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I didn't find any water collecting robots. Found some articles about how one day we might have robots do those things. I also didn't find anything on robots replacing loggers or processing cement or asphalt or steel or aluminum.
So your Google is broke, then. Well...
Fully Autonomous Oil Drilling Rig--Enabled by Energid's Actin software
If we can drill for oil without people, we can probably drill for water.
Titanium is light enough to do the job? If you want to build jet engines or super thin fuel tanks for spacecraft then yes, other than that it's way too expensive and not preferred over aluminum or composite. If you want them to have some weight because they need to move heavy material then just use steel. Metals won't corrode on Mars, you need oxygen for that to happen.
Titanium is light enough to do the job.
Since steel corrodes when it's sitting on the ocean floor, to what process do you attribute that corrosion if, as you say, metals won't corrode on Mars?
There are three reason I selected Titanium alloy. It's lighter than stainless steel, it's corrosion resistant, and it's nowhere near as paramagnetic as aluminum-copper alloys are.
A 58 gallon Titanium fuel tank that weighs 11kg can withstand pressurization to 21.7 atmospheres of pressure and my water robot needs a heavy counter-weight to help it lift the drilling pipe using mechanical leverage. So, yeah, I'd use Titanium alloy.
If the cost of sending 1000L of water or 264 gallons of water to Mars is $50M, then the Titanium alloy is quite cheap.
What profit is there in education? Education is an expense for a capitalist system. The system pays for 12 years of education and some of the people end up in jail (more expense to the system), being housewives, and under employed while others work hard and pay for the less talented and lazy.
Education makes a profit for the universities and banks.
Did I go to college? Yes, five years, GPA was 3.72, what was yours?
Did you take any basic mathematics or science courses while you were there?
You pay for water and trash service? But that is not profit to the capitalist system. Those utilities receive the amount of money needed to provide the service. It balances out, there is no excess money going to the government. There is no "profit".
I'm getting some Socialism mixed in with my Capitalism? Yeah, I am, but that's what modern Capitalism is. There is no pure socialism and no pure capitalism other than in the textbooks.
It's profit for the people I pay.
The Bigelow has 18" thick walls for shielding? Can't be 18 inches of solid fabric, has to be an air cavity with an outer layer of fabric and an inner layer. That's not shielding.
The Bigelow B330 has 18" thick walls because it has 18" thick walls. The materials in the walls happen to be hydrogen rich, which is useful for stopping the light ions from GCR's. The heavy ions will penetrate and the heavier ions do more damage, even though the overwhelming majority of the ions are protons (Hydrogen nuclei). I made a comment in a previous post about aerospace vehicles being incapable of stopping the heavy ions that do the most brain damage. My plan is to reduce the exposure time.
There are various research articles, books, and other resources for figuring out how well shielding materials work. Invest some of your time to read them.
Your colonists launch on a Falcon Heavy that also has fuel for the large transport? Okay, so the Falcon Heavy docks with the ISS, offloads 12 people who go over to the large transport, the Falcon refuels the large transport, transfers a heat shield to it, then the Falcon comes back to the Earth and the transport goes to Mars?
Yes. ISS can use its robotic manipulator arm to insert and remove the fuel tanks.
If the transport is getting to Mars in 30 days it's really moving, it would use a great deal of fuel to accelerate and slow down.
If your specific impulse and thrust are high enough, you can do that.
The Cygnus would fly from Mars up to the transport, the colonists would somehow install a new heat shield onto it, then land?
The colonists wouldn't install anything. The Cygnus would attach itself to the heat shield.
There is way, way, too much risk in this idea.
Why would that be?
We'll soon have three different lift vehicles in competition? Sounds like NASA could contract SpaceX to use it's Falcon Heavy to send it's Zubrin tuna can's to Mars.
That could be a bit difficult since the tuna can is so wide. GW can explain this to you.
You need a cafeteria to feed dozens of people? Yeah, in about 500 years from now. Or, the 4 first settlers could grab a food packet, add a little water, toss it into the microwave on their own. See, no cafeteria needed.
The cafeteria won't have a little old lunch lady in it, Dook. They're going to feed themselves. The cafeteria is a centralized place to store food and water.
You want sulfacrete shelves? Or we could just send fiberglass shelves and fiberglass panels that can be assembled into cabinets, drawers, and picnic tables.
All that stuff is unnecessary if you can build it on Mars. I've sat on concrete benches. They weren't any better or worse than wood benches. If the concrete doesn't cost anything except what the machines that make the concrete cost, then you'll rapidly recoup your investment given today's launch services costs.
Sifting sand is too much work? Nothing is too much work if it needs to be done. If it doesn't need to be done, then that becomes a problem.
If you want to dramatically reduce weight, you reuse all your vehicles to the extent possible and don't ship anything you can reasonably make a functional facsimile thereof at your destination.
You're creating work just to create work. It's inefficient and not a single part of it adds any food, water, or oxygen. Just habitat, oh, and a cafeteria.
If you send robots to fetch water and build greenhouses, then you're adding food and water. The water and building materials have to come from somewhere and it may as well be Mars if the cost to send something there is $50,000/kg or $22,727/lb.
Have I ever sprayed concrete 1 yard thick? No, I have people do that for me. They poured concrete about a foot thick for my home foundation. It took them a couple of hours to set up the posts and framing and about an hour to actually walk around pouring in the cement.
How many square feet was the foundation?
Did the people who did that for you do it entirely by hand or did they use machines to mix the concrete?
If a machine could do the exact same job for less money, would you hire a company using a machine or would you insist on paying more so humans could do it?
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For my mission proposal
http://newmars.com/forums/viewtopic.php?id=7670
I suggest that having identified a landing area (Chryse Planitia looks good) we drop maybe 5 small rovers (from a single transit craft) on to the idenitifed landing zone, so they can establish some basics in the particular area they land e.g. terrain (how rocky), water signature and iron ore presence. We then choose the best of the five landing sites and use transponders on all five to accurately pinpoint the preferrred landing point for the following pre-landing missions taking in supplies and other robot rovers etc.
Land an unmanned rover first to confirm the water resource. That rover could land a significant distance away, and drive to the ice. Just as Spirit/Opportunity or Curiosity does. In this case the rover would be about the size of Spirit/Opportunity, with a multi-segment drill to take core samples. That same rover could drop a landing beacon. With a beacon, the manned mission could land with precision. Imagine if Curiosity landed with it's aeroshell/parachute/skycrane, but it's skycrane homed in on the beacon. Also remember the aeroshell had the ability to steer. I argue for landing rockets on the lander, and legs with shock absorbers. So it would land like the Apollo LM. But instead of a single large engine, it would have several smaller ones. Viking landers and Mars Phoenix had several smaller engines, and the Curiosity skycrane. Several smaller engines means exhaust impact on soil during landing is spread out, so less chance of digging yourself a hole. And several small engines can be arranged around the periphery, so a Mars rover can be stored in the centre of the lower deck of the lander. But again, homing on a beacon means high precision landing.
Let's Go to Mars...Google on: Fast Track to Mars blogspot.com
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The landing beacon only works with a Red Dragon rocket that uses massive amounts of rocket fuel to manuever but because of all the rocket fuel carried it can't send much payload to Mars, only about a ton.
A Zubrin tuna can lander uses a parachute and then fires a rocket engine for only the final moments before landing so it doesn't carry nearly as much rocket fuel. Using a beacon to help land a tuna can would be useless.
This idea of going to get water or ice just has way too much risk for very little benefit.
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I knew you would say that. Which is why I gave a long description of Curiosity. They were able to land within an ellipse 7km x 20km. Curiosity ignited it's skycrane thrusters 1.3km above the surface. That gave it significant manoeuvring ability.
Curiosity EDL
Last edited by RobertDyck (2017-04-19 17:05:18)
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kbd512
I looked at the website, it shows a guy up on top of the rig. The website is about drilling software, not a real autonomous drill rig that can move around on it's own and choose the right place to drill. Once in place it can drill on it's own, that's it.
Titanium is light enough to do the job? And aluminum and composites are even lighter and less expensive and composites don't corrode.
Steel corrodes when it's sitting on the ocean floor? When alloy elements are added to make iron become steel or aluminum become aluminum alloy it increases strength but makes galvanic corrosion cells. Pure iron and pure aluminum are corrosion resistant. Alloy's are not. When something gets on the surface of an alloy and makes an electrical connection between the iron and the alloy element it creates a corrosion cell. Salt water conducts electricity. So, if you want to keep your vehicles on Mars rust free, paint them (like Navy ships), and keep them away from salty water.
Education makes a profit for universities and banks? But that profit doesn't go to the government.
Did I take basic mathematics or science courses in college? Math is not my best area. Efficiency is. Other people can't think efficiently while to me it comes naturally. When they have to design something they always make a Rube Goldberg device at first. The thing is this, Rube Goldberg devices work, they're incredibly inefficient but so what, most of the time it doesn't really matter that much. On Mars, it matters.
Paying for trash and water is profit to the people who do the work? Not all of what you pay is profit, some of it, still, it's not profit for the government.
The Bigelow has walls that are hydrogen rich? So, you're saying that if we put a sack in the walls of the Zubrin tuna can and fill it with hydrogen that would provide better shielding? And then on Mars we can add oxygen to the hydrogen and get water.
The tuna can won't fit in a Falcon Heavy? You really get stuck easily. Then we make it more narrow so it fits. See how easy that is. No robots needed.
The cafeteria is a central place to store food and water? You mean like a kitchen?
Having to ship lightweight fiberglass shelves to Mars is not necessary if you can make them on Mars? Not if it takes months to make a few shelves and risks people's lives and takes time away from food production and Moxie, solar panel, greenhouse, and habitat maintenance.
If you want to dramatically reduce weight you reuse all your vehicles and don't ship anything? That would be true if weight was the only objective. We wouldn't ship any water at all in that case but the colonists would die of dehydration.
We can have robots build greenhouses and get our water on Mars? Cool beans man, let's wait until the technology is available to do that.
