, is not very high.

A number of mock-ups have been part of various Mars base and and martian vehicles over the years, there does not seem to have been any serious design effort done yet. 

- What is the correct name for 'it' ?  An airlock, a port, a pressure door?
- Should it open in, open ot, or dilate like a SF movie door?
- What is the best way to signify 'open' and 'closed'? 
- Can the port do some of the connecting work, or is it all done by the vehicle?
- How high off the ground should it be?  If it is high up how do 'walkers' reach it?
- Should it be used in space as well?
- Should it have a doorknob?  :)
- What are the visual signals required for operating it safely?
- Must it have a manual override?

To kick things off, here is the design I have been using lately, with a few images of its use.  It's a rectangular door with rounded edges, latches for strong connections, a flexible neck for angular corrections and a seal with mainly lateral forces.


Offline grythumn

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Re: Airlocks for Mars Colony
« Reply #46 on: 08/23/2019 02:33 pm »
This is a spin-off thread from the Amazing Martina habitats thread.

The existing docking and berthing ports may not be adequate for use on the surface of Mars.  The docking ports are very small, and the berthing cargo port, although wide, is not very high.

A number of mock-ups have been part of various Mars base and and martian vehicles over the years, there does not seem to have been any serious design effort done yet. 

- What is the correct name for 'it' ?  An airlock, a port, a pressure door?

The picture seems to portray a single port or pressure door.

Airlock implies a two-doored chamber that can depressurize independently from the connected habitable space.

Quote
- Should it open in, open ot, or dilate like a SF movie door?

Open in is the usual concept, so if there is a large pressure gradient between the hab and outside the door, it cannot be opened and depressurize the hab space, as a safety measure.

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #47 on: 08/23/2019 03:27 pm »
This is a spin-off thread from the Amazing Martina habitats thread.

The existing docking and berthing ports may not be adequate for use on the surface of Mars.  The docking ports are very small, and the berthing cargo port, although wide, is not very high.

A number of mock-ups have been part of various Mars base and and martian vehicles over the years, there does not seem to have been any serious design effort done yet. 

- What is the correct name for 'it' ?  An airlock, a port, a pressure door?

The picture seems to portray a single port or pressure door.

Airlock implies a two-doored chamber that can depressurize independently from the connected habitable space.

Quote
- Should it open in, open ot, or dilate like a SF movie door?

Open in is the usual concept, so if there is a large pressure gradient between the hab and outside the door, it cannot be opened and depressurize the hab space, as a safety measure.
Yes, would need two doors to make an airlock.  Should the system be systematically configured as an airlock, or can it vary from single doors to double doors (airlocks)?  Or be designed to be able to offer both configurations?
How often are airlocks required, if they are mostly used for connection between pressurized elements?  Or is the safety of an airlock an essential design element?

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #48 on: 08/23/2019 03:30 pm »
How important/useful are alignment guides?

Will an airlock/port be operated using artificial intelligence controls to provide docking adjustments?  Just how possible are docking maneuvers between vehicles and habitats in the real world?

Offline Lar

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Re: Airlocks for Mars Colony
« Reply #49 on: 08/23/2019 03:43 pm »
An airlock can use two of the doors shown, or perhaps since the outer door has to cope with both sides depress (just before opening or closing) maybe it's different?

The door shown for sure has to handle pressure on one side and vacuum on the other. Does that mean it's asymmetric (the always pressure side is different than the sometimes vacuum side) ?
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Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #50 on: 08/23/2019 04:03 pm »
Oups!  Just found a pre-existing thread from RocketmanUS  (the search function on the website is not very good BTW :-)  I even posted to it  :-[

Perhaps we can merge the two?

https://forum.nasaspaceflight.com/index.php?topic=42098.0

That was more for whole vehicle airlocks, rather than the smaller doors/hatches I'm illustrating here, but still.
« Last Edit: 08/23/2019 04:05 pm by lamontagne »

Offline Lar

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Re: Airlocks for Mars Colony
« Reply #51 on: 08/23/2019 04:10 pm »
Oups!  Just found a pre-existing thread from RocketmanUS  (the search function on the website is not very good BTW :-)  I even posted to it  :-[

Perhaps we can merge the two?

https://forum.nasaspaceflight.com/index.php?topic=42098.0

That was more for whole vehicle airlocks, rather than the smaller doors/hatches I'm illustrating here, but still.
Sure. But now I have to ponder which thread is in the right place, LOL.
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Re: Airlocks for Mars Colony
« Reply #52 on: 08/23/2019 04:14 pm »
back on track, what are some of the design considerations here? does it matter which side or sides will be exposed to vacuum? What about gas composition, if a greenhouse is much higher C02, does that matter (I think not)
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
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Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #53 on: 08/23/2019 04:50 pm »
I see three functions:

Habitat connector.
Vehicle connector.
Airlock hatch.

Habitat connectors, if they have a door at all, will be safety features.  So the pressure can be on either side and the function is to keep the pressure on the non depressurized side.  These can be male/female connectors, but this limits configurations and means everything needs to be planned.  If they are rigid, then the habitats need rigid foundations, because you want to reduce strain on these connecting elements.

Vehicle connectors are vacuum outside, pressure inside.  They become part of an airlock if the vehicle cannot be exposed to vacuum and if they also serve as exit ports for space suited crew members.  Vehicle connectors would need to be androgynous, or else they would need to be two per vehicle.  A vehicle could have a vehicle connector and a separate airlock, or suitports.

An airlock hatch has no connector function, so the male/female question is not a problem.  The outer door and the inner door are probably vacuum outside, pressure inside.  This would probably be the same design for a pressurized hab, low pressure greenhouse arrangement.

Specs:
Operating pressure: 15 psi (101 kPa)
Dimensions: 1000mm x 2200mm
Alignment requirements :TBD
Angular motion: TBD

Can a single connector/hatch/port serve all these purposes?  Or is that a road to overdesign?
« Last Edit: 08/23/2019 04:51 pm by lamontagne »

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #54 on: 08/23/2019 04:53 pm »
Here is a nice NASA presentation on inflatable airlocks.

They are aiming for 15 psi.
They favor some kind of internal structure.
They don't seem to have though of these as vehicle ports?  Not sure about that.

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Re: Airlocks for Mars Colony
« Reply #55 on: 08/23/2019 05:32 pm »
Vehicle real estate is at a premium so it may be worth it to have your docking door and your airlock door be the same door...  when independent you go through an inner door, airlock operates, and then through the outer to get outside. When at base, you go through an inner door, there may be a brief pressure equalization (or not) then through the outer to get to the base.

So the inner has to be able to handle pressure/pressure and pressure/vacuum while the outer has to be able to handle pressure/pressure (while docked) pressure/vacuum (while airlock is pressurised) and vacuum/vacuum (while airlock is depress, just before opening).

Note I use vacuum to also stand in for "Mars Ambient"
« Last Edit: 08/23/2019 05:32 pm by Lar »
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Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #56 on: 08/23/2019 05:43 pm »
Vehicle real estate is at a premium so it may be worth it to have your docking door and your airlock door be the same door...  when independent you go through an inner door, airlock operates, and then through the outer to get outside. When at base, you go through an inner door, there may be a brief pressure equalization (or not) then through the outer to get to the base.

So the inner has to be able to handle pressure/pressure and pressure/vacuum while the outer has to be able to handle pressure/pressure (while docked) pressure/vacuum (while airlock is pressurised) and vacuum/vacuum (while airlock is depress, just before opening).

Note I use vacuum to also stand in for "Mars Ambient"
Seems correct.  Adding vacuum vacuum to the concept.

And here is another paper, a bit old, that seems to bemoan the point that there isn't really that much going on in hatch and airlock design.  Interestingly, it adds another type of airlock, the sample airlock for exploration vehicles.  I guess we could add the whole vehicle airlock, and therefore have up to five type of airlocks for a martian base.  Although the whole vehicle airlock is for a big base :-)

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #57 on: 08/23/2019 05:47 pm »
An airlock can use two of the doors shown, or perhaps since the outer door has to cope with both sides depress (just before opening or closing) maybe it's different?

The door shown for sure has to handle pressure on one side and vacuum on the other. Does that mean it's asymmetric (the always pressure side is different than the sometimes vacuum side) ?
I would expect the door to be asymmetrical.  The inverted operation of the safety door between two habitats seems like the main case where a door would need to function in Pressure/vacuum in two directions.  That might best be served by a symmetrical door?

Offline RonM

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Re: Airlocks for Mars Colony
« Reply #58 on: 08/23/2019 06:28 pm »
An airlock can use two of the doors shown, or perhaps since the outer door has to cope with both sides depress (just before opening or closing) maybe it's different?

The door shown for sure has to handle pressure on one side and vacuum on the other. Does that mean it's asymmetric (the always pressure side is different than the sometimes vacuum side) ?
I would expect the door to be asymmetrical.  The inverted operation of the safety door between two habitats seems like the main case where a door would need to function in Pressure/vacuum in two directions.  That might best be served by a symmetrical door?

There's no need for an asymmetrical hatch design. Each habitat module should have its own hatch for safety, so when two modules are connected there are two doors. As long as you leave enough room in the design, by default you get a one-person airlock when you connect two hatch assemblies.

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #59 on: 08/23/2019 07:05 pm »
An airlock can use two of the doors shown, or perhaps since the outer door has to cope with both sides depress (just before opening or closing) maybe it's different?

The door shown for sure has to handle pressure on one side and vacuum on the other. Does that mean it's asymmetric (the always pressure side is different than the sometimes vacuum side) ?
I would expect the door to be asymmetrical.  The inverted operation of the safety door between two habitats seems like the main case where a door would need to function in Pressure/vacuum in two directions.  That might best be served by a symmetrical door?

There's no need for an asymmetrical hatch design. Each habitat module should have its own hatch for safety, so when two modules are connected there are two doors. As long as you leave enough room in the design, by default you get a one-person airlock when you connect two hatch assemblies.
Indeed.  Most buried inflatables will need to be connected by corridors anyway, and I expect there would be nodes with multiple doors serving the purpose of airlocks.  The only time a door might be used with vacuum on either side might be in a large colony, when modules would be so large that airlocks might no longer be practical.  And in such a case there will be specific designs. 
So one option less; we can have all the doors similar, opening the same way, and designed to hold pressure on the side the door opens, with the door pressed against a seal.