How many square feet was my foundation? Hmm, don't know, guessing it was about 735 cubic feet.
They used seven cement mixing trucks that dumped into another machine that pumped the cement up hill through a long hose and walked the hose by hand. And another guy used the vibration device to get the air out, which you have to do because there were big air bubbles trapped in it.
If a machine could do the entire job cheaper than paying people would I pay for the machine? Yes, but that's not possible yet.
I'm okay with waiting for machines to do all these things for us on Mars, I'm very okay with it.
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I looked at the website, it shows a guy up on top of the rig. The website is about drilling software, not a real autonomous drill rig that can move around on it's own and choose the right place to drill. Once in place it can drill on it's own, that's it.
One company provides software and another company provides robots. Most of the time, multiple companies collaborate to make sophisticated systems and tools possible. This is a very common occurrence in aerospace and defense industries.
Titanium is light enough to do the job? And aluminum and composites are even lighter and less expensive and composites don't corrode.
Aluminum wheels haven't demonstrated very good durability over the jagged volcanic terrain of Mars. Composites would fare worse and we don't use composite wheels off-road here on Earth. Something a bit tougher is required. If the water sphere was punctured on Mars, it'd be a very expensive failure. Titanium alloy has mechanical properties that work well for this particular application. A high grade stainless steel would also work, but it would weigh more.
Steel corrodes when it's sitting on the ocean floor? When alloy elements are added to make iron become steel or aluminum become aluminum alloy it increases strength but makes galvanic corrosion cells. Pure iron and pure aluminum are corrosion resistant. Alloy's are not. When something gets on the surface of an alloy and makes an electrical connection between the iron and the alloy element it creates a corrosion cell. Salt water conducts electricity. So, if you want to keep your vehicles on Mars rust free, paint them (like Navy ships), and keep them away from salty water.
We're not going to keep a water robot away from salty water on Mars and we won't use any paint on the interior of a container that someone will drink from since paint is just one more contaminant to filter out of the water.
Education makes a profit for universities and banks? But that profit doesn't go to the government.
Yes, education makes a profit for universities and banks. Some of the profit goes to the government. It's called taxation.
Did I take basic mathematics or science courses in college? Math is not my best area. Efficiency is. Other people can't think efficiently while to me it comes naturally. When they have to design something they always make a Rube Goldberg device at first. The thing is this, Rube Goldberg devices work, they're incredibly inefficient but so what, most of the time it doesn't really matter that much. On Mars, it matters.
In engineering, determining efficiency generally involves some mathematics. A bit of basic math would indicate how well or poorly something would work. The water wall shielding idea is a great example. Someone at NASA already thought about filling a tuna can with water as a form of passive radiation shielding, but the water alone (no tuna can) in a tuna can the same diameter as SLS, 8.4m or same as Dr. Zubrin's tuna can, weighs 389t or 855,800lbs. That's about as much as a loaded Boeing 747 weighs.
The conclusion was that we'd need a rocket the size of ITS just to launch the tuna can into Earth orbit and then we'd need another gargantuan rocket to launch it to Mars. As far as landing that on Mars, there was no chance of that happening. ITS may weigh more, but it's mostly LOX/LCH4 propellants to propulsively land on Mars.
The water wall idea was a non-starter, but was proposed as an alternative if active radiation shielding failed. Active radiation shielding using an electrified plasma was the alternative, and that's one of the things Boeing and other companies are working on. However, an active radiation shield is only intended to be used in space during the transit to and from Mars.
Skylab II Making a Deep Space Habitat from a Space Launch System Propellant Tank
Paying for trash and water is profit to the people who do the work? Not all of what you pay is profit, some of it, still, it's not profit for the government.
If you're trying to make the point that our government does things that aren't for its own benefit, and maybe not even for anyone else's benefit, that's fairly obviously. However, if the government is hiring someone who isn't a government employee to provide goods or services, then that someone is doing that work for-profit. Lockheed-Martin sells F-35's to the US Air Force. It's not making fighter jets for anything as noble as love of country. They expect to be paid. If our government quit paying them, they'd quit making F-35's. That was my point.
Our government hires for-profit defense contractors to provide launch services, so I have no idea where this argument is supposed to go as it relates to the cost of space exploration and colonization. ULA (Boeing and Lockheed-Martin partnership) / Orbital ATK / SpaceX / Blue Origin / StratoLaunch are all defense contractors, even if they have secondary or tertiary goals to explore and colonize space.
The Bigelow has walls that are hydrogen rich? So, you're saying that if we put a sack in the walls of the Zubrin tuna can and fill it with hydrogen that would provide better shielding? And then on Mars we can add oxygen to the hydrogen and get water.
I already said that the tuna can would pose less of a radiation hazard for its occupants if it wasn't made out of thin aluminum alloy. The tuna can is made from thin aluminum because it has to be light since a rocket must push it all the way to Mars. This poses a problem for radiation shielding since aerospace vehicles obviously need to be light. Thus, tuna cans can't be well shielded. By that, I mean the structure of the aerospace vehicle itself doesn't provide very good shielding and the materials that provide decent shielding are either heavy (water), impractical (liquid hydrogen), or experimental (hydrogenated Boron Nitride NanoTubes / BNNT composites).
Obviously consumables in the tuna can (food and water) or regolith (when the tuna can is on Mars) can be piled around the tuna can to increase radiation shielding effectiveness. The radiation doesn't adversely affect the food or water because it doesn't make it radioactive to any substantial degree.
Hydrogen rich and other "low-Z" materials provide the best shielding against protons and neutrons:
The tuna can won't fit in a Falcon Heavy? You really get stuck easily. Then we make it more narrow so it fits. See how easy that is. No robots needed.
I'm not stuck on anything. If you make the tuna can smaller, then you reduce the space in the tuna can for food / water / humans.
Can you understand why NASA wants to use inflatables?
The inflatable fits inside the small diameter payload fairing of Falcon Heavy / Vulcan Heavy / New Glenn for launch, inflates to a much larger diameter in space, weighs substantially less than an aluminum can with the same pressurized habitable volume, has better micro meteoroid impact protection than a thin solid aluminum can, and produces far less secondary radiation effects for its occupants.
The cafeteria is a central place to store food and water? You mean like a kitchen?
Call it whatever you want. It's the place the colonists gather to eat meals because their food and water are stored there.
Having to ship lightweight fiberglass shelves to Mars is not necessary if you can make them on Mars? Not if it takes months to make a few shelves and risks people's lives and takes time away from food production and Moxie, solar panel, greenhouse, and habitat maintenance.
Once again, all this will be built before the colonists show up. No colonists will be on Mars when their habitat is built. If I can avoid shipping something from Earth, I will. A shelf is a shelf. It doesn't matter if it's concrete or fiberglass. It's either there and available for the colonists to use, or it's not.
If you want to dramatically reduce weight you reuse all your vehicles and don't ship anything? That would be true if weight was the only objective. We wouldn't ship any water at all in that case but the colonists would die of dehydration.
The robots collect the water before the colonists show up.
We can have robots build greenhouses and get our water on Mars? Cool beans man, let's wait until the technology is available to do that.
I think that's what we're already doing.
How many square feet was my foundation? Hmm, don't know, guessing it was about 735 cubic feet.
They used seven cement mixing trucks that dumped into another machine that pumped the cement up hill through a long hose and walked the hose by hand. And another guy used the vibration device to get the air out, which you have to do because there were big air bubbles trapped in it.
If a machine could do the entire job cheaper than paying people would I pay for the machine? Yes, but that's not possible yet.
I'm okay with waiting for machines to do all these things for us on Mars, I'm very okay with it.
The only way to get better technology is to spend the time and money to create it. I'm okay with waiting for better technology, too. Current life support technology isn't up to the task, in my opinion. The evidence is the repeated failures aboard ISS. I wouldn't trust any single technology to function as expected, 100% of the time, either.
By the time we're ready for colonization, pre-cursor missions to deliver robots to collect local resources should be available. As you said before, you can't just land 100 people on Mars and expect that everything will go according to plan. You have to gradually build up infrastructure and support services. I think a good first step is to design and test technologies that can collect local resources because the cost of bringing things like water and building materials from Earth is prohibitive. The colonists who came to the Americas didn't take dirt from Europe with them, either. They used American dirt.
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kbd512
The drill rig does not operate on it's own. It doesn't drive around, find the right spot, and drill on it's own. It's driven by a human and the spot where it drills is picked by a human. We don't have machines that can do complex things completely on their own and even if we did they would need a human to repair them.
Aluminum wheels for machines on Mars would work but composite wheels probably would not? Make the frame out of composite and the wheels out of aluminum.
The water sphere needs to be strong? The tuna can would have it's water storage built into the structure. The greenhouse would have it's water storage, mostly, in humidity, but water would condense onto the panels every night and run down into trays that would be used to water the plants. Now, some water would have to be delivered for the greenhouse. Those tanks could be used as more water storage or even as oxygen storage tanks.
Your water robot is going to drive into slushy salt water on Mars? It's going to get stuck.
We won't paint the interior of a container to give it corrosion resistance against salt water? No, we won't. Transporting salt water has to be done in a plastic container. Any metal will corrode quickly if exposed to salt water.
Taxation is profit? Okay, you can call it that if you want but then the goal of your Capitalist system is taxation.
A tuna can using water shielding would need to much water and be too heavy? What will the Falcon Heavy launched hab or the ITS use? I'm not buying the idea that the Bigelow's thin fabric is better radiation shielding than a layer of water. I'm also not buying the idea that the Bigelow uses fabric that is 18" thick either.
Also, a study conducted by the International Conference on Environmental Systems (ICES 2016)determined that a crew on Mars would not exceed NASA lifetime radiation exposure guidelines.
You can make a tuna can out of carbon composite. It doesn't have to be aluminum.
You guys are really stuck on the tuna can label. Fine, I'll try to remember to refer to it as MarsHab instead, but, we all know it's just a modified tuna can.
Can I understand why NASA wants to use inflatables? I can understand why NASA would want to test it. If an inflatable turns out to be a better option, I'm okay with it. I don't like the idea of having a crew transfer in orbit twice, so, to me, that's not a better option than Mars Direct. The inflatable needs to be able to enter Mars atmosphere and land on Mars and provide a long term habitat.
We'll use robots to assemble the Mars habitat and get water before colonists arrive? Sounds great. I'm all for waiting until that gets done.
We're already using robots to build greenhouses on Mars and get water? You have to provide me a link to that one, can't wait to see it. If the link is to some Area 51/alien structure on Mars forum, don't bother.
Current life support is not up to the task? Okay, so what's wrong with filtering urine then boiling it on Mars and using a tank in our greenhouse as a feces settling tank? That would recycle all of the water that a Mars colony would use. All of it, not 90%, but 100%.
Last edited by Dook (2017-04-20 12:21:15)
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The drill rig does not operate on it's own. It doesn't drive around, find the right spot, and drill on it's own. It's driven by a human and the spot where it drills is picked by a human. We don't have machines that can do complex things completely on their own and even if we did they would need a human to repair them.
There's a human operating the drill, just like there's a human sending radio signals to our Curiosity robot to tell it where to drive to next on Mars. The human isn't doing any drilling, he's standing there watching the robot drill. He could probably stand at his console on Earth and watch it drill using a camera and radio signals, or at least that's what JPL's staff do when their rovers drill into rocks on Mars. Curiosity hasn't been repaired since it was sent to Mars. That was years ago. It's still driving around on Mars. Since Curiosity can drive around on Mars and drill into rocks using commands a human sends to it on Earth, we can probably send commands to a robotic drill to drive around and drill for water.
If you've seen the last Star Wars movie, then you've seen the BB-8 robot. That's a "ball balancing" robot. My wife bought one for the kids to play with. The water tank is the wheel, that's why it needs to be made from a durable material. The water tank is also the counterweight the drill robot uses to lift the pipe to drill with. There are no exposed components. It uses permanent magnets to spin the wheel. The drill is much, much smaller than the one on the automated drill rig. There is a robotic drill on Mars right now. It's attached to a rover we sent there. It drills into rocks.
Aluminum wheels for machines on Mars would work but composite wheels probably would not? Make the frame out of composite and the wheels out of aluminum.
I need a durable counter-weight. The spherical Titanium tank / wheel is a durable counter-weight that also stores the water.
The water sphere needs to be strong? The tuna can would have it's water storage built into the structure. The greenhouse would have it's water storage, mostly, in humidity, but water would condense onto the panels every night and run down into trays that would be used to water the plants. Now, some water would have to be delivered for the greenhouse. Those tanks could be used as more water storage or even as oxygen storage tanks.
Yes, the tank needs to be strong for reason already stated in previous posts and this post.
Your water robot is going to drive into slushy salt water on Mars? It's going to get stuck.
The robot is going to drive on sand and rocks. There's no liquid water for it to get stuck in.
We won't paint the interior of a container to give it corrosion resistance against salt water? No, we won't. Transporting salt water has to be done in a plastic container. Any metal will corrode quickly if exposed to salt water.
Titanium doesn't.
A tuna can using water shielding would need to much water and be too heavy? What will the Falcon Heavy launched hab or the ITS use? I'm not buying the idea that the Bigelow's thin fabric is better radiation shielding than a layer of water. I'm also not buying the idea that the Bigelow uses fabric that is 18" thick either.
ITS could lift a tuna can with a water shield. Regarding the B330, buy whatever you want. The B330's walls are still 18" thick.
Also, a study conducted by the International Conference on Environmental Systems (ICES 2016)determined that a crew on Mars would not exceed NASA lifetime radiation exposure guidelines.
Was the crew staying there for the rest of their lives?
You can make a tuna can out of carbon composite. It doesn't have to be aluminum.
NASA is working on that. Hydrogenated BNNT is very light. They're working on making it a structural material for aerospace vehicles like the tuna can.
You guys are really stuck on the tuna can label. Fine, I'll try to remember to refer to it as MarsHab instead, but, we all know it's just a modified tuna can.
I don't care what you call it. When you say tuna can, I think Mars habitat module.
Can I understand why NASA wants to use inflatables? I can understand why NASA would want to test it. If an inflatable turns out to be a better option, I'm okay with it. I don't like the idea of having a crew transfer in orbit twice, so, to me, that's not a better option than Mars Direct. The inflatable needs to be able to enter Mars atmosphere and land on Mars and provide a long term habitat.
They've had this in all their DRM proposals for some time now. They recognized that weight, pressurized volume, micro meteoroid protection, and radiation protection were all problems that the inflatable tuna can helped solve. I think NASA called it TransHab, but it's still just a tuna can.
We'll use robots to assemble the Mars habitat and get water before colonists arrive? Sounds great. I'm all for waiting until that gets done.
Me, too.
We're already using robots to build greenhouses on Mars and get water? You have to provide me a link to that one, can't wait to see it. If the link is to some Area 51/alien structure on Mars forum, don't bother.
No, but we've built houses and rocket engines here on Earth using 3D printers and we've even sent a 3D printer to ISS. Similarly, while we do have robotic trucks driving around, I haven't seen any robotic cement trucks. Does that mean I can't take a robotic truck and stick a cement mixer on the back of it? I would say no, but I just know you'll come back with some sort of counter-point or counter-example.
Current life support is not up to the task? Okay, so what's wrong with filtering urine then boiling it on Mars and using a tank in our greenhouse as a feces settling tank? That would recycle all of the water that a Mars colony would use. All of it, not 90%, but 100%.
There's nothing wrong with recycling water. I never suggested not recycling water. I suggested that obtaining local water and recycling it is the way to go when you need thousands of gallons of water because water is heavy and aerospace vehicles need to be light. Take the water required to go to Mars from Earth, but get your water from Mars once you're on Mars. More importantly, get the water you need to live on Mars from Mars before you set foot on Mars.
There is no 100% efficient recycling system that I'm aware of. It sounds great and much like a robot building a greenhouse on Mars, I'd love to see a completely closed-loop system that's 100% efficient. Much like the robotic greenhouse builder, the 100% efficient closed-loop life support system doesn't exist yet.
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kbd512
Curiosity is guided by humans on Mars and hasn't needed to be fixed yet? Correct. What happened to Spirit?
We can use a robot guided from the Earth to drill for water on Mars? We could. Or we could use zeolite panels wheeled outside at night and brought inside the greenhouse in the morning to warm and produce about 13.48 lbs of water a day in summer.
There is no liquid water for a robot to get stuck in? If there is salt in the water/ice on Mars then it will be in a liquid state for much longer periods than pure water would. Pure water is liquid for about 6 minutes a day on Mars. If it's salty it would be liquid for much longer depending on how much salt is in it. If you drive into it you get stuck.
Titanium doesn't corrode? It does but the corrosion layer it forms seals it from further corrosion. Also, a smooth sphere of titanium wouldn't give you much traction going up hill. Another option would be to use a thick rubber outer surface with an interior plastic sphere container for the salt water, but, as I said, I would just use the zeolite panels and a 100% recycling of water.
Was the ICES study on the radiation hazard for settlement or an exploration team? It was for an exploration team. Any habitat on Mars could have regolith put on top to help.
We've built houses and rocket engines on the Earth using 3D printers? 3D printers spray. Spraying is not assembly. They're good for some things if you already have all the raw material. They're just not good for a first settlement on Mars. And the 3D printer did not spray a rocket engine, it made some parts for a rocket engine.
A 3D printer was sent to the ISS? Heck, then why isn't it using the 3D printer to produce spacecraft and rocket fuel? And why are we constantly sending resupply shipments to the ISS? Why can't they just print whatever it is they need?
Water is heavy to ship to Mars but we don't really have a choice. The settlers will need water on the way there so some water is going to get shipped anyway. Once there we'll need some to get our greenhouse going.
Another option would be to pre-land a WAVAR system that was on tracks. Run it a little bit just to make sure it works but not too much because it would become too heavy. Then send your crewed habitat. Once on Mars use the long range rover to drive over and get the WAVAR and tow it back to the base, then turn it on to make water.
There is no 100% recycling system that you are aware of? All of the water a human uses comes out as either sweat, in our breath, as urine, or in feces. Sweat and water vapor in our breath humidifies the air so we use a dehumidifier to get that water back. We boil the urine to get that water back. Then, we put the feces into a settling tank inside our greenhouse to allow the bacteria to break it down, but the water in the feces stays in the greenhouse. So, where is the water loss?
The only loss would be tiny amounts of water vapor escaping when you open the Mars Hab or greenhouse hatch, so, we're talking a water recycling rate close to 100%. And we can replace that water and get even more water in summer using zeolite panels, perhaps as much as 13 lbs a day.
Last edited by Dook (2017-04-20 14:18:47)
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Curiosity is guided by humans on Mars and hasn't needed to be fixed yet? Correct. What happened to Spirit?
I didn't propose using a solar panel powered robot with Lithium-ion batteries that degrade much faster with charge/discharge cycles than a RTG does. Curiosity has been in operation for years. Spirit and Opportunity were also operated for quite some time on Mars without repair.
This robot will be simpler than any of those rovers.
We can use a robot guided from the Earth to drill for water on Mars? We could. Or we could use zeolite panels wheeled outside at night and brought inside the greenhouse in the morning to warm and produce about 13.48 lbs of water a day in summer.
You said I couldn't get much water by drilling for it, even though there are 36 cubic miles of the stuff ringing the planet in two belts, but you want to stick zeolite panels outside in the summer in an atmosphere that's drier than most of the deserts are here on Earth?
There is no liquid water for a robot to get stuck in? If there is salt in the water/ice on Mars then it will be in a liquid state for much longer periods than pure water would. Pure water is liquid for about 6 minutes a day on Mars. If it's salty it would be liquid for much longer depending on how much salt is in it. If you drive into it you get stuck.