Offline KelvinZero

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Re: Airlocks for Mars Colony
« Reply #60 on: 08/24/2019 12:12 am »
(KelvinZero is another strong proponent.)
...
I've suggested a low pressure airlock at the outer-end, just enough pressure to reduce boil-off at the target temperature, and high enough humidity to eliminate further evaporation.
Yeah I do often bring this up.. though just as a cool gimmick, often combined with an assumption that we are maintaining large bodies of water for other reasons.

A low pressure door sounds a lot more straight forward. I could imagine this becoming practical if a few other features line up, like it turns out we do have most of our habitation tens of meters underground, we do have large reservoirs of water, and decontamination of suits is a nice bonus.

Offline KelvinZero

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Re: Airlocks for Mars Colony
« Reply #61 on: 08/24/2019 12:29 am »
The goal here, for daily use, is to move humans between surface suits and inside living/working areas.  Maintenance can be handled differently.

NASA already has surface suit concepts where humans will access the suit through a hatch on the back of the suit.  Which means the amount of area that needs to be cleaned for human-transfer operations is just the hatch on the back, which likely won't be as dirty as the feet and hands of the suit.  Also there could be a cover on the "hatch" so that it stays clean during surface operations, also reducing the amount of cleaning required when "docking".

But if you want to reduce the amount of air lost when leaving a station, then one way would be to have a "balloon" inflate inside the airlock to force out as much station air as possible, then retract when suited worker is ready to leave the lock.  That should require less energy than trying to evacuate the entire lock.

Someone above mentioned 'no free lunch'... how do you retract without pumping?  Suggest you save the balloon for something more useful.
This is a really old message but I didn't spot a reply.

The thing is that there are lots of ways to compress a balloon without pumping. It generally comes down to some sort of piston operation. Alternatives to a balloon could be a child's ball pit (with slightly squishy balls that flatten together) or one of those pin-impression toys. I can't point to a sensible implementation but the principle exists and it really would ace the problem with pumping where you can only asymptotically approach vacuum.

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #62 on: 08/24/2019 12:08 pm »
The existing docking and berthing ports may not be adequate for use on the surface of Mars.  The docking ports are very small, and the berthing cargo port, although wide, is not very high.
[...]
- Should it open in, open [out],

All hatches between pressurised and unpressurised areas must open towards the side which will be pressurised during normal use (which we'll define as "inward") and away from the area exposed to low pressure. They never open outward.

The only exception is a back-hatch on an EVA hard-suit (and even there you would if you could.)

You see this on ship/submarine hatches and bulkhead doors. Although they generally open outwards it is due to the same logic, always open towards the thing pushing on the door.

The reason is that: a) you use the force of the air (or water) pressure on the hatch to press it into its seal, b) you can't open the hatch until the pressure is equalised, OTOH during a breach you can close it even when air (or water) is rushing through, and, critically, c) you don't want the hatch basically hanging by its latches when pressurised. Even at EVA pressure, a small 1m˛ crawl-through hatch will have about 2 tonnes of pressure against it. A very large module-berthing hatch, say 3-4m˛, at a full 1atm, would have up to 40 tonnes of pressure. You want that pressure to be holding it shut, not trying to pull it open.

As a bonus, you can't accidentally or intentionally "blow" the hatch. The most a careless or malicious person can do is open the pressure-equalisation valve on the outer hatch, which will need to depressurise the whole base, which could take hours or even days through such a small opening. Bit less dramatic on film.

(Obviously, a malicious actor can do other things to threaten a hab. Pressurised environments are fragile.)

If a particular situation means that the direction of pressurised-vs-unpressurised can change, then you should have two hatches opening in opposite directions. (For example, where modules join, sometimes the hatches might be internal connections, sometimes external. Or for use as an internal bulkhead, where you don't know which side will breach.) That is simplified by having one hatch always opening inward to each potentially pressurisable volume: connect two such volumes and you automatically have two hatches opening in opposite directions, both "inward". That also means you can move modules without depressurising them. It also means that only the volume between the hatches (in essence, "outside" each module) needs to be depressurised before they are disconnected/unberthed.

or dilate like a SF movie door?

Ugh. No.

And no computer controls. Hence no "manual override".

You open a valve to equalise the pressure. There is a mechanical gauge which shows any pressure difference, letting you see when the pressure is equalised (and note that this works regardless of whether it's vacuum-vacuum or pressure-pressure). Once pressure is equalised, you crank the crank-handle to withdraw any latches. You grab the grab-handles and pull the hatch open. If you screw up and there's still a pressure difference, you won't be able to move the hatch. In theory you can leave it unlatched and rely on the pressure difference alone to keep it sealed. The latches are just belt-and-braces.

Do the steps in reverse order to reseal it before pressurising. Instructions are clearly printed on the door, along with big direction arrows and labels. Everything is oversized but easy to manipulate unassisted, one-handed, with suit-gloves.

When going through an air-lock, you do this twice, once for each hatch. And both hatches open in the same direction, the inner one opens into the habitat, the outer one into the airlock. (Note that is different to the connection between two hab-modules.)

- What is the best way to signify 'open' and 'closed'?

Uh... the big gap in the wall is usually a dead give-away, so I assume you were referring to something else?

- Should it have a doorknob?  :)

There are, no doubt, whole volumes of NASA design studies that were done on the right kind of crank-handle (wheel or handle), whether it can be used as a grab-handle or you need separate handles, whether it should be permanently out or folded away, the exact force required, the amount of feedback from the dogs through the handle, etc etc etc.



Examples:

Below is, I believe, an ISS hatch, we're looking at the inside face, and it opens towards us. (Googling suggests one of the six on the Harmony module.)

« Last Edit: 08/25/2019 04:51 am by Paul451 »

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #63 on: 08/24/2019 12:10 pm »
But if you want to reduce the amount of air lost when leaving a station, then one way would be to have a "balloon" inflate inside the airlock to force out as much station air as possible, then retract when suited worker is ready to leave the lock.  That should require less energy than trying to evacuate the entire lock.
Someone above mentioned 'no free lunch'... how do you retract without pumping?  Suggest you save the balloon for something more useful.
The thing is that there are lots of ways to compress a balloon without pumping. It generally comes down to some sort of piston operation.

A piston is a pump. The only difference is whether the airlock itself is being used as the inside of the pump or the pump is a separate thing connected to the airlock. The energy is the same.

Alternatives to a balloon could be a child's ball pit (with slightly squishy balls that flatten together)

Do you mean with the balls replacing the airlock, ie, the ball-pit is like a water-lock? If so, remember that at EVA pressures, you need to hold about 2 tonnes per square metre.

Or do you mean that the balls are pushed into the airlock volume to cycle it (to displace the air), so the balls replace the piston? In which case, the same "a piston is a pump" rule applies.

or one of those pin-impression toys.

Ditto. If you mean that the pins pump the airlock (displace the air), then a piston is a pump, even if there's a thousand little pistons, the energy required is the same.
« Last Edit: 08/25/2019 04:59 am by Paul451 »

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #64 on: 08/24/2019 12:26 pm »
An airlock can use two of the doors shown, or perhaps since the outer door has to cope with both sides depress (just before opening or closing) maybe it's different?
The door shown for sure has to handle pressure on one side and vacuum on the other. Does that mean it's asymmetric (the always pressure side is different than the sometimes vacuum side) ?
I would expect the door to be asymmetrical.  The inverted operation of the safety door between two habitats seems like the main case where a door would need to function in Pressure/vacuum in two directions.  That might best be served by a symmetrical door?
There's no need for an asymmetrical hatch design. Each habitat module should have its own hatch for safety, so when two modules are connected there are two doors.

As I'm reading it, when Lar and Lamontagne say "asymmetry", they are referring to the two sides of a single hatch. Ie, is the front different from the back? (Answer: Yes it is.)

Whereas when you say "asymmetry", you mean where there are two types of docking adaptors, male and female versions that can only connect M-F, not M-M, F-F. In that case, "symmetry" means two identical (but individually asymmetrical) hatches able to connect outside-to-outside.

And I agree with your conclusions. The vehicle docking ports have to be symmetrical so that vehicles can dock to each other as well as to hab-modules. And the berthing adaptors on hab-module have to be symmetrical, so you have flexibility in moving them around. You don't want to be forced to use dedicated "nodes" or adaptors between them.

The interesting question, to me, is whether the vehicle docking adaptor should also be the same as the inter-module berthing adaptor. Or are the vehicle docking adaptors a removable assembly attached to one of the hab's berthing adaptor (as they will be for commercial-crew on ISS.) Or are the vehicle docks different than berthing adaptors, but are fixed features only on particular modules, in place of berthing adaptors at that location (as on the Soyuz/Progress docking ports on ISS.)

Likewise the EVA hatches. Is there a dedicated airlock module, attached to any berthing adaptor on a regular module (as with ISS), with the outer hatch being a dedicated EVA hatch. Or is the outer EVA hatch on the airlock module also the standard berthing adaptor.

Each habitat module should have its own hatch for safety, so when two modules are connected there are two doors. As long as you leave enough room in the design, by default you get a one-person airlock when you connect two hatch assemblies.

No. One of the hatches in that configuration is opening in the wrong direction, it won't be usable as an airlock even if all the other requirements for an airlock were met.

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #65 on: 08/24/2019 12:27 pm »
Most buried inflatables will need to be connected by corridors anyway

Why?

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #66 on: 08/24/2019 05:46 pm »
Most buried inflatables will need to be connected by corridors anyway

Why?
Because of the slope of the regolith on top of them.  They can connect to one another underground, but they need at least a small corridor to the outside.

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #67 on: 08/24/2019 06:43 pm »
An airlock, and an intermodular/intervehicle connection.

A very badly aligned connection; 10 degrees.  Would the connector compensate, as shown here, or would the vehicle compensate using active suspension?  (Please ignore the grey bellows, or just imagine that they actually followed the change in angle :-)
Would it be useful to have a few degrees of freedom in the connector, or should we expect the construction to be aligned?

The airlock requires a lot of space in a vehicle, due to the door opening inwards.  Seems unavoidable though.

An individual rover, invented by IonMars.  Would this reduce the need for spacesuits, and therefore the need for airlocks on vehicles?
« Last Edit: 08/24/2019 06:45 pm by lamontagne »

Offline RonM

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Re: Airlocks for Mars Colony
« Reply #68 on: 08/24/2019 06:51 pm »
The interesting question, to me, is whether the vehicle docking adaptor should also be the same as the inter-module berthing adaptor. Or are the vehicle docking adaptors a removable assembly attached to one of the hab's berthing adaptor (as they will be for commercial-crew on ISS.) Or are the vehicle docks different than berthing adaptors, but are fixed features only on particular modules, in place of berthing adaptors at that location (as on the Soyuz/Progress docking ports on ISS.)

Likewise the EVA hatches. Is there a dedicated airlock module, attached to any berthing adaptor on a regular module (as with ISS), with the outer hatch being a dedicated EVA hatch. Or is the outer EVA hatch on the airlock module also the standard berthing adaptor.

I think there should be two standard sizes for ports and corresponding berthing and docking rings to connect the ports. A large port for big hatches in modules or cargo vehicles and a smaller port for small modules, vehicles, or EVA. You would use either a berthing or docking ring depending on the application.

Like on ISS, an adapter to from large port to small would be useful.

An exterior EVA hatch wouldn't need a connecting ring. A platform and stairs could be bolted on instead.

Each habitat module should have its own hatch for safety, so when two modules are connected there are two doors. As long as you leave enough room in the design, by default you get a one-person airlock when you connect two hatch assemblies.

No. One of the hatches in that configuration is opening in the wrong direction, it won't be usable as an airlock even if all the other requirements for an airlock were met.

Doh! Not as useful as I thought. Still a good idea to have a hatch on each module.

Offline KelvinZero

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Re: Airlocks for Mars Colony
« Reply #69 on: 08/25/2019 10:01 am »
A piston is a pump. The only difference is whether the airlock itself is being used as the inside of the pump or the pump is a separate thing connected to the airlock. The energy is the same.
Hi I hadn't really thought about the problem of energy. I was only talking about avoiding the asymptotic nature of pumping air out of a chamber. Im guessing that normally you are halving the number of molecules every interval X, eg every 10 seconds or whatever, so in 20 seconds you have 1/4 pressure, in 30 seconds you have 1/8th etc but you never reach zero. With a piston you can evacuate a volume 100% in a finite (and generally short) period.

As I said, I hadn't really thought about energy. I guess the goal would be to limit the energy to what is needed to evacuate a volume equivalent to that of the spacesuit rather than that of an entire chamber. You could at least do that with the above ideas. Eg the pin-bed idea is exactly the same as a fixed volume chamber, except you have adapted that chamber to exactly conform to the suit volume.
« Last Edit: 08/25/2019 10:01 am by KelvinZero »

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #70 on: 08/25/2019 11:24 am »
The airlock requires a lot of space in a vehicle, due to the door opening inwards.  Seems unavoidable though.

I think most vehicles won't have airlocks. If they are used as a mobile base for EVAs, then the entire vehicle would be depressurised during the EVA. Similar to how space capsules have worked. Given the "buddy system"-requirements of EVA, any vehicle too small for an airlock is precisely the vehicle where the whole crew is either EVA or not.

And vehicles not intended for EVA would only transfer passengers via a pressurised dock. Even then, IMO, the crew should wear IVA-type suits in vehicles, capable of surviving a depressurisation emergency, but not intended for use on the surface. Belt'n'braces.

[Aside: The actual hatch doesn't need to be standardised at all, only the docking-collar. So a smaller vehicle can have a small crawl-through hatch, while still being able mate with a larger habitat dock. Also hatches can pivot along a wall (without being a silly sci-fi sliding door), they don't have to swing on a simple hinge out into the cabin space. See the ISS hatch I posted earlier, note that it doesn't have a hinge but instead slides out of the way on four rails. A smaller hatch could even be removable once opened, letting it stow anywhere.]

A very badly aligned connection; 10 degrees.  Would the connector compensate, as shown here, or would the vehicle compensate using active suspension?

It seems logical to me to put that flexibility in the vehicles themselves, down to a centimetre or so alignment. (That are, after all, already moving around.) With the docking-collars themselves being capable of handling the rest.

However, any docking port on a habitat needs to be more protected against "aggressive" docking, so at the very least it will need a soft-dock to act as a shock-absorber, and that might give you more adaptability in alignment...

Would it be useful to have a few degrees of freedom in the connector, or should we expect the construction to be aligned?

There's two parts, soft-dock and hard-dock. Once you soft-dock, you can, in effect, screw/winch/jack the two docking collars together to create the air-tight seal. So you can have that non-airtight shock-absorbing soft-dock for flexibility, then screwing-down the docking collars to force the final stricter alignment to an airtight hard-dock.

For example, IDA for commercial crew:



Another possible avenue for adding flexibility is to have an offset docking adapter which can rotate. That lets you move the end of the adapter, allowing you to work with vehicles of different heights.

For example, imagine if the PMA (which the IDA, above, is attached to) could rotate around its larger end:


Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #71 on: 08/25/2019 12:35 pm »
[pistons and pins and balls (oh my)]

I think I figured out what was confusing me.

I was picturing your proposal as: The astronaut goes into the normal sized airlock, closes the inner hatch. A bunch of pins (or balls or balloon or whatever), acting as a giant piston, squeezes the air out of the airlock, while conforming to the shape of the astronaut. Then the pins are withdrawn, restoring the normal sized airlock but now with a vacuum. Then the outer door opens. The highlighted part is where I objected: you would need a system behind the pins that is, in effect, doing the same job as a vacuum pump anyway.

Having had a thunk about it, I'm now wondering if you mean: Throw the astronaut into a box with a bunch of packing peanuts. Packing peanuts displace the air in the box. Close the inside lid, then open the outside lid. Astronaut and peanuts are now on the surface. Use the same packing peanuts to come back inside. There's no system to withdraw the packing peanuts after the inner hatch closes in order to create a vacuum (or the Mars ambient near-vacuum) inside the box. Therefore there's no energy required to push the air out, or to pull the peanuts back against the vacuum they created.

If the latter, then yes. That might work. The "dock" for the Suitport works a bit like that. The PLSS and back-hatch fill up the conformal shape in the vehicle hatch, without leaving an empty space, so there's no pump down/up to "cycle" it.



You could similarly have a pair of rigid but shaped hatches that fit around the entire suit. Open the shaped inner-hatch, press your face/chest against the shaped outer-hatch, pull the shaped inner-hatch closed against your back. Your suit has displaced the air. Then open the outer hatch and step out.

Since different crew will be different sizes, you could have spacers that are sized to each size of spacesuit part. Eg, the medium torso has a front-back pair of spacers, the large legs have their pair, the small gloves have their pair, etc. You put the spacers in the coffin before you get in, in order to create a size that fits the size of suit you've put together.

In this version, you'd need a separate equipment airlock. But a set of similar spacers could be used on tools and parts, with generic blocks to fill up the empty space in the equipment-lock.



Only thing that bothers me is the outer hatch must open outwards. That's a bad thing.

It's not as bad as it would be if it was a normal airlock, because you wouldn't be relying on that shaped hatch to protect the entire base. You'd surely have a full sized airlock door behind the suit-coffin-box-thing acting as a safety bulkhead; just that under normal operations, when everything's working and you're using the coffin-thing, you don't need to pump out the airlock.

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #72 on: 08/25/2019 07:23 pm »
A more complete hatch.

First the Soft Capture docking Collar.  It includes the hatch, the equalizing valve, two viewports, the main handle (yellow at center) a manometer an instructions.  The hatch has a number of clamps all around, just in case it is required to operate in an inverted fashion.
The capture collar incluse 4 cam type attachments, that make a rigid connection between two facing collars.

The fabric bellows, with four actuating elements for fine adjustments.  This is 200mm (8in) long neutral, so could go down to 100mm (4in), and up to about 250 mm (10 in).  So it can angle on three axes.

The mounting frame.  This can take many forms, depending on if the system is used as an airlock or as a connector between modules.  It can attach to a rigid hull, or to a flexible fabric hull.

The hatch is 1200 x 2200mm free.  The hatch does obstruct passage just a bit when it is open.

The position of the hatch can be adjusted using the actuators, and a program can be used to actuate the final positioning and capture, with coordinated actions between the two capture collars.

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #73 on: 08/25/2019 07:33 pm »
A few details.

Offline A_M_Swallow

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Re: Airlocks for Mars Colony
« Reply #74 on: 08/25/2019 10:21 pm »
A few details.


The picture shows a rotating knob are the two arrows pointing in the same direction?

If the texts are together then the arrows are pointing in opposite directions.

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #75 on: 08/25/2019 11:50 pm »
Oups!
Thanks for the review!  Corrected.

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #76 on: 08/26/2019 06:42 am »
A more complete hatch.

I always feel bitchy criticising someone who has actually put in the effort, but... I think you're focusing too much on the "hatch", the door. The critical part of any docking system is the docking collar and surrounds. The hatch itself is, in a way, an afterthought.

How do the two sides connect? How do they align? How do they make an airtight seal? How do they do all that while leaving an unobstructed hole in the middle for people to move through? What utilities need to pass through the collar, in addition to the opening/tunnel for people? Do the utilities need to be inside the pressurise (airtight) part, or outside (but still connected by the process of docking), and how do those connections align? How tolerant is the seal to dirt/dust, to wear, even to collision?

Once you've solved that, you can stick a hatch at the back of the hole.

[Edit: This complexity might mean that an EVA airlock must be different from a vehicle docking port. Which means, if you're focused on the airlock, you can ignore the docking part, as long as you realise it probably can't be tacked on afterwards. It also means that a vehicle that is used for EVAs needs two hatches, the EVA side and the vehicle-to-hab docking side; both of which take up space and structure, but skip either one and you limit the use of the vehicles.]
« Last Edit: 08/26/2019 06:45 am by Paul451 »

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #77 on: 08/26/2019 12:51 pm »
A more complete hatch.

I always feel bitchy criticising someone who has actually put in the effort, but... I think you're focusing too much on the "hatch", the door. The critical part of any docking system is the docking collar and surrounds. The hatch itself is, in a way, an afterthought.