The glaciers have regolith and rock over the top of them, so I'm not parking the robot in a pool of liquid water.
Titanium doesn't corrode? It does but the corrosion layer it forms seals it from further corrosion. Also, a smooth sphere of titanium wouldn't give you much traction going up hill. Another option would be to use a thick rubber outer surface with an interior plastic sphere container for the salt water, but, as I said, I would just use the zeolite panels and a 100% recycling of water.
The iron oxide in the regolith will adhere to the sphere because the sphere has two Halbach arrays that the drill robot uses to drive the sphere. The drill robot will have brushes to prevent more than a thin layer of regolith from building up on the halbach array. However, the regolith that adheres to the sphere, because it has permanent magnets embedded inside it, will provide traction.
Was the ICES study on the radiation hazard for settlement or an exploration team? It was for an exploration team. Any habitat on Mars could have regolith put on top to help.
Let's do some math to see how well that would work...
Average Martian regolith has a density of 1.52g/cm^3. This figure comes from actual measurements taken by our rovers of numerous samples from Mars. It's not a guess, it's based on actual data.
1 cubic inch is 16.3871 cubic centimeters.
16.3871 * 1.52 = 24.9g/in^3, so 1 cubic inch of Martian regolith weighs 24.9 grams
1 cubic yard is 46656 cubic inches
46656 * 24.9 = 1,161,734.4g = 1,161.7kg = 2,555.8lbs
1 cubic yard of Martian regolith weighs 2,555.8lbs
1 cubic yard of water at STP weighs 1,685.55lbs for comparison purposes
1 Dr. Zubrin tuna can is 33 feet in diameter, so to pile 1 meter / 1 yard / 36 inches of regolith on top, the habitat module has to withstand a load of 855.3 cubic yards of regolith.
855.3 * 2,555.8 = 2,185,975.7lbs
123,163 square inches in a 33ft diameter circle
The tuna can is pressurized to 14.7psi at Earth sea level, so...
123,163 * 14.7 = 1,810,496.1 pounds of force pushing outwards over a 33ft diameter circle
So the tuna can has to withstand an additional 375,479.6 *.38g = 142,682.2lbs or 64.8t of force [Edit: over the top of what the roof and anything hanging from it actually weighs more than what] is pushing outward on the top of the cylinder. We'll elect to ignore its own mass on Mars since it's so small in comparison to [Edit: the weight of the regolith]. Maybe you could design the tuna can to withstand that kind of force, but it'd definitely be a lot heavier than it is. I think GW already explained how pressure vessels work and why they're shaped the way they are. If it ever loses pressure, even a little, take a wild guess at what will happen with that much weight on top of it.
I'm done arguing this point with you unless you post your numbers.
We've built houses and rocket engines on the Earth using 3D printers? 3D printers spray. Spraying is not assembly. They're good for some things if you already have all the raw material. They're just not good for a first settlement on Mars. And the 3D printer did not spray a rocket engine, it made some parts for a rocket engine.
There have been entire engines printed from 3D parts, to include jet engines and rocket engines. Use Google.
The walls and foundation of the house I already provided a link to were sprayed / 3D printed / I don't care what you call it. The robot was sitting in the center of the house it printed, so it obviously couldn't "spray" the roof into place. We already have robots that can pick up cars, so we have robots that can pick up airlocks, empty water tanks, etc.
A 3D printer was sent to the ISS? Heck, then why isn't it using the 3D printer to produce spacecraft and rocket fuel? And why are we constantly sending resupply shipments to the ISS? Why can't they just print whatever it is they need?
The printer requires material. The material is available on Mars. There's very little material to use in low Earth orbit, and certainly no rock and sulfur.
Water is heavy to ship to Mars but we don't really have a choice. The settlers will need water on the way there so some water is going to get shipped anyway. Once there we'll need some to get our greenhouse going.
Some water will have to be shipped just to get people to Mars. There's no need to ship water all the way to the surface of Mars when there is water on the surface of Mars.
Another option would be to pre-land a WAVAR system that was on tracks. Run it a little bit just to make sure it works but not too much because it would become too heavy. Then send your crewed habitat. Once on Mars use the long range rover to drive over and get the WAVAR and tow it back to the base, then turn it on to make water.
Sounds great. Let's do it. Mars has water, so let's use it.
There is no 100% recycling system that you are aware of? All of the water a human uses comes out as either sweat, in our breath, as urine, or in feces. Sweat and water vapor in our breath humidifies the air so we use a dehumidifier to get that water back. We boil the urine to get that water back. Then, we put the feces into a settling tank inside our greenhouse to allow the bacteria to break it down, but the water in the feces stays in the greenhouse. So, where is the water loss?
The only loss would be tiny amounts of water vapor escaping when you open the Mars Hab or greenhouse hatch, so, we're talking a water recycling rate close to 100%. And we can replace that water and get even more water in summer using zeolite panels, perhaps as much as 13 lbs a day.
NASA already has their air and water recycling system efficiencies posted in various technical reports. Less than 100% recycling efficiency is what actually happens aboard ISS in the real world and it's still what happens using the next generation systems in testing. Take this point up with them.
There's no such thing as a perfect seal, either:
Trending of Overboard Leakage of ISS Cabin Atmosphere
As long as the leakage is mitigated, it's not a major problem because we keep sending them air and water.
Last edited by kbd512 (2017-04-20 18:05:45)
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Opportunity is still operating.
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kbd512
Your robot that collects water will be more simple than Opportunity? Will it be more simple than using zeolite panels mounted on a fiberglass cart?
I said you couldn't get much water by drilling for it? Not using a hollow drill that expects the water vapor to just flow naturally upward through the drill bit into the tank.
I want to use zeolite panels outside on Mars in a dry climate? Yep, you might want to look up the WAVAR. It is estimated that it will produce 13 gallons a day in summer, no moving around, it stays in one place. How much water is your drill contraption going to produce?
The glaciers have regolith and rock so you're not parking the robot in a pool of liquid water? The salt water places won't look like a pool of liquid, it will be a mixture of sand and salt water, you drive into it and you sink. Game over.
Mars regolith is too heavy to put 1 meter of regolith on top of the tuna can? I didn't say the regolith would be piled 1 meter thick on top of the tuna can. Also, you forgot the water sack shielding in the ceiling. And, all we have to do is use 18" of your "magic fabric" in the ceiling as well and we're good.
There have been entire engines printed with 3D printers? The article says that 75% of that rocket engine was printed, not 100%. Why isn't the ISS churning out rocket engines left and right? If all you need is a 3D printer then they should be completely independent now, right?
There's material on Mars that a 3D printer can use? Too bad it's mixed with other stuff.
There's water on the surface of Mars? How does your robot water drilling machine separate the salt from the Mars water? It doesn't, right? So, now you need another robot to do that. It just goes on and on and on.
The ISS water recycling system is less than 100% efficiency? What do they do to get all the water out of feces?
There's no such thing as a perfect seal? Uhh, next time you get on an airplane ask them how well their hydraulic system lines seal. If they say it's less than perfect, don't get on the plane, hehe...
I guess the "no perfect seal" remark was supposed to tell me that there will be leaks in the tuna can and greenhouse and somehow water will escape as tiny amounts of water vapor? I'm sure some extremely small amounts of water vapor will escape. But, many, many times that amount will be made by the WAVAR.
We keep sending the ISS water and oxygen? I thought they had a 3D printer?
Last edited by Dook (2017-04-20 18:13:50)
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Opportunity is still operating.
And Spirit?
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Rob,
I goofed. Opportunity is still alive. Is it still mobile?
Curiosity has been roving Mars for nearly 5 years now and so far as I know, nobody has replaced any parts.
That means we made 3 robots that don't require much in the way of maintenance and all were operable for multiple years on Mars.
Even after a colony starts operating, water robots can continue to fetch water and the colonists can repair or upgrade the robots, if required to do so. Since the water robot is fetching more than a couple hundred gallons per trip to the nearest glacier, it's a safe bet that the colonists will have water as long as either their water recycling systems or water robots keep operating. I'd send 3 water robots for every colony and have the robots fetch water about once a month.
If robot manages an average speed of 1km/h, it can cover 24km in a day, 168km per week, 730km per average month. The colony could be located quite a distance from the glacier, nearer to the equator or an area with a sulfur-rich deposit, and the robots should have ample time to travel to the glacier to collect water and return the water to the colony's water storage tanks.
Equator to pole, Mars circumference is about 5,311km. In a worst case scenario where the colony was located at the equator and the 3 water robots had to fetch water from the very top of the north pole, 3 operational robots could collect water in a little less than 5 months. Since the ice caps are so expansive, the robots obviously wouldn't have to go all the way to the pole.
I'd rather get resupplied with water every month, or even every five months, than every two years.
Let's call the empty 250 gallon water robot 250kg and the launch cost to ship each robot to Mars $12.5M, at a price of 50,000/kg.
8.34 * 250 = 2,085 lbs or 948kg
948kg * $50,000 = $47.4M for 948kg of water
If each water robot costs $100M, then it's paid for itself after the 3rd trip.
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Rob,
I goofed. Opportunity is still alive. Is it still mobile?
It's still mobile.
JPL, April 19, 2017: NASA's Mars Rover Opportunity Leaves 'Tribulation'
NASA's senior Mars rover, Opportunity, is departing "Cape Tribulation," a crater-rim segment it has explored since late 2014, southbound for its next destination, "Perseverance Valley."
...
Now more than 13 years into a mission originally scheduled to last three months on Mars, Opportunity remains unexpectedly capable of continued exploration. It has driven about four-tenths of a mile (two-thirds of a kilometer) since the start of 2017, bringing the total traverse so far to 27.6 miles (44.4 kilometers). The current season on Mars is past the period when global dust storms might arise and curtail Opportunity's solar power.
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Your robot that collects water will be more simple than Opportunity? Will it be more simple than using zeolite panels mounted on a fiberglass cart?
Obviously not, but how many days will your zeolite panels have to collect water to obtain 250 gallons worth of water and how much will the panels weigh?
I said you couldn't get much water by drilling for it? Not using a hollow drill that expects the water vapor to just flow naturally upward through the drill bit into the tank.
Water flashes to steam when something hot enough to melt aluminum touches it in an enclosed in a bore hole. If the ice is relatively solid, as most compacted glaciers are, then the steam only has one place to go to relieve the pressure, that place is up, and the water tank is connected to where "up" is.
I want to use zeolite panels outside on Mars in a dry climate? Yep, you might want to look up the WAVAR. It is estimated that it will produce 13 gallons a day in summer, no moving around, it stays in one place. How much water is your drill contraption going to produce?
I have several documents on WAVAR that claim it can make 3,900kg of water (about 1,029 gallons) with 1,200kg of seed hydrogen sent from Earth. Some of the LH2 boils off during transit, presuming a .5% loss rate per day of transit, and a 200 day transit to Mars, which is how the 1,200kg figure was arrived at by the people who did the study. The WAVAR device itself consists of 885kg worth of hardware. That means the TMI mass is 2,085kg. The electrical power requirement ranges between 8kWe and 12kWe, which means you need quite a bit of power for that device. However, we're going to ignore the mass associated with provisioning a minimum of 8kWe. Over the course of several hundred sols, WAVAR could produce 3,900kg of water. Once you run out of LH2, no more water.
1 gallon of water contains 418 moles of Hydrogen, so .418kg of hydrogen per gallon of water.
2,340 gallons of water contains 978kg of hydrogen, so you'd need to more than double the mass of seed hydrogen to 2,400kg, as a function of boil-off between the time it leaves Earth and the time it arrives on Mars.
So, you want to ship 3,285kg worth of WAVAR and seed LH2 to Mars to make 8,871kg worth of water? Our max power requirement is only 25kWe. Hmm... I think this idea has potential for an exploration mission.
If I send 3 robots that collect 250 gallons of water each over a two month period of time, then the robots collect 2,250 gallons over the same time period. After you make 8,871kg of water, you're done because you don't have anymore LH2 unless you ship it from Earth, which you can only do every 2 years. I have 36 cubic miles of ice to send my robots to, so I'm never going to run out of ice.
For a short term mission, WAVAR looks pretty good to me. Long term, it's not viable because you run out of hydrogen.
The glaciers have regolith and rock so you're not parking the robot in a pool of liquid water? The salt water places won't look like a pool of liquid, it will be a mixture of sand and salt water, you drive into it and you sink. Game over.
The glaciers are frozen solid. Game not possible to begin with.
Mars regolith is too heavy to put 1 meter of regolith on top of the tuna can? I didn't say the regolith would be piled 1 meter thick on top of the tuna can. Also, you forgot the water sack shielding in the ceiling. And, all we have to do is use 18" of your "magic fabric" in the ceiling as well and we're good.
I thought we already discussed why this wouldn't work. Laying material that weighs substantially more than the internal pressure pushing out on the walls of the habitat won't work, no matter what the habitat is made from, unless it's substantially stronger or has less material than what is required for long term protection.
Go back and re-read posts, if necessary. Doing a little math wouldn't kill you, either. So what if you make a mistake? Just correct it and move on. Perfection is not required. It's an internet forum. Nobody will die if your numbers are off.
There have been entire engines printed with 3D printers? The article says that 75% of that rocket engine was printed, not 100%. Why isn't the ISS churning out rocket engines left and right? If all you need is a 3D printer then they should be completely independent now, right?
After you get to ISS, you've already used your rocket engines. Why would you make something you need to get to where you're going after you're already there?
There's material on Mars that a 3D printer can use? Too bad it's mixed with other stuff.
The "other stuff" is needed to actually make sulfacrete.
There's water on the surface of Mars? How does your robot water drilling machine separate the salt from the Mars water? It doesn't, right? So, now you need another robot to do that. It just goes on and on and on.
All water recycling systems filter water, but Google "seawater flash evaporation". While you're at it, Google "solution chemistry".
The ISS water recycling system is less than 100% efficiency? What do they do to get all the water out of feces?
It's either vacuum desiccation or a fiery reentry aboard one of the resupply vehicles.
There's no such thing as a perfect seal? Uhh, next time you get on an airplane ask them how well their hydraulic system lines seal. If they say it's less than perfect, don't get on the plane, hehe...
In the two years that I was assigned to an EA-6B squadron, I never saw a jet from my squadron or any other squadron that didn't leak hydraulic fluid, fuel, and oil. The leak can't be excessive, but all jets leak. The arresting gear leaks hydraulic fluid. The steam catapults leak 3steam
If the SR-71 didn't leak fuel on the ground, and a lot of it, it would've come apart at Mach 3.
I recently started learning to fly. When I do my walk-around of the Cessna 172RG, there's hydraulic fluid under the landing gear, fuel under the wings, and a little oil under the motor. Somehow, it still flies. If I don't see a little fluid on the tarmac, that concerns me!
I guess the "no perfect seal" remark was supposed to tell me that there will be leaks in the tuna can and greenhouse and somehow water will escape as tiny amounts of water vapor? I'm sure some extremely small amounts of water vapor will escape. But, many, many times that amount will be made by the WAVAR.
You can think or believe whatever pleases you, but in the real world, ships, aircraft, and spacecraft leak whatever it is that they have onboard that can leak. When you see all that "steam" coming from rockets loaded with cryogenic oxidizers and fuels, what do you think you're looking at?
We keep sending the ISS water and oxygen? I thought they had a 3D printer?
I thought you were an adult, but you keep making comments like this one that don't add any value to the topic of this thread.
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kbd512
How many days for the zeolite panels to obtain 250 gallons of water? The estimate is that they will produce 13.48 gallons a day, so it would take 19 days. That estimate is in summer only, the winter humidity on Mars is too low for it to provide any water at all. And the estimate is for a location in the northern hemisphere in between the equator and north pole.
How much will the panels weigh? The WAVAR unit uses a single 180 degree arch shape packed with zeolite pellets that is 10.8 m long, .93 m high, and .04 m thick, and weighs 240 kg.
The entire WAVAR unit weighs 1,947 lbs because it has microwave heaters and a storage tank. I think the tuna can, oops, Mars Hab, needs to have a WAVAR unit but once we have a greenhouse there would be no need for microwaving zeolite to get water vapor out because the greenhouse heat would do it. So, we could just use zeolite panels mounted on a wheeled fiberglass cart.
Water will flash to steam and have to rise? Okay, why would it go into a tank and naturally pressurize itself when it can go around the drill bit and escape into a vacuum?
You have documents on a WAVAR that uses hydrogen sent from the Earth to make a lot of water on Mars? This is the one I'm talking about.
http://www.lpi.usra.edu/publications/re … ington.pdf
The glaciers are frozen solid? The glaciers probably are, do you know where the salt water is? If you don't how can you avoid it? We haven't driven across all of Mars. There could be more very dangerous places. We already know that some places are deep sand and others are impassable rock fields.
The regolith is too heavy to put on top of a Mars Hab? Yep, if your weights are correct regolith is too heavy. Are you sure you used Mars gravity and not Earth for the weight? No matter what lander we use they are going to have the same problem.
Why would the ISS make rocket engines when everything sent to the ISS already has it's own rocket engine? So if you send something somewhere inside a, let's say a habitat, then it doesn't need to make another habitat?
The other stuff is needed to make sulfacrete? Yeah, I think the other stuff is supposed to be 1 mm size aggregate. So you have to process it. You have to go out, sift Mars dirt, roll the right size stuff into a bucket, repeat over and over and over again.
The WAVAR is just a much better option to get fresh water at a Mars base than robotic drilling rovers.
You never saw a jet from your squadron that didn't leak hydraulic fluid? That's because the actuators are designed to leak a tiny bit to lubricate the o-ring seals. If they didn't, the chrome actuator would be dry and grab the o-ring and tear it. The hydraulic tubing and hoses should never leak, not even one drop.
Some things have allowable leakage, other things don't. I'm saying that the water used in a Mars Hab and greenhouse should be almost 100% contained.
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How many days for the zeolite panels to obtain 250 gallons of water? The estimate is that they will produce 13.48 gallons a day, so it would take 19 days. That estimate is in summer only, the winter humidity on Mars is too low for it to provide any water at all. And the estimate is for a location in the northern hemisphere in between the equator and north pole.
The average output estimates I saw were between about 10 to 15 kilograms per day. At an 11kg/day output rate that's a little over 3 gallons per day. That's enough to offset losses on an exploration mission. That was the original intent behind WAVAR. Faster output is clearly better since the system constantly loses its seed hydrogen to boil-off. WAVAR may be capable of a peak output rate of 13 gallons per day, dependent upon the temperature range over which it's operated. The more people you have to provision water for, the more hydrogen you have to ship to Mars. The output rate of CO2/LH2-based water system is critical. Getting to Mars faster is also desirable.
Current solar panel and battery technology should easily provide the 8kWe to 12kWe and deal with the 25kWe peak demand, too, without requiring an excessively large battery.
Let's do some math on how much power MOXIE would need to produce the same mass of oxygen per day. We can react the oxygen from the MOXIE with the hydrogen from the storage tank from WAVAR using a fuel cell to produce both water and power to power MOXIE during water production. The Space Shuttle stored LOX/LH2 to make water and power for the crew. A fuel cell would offset the electrical power and power storage requirement to use MOXIE.
NASA has 3kWe fuel cells that weighs 85kg complete.
The NASA Advanced Space Power Systems Project
We can guestimate what the 1% demonstrator unit weighs (10kg*), how big it is (9.4 x 9.4 x 12.2 inches), what it's output should be (22g/hr or 240g/day), and how much power it consumes (168We). Simply using an array of 40 1% demonstrator units to produce a 40% scale device, the 40% scale device weighs 400kg, outputs 440g/hr, and requires 6.72kWe. We will obviously delete the pre-compressed CO2 tank, so we're saving at least 2kg over the original design, but we're going with 400kg because piping will eat up that 2kg we saved.