How do the two sides connect? How do they align? How do they make an airtight seal? How do they do all that while leaving an unobstructed hole in the middle for people to move through? What utilities need to pass through the collar, in addition to the opening/tunnel for people? Do the utilities need to be inside the pressurise (airtight) part, or outside (but still connected by the process of docking), and how do those connections align? How tolerant is the seal to dirt/dust, to wear, even to collision?

Once you've solved that, you can stick a hatch at the back of the hole.

[Edit: This complexity might mean that an EVA airlock must be different from a vehicle docking port. Which means, if you're focused on the airlock, you can ignore the docking part, as long as you realise it probably can't be tacked on afterwards. It also means that a vehicle that is used for EVAs needs two hatches, the EVA side and the vehicle-to-hab docking side; both of which take up space and structure, but skip either one and you limit the use of the vehicles.]
Not at all, that's why I submit these little things for your review and criticism! 
So added the ports that I think are required, from top to bottom: 

Comm, fibre and wire
Power, 240V 100 A, 120/240 and ground.  4 pins
Water, heat recover loop in, 38mm, 150 Psi ( 1000 kPa)
Water heat recovery loop out, 38mm, 150 psi ( 1000 kPa)
Potable water: 25mm, 150 psi ( 1000 kPa)
Sanitary water. 38mm, 15 psi (100 kPa)
The left side block is fixed, on a resilient slightly flexible base
The right side block moves 12mm out and each connector has a exterior ring that screws up to the other side.

A sliding cover on Each side covers the ports when not connected.
About 1mm of adjustment possible?

The wiring/piping to these connectors is going to take a bit of figuring out.... my main concern would be space for shut off actuators and valves.

The connection is through the four cam and rod attachments, one at each corner.
The alignment must be pretty precise. The cam and rods should be able to make final adjustments.
The seal is a metal spring plate, with a low temperature flex facing.  Seal is pushed to close by air pressure.


« Last Edit: 08/26/2019 01:11 pm by lamontagne »

Offline Paul451

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Re: Airlocks for Mars Colony
« Reply #78 on: 08/26/2019 02:15 pm »
The connection is through the four cam and rod attachments, one at each corner.
The alignment must be pretty precise. The cam and rods should be able to make final adjustments.

So that's a female half of a male/female pair? Ie, an asymmetric system. Which means the vehicles fitted with the male half of this collar can't dock with each other.

[Edit: Also, re: utilities. You've put them all outside the collar's seal (assuming the yellow is meant to represent however the collars create an airtight seal against each other). That means they are, in effect, outside the pressure vessels on both the habitat and vehicles. So strictly EVA for maintenance.]
« Last Edit: 08/26/2019 02:21 pm by Paul451 »

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #79 on: 08/26/2019 02:49 pm »
The connection is through the four cam and rod attachments, one at each corner.
The alignment must be pretty precise. The cam and rods should be able to make final adjustments.

So that's a female half of a male/female pair? Ie, an asymmetric system. Which means the vehicles fitted with the male half of this collar can't dock with each other.

[Edit: Also, re: utilities. You've put them all outside the collar's seal (assuming the yellow is meant to represent however the collars create an airtight seal against each other). That means they are, in effect, outside the pressure vessels on both the habitat and vehicles. So strictly EVA for maintenance.]
Nope, to match vehicles you always reverse the faces.  The cam and rods always match.  Like the connection ports.  Asymmetrical vertical left/right works, asymmetrical one female port, one male port does not work, asymmetrical horizontal doesn't work.

I guess my vertical connectors are all redundant, the way I've done them.  Might be a bit overkill.  One the other hand, if one fails, the other can be good.

Yes, exterior maintenance. Hadn't thought of that as a problem, but might not be the best.


Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #80 on: 08/26/2019 02:58 pm »
Looking at it again, I guess I could also have the cam and rods inside the seal, so they might be visually inspected, if need be.

Offline A_M_Swallow

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Re: Airlocks for Mars Colony
« Reply #81 on: 08/26/2019 06:02 pm »
If the connectors are duplicated on the left hand side of the door and the right hand side of the door it become  androgynous. This eliminates problems due to both airlocks being say male. This technique is used in the NASA Docking system.

e.g. page 57
http://www.internationaldockingstandard.com/download/IDSS_IDD_Revision_D_043015.pdf

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #82 on: 08/27/2019 01:26 am »
There, tried to follow all the rules  :-)

Double seal
Double connectors
Flexible soft connector
Shut off valves

Offline Twark_Main

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Re: Airlocks for Mars Colony
« Reply #83 on: 12/01/2019 10:44 pm »
Most buried inflatables will need to be connected by corridors anyway

Why?
Because of the slope of the regolith on top of them.  They can connect to one another underground, but they need at least a small corridor to the outside.

Attachment:



Wouldn't a reinforced earth retaining wall ("reinforced mars" sounds weird) be an alternative here?

At large sizes, reinforced earth construction converges with the materials/construction used in HESCO bastions — steel mesh tensile reinforcements extend horizontally into the dirt, faced with more mesh and an inner synthetic fabric geotextile to retain the earth (and typically covered by a final rainproof/aesthetic concrete facing system, which can be omitted on Mars).

I think shipping the material for constructing a retaining wall would use far less mass than shipping the longer pressurized tunnel (or if they're made ISRU on Mars, lower mass also reduces cost). The earth pressure behind the wall is much smaller than 1 atm, so the physics/math "sanity check" works out.

Obviously the retaining wall would only need to be a "notch" around the tunnel outlet (see attached image), not the entire perimeter of the building. This minimizes mass.

On a (very) minor side-note, it looks like there's only about 1 meter of regolith on top of the buried hab. This seems too thin imo.
« Last Edit: 12/01/2019 11:04 pm by Twark_Main »
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Online Coastal Ron

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Re: Airlocks for Mars Colony
« Reply #84 on: 12/02/2019 12:42 am »
Wouldn't a reinforced earth retaining wall ("reinforced mars" sounds weird) be an alternative here?

Or, bury the entire complex and have the rovers drive down into a tunnel. Because the vehicles will need to be protected too when they are not on the surface.

Not sure I've stumbled across this topic before, but I'm glad I did because what is designed and defined here might be applicable to rotating space stations.

One thought I've had for first generation rotating space stations is that we could use the Common Berthing Mechanism (CBM), though with a much quicker way of latching and unlatching. And yes this is a passive port, not meant for docking, and that is because I envision it truly will be more like berthing than docking.

Which brings up the question for this thread, is there is need for "docking" vs "berthing". I'm thinking that there will be some version of an "active berthing mechanism", but otherwise the docking hardware needed for spacecraft today will be overkill for mating two habitable objects on Mars.

What do you think?
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #85 on: 12/02/2019 01:37 am »
Wouldn't a reinforced earth retaining wall ("reinforced mars" sounds weird) be an alternative here?

Or, bury the entire complex and have the rovers drive down into a tunnel. Because the vehicles will need to be protected too when they are not on the surface.

Not sure I've stumbled across this topic before, but I'm glad I did because what is designed and defined here might be applicable to rotating space stations.

One thought I've had for first generation rotating space stations is that we could use the Common Berthing Mechanism (CBM), though with a much quicker way of latching and unlatching. And yes this is a passive port, not meant for docking, and that is because I envision it truly will be more like berthing than docking.

Which brings up the question for this thread, is there is need for "docking" vs "berthing". I'm thinking that there will be some version of an "active berthing mechanism", but otherwise the docking hardware needed for spacecraft today will be overkill for mating two habitable objects on Mars.

What do you think?
I think that the vehicles with adaptive suspension can do some of the docking/berthing work, and that bellows on the airlock can help as well.  The airlock I propose has four cam attachments at the corners that pull in the two facing plates one against the other. 
As far as bolting building components together, large flanges with gaskets are indeed probably enough.  But it might make sense to size these so that they can have a complete docking mechanism, eventually an airlock, attached to them.

I usually imagine the vehicles as going to park themselves in an infra red heated surface enclosure.

Offline Twark_Main

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Re: Airlocks for Mars Colony
« Reply #86 on: 12/03/2019 11:31 am »
Wouldn't a reinforced earth retaining wall ("reinforced mars" sounds weird) be an alternative here?

Or, bury the entire complex and have the rovers drive down into a tunnel. Because the vehicles will need to be protected too when they are not on the surface.

Not sure I've stumbled across this topic before, but I'm glad I did because what is designed and defined here might be applicable to rotating space stations.

One thought I've had for first generation rotating space stations is that we could use the Common Berthing Mechanism (CBM), though with a much quicker way of latching and unlatching. And yes this is a passive port, not meant for docking, and that is because I envision it truly will be more like berthing than docking.

Which brings up the question for this thread, is there is need for "docking" vs "berthing". I'm thinking that there will be some version of an "active berthing mechanism", but otherwise the docking hardware needed for spacecraft today will be overkill for mating two habitable objects on Mars.

What do you think?
I think that the vehicles with adaptive suspension can do some of the docking/berthing work, and that bellows on the airlock can help as well.  The airlock I propose has four cam attachments at the corners that pull in the two facing plates one against the other. 
As far as bolting building components together, large flanges with gaskets are indeed probably enough.  But it might make sense to size these so that they can have a complete docking mechanism, eventually an airlock, attached to them.

I usually imagine the vehicles as going to park themselves in an infra red heated surface enclosure.

Makes sense to me. I like the autonomous parking particularly.

This is really getting down into the weeds, but what do you think about having six cam attachments instead of four? It seems that you'd want each attachment to hold roughly the same structural loads, otherwise some of them are over/under-built. The "span" of the door's top and bottom sill is half that of the sides, so it seems that each side would do better with two cam attachment points instead of one.

In general the more attachment points the lighter the door, since the frame can be less overbuilt. To take an extreme example, imagine using just one or two attachment points, vs using dozens.

And besides all that right brain logical reasoning, when I draw it on paper that layout just "feels" more "right," not just structurally but aesthetically speaking (at least to me). Would you agree?
« Last Edit: 12/03/2019 11:48 am by Twark_Main »
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Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #87 on: 12/15/2019 05:17 pm »
Wouldn't a reinforced earth retaining wall ("reinforced mars" sounds weird) be an alternative here?

Or, bury the entire complex and have the rovers drive down into a tunnel. Because the vehicles will need to be protected too when they are not on the surface.

Not sure I've stumbled across this topic before, but I'm glad I did because what is designed and defined here might be applicable to rotating space stations.