* Given that MOXIE is one of over half dozen science experiments on the Mars 2020 rover and the entire scientific instrument package weighs 45kg, let's assume a 1% scale MOXIE weighs 10kg. We already know that the Air Squared CO2 compressor weighs 2kg. MOXIE also contains a supply of pre-compressed CO2 as a backup to the primary experiment and a cryocooler that we don't need since we're feeding the O2 directly to a 3kWe O2/H2 NFT PEM fuel cell. A production unit should weigh less than this experiment by deleting the pre-compressed CO2 tank and cryocooler, but let's assume MOXIE is nearly 1/4 the weight of the entire scientific instrument package aboard our Mars 2020 rover.
If you feed it oxygen and hydrogen, it'll produce both electricity to power the MOXIE's and water.
1 liter of water weighs 1kg and contains 888.81g of oxygen and 111.19g of hydrogen.
In a little over 2 hours, our MOXIE + LH2 tank from WAVAR produces 1kg of water, or about 12kg of water per day.
It takes 325 days to produce the same amount of H2O as WAVAR, so overall performance is about the same. The difference is that the fuel cells power the MOXIE units, so you don't have to come up with a way to produce 25kWe peak power and 12kWe continuous power for the fan motor to move CO2 over the zeolite bed.
I'm just brainstorming here (feel free to poke holes in the idea):
If a 100% scale MOXIE unit that produces 2.2kg/hr has a 38kg compressor that requires 12kWe, then combine that with four 3kWe fuel cells.
Let's say the .14m^2 active SOXE area weighs 4kg and has to be scaled up 100% and weighs 400kg
38kg for CO2 Compressor
400kg for SOXE (the solid oxide electrolysis unit)
340kg for 4 3kWe NFT PEM fuel cells
778kg for the entire setup, not including the water wall or plumbing, and let's call the entire thing equivalent to WAVAR in total mass
2.4 gallons per hour or 57.6 gallons day or 480kg per day or a little over 8 days to consume our entire supply of hydrogen. We're going to lose a LOT less seed hydrogen from boil-off, so we should be able to make more than 3,900kg of water with 1,200kg of seed hydrogen.
Whichever setup has the lowest mass and fastest production rate is preferable because the hydrogen is constantly being lost. If we get to Mars in 90 days, we start with 764kg of seed hydrogen instead of 440kg, so we can make substantially more than 3,900kg of water with 1,200kg of seed hydrogen.
How much will the panels weigh? The WAVAR unit uses a single 180 degree arch shape packed with zeolite pellets that is 10.8 m long, .93 m high, and .04 m thick, and weighs 240 kg.
This is for the entire unit that produces the chemical reaction, right?
The entire WAVAR unit weighs 1,947 lbs because it has microwave heaters and a storage tank. I think the tuna can, oops, Mars Hab, needs to have a WAVAR unit but once we have a greenhouse there would be no need for microwaving zeolite to get water vapor out because the greenhouse heat would do it. So, we could just use zeolite panels mounted on a wheeled fiberglass cart.
The WAVAR weighs 885kg, but you also need 1,200kg of hydrogen and only get to use some of that since you lose some during every day of storage. NASA is working on technologies to reduce LH2 boil off rate, so-called ZBO or Zero Boil-Off technologies, so you should check to see where they are with that. The less you lose, the lower the total mass. Also, we finally have all solid-state cryocoolers.
Water will flash to steam and have to rise? Okay, why would it go into a tank and naturally pressurize itself when it can go around the drill bit and escape into a vacuum?
The tank has to vent some steam to equalize the pressure, but the temperature gradient between the drill bit and tank is pretty steep.
You have documents on a WAVAR that uses hydrogen sent from the Earth to make a lot of water on Mars? This is the one I'm talking about.
Ok, this is one of the documents I have. Is the total production quantity around 3,900kg?
The glaciers are frozen solid? The glaciers probably are, do you know where the salt water is? If you don't how can you avoid it? We haven't driven across all of Mars. There could be more very dangerous places. We already know that some places are deep sand and others are impassable rock fields.
Maybe the daytime temperatures can liquefy some of the water, but the Martian nights would freeze the saltiest ocean water solid and the water is located under a few meters of rock and dust. I seriously doubt the empty 95kg (on Mars) robot would sink that far into the regolith.
The regolith is too heavy to put on top of a Mars Hab? Yep, if your weights are correct regolith is too heavy. Are you sure you used Mars gravity and not Earth for the weight? No matter what lander we use they are going to have the same problem.
Did you see the part at the end where I multiplied by ".38g" in that previous post? Even at .38g, regolith is heavier than water. If the lander is something big enough for 6 people and voluminous to carry all of their food and water, then making it out of something to withstand that kind of compressive load when it's designed to operate in tension is going to be very problematic at best. Nothing is impossible, but there are always trade-offs.
Why would the ISS make rocket engines when everything sent to the ISS already has it's own rocket engine? So if you send something somewhere inside a, let's say a habitat, then it doesn't need to make another habitat?
All I know is that when you have the technology and means to production, you can do a lot more with what you can make than what you can carry with you.
The other stuff is needed to make sulfacrete? Yeah, I think the other stuff is supposed to be 1 mm size aggregate. So you have to process it. You have to go out, sift Mars dirt, roll the right size stuff into a bucket, repeat over and over and over again.
Sifting sand isn't that big a deal when there's so much loose material to work with. Most of what the rovers travel through has the consistency of talcum powder. This can't possibly be that big a deal. Finding a rich sulfur deposit is what matters most.
The WAVAR is just a much better option to get fresh water at a Mars base than robotic drilling rovers.
Short term, yes. It should work quite nicely for an exploration mission. Long term, the mass requirement is substantially higher than for three robots. Once you run out of hydrogen, you can't produce any more water until you get more hydrogen from Earth. If you can do a superlative job of sealing the habitat and the greenhouse is directly connected to the habitat so no atmosphere and water are vented, then it depends on the water requirements.
A nuclear powered robot has been driving around the surface of Mars for nearly 5 years now and its mission has been indefinitely extended. One of the MER rovers has been driving around for substantially longer than that now. The satellites we have in orbit right now are capable of picking out the individual spacecraft that have landed there. We're sending another Curiosity type rover there in 2020. Solar and RTG powered electric motor driven robots are pretty well proven technology at this point. It works, better than anyone involved in the projects ever imagined it would.
You never saw a jet from your squadron that didn't leak hydraulic fluid? That's because the actuators are designed to leak a tiny bit to lubricate the o-ring seals. If they didn't, the chrome actuator would be dry and grab the o-ring and tear it. The hydraulic tubing and hoses should never leak, not even one drop.
My point was that real mechanical systems leak fluids. ISS leaks atmosphere. The ground astronauts or colonists and crews track the loss rates and NASA has come up with methods to find and repair significant leaks. The tuna cans and greenhouses will leak atmosphere, too. It can be minimized, but not prevented entirely.
Some things have allowable leakage, other things don't. I'm saying that the water used in a Mars Hab and greenhouse should be almost 100% contained.
Agreed. As long as the colonists don't open any airlocks, water leakage should be minimized. Atmospheric leakage is unavoidable. Any routine opening of airlocks is going to vent pounds of air and water to the near-vacuum of the Martian surface. That's just the way all real airlocks work. It may be possible to pump some of the atmosphere (O2 / N2 / CO2 / water vapor) from the airlock into the tuna can and that could minimize losses. Doing that may decrease the life of the tuna can, in the same way that every pressurization / depressurization cycle reduces the life of the airlock. This is related to the fatigue life of the material that the tuna can is constructed from. It's quite good for modern aluminum alloys, but there's an upper limit before the welds start to fail.
Here's a short little slide set about the ISS Sabatier reactor used to react waste CO2 from ISS crew exhalation with hydrogen to produce water from 2011. Note the 77% recovery efficiency improving to 85% recovery efficiency with the Sabatier reactor installed by using waste CO2 and waste H2 from the ISS Oxygen Generator System that was previously vented into space. Recall my notes in a previous post about the Paragon IWP ionomer membrane water processor recovering 85% to 90% of the water from very salty brines of urine and waste water. The water quality from the IWP is not quite up to NASA standards
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kbd512
The WAVAR doesn't need seed hydrogen to work on Mars. It will absorb water vapor directly from Mars atmosphere.
I don't like the idea of taking seed hydrogen and oxygen to make water on the trip to Mars or on Mars. Why not just take the water the crew needs and not depend on a machine for water? If the machine breaks in flight the crew dies.
Also, I don't like the unneeded weight the WAVAR has. You don't have to microwave heat zeolite to get it to outgas water vapor, you can just a wheeled cart with zeolite panels inside your greenhouse and let it's daytime heat do it for you. But, building a greenhouse will take time so the crew will only have the water they brought with them. And they won't be able to use a solar cooker to boil urine to recycle it's water until they have a greenhouse to catch the water vapor.
I just wonder if they could build a quick temporary greenhouse when they get to Mars to quickly process all their urine back into fresh water and begin using a wheeled zeolite cart in the temporary greenhouse. The temp. greenhouse wouldn't have to be that big and you could use the same panels that go to the large greenhouse until it needs them.
I also don't like the idea of having a fuel cell for power. They'll have an RTG and a large solar array, that should be enough.
The measurements were just for the WAVAR zeolite bed, not the whole unit. The WAVAR zeolite bed is very large, it's 35 feet long. I think we could cut it down to five panels each 6' by 5' that fit into slots on a wheeled fiberglass cart and get rid of the microwave, pump, and storage tank to save a lot of weight.
You don't need to take seed hydrogen if you keep your crew down to four people and don't have to make rocket fuel.
Your robot drill bit machine, even if the storage tank and Mars atmospheric pressure are equal you won't get much water vapor moving into it. You would have to open a valve on the top of the tank, open another valve on your drill to allow water vapor to go up into the tank, use a fan to bring water vapor into your tank, close both valves, pressurize the tank for water to form, then pump the water into another water storage tank on the rover, then repeat this process over and over. You're only going to get drops of water each time.