One thought I've had for first generation rotating space stations is that we could use the Common Berthing Mechanism (CBM), though with a much quicker way of latching and unlatching. And yes this is a passive port, not meant for docking, and that is because I envision it truly will be more like berthing than docking.

Which brings up the question for this thread, is there is need for "docking" vs "berthing". I'm thinking that there will be some version of an "active berthing mechanism", but otherwise the docking hardware needed for spacecraft today will be overkill for mating two habitable objects on Mars.

What do you think?
I think that the vehicles with adaptive suspension can do some of the docking/berthing work, and that bellows on the airlock can help as well.  The airlock I propose has four cam attachments at the corners that pull in the two facing plates one against the other. 
As far as bolting building components together, large flanges with gaskets are indeed probably enough.  But it might make sense to size these so that they can have a complete docking mechanism, eventually an airlock, attached to them.

I usually imagine the vehicles as going to park themselves in an infra red heated surface enclosure.

Makes sense to me. I like the autonomous parking particularly.

This is really getting down into the weeds, but what do you think about having six cam attachments instead of four? It seems that you'd want each attachment to hold roughly the same structural loads, otherwise some of them are over/under-built. The "span" of the door's top and bottom sill is half that of the sides, so it seems that each side would do better with two cam attachment points instead of one.

In general the more attachment points the lighter the door, since the frame can be less overbuilt. To take an extreme example, imagine using just one or two attachment points, vs using dozens.

And besides all that right brain logical reasoning, when I draw it on paper that layout just "feels" more "right," not just structurally but aesthetically speaking (at least to me). Would you agree?
I agree six might be better.  For the design illustrated, the center is taken up by the angling and restraining mechanism in the bellows.  Perhaps even eight might be more appropriate. For the moment. I've just planned for a thicker flange.

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #88 on: 12/19/2019 10:11 pm »
Looking at the model again, I actually placed the four cam attachments symmetrically and almost equidistant from one another.  They are in a 1,42 and 1,43 m rectangle.  Don't know if this is good or bad, really, since the rigidity of the frame comes from an angled shaped structure and not that much from the cams.
I do think alignment might be a real problem for a surface vehicle connection, it's hard to say how well an active adapter would do.  It would be interesting if someone was actually testing this, but I guess the requirement is still perhaps a decade in the future, so no great rush. 

For spaceship to spaceship, the existing androgynous docking ports would be sufficient, I guess.  And until there are a lot of people on Mars the existing berting standard of 1300mm (50 inches) can be used for module assembly, even if a lot of people will hit their head over time  :-)

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Re: Airlocks for Mars Colony
« Reply #89 on: 12/27/2019 04:29 pm »
Looking at the model again, I actually placed the four cam attachments symmetrically and almost equidistant from one another.  They are in a 1,42 and 1,43 m rectangle.  Don't know if this is good or bad, really, since the rigidity of the frame comes from an angled shaped structure and not that much from the cams.

The cams are resisting the enormous pressure forces pushing the frames apart. Keeping the cams at the same spacing interval minimizes the structural mass required to avoid unacceptable deflection of the frame.
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Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #90 on: 12/27/2019 07:18 pm »
Looking at the model again, I actually placed the four cam attachments symmetrically and almost equidistant from one another.  They are in a 1,42 and 1,43 m rectangle.  Don't know if this is good or bad, really, since the rigidity of the frame comes from an angled shaped structure and not that much from the cams.

The cams are resisting the enormous pressure forces pushing the frames apart. Keeping the cams at the same spacing interval minimizes the structural mass required to avoid unacceptable deflection of the frame.
So it does.  6 to 7 tonnes per cam for a full atmospheric pressure airlock. At least 1 to 2 inches square of metal.  So I guess there would be a beam of 1.4m long, with two end points and a support point in the middle.  It would be much simpler if there were a large number of attachments, that would strengthen the assembly.  I wouldn't be surprised if the deflexion for four cams only is too high.  The cams would then mainly serve as hooks, and some kind of screwed attachment points would serve to maintain the integrity of the  airlock.

Offline Kenm

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Re: Airlocks for Mars Colony
« Reply #91 on: 12/31/2019 10:31 pm »
Here is a different design for a docking airlock. Not nearly as pretty
drawings as those by Lamontagne but they should illustrate the general idea.

It is bellows walled tube (doors not shown) which is moved into position with
6 blue actuators acting as a Stewart platform. These motions would be carried out with the pressure in the tube equal to the outside pressure so there would be no large forces involved.
The rectangular opening can be moved in three directions and tilted in two. The bellows will prevent rotation of the doorway around the axis of the tube so a rotary seal was added between the outer ring and the green doorway frame. 
Once the tube is in position the doorway can be locked in place with with latches like the
International docking system.
In principal the actuators could also be used to resist the force from the air pressure and since they
would be in tension buckling would not be a worry. However these large forces would likely require very heavy actuators so I added 12 1/2" dia red Dyneema rope lines to resist the air pressure. Each line has a 21,500 lb breaking strength. They are attached to winches which need to be able to apply enough tension to keep the ropes orderly during motions and to lock in position before the air pressure is applied. The rope will stretch about 1% as the load is applied.

One comment about running service lines through the door frame. Can we move the waste water lines to the floor level? If I was working on a waste line I would want it as far as possible from any potable water lines. All of the lines should probably be purged and vented before disconnection so they don't boil out all over the doorway.
 

Offline sghill

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Re: Airlocks for Mars Colony
« Reply #92 on: 01/03/2020 03:21 pm »
Which brings up the question for this thread, is there is need for "docking" vs "berthing". I'm thinking that there will be some version of an "active berthing mechanism", but otherwise the docking hardware needed for spacecraft today will be overkill for mating two habitable objects on Mars.

What do you think?

Related to that thought is the need for docking/berthing seal maintenance.

IMHO, the seals for a docking port will need to be easily serviceable and cheap to replace owing to the wear and tear they will experience on a daily, if not hourly basis.  However, they may not need to be as effective as a less-often-used berthing seal. A slight positive pressure (e.g. air leaks) to force contaminants out of the airlock and also the seal may not be a bad thing.

A frequently used airlock in my mind would consist of a docking door with seals that are replaced as much as monthly, then a surface exposure decontamination hallway to remove soils and perchlorates, then a higher-level seal and door behind it.

A berthing airlock would have sets of doors that are rarely cycled, whose seals will last for months or years between replacements, and no decontamination hallway.
« Last Edit: 01/03/2020 03:21 pm by sghill »
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Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #93 on: 01/03/2020 03:59 pm »
Here is a different design for a docking airlock. Not nearly as pretty
drawings as those by Lamontagne but they should illustrate the general idea.

It is bellows walled tube (doors not shown) which is moved into position with
6 blue actuators acting as a Stewart platform. These motions would be carried out with the pressure in the tube equal to the outside pressure so there would be no large forces involved.
The rectangular opening can be moved in three directions and tilted in two. The bellows will prevent rotation of the doorway around the axis of the tube so a rotary seal was added between the outer ring and the green doorway frame. 
Once the tube is in position the doorway can be locked in place with with latches like the
International docking system.
In principal the actuators could also be used to resist the force from the air pressure and since they
would be in tension buckling would not be a worry. However these large forces would likely require very heavy actuators so I added 12 1/2" dia red Dyneema rope lines to resist the air pressure. Each line has a 21,500 lb breaking strength. They are attached to winches which need to be able to apply enough tension to keep the ropes orderly during motions and to lock in position before the air pressure is applied. The rope will stretch about 1% as the load is applied.

One comment about running service lines through the door frame. Can we move the waste water lines to the floor level? If I was working on a waste line I would want it as far as possible from any potable water lines. All of the lines should probably be purged and vented before disconnection so they don't boil out all over the doorway.
-Very interesting design.  Offers a lot more interior space than my proposal, and since there are a lot of recommendations out there on using a buddy system for airlock use it might be a basic design requirement to have more space.
-Regarding the water lines on my design, I would expect the waste water line to be pumped, so there could/would be a 'wash cycle' before the line was connected or disconnected.  There is a valve in the design, right behind the outer wall, for all the lines to reduce waste to the minimum and risk of leakage.  There is a mechanical attachment below the floor, so not really much space there.
-It might be a good idea to have purge valves to empty out the small space between the two valves.  Would need to use some air for the purging, in particular in 0g.

-Why so much built-in travel? 
-With the door closed, the pressure will be taken up on the actuators and the reels.  Are there fail safe mechanisms that ensure that the system is operational without power?  Is that even a requirement?
-Is rotational misalignment a possibility?  Or does the docking system automatically put the doors in the proper orientation?  Trying to avoid the rotating seal. 
-Have you tried mating this to vehicles?  As my design started as a vehicle airlock, it needed to be compact.  But it's probably overdesing as a permanent connection.

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #94 on: 01/03/2020 04:11 pm »
Which brings up the question for this thread, is there is need for "docking" vs "berthing". I'm thinking that there will be some version of an "active berthing mechanism", but otherwise the docking hardware needed for spacecraft today will be overkill for mating two habitable objects on Mars.

What do you think?

Related to that thought is the need for docking/berthing seal maintenance.

IMHO, the seals for a docking port will need to be easily serviceable and cheap to replace owing to the wear and tear they will experience on a daily, if not hourly basis.  However, they may not need to be as effective as a less-often-used berthing seal. A slight positive pressure (e.g. air leaks) to force contaminants out of the airlock and also the seal may not be a bad thing.

A frequently used airlock in my mind would consist of a docking door with seals that are replaced as much as monthly, then a surface exposure decontamination hallway to remove soils and perchlorates, then a higher-level seal and door behind it.

A berthing airlock would have sets of doors that are rarely cycled, whose seals will last for months or years between replacements, and no decontamination hallway.
If by berthing you mean a permanent connection between prefabricated habitat sections I agree that a simple seal, rather like a giant version of a pipe flanged assembly, will probably be sufficient.  I think it might follow the same dimensional specs as the rectangular door though, but even that would be too small for a 'second generation' settlement, where you might want junctions large enough to pass entire vehicles through.
Airlock designs I've seen for the Moon have exactly that, a dust room, after the airlock, for decontamination.  I've also seen some pretty severe criticism of back entry suits, so perhaps the ailocks might be used more often than I expected for entry with 'conventional' suits.  Perhaps I'm making a mistake by trying to use a port designed for connecting vehicles as an airlock design; I should perhaps work the other way around:  Define the airlock requirements, and then deduce the port that can satisfy them.

Offline sghill

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Re: Airlocks for Mars Colony
« Reply #95 on: 01/04/2020 02:23 pm »
Airlock designs I've seen for the Moon have exactly that, a dust room, after the airlock, for decontamination.  I've also seen some pretty severe criticism of back entry suits, so perhaps the ailocks might be used more often than I expected for entry with 'conventional' suits.  Perhaps I'm making a mistake by trying to use a port designed for connecting vehicles as an airlock design; I should perhaps work the other way around:  Define the airlock requirements, and then deduce the port that can satisfy them.

"First Principles" are always the correct place to start a problem solving exercise. :)

A coupling system differs in requirements from an airlock system.

An airlock system must:
1) Keep the inside environment in and the outside environment out
2) Prevent contamination of people, air, and equipment inside the habitat
3) Allow for repeated entry and exit- but not necessarily in both directions for the same system.

After that, and I think we are moving away from first principles and into feature sets.

Any more?
« Last Edit: 01/04/2020 02:24 pm by sghill »
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Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #96 on: 01/04/2020 03:06 pm »
Airlock designs I've seen for the Moon have exactly that, a dust room, after the airlock, for decontamination.  I've also seen some pretty severe criticism of back entry suits, so perhaps the ailocks might be used more often than I expected for entry with 'conventional' suits.  Perhaps I'm making a mistake by trying to use a port designed for connecting vehicles as an airlock design; I should perhaps work the other way around:  Define the airlock requirements, and then deduce the port that can satisfy them.

"First Principles" are always the correct place to start a problem solving exercise. :)

A coupling system differs in requirements from an airlock system.

An airlock system must:
1) Keep the inside environment in and the outside environment out
2) Prevent contamination of people, air, and equipment inside the habitat
3) Allow for repeated entry and exit- but not necessarily in both directions for the same system.

After that, and I think we are moving away from first principles and into feature sets.

Any more?
You know what?  I think I even got the title of the thread wrong.  Airlocks for Mars colony was not what I was looking for, it was Connection Ports for a Martian Settlement (moving away from the 'C' word... ;-).  A connection port is not an airlock, although it is a part of the airlock.  Didn't Musk also say that definitions were the hardest part?  Identify the problem and ask the right question?


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Re: Airlocks for Mars Colony
« Reply #97 on: 01/04/2020 03:20 pm »
If by berthing you mean a permanent connection between prefabricated habitat sections I agree that a simple seal, rather like a giant version of a pipe flanged assembly, will probably be sufficient.

I was ambiguous about what I meant on that topic. I had been thinking of the existing docking and berthing ports we use today.

And while docking ports are only used for visiting vehicles, the Common Berthing Mechanism (CBM) is used to attach ISS segments together, plus it is used as the interface for cargo vehicles.

For Mars I was not considering the interfaces needed for buildings - that is a different topic. My interest is what we use for human occupied vehicles, which could be mated and de-mated multiple times per day. How do we do that in a safe way?

Quote
Define the airlock requirements, and then deduce the port that can satisfy them.

Agreed.

One material I've been considering for space station docking ports is silicone, which is flexible and stable over a wide temperature range (-60°C to +250°C). And after doing some searching on scuba forums, it appears that silicone is resistant to chlorine, which is a big consideration on Mars since it has relatively high concentrations of perchlorate compounds containing chlorine.

Suffice it to say that whatever docking/berthing ports we have we'll need ways to keep Mars dust off of them. That said, there could be docking/berthing ports for both clean and dirty environments.

For instance, for "public transports" that move between parts of a colony (or between colonies) where the occupants are in a shirtsleeve environment, the docking/berthing ports don't have to worry as much about dust. But a rover that could be used by its occupants to work out on the surface would need far more extensive dust handling capabilities.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #98 on: 01/04/2020 03:41 pm »
I expect I've been overthinking the problem.  Perhaps best to just suppose a slightly taller than wide berthing port, with the same details as the existing berting connector technology, and have some manually connected piping under a floor going through the port.

This does make a side port for a moving surface vehicle more or less impossible; it would have to always back-up to the static port on the settlement.  But is that such a great loss?

Or the vehicle can use the swiveling wheels found on the MMSEV.  So it can move sideways and the problem goes away.

I guess the seals on the existing berting ports are already specified for difficult temperature environments, but dust is perhaps a new design issue, as Coastal Ron mentions.

As far as research goes, very interesting NASA paper joined.

Offline sghill

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Re: Airlocks for Mars Colony
« Reply #99 on: 01/05/2020 02:32 pm »
I guess the seals on the existing berting ports are already specified for difficult temperature environments, but dust is perhaps a new design issue, as Coastal Ron mentions.

It's not the dust, it's the abrasiveness of the dust. And the corrosiveness of the perchlorates that will be the problem.

You need something super cheap and easily replaceable for a door seal that is used often in that environment.

Also, a door seal doesn't have to be one compound. You could use several materials to achieve the required results and be cheap.

Think of oven doors. Woven asbestos or fiberglass fiber covering a silicon tubing core would make very abrasion and temperature resistant seals that are extremely flexible so that a nice seal may be achieved with mechanical pressure applied from both sides.

And unlike orbital seals, a little leak while the airlock chamber is in use wouldn't be horrible because you have a source of replenishment gas.

A 99% sealed system may be just fine for an outside door that is used all the time if the inner airlock door has a better seal that doesn't see radiation, thermal expansion or the same level of abrasive dust and corrosive perchlorates, and so its seal is replaced less often.

I'm sure there are dozens of other combinations that would make nice door seals.


« Last Edit: 01/05/2020 02:33 pm by sghill »
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Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #100 on: 01/05/2020 04:21 pm »
I guess the seals on the existing berting ports are already specified for difficult temperature environments, but dust is perhaps a new design issue, as Coastal Ron mentions.

It's not the dust, it's the abrasiveness of the dust. And the corrosiveness of the perchlorates that will be the problem.

You need something super cheap and easily replaceable for a door seal that is used often in that environment.

Also, a door seal doesn't have to be one compound. You could use several materials to achieve the required results and be cheap.

Think of oven doors. Woven asbestos or fiberglass fiber covering a silicon tubing core would make very abrasion and temperature resistant seals that are extremely flexible so that a nice seal may be achieved with mechanical pressure applied from both sides.

And unlike orbital seals, a little leak while the airlock chamber is in use wouldn't be horrible because you have a source of replenishment gas.

A 99% sealed system may be just fine for an outside door that is used all the time if the inner airlock door has a better seal that doesn't see radiation, thermal expansion or the same level of abrasive dust and corrosive perchlorates, and so its seal is replaced less often.

I'm sure there are dozens of other combinations that would make nice door seals.
I've been reading about spacesuits, and the plan seems to be monthly maintenance.  I expect the door seals would require similar servicing.  Would probably be a good idea to have them washable and easy to remove and reset in place.  If I understand correctly washing in lots of water dilutes and neutralises the perchlorates pretty well?

In fact, perhaps it's a good idea to wash down the rovers fairly frequently?  I know in mining they frequently wash down the trucks, to reduce dust and grease buildup, that can mass up to one tonne on large mining trucks.

I guess we could have the following possible functions for the port:

1-Assembly of prefabricated habitat elements.  These are more of less single use assemblies.

2-Perpendicular Docking Ports, with one 'fixed' port on the target and one 'fixed 'port on a moving vehicle. The vehicle backs into, or drives into the fixed port and the vehicle does most of the adjusting from proper mating of the ports.

3- Parallel Docking Ports, where the vehicle(s) are brought close to one another and the port(s) is (are) extended to mate with the other vehicle.

4- Airlock ports. The doors open into a vacuum, or towards very low Martian air pressure.  Airlock ports will require a second door to create the airlock, and a dust removal room after the second door to clean off the suits, on planetary surfaces.

Function 4 can be combined with 1,2 or 3.

Ports of type 3 can also be used for type 2, but not the other way around. 
A vehicle with swivel wheel can operate as a type 2 port with a type 3 function.

Parallel docking is really only an issue if two rovers meet in the field.  When they dock to a habitat, I think it would make sense to provide the habitat port with more motion capabilities.

So, this raises the question, that might be better answered in another thread, but still:  Are swivel wheels on a martian Rover an asset, because they can simplify port design and offer great manoeuvrability, or a liability because they have their own limitations, including ( perhaps?) limiting the speed of the vehicles? As usual, I ask not for the first few exploration vehicles, but as a longer term general vehicle design requirement.

Or perhaps rovers should just always dock perpendicularly? If they do have a side port, the habitat can extend it's mating port and other rovers can come in and dock in a perpendicular way?

« Last Edit: 01/05/2020 04:28 pm by lamontagne »

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #101 on: 01/05/2020 07:08 pm »
A NASA paper basically stating, I think, than an airlock is not a good solution for a Rover and that suitports are the way to go.
It also mentions that the questions of surface docking has not really been addressed by NASA and that the berthing port sized system is probably not a good solution for rovers.

And a second paper on airlocks vs suitlocks, 2008 so more recent than the first suitport paper.  However, this one doesn't address rovers all that much.  Mostly access to a fixed habitat.  I'm pretty certain it directly contradicts the first paper and omits what the first author calls the 'Skylab lesson':  An airlock shouldn't act as an obstruction between the habitat and the vehicle.

Sadly, this seems to complete the 'research previous art' part of the airlock/port design analysis process.  I get the feeling that the ports we saw on the MMSEV were just mock-ups, without all that much science behind them?

I think than Kenm' design may be closer to what is truly feasible.  But perhaps the strain on large doors may be a bit much for it.  The Space shuttle, it seems, used a docking port with a single wire going through a number of pulleys to get a similar result to the wires he describes in his design.  See the third paper.


Offline Kenm

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Re: Airlocks for Mars Colony
« Reply #102 on: 01/06/2020 05:13 am »
Here is a different design for a docking airlock. Not nearly as pretty
drawings as those by Lamontagne but they should illustrate the general idea.