The WAVAR report says the total mass of water collected at New Houston is 4730 kg with fog, and 2041 kg without.
Mars night time would freeze even salt water? Yeah, it would, but you can't operate at night unless you're going entirely on batteries. I'm just saying that driving on Mars is going to be dangerous, even if there isn't salty areas, some areas are impassable rock fields, others are deep sand drifts. Why depend on a robot water machine when we can use zeolite panels at the base?
If the Mars Hab has an outer shell of carbon composite and has an inner shell that is 18" of the Bigelow hydrogen impregnanted fabric, then a 6" thin water sack shield that is full of water for flight and another 6" water sack that is filled on Mars with zeolite water, that should provide enough strength to withstand some regolith put on top.
Having production capability is better than having to ship everything from the Earth? It is if that production can make the things that are necessary to sustain life, those things are oxygen, food, water, and then shelter but shelter is not a need if every crew lands in a habitat.
Manufacturing iron or steel or sulfur does not get us those things. The Moxies have to come from the Earth. More zeolite panels have to come from the Earth. Plastic greenhouse panels have to come from the Earth. The settlement needs to maintain their equipment and grow plants in the greenhouse.
Shifting sand is not that big of a deal? It's not if that's all you have to do but that just gets you half of your sulfacrete. You still have to gather material, which is probably 4-6% sulfur, heat the material to get the sulfur and do it over and over and over again to separate it. And, even when you do all of that it doesn't get you oxygen, food, or water. It just gets you a shelter that needs extra pressure door, water system, oxygen system, CO2 scrubber.
Long term you're saying a WAVAR system mass is substantially higher than three robots? No way. Your robot drilling machine would be as large as my long range rover and weigh more (because my LRR is just a carbon composite tube, yours has storage tanks and a drill) and I estimated my LRR to weigh around 2,000 lbs.
Solar works great for rovers on Mars, just don't get in too much of a hurry.
The Mars Hab will leak some, probably not too much. The greenhouse could have a lot of leaks and they could be tough to find and fix if the crew doesn't do a good job of sealing the panels when the assemble it. This is another reason why I don't like the idea of having the crew mess around collecting regolith to make homes, they will have to fix and maintain the equipment that gives them life.
The habitats will lose water vapor whenever an air lock is opened? Tiny amounts if there is a double door airlock. The Zubrin tuna can had the pressure door go to the central shielding area and, I assume, a hatch in the bottom of that area to leave the tuna can. In my plan, the tuna can would dock with the rover hanger and both go to Mars. So, they would go through the pressure door into the central air lock, close the door behind them, then go through the hatch into the rover hanger below.
Last edited by Dook (2017-04-22 20:32:17)
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The WAVAR doesn't need seed hydrogen to work on Mars. It will absorb water vapor directly from Mars atmosphere.
This assumes that there is enough water vapor to absorb from the atmosphere. The Martian atmosphere is exceptionally dry. It does contain trace amounts of water vapor, but since the atmospheric pressure varies substantially as a function of elevation, day/night/season of the year, this is still a big question mark. NASA is actively trying to better characterize the atmosphere just to reliably land on Mars.
I don't like the idea of taking seed hydrogen and oxygen to make water on the trip to Mars or on Mars. Why not just take the water the crew needs and not depend on a machine for water? If the machine breaks in flight the crew dies.
The WAVAR in the concept paper uses seed hydrogen brought from Earth. The crew is going to have some water onboard since they have to travel through space to get to Mars. The question is how much water do they need. If you can make more on Mars, through whatever method is selected, then it's value added to the colony or even an exploration mission as a function of the mission duration.
Also, I don't like the unneeded weight the WAVAR has. You don't have to microwave heat zeolite to get it to outgas water vapor, you can just a wheeled cart with zeolite panels inside your greenhouse and let it's daytime heat do it for you. But, building a greenhouse will take time so the crew will only have the water they brought with them. And they won't be able to use a solar cooker to boil urine to recycle it's water until they have a greenhouse to catch the water vapor.
The wheeled cart would have to contain a sealed vessel to prevent the water from subliming or outgassing back into the Martian atmosphere since the average ambient pressure is 7 mbar. The panels can't weigh 240kg (91.2kg on Mars), either, or you'd need at least two astronauts to lift that much weight. They also have to open the airlock to go outside and we already know that cycling airlocks causes atmospheric and water losses since this happens every time the astronauts perform a spacewalk aboard ISS.
I think you're right about using solar instead of microwaves. You need 25kWe of electrical power for the magnetron. Solar heat is free and a fresnel lens is much simpler than a water-cooled high-power magnetron. The lens will weigh more than the magnetron, but the weight of the lens is more than offset by the weight of electrical power generation and storage equipment required.
I just wonder if they could build a quick temporary greenhouse when they get to Mars to quickly process all their urine back into fresh water and begin using a wheeled zeolite cart in the temporary greenhouse. The temp. greenhouse wouldn't have to be that big and you could use the same panels that go to the large greenhouse until it needs them.
Quick and easy usually means lower quality and less design life. Any greenhouse built on Mars needs to last a long time. It can be small, but it has to be built to last.
I also don't like the idea of having a fuel cell for power. They'll have an RTG and a large solar array, that should be enough.
The RTG isn't really for manned systems, as a function of power output levels. Do you mean small fission reactor (1kWe to 10kWe), like Kilopower?
I want you to peruse the manual I use for RTG information to get an understanding of the mass and output levels of these devices:
Radioisotope Power Systems Reference Book for Mission Designers and Planners
I also want you to peruse these documents from the companies that have designed and built RTG's:
Science.gov Results for Mars+Rover+RTG
The now discontinued GPHS-RTG's used on Cassini were 300We BOL (Beginning-Of-Life) systems, meaning 3 100 Watt lightbulbs when the RTG is brand new. IIRC, it's 28VDC to 36VDC at between 10.7 Amps (28VDC) and 8.3 Amps (36VDC). These RTG's weigh 56kg.
The total system mass for ATK's new MegaFlex 250We/kg panels is about 7kg per kW. For 12kWe, that's 84kg. You only get peak output for 4 hours of the day and it's lower for the other 8 hours. SpaceNut knows more about this than I do and can fill in information I don't know. We discussed this in the nuclear powered rover thread. That means you need a much larger array and a high capacity Lithium-ion battery for 24/7 operations.
The new Lithium-ion batteries from Tesla and Panasonic are 250Wh/kg or 4kg/kWh. A 192kWh battery pack 768kg just for the cells, not including the packaging, charge/discharge controller, or insulation. The extra capacity is required to maintain output levels when the PV arrays aren't producing peak power and to prevent excessive DoD (Depth of Discharge) from ruining the batteries. In most testing, I believe an 80% DoD is used to measure performance. Again, SpaceNut knows more about photovoltaics and batteries than I do. The extreme cold of the Martian nights requires radioisotope and/or electric heating (more battery). Spirit and Opportunity use these systems to keep their batteries and electronics alive at night.
A fuel cell will run at peak output 24/7, as long as oxygen and hydrogen are delivered at the correct rate. As previously stated, 340kg for 3 of the new 3kWe NFT (Non-Flow-Through) PEM (Polymer Electrolyte Membrane) fuel cells (I think they're made for NASA by Qinetiq) to produce 12kWe. As a function of the mass of the battery, the fuel cells will weigh less. Storing electrical power is where our current technology falls short.
The measurements were just for the WAVAR zeolite bed, not the whole unit. The WAVAR zeolite bed is very large, it's 35 feet long. I think we could cut it down to five panels each 6' by 5' that fit into slots on a wheeled fiberglass cart and get rid of the microwave, pump, and storage tank to save a lot of weight.
WAVAR used a fan to move atmosphere over the zeolite bed. That's not going away since the atmosphere is so thin.
This document says WAVAR produces 1kg of water per day by just moving atmosphere over the zeolite bed:
Mars ISRU technology - Springer
You don't need to take seed hydrogen if you keep your crew down to four people and don't have to make rocket fuel.
I think you do need the seed hydrogen. The document shown above illustrates why you do. You have to move 37,000L of atmosphere over the sorption bed to obtain 1kg of water per day with a total power investment between 4.4kWh, if the water concentration is higher, and 6.6kWh, if the water content is at the planetary average.
Now we're down to four people from six. Since they're not coming back, they don't need rocket fuel to return to Earth.
Your robot drill bit machine, even if the storage tank and Mars atmospheric pressure are equal you won't get much water vapor moving into it. You would have to open a valve on the top of the tank, open another valve on your drill to allow water vapor to go up into the tank, use a fan to bring water vapor into your tank, close both valves, pressurize the tank for water to form, then pump the water into another water storage tank on the rover, then repeat this process over and over. You're only going to get drops of water each time.
I see we're back to this again. Some basic science course work would really help, but since I'm not a science teacher, watch this YouTube video:
The WAVAR report says the total mass of water collected at New Houston is 4730 kg with fog, and 2041 kg without.
The numbers you're quoting above involve using seed hydrogen. The 1,200kg to 3,900kg of water figures I quoted also require hitherto unheard of boil-off rates for LH2.
At a .063% water content, twice the planetary average, you have to process 1,000kg of atmosphere to obtain 630g of water. To obtain 1 gallon of water per day at an atmospheric water vapor concentration of more than double the planetary average, you have to process 6,444kg of atmosphere per day.
Mars night time would freeze even salt water? Yeah, it would, but you can't operate at night unless you're going entirely on batteries. I'm just saying that driving on Mars is going to be dangerous, even if there isn't salty areas, some areas are impassable rock fields, others are deep sand drifts. Why depend on a robot water machine when we can use zeolite panels at the base?
The water robots have no batteries at all and no electric motors that are not completely sealed. The robot uses a RTG to charge a super capacitor. The super capacitor provides power to the electric motors. It's a start / stop system. You do work for a few minutes, then stop to recharge the capacitor, then do some more work. The drill robot uses magnetic gearing to "drives" the water tank by rotating permanent magnet Halbach arrays attached to small electric motors in the drill robot. The Halbach array in the water tank is the second part of the gearing.