It is bellows walled tube (doors not shown) which is moved into position with
6 blue actuators acting as a Stewart platform. These motions would be carried out with the pressure in the tube equal to the outside pressure so there would be no large forces involved.
The rectangular opening can be moved in three directions and tilted in two. The bellows will prevent rotation of the doorway around the axis of the tube so a rotary seal was added between the outer ring and the green doorway frame. 
Once the tube is in position the doorway can be locked in place with with latches like the
International docking system.
In principal the actuators could also be used to resist the force from the air pressure and since they
would be in tension buckling would not be a worry. However these large forces would likely require very heavy actuators so I added 12 1/2" dia red Dyneema rope lines to resist the air pressure. Each line has a 21,500 lb breaking strength. They are attached to winches which need to be able to apply enough tension to keep the ropes orderly during motions and to lock in position before the air pressure is applied. The rope will stretch about 1% as the load is applied.

One comment about running service lines through the door frame. Can we move the waste water lines to the floor level? If I was working on a waste line I would want it as far as possible from any potable water lines. All of the lines should probably be purged and vented before disconnection so they don't boil out all over the doorway.
-Very interesting design.  Offers a lot more interior space than my proposal, and since there are a lot of recommendations out there on using a buddy system for airlock use it might be a basic design requirement to have more space.
-Regarding the water lines on my design, I would expect the waste water line to be pumped, so there could/would be a 'wash cycle' before the line was connected or disconnected.  There is a valve in the design, right behind the outer wall, for all the lines to reduce waste to the minimum and risk of leakage.  There is a mechanical attachment below the floor, so not really much space there.
-It might be a good idea to have purge valves to empty out the small space between the two valves.  Would need to use some air for the purging, in particular in 0g.

-Why so much built-in travel? 
-With the door closed, the pressure will be taken up on the actuators and the reels.  Are there fail safe mechanisms that ensure that the system is operational without power?  Is that even a requirement?
-Is rotational misalignment a possibility?  Or does the docking system automatically put the doors in the proper orientation?  Trying to avoid the rotating seal. 
-Have you tried mating this to vehicles?  As my design started as a vehicle airlock, it needed to be compact.  But it's probably overdesing as a permanent connection.

I was going for a long travel to have a look at the tradeoff between a flexible airlock and easy parking vs a less flexible lock and precision parking. I am tending to think that an active suspension with swiveling wheels would give a net payoff by simplifying airlock design and allowing precision placement of loads carried by the vehicles.

As far as fail safe mechanisms the actuators and reels would be locked without power. Some questions arise in general about how we want the latching mechanisms to act during a power failure. Do we want to be able feed power from the other
vehicle or to manually operate the latches from inside or from outside?
The International Docking System Standard has a ring of active and passive hard capture hooks on each vehicle. If you have the misfortune of having your passive hooks held by malfunctioning active hooks on the other vehicle you may be able to take the load on your active hooks and manually release the other vehicles active hooks before performing a normal undocking.

I just saw your post on the cable restraint on the Shuttle dock, great find. I was using many winches and criss-crossed lines
to help hold the door in place when it is offset sideways. With better alignment things can be simplified a lot.

I have been thinking about using inflatable rubber seals as a way of reducing a lot of precision alignment needed with the flat
face seals used on the current docking ports.
http://www.iksonic.com/product-category/molded-rubber/custom-inflatable-rubber-seals/

Venting vs pumpdown is another question which needs looking at. With the high power density of lithium ion batteries a fast pumpdown may be possible but there is still the mass of the pumps to consider.

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Re: Airlocks for Mars Colony
« Reply #103 on: 01/12/2020 08:50 pm »
Here is another try at an airlock design. This one needs the rover to bring the two airlocks into contact and uses inflatable seals
to avoid having to pull the seal faces together. In this design there are no actuators which need to resist the air pressure.

Each airlock has a gimbal located near the body of the rover which is used to bring the ports into alignment before contact. A bellows would seal the joint within the gimbal which is not shown.
This design has eight tang and clevis sets to hold against the air pressure. When the tang bottoms out in the clevis the holes will be lined up so the pin can be inserted. Since the inflatable seals can compensate for a gap the pins can be a loose fit in the holes so as to avoid problems with dust. The hole in the tangs are elongated to allow for a slight rotational misalignment around the axis of the airlock.
 


Online Coastal Ron

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Re: Airlocks for Mars Colony
« Reply #104 on: 01/12/2020 10:13 pm »
Regarding extendable airlock designs, it seems to me that there are three possible versions to consider:

A. The vehicle has a dock door only, no extendible docking mechanism.

B. The habitat has a dock door only, no extendible docking mechanism.

C. Both the vehicle and the habitat have an extendible docking mechanism.

I think the disadvantage of both A & B is that it eliminates a potential redundancy.

With C you could have a version for vehicles that doesn't have to extend in normal use, the habitat dock would normally always extend to the vehicle. That would reduce the maintenance needs of the vehicle, but allow the vehicle to have the ability to mate to a non-functional vehicle or habitat.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #105 on: 01/13/2020 02:25 am »
Here is another try at an airlock design. This one needs the rover to bring the two airlocks into contact and uses inflatable seals
to avoid having to pull the seal faces together. In this design there are no actuators which need to resist the air pressure.

Each airlock has a gimbal located near the body of the rover which is used to bring the ports into alignment before contact. A bellows would seal the joint within the gimbal which is not shown.
This design has eight tang and clevis sets to hold against the air pressure. When the tang bottoms out in the clevis the holes will be lined up so the pin can be inserted. Since the inflatable seals can compensate for a gap the pins can be a loose fit in the holes so as to avoid problems with dust. The hole in the tangs are elongated to allow for a slight rotational misalignment around the axis of the airlock.
Does the rover really need an airlock?  Might it be better off with a suitport(s) and a docking port, while the movable and flexible airlock was on the base only?
I think the gimbal is perhaps a bit too much flexibility?  Would really love to see two vehicles really doing the matching up manoeuver.

I've joined a paper on the NASA Athlete vehicle for some docking details.  There's also an interesting youtube video.




The rover might just have a rigid docking port first shirtsleeve transfer

Offline Kenm

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Re: Airlocks for Mars Colony
« Reply #106 on: 01/14/2020 06:04 am »
Here is another try at an airlock design. This one needs the rover to bring the two airlocks into contact and uses inflatable seals
to avoid having to pull the seal faces together. In this design there are no actuators which need to resist the air pressure.

Each airlock has a gimbal located near the body of the rover which is used to bring the ports into alignment before contact. A bellows would seal the joint within the gimbal which is not shown.
This design has eight tang and clevis sets to hold against the air pressure. When the tang bottoms out in the clevis the holes will be lined up so the pin can be inserted. Since the inflatable seals can compensate for a gap the pins can be a loose fit in the holes so as to avoid problems with dust. The hole in the tangs are elongated to allow for a slight rotational misalignment around the axis of the airlock.
Does the rover really need an airlock?  Might it be better off with a suitport(s) and a docking port, while the movable and flexible airlock was on the base only?
I think the gimbal is perhaps a bit too much flexibility?  Would really love to see two vehicles really doing the matching up manoeuver.

I've joined a paper on the NASA Athlete vehicle for some docking details.  There's also an interesting youtube video.




The rover might just have a rigid docking port first shirtsleeve transfer

Without an airlock there is no way to move anything in or out of the rover.
If you need a tool or want to work on something without gloves on you have to head
back to base. This suggests that at least a small equipment airlock would be useful.

Another question is how can we transfer crew if one of the rovers is disabled
and unable to connect to a docking port. Having spare empty suitports on the rovers
would allow the crew to move in their suits to the rescue rover. Of course if you are
not using suitports an airlock would be available on each rover.


Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #107 on: 01/14/2020 12:31 pm »
Here is another try at an airlock design. This one needs the rover to bring the two airlocks into contact and uses inflatable seals
to avoid having to pull the seal faces together. In this design there are no actuators which need to resist the air pressure.

Without an airlock there is no way to move anything in or out of the rover.
If you need a tool or want to work on something without gloves on you have to head
back to base. This suggests that at least a small equipment airlock would be useful.

Another question is how can we transfer crew if one of the rovers is disabled
and unable to connect to a docking port. Having spare empty suitports on the rovers
would allow the crew to move in their suits to the rescue rover. Of course if you are
not using suitports an airlock would be available on each rover.

Absolutely, a small sample/tool airlock is included with most designs I've seen for rovers and should be expected.

How about a movable and agile airlock?  If instead of depending on an agile rover, what if the airlock was itself on an agile platform, like a smaller version of the Athlete platform?  You could carry it around like a limpet, and it could move out and move around if required.  Connecting to any number of rovers in different attitudes like a local shuttle service.  No need to pump out as well.  Longer term installations would connect port to port.  A bit like these flatbed trailers used for deliveries.
« Last Edit: 01/14/2020 12:32 pm by lamontagne »

Offline sghill

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Re: Airlocks for Mars Colony
« Reply #108 on: 01/14/2020 09:48 pm »


How about a movable and agile airlock?  If instead of depending on an agile rover, what if the airlock was itself on an agile platform, like a smaller version of the Athlete platform?  You could carry it around like a limpet, and it could move out and move around if required.  Connecting to any number of rovers in different attitudes like a local shuttle service.  No need to pump out as well.  Longer term installations would connect port to port.  A bit like these flatbed trailers used for deliveries.

I love it! I was thinking more along these lines, however. Why reinvent the wheel?



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Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #109 on: 01/14/2020 10:20 pm »


How about a movable and agile airlock?  If instead of depending on an agile rover, what if the airlock was itself on an agile platform, like a smaller version of the Athlete platform?  You could carry it around like a limpet, and it could move out and move around if required.  Connecting to any number of rovers in different attitudes like a local shuttle service.  No need to pump out as well.  Longer term installations would connect port to port.  A bit like these flatbed trailers used for deliveries.

I love it! I was thinking more along these lines, however. Why reinvent the wheel?
That type of arrangement makes sense for the base/settlement/colony but I think Kenm was wondering about a field trip and eventually a problem with a rover far in the field.
-A simple protocol without an airlock might just be to design a vehicle than can survive being depressurized and to carry spare spacesuits.  But this probably fails if someone is incapacitated, or can you just shove somebody into a light suit similar to a flight suit?
-Another possibility would be to use the suitport, switching out the suit in place, but it also requires a mobile crew.
-This is where a very agile airlock, or even going as far as my proposed mobile air lock might find some use.  In all other situations, just use the standard docking procedure, whatever it turns out to be.

Would there be, at least the first few years, an obligation to go exploring at least two rovers at a time?  Seems wise.

Wonder if the tool/sample airlock should be sized to be able to bring a helmet and suit into the vehicle? Or perhaps just always check you have enough suits on board.  How tightly can you pack a spacesuit?

Offline Barley

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Re: Airlocks for Mars Colony
« Reply #110 on: 01/15/2020 01:42 am »
How tightly can you pack a spacesuit?
Is a Personal Rescue Enclosure a spacesuit?



You'd probably want a cylinder rather than a sphere for easier handling in gravity.

A fabric airlock designed to connect to a standard or emergency hatch would also be useful.  With an inner door it could do double duty for emergency transport.  If it's big enough for a person in a space suit it's not a big stretch to holding a patient and a medic in shirt sleeves.


Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #111 on: 01/15/2020 01:46 am »
Here is the image of the truck carrying the little airlock/explorer around with it.
The Athlete has drawn up its wheels as high as possible and is suspended from the port.  If I recall, the docking ports of the ISS are good for 100 tonnes of force, so the little guy shouldn't strain it much.

The small vehicle does double duty as a very agile shirtsleeve explorer for difficult terrain at low speed, as well as an emergency airlock/transfer vehicle.  It can be pumped out to vacuum, detach and then open the door, if need be.
Seems very versatile, if I must say so myself  :-)

Credit for the small vehicle all goes to IonMars.

In a pinch, if you remove the wheels and put in some cold gas thrusters you might end up with a space taxi pod.  Follows in the footsteps of the MMSEV logic, I guess.

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #112 on: 01/15/2020 01:59 am »
How tightly can you pack a spacesuit?
Is a Personal Rescue Enclosure a spacesuit?

You'd probably want a cylinder rather than a sphere for easier handling in gravity.

A fabric airlock designed to connect to a standard or emergency hatch would also be useful.  With an inner door it could do double duty for emergency transport.  If it's big enough for a person in a space suit it's not a big stretch to holding a patient and a medic in shirt sleeves.
Thanks, I knew these existed but couldn't find their name!
This raises the question, could you have some kind of fabric tube with a frame and hatch mated to a suit port?  Don't see why not.  As an emergency device, you can be 'poured' into it, rather than need to move yourself inside?  Even add a set of wheels if need be....

Or just have a strong fabric tube with two light frames that match up with two docking ports.  They would have to be handleable by a single astronaut.  Stretch from one vehicle to the next and pressurise.  No need for an airlock or precise matching of positions  The docking ports supply the rigidity and structural strength required.  But again, as an emergency device rather than a fixed connection.  Hard to keep clean and rather bulky....



« Last Edit: 01/15/2020 01:59 am by lamontagne »

Offline Kenm

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Re: Airlocks for Mars Colony
« Reply #113 on: 01/16/2020 02:50 am »
Here is a good pdf on EVA, airlocks and suitports from 2018
I like the suitport-airlocks on Page 32 where the suitports are
on the inner bulkhead of an airlock. With the airlock depressurized
the suitports work normally but by pressurizing the airlock you can
service the suitports and suits or transfer goods or extra crew into the rover/hab.
With an inflatable stretcher the emergency transfer is also covered.
One would have to be careful about rover and hab air pressures if you
want to be able to quickly use the suits without pre-breathing.

https://www.lpi.usra.edu/lunar/constellation/Mary-2018-EVA%20Airlocks-And-Alternative-Ingress-Egress-EVA-EXP-0031.pdf

Some details on the Suitport mechanisms here (Constellation Architecture Team)
it looks like you could disconnect an empty suit and attach your suit all from outside.

https://slideplayer.com/slide/3983178/

"A modular habitation system for planetary and space exploration" A. Scott Howe JPL
lots of rovers, habs, airlocks and suitports here

https://ttu-ir.tdl.org/bitstream/handle/2346/64284/ICES_2015_submission_4.pdf

Offline Twark_Main

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Re: Airlocks for Mars Colony
« Reply #114 on: 02/03/2020 02:09 am »
Here is a different design for a docking airlock. Not nearly as pretty
drawings as those by Lamontagne but they should illustrate the general idea.

It is bellows walled tube (doors not shown) which is moved into position with
6 blue actuators acting as a Stewart platform. These motions would be carried out with the pressure in the tube equal to the outside pressure so there would be no large forces involved.
The rectangular opening can be moved in three directions and tilted in two. The bellows will prevent rotation of the doorway around the axis of the tube so a rotary seal was added between the outer ring and the green doorway frame. 
Once the tube is in position the doorway can be locked in place with with latches like the
International docking system.
In principal the actuators could also be used to resist the force from the air pressure and since they
would be in tension buckling would not be a worry. However these large forces would likely require very heavy actuators so I added 12 1/2" dia red Dyneema rope lines to resist the air pressure. Each line has a 21,500 lb breaking strength. They are attached to winches which need to be able to apply enough tension to keep the ropes orderly during motions and to lock in position before the air pressure is applied. The rope will stretch about 1% as the load is applied.

One comment about running service lines through the door frame. Can we move the waste water lines to the floor level? If I was working on a waste line I would want it as far as possible from any potable water lines. All of the lines should probably be purged and vented before disconnection so they don't boil out all over the doorway.



Those flexible bellows would have to withstand the hoop stress of the internal atmosphere when pressurized. What would they be made out of?
"The search for a universal design which suits all sites, people, and situations is obviously impossible. What is possible is well designed examples of the application of universal principles." ~~ David Holmgren

Offline lamontagne

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Re: Airlocks for Mars Colony
« Reply #115 on: 02/04/2020 02:00 am »
Here is a different design for a docking airlock. Not nearly as pretty
drawings as those by Lamontagne but they should illustrate the general idea.

Those flexible bellows would have to withstand the hoop stress of the internal atmosphere when pressurized. What would they be made out of?

Probably fairly thin stainless steel.  Kevlar cloth should also work for a more rounded look, but might be sensitive to the cold.
« Last Edit: 02/04/2020 02:00 am by lamontagne »

Offline Kenm

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Re: Airlocks for Mars Colony
« Reply #116 on: 02/04/2020 02:38 am »
Here is a different design for a docking airlock. Not nearly as pretty
drawings as those by Lamontagne but they should illustrate the general idea.

Those flexible bellows would have to withstand the hoop stress of the internal atmosphere when pressurized. What would they be made out of?

Probably fairly thin stainless steel.  Kevlar cloth should also work for a more rounded look, but might be sensitive to the cold.


The strain on the fabric can be reduced by running rope around each of the mimimum
diameter valleys in the bellow. Each rope would have a tension equal to the width
of the convolution times the radius of the bellows times the pressure. I was lazy when
drawing the bellows there should probably be more convolutions so that when the pressure
is applied the fabric can expand and wrap around the rope instead of trying to pull on the
airlock ends.

So for Width =0.1 meter Radius = 1 meter P=10^5 nt/m^2 the tension in the rope is 10^4 nt
or about the weight of 1 ton.

The tension in the fabric as it turns around the rope is 0.5 * the convolution width times
the pressure or T = 0.05 meter * 10^5 nt/m^2 =5000 nt/meter or about 500Kg weight /meter
The rope will take almost all the tension in the hoop direction.

This PTFE coated fiberglass fabric is available with a tensile strength up to 1000 lbs/inch
which is about 30 times what we need.

https://www.tensionstructures.com/fabrics/ptfe-teflon-coated-fiberglass/

PTFE is good for UV resistance and use over a wide temperature range.
I'm not sure how well air tight joints can be made and what the fatique life is.

Metal bellows can be used as they can give zero leakage, take heat and cold well and don't care
about UV radiation. I'm not sure about bellows meters in diameter but edge welded metal bellows
can be very flexible and compress down to almost nothing.

https://flexonics.com/welded-metal-bellows-benefits/

Offline Genial Precis

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Re: Airlocks for Mars Colony
« Reply #117 on: 02/05/2020 04:34 pm »
A bellows that size makes my brain hurt. Sounds super expensive (I play with little bellows though, no claims to experience with big stuff). How about telescoping steel rings as a sheath over fabric-reinforced silicone rubber? That gives you UV-protection, tensile strength and flexibility at low temperature, respectively.

Offline sghill

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Re: Airlocks for Mars Colony
« Reply #118 on: 02/26/2020 02:52 pm »
How tightly can you pack a spacesuit?
Is a Personal Rescue Enclosure a spacesuit?

You'd probably want a cylinder rather than a sphere for easier handling in gravity.

A fabric airlock designed to connect to a standard or emergency hatch would also be useful.  With an inner door it could do double duty for emergency transport.  If it's big enough for a person in a space suit it's not a big stretch to holding a patient and a medic in shirt sleeves.
Thanks, I knew these existed but couldn't find their name!
This raises the question, could you have some kind of fabric tube with a frame and hatch mated to a suit port?  Don't see why not.  As an emergency device, you can be 'poured' into it, rather than need to move yourself inside?  Even add a set of wheels if need be....

Or just have a strong fabric tube with two light frames that match up with two docking ports.  They would have to be handleable by a single astronaut.  Stretch from one vehicle to the next and pressurise.  No need for an airlock or precise matching of positions  The docking ports supply the rigidity and structural strength required.  But again, as an emergency device rather than a fixed connection.  Hard to keep clean and rather bulky....

True story. I've been INSIDE one of those rescue balls!

In 1980's Space Camp in Huntsville, one of the mission scenarios was the transfer of an astronaut from one space shuttle to another without docking. We also assumed the astronaut was injured. I was curled up inside the ball and given a respirator and small room heater device (both non-functioning). Two camper astronauts then maneuvered the ball out an airlock, and using the Canadarm, brought the astronaut and the ball over to the other space shuttle cargo bay. The ball was real NASA equipment, and was intended for zero-g use only, but it was plenty strong to hold a teenager.

(Interesting side note, Space Camp there at Marshall Space Flight Center also had several of the famed blue US Air Force Manned Orbital Observatory space suits from the Gemini-era spy program. I got to wear the suit to train several times, but the significance of the blue suit was unknown to me as a kid). https://www.gizmodo.co.uk/2015/10/newly-declassified-photos-show-the-crewed-usaf-spy-spacecraft-that-almost-was

Bring the thunder!

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