It may be necessary to go around some rock fields, but the ball balancing water robot is not significantly range limited since it uses a small RTG and super capacitors.
Your WAVAR system can produce about 365 gallons per year without LH2, assuming the tuna can lands in a spot with twice the planetary average water vapor concentration. It's enough to contend with losses, but that's about it.
If the Mars Hab has an outer shell of carbon composite and has an inner shell that is 18" of the Bigelow hydrogen impregnanted fabric, then a 6" thin water sack shield that is full of water for flight and another 6" water sack that is filled on Mars with zeolite water, that should provide enough strength to withstand some regolith put on top.
What are the dimensions of the habitat? How fast can you fill the water tank when you're only producing 365 gallons per year and losing some each day when the astronauts go outside to put the zeolite panels in the sealed container so the solar heater can extract the water from the zeolite panels?
Having production capability is better than having to ship everything from the Earth? It is if that production can make the things that are necessary to sustain life, those things are oxygen, food, water, and then shelter but shelter is not a need if every crew lands in a habitat.
The shelter needs to do just that. It has to protect the crew from GCR and SPE radiation and maintain pressurization.
Manufacturing iron or steel or sulfur does not get us those things. The Moxies have to come from the Earth. More zeolite panels have to come from the Earth. Plastic greenhouse panels have to come from the Earth. The settlement needs to maintain their equipment and grow plants in the greenhouse.
Sulfur plus sand makes concrete. Concrete provides shelter that could not otherwise be provided.
Shifting sand is not that big of a deal? It's not if that's all you have to do but that just gets you half of your sulfacrete. You still have to gather material, which is probably 4-6% sulfur, heat the material to get the sulfur and do it over and over and over again to separate it. And, even when you do all of that it doesn't get you oxygen, food, or water. It just gets you a shelter that needs extra pressure door, water system, oxygen system, CO2 scrubber.
The rovers driving through the sand have literally uncovered that yellow stuff that we need. As volcanic as the Martian past obviously was, the sulfur is clearly there. We don't have to dig a mine a thousand feet deep to get to it. It's there on the surface because the volcanos spewed it all over the planet.
Long term you're saying a WAVAR system mass is substantially higher than three robots? No way. Your robot drilling machine would be as large as my long range rover and weigh more (because my LRR is just a carbon composite tube, yours has storage tanks and a drill) and I estimated my LRR to weigh around 2,000 lbs.
My robot is nothing more than a 250 gallon tank and an articulating drill on rollers that "rides" atop the water tank. In other words, it's a ball balancing robot with a detachable drill. The water robots would weigh about 250kg each and I want to send 3 of them, so all three don't even weigh as much as your 909kg long range rover. It's weight when loaded with water on Mars has no correlation with its launch weight.
Solar works great for rovers on Mars, just don't get in too much of a hurry.
Let's hope.
The Mars Hab will leak some, probably not too much. The greenhouse could have a lot of leaks and they could be tough to find and fix if the crew doesn't do a good job of sealing the panels when the assemble it. This is another reason why I don't like the idea of having the crew mess around collecting regolith to make homes, they will have to fix and maintain the equipment that gives them life.
False premise. The crew isn't collecting regolith to build the colony. The robots collect the water, the regolith, and construct the habitats before the humans show up and I've stated that multiple times now. There's a robot with a rock drill on Mars right now. It's been there for years and there are pictures of the holes it made in several rocks on the internet.
The habitats will lose water vapor whenever an air lock is opened? Tiny amounts if there is a double door airlock. The Zubrin tuna can had the pressure door go to the central shielding area and, I assume, a hatch in the bottom of that area to leave the tuna can. In my plan, the tuna can would dock with the rover hanger and both go to Mars. So, they would go through the pressure door into the central air lock, close the door behind them, then go through the hatch into the rover hanger below.
It would help if you understood the mechanics involved in what you want to do. You want the crew to go outside every day to put some zeolite panels in the sun to bake the water out. Even if the job only requires one person, safety practice is to send two people.
When astronauts aboard ISS prep for a space walk, they "camp out" in the airlock overnight. The pressure aboard ISS is Earth sea level. This is reduced to about 70% of sea level in the airlock after the astronauts enter the airlock. The astronauts breathe in this lower pressure atmosphere overnight to reduce the duration of the pure oxygen pre-breathe required to completely flush the nitrogen in their blood. Several hours before the actual EVA starts, they begin pre-breathing pure oxygen. After that, it takes about 30 minutes or so to depressurize and 45 minutes to re-pressurize the airlock.
You're going to have two of your four crew colonists, down from six, spending at least 8 hours of their day in an airlock to perform a couple hours worth of work to obtain one gallon of water per day, presuming the spot you land always contains double the amount of atmospheric water vapor?
Is it possible to use a pump to evacuate the airlock to save most of the atmosphere? Absolutely. This is done on ISS.
There is such a thing as a suit port that lowers the amount of atmosphere vented, but the pre-breathe requirements are much longer if the atmosphere in the habitat module is Earth sea level. The life support "backpack" that the space suit has functions as the airlock. These technologies are still in testing, but it does work.
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We can extract water vapour on Mars according to this detailed study:
http://www.lpi.usra.edu/publications/re … ington.pdf
45 Kgs of water per sol for 885 Kg mass of a machine and 15Kws constant power.
This assumes that there is enough water vapor to absorb from the atmosphere. The Martian atmosphere is exceptionally dry. It does contain trace amounts of water vapor, but since the atmospheric pressure varies substantially as a function of elevation, day/night/season of the year, this is still a big question mark. NASA is actively trying to better characterize the atmosphere just to reliably land on Mars.
Let's Go to Mars...Google on: Fast Track to Mars blogspot.com
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Louis,
About that 45kg figure you just threw out:
1. The document says 42kg, not 45kg
2. Assumes WAVAR is operated at the north pole
3. If you were at the north pole, why mess with WAVAR? Stick a hot knife into that giant ice sheet that covers the ground up there, melt the ice in a vacuum thermos using a RTG, and you have water. The RTG has no moving parts and would weigh far less than a power source that could provide 15kWe. You'll get as much water as you can stick a hot knife into.
You guys are so over-excited about this thing that you're not even quoting from the documents. For the uninitiated, the north pole of Mars can get down to -243F. Another 15 degrees and you won't need a cryocooler to liquefy methane for that LOX/LCH4 plant. Let's put the colonists in a cryogenic environment since living on Mars isn't challenging enough as it is.
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kbd512
The WAVAR report assumes there is enough water vapor to absorb from the atmosphere? It does based on Viking 1, Viking 2, and Pathfinder water vapor measurements. They believe that Mars atmosphere has 100% humidity at night at low altitudes.
The atmospheric pressure changes on Mars? It does but only by a few milibars. We have to select a base location that is low in altitude so the base has higher pressure to help with fans in the WAVAR, mini-Moxie, and to provide radiation and micro-meteorite shielding.
The WAVAR uses seed hydrogen? No, it doesn't. The report does talk about seed hydrogen, it is confusing, but what they are saying is that the mass of the WAVAR was designed to be less than the mass of seed hydrogen, otherwise, why take a WAVAR at all when you can just take seed hydrogen.
I guess there are different kinds of zeolite, some absorb just water vapor and others absorb water vapor and CO2. Don't take my word on that, I'm still trying to figure it out but there seems to be a lack of detailed information about it.
The wheeled zeolite cart would have to contain a pressure vessel to prevent the water from outgassing back into the Martian atmosphere? It does not need a pressure vessel. The panels need to be exposed at night and they should have a fan to blow Mars atmosphere over the panels at night. The outgassing doesn't happen until you heat the panels so you push the wheeled cart back inside the greenhouse so they outgas the water vapor inside.
I think the panels only need to be heated to 50 degrees F to outgas but I need to verify that.
The zeolite panels can't weigh 240 kg? Yeah, that's 528 lbs on Earth but only 200 lbs on Mars. That's why I want them mounted to a fiberglass cart on wheels.
The quick and easy temporary greenhouse would just be to start getting water immediately on Mars with the zeolite cart and be able to boil urine to get water. Once the large permanent greenhouse is being built and needs those panels the temporary greenhouse would be torn down.
I mean a big RTG and a large thin solar array spread out on the surface. The Mars Hab would also have another circular solar array placed on top of it to cover the regolith. These are not solar panels, they are very lightweight thin solar arrays that can be stored rolled up in the Mars Hab for flight and rolled out on Mars.
I know you guys want a nuclear reactor and massive amounts of power but once you get rid of all the production and manufacturing ideas you will realize that you don't need that much power.
You just need to power the Mars Hab (one mini-Moxie, the WAVAR, life support system, lights, laptops, DC shower pump, and CO2 scrubber), the fan on your greenhouse, the fan on your zeolite cart, and be able to recharge the two ATV's (the long range rover can recharge itself).
The extreme cold of Martian nights requires electric heating? The Mars Hab would be very, very insulated. It has an outer shell of carbon composite, an inner shell of 18" of fabric, a 6" thick water sack that is full, another 6" water sack that would be filling from the WAVAR mounted in the ceiling. When I was building my house I slept in a trailer at the bottom of my property. I didn't use the heater at night because it would kick on every 20 min or so and wake me up so I just used two blankets and a sleeping bag. It would be 17 degrees inside the trailer in the morning but I was warm, usually too warm. No fuel cell needed.
The Mars ISRU Springer estimates that their WAVAR unit would produce only 1kg of water a day? They use a different design and their zeolite is a 1 cm by 62 cm wheel. The amount of zeolite we take determines how much water we get. Oversize is better.
This is another reason why taking a 3D printer and manufacturing equipment is bad for the first settlement. Everything you take to produce sulfur reduces the amount of oxygen equipment, water equipment, and food producing equipment you can take.
Seed hydrogen is used along with CO2 in a Sabatier reaction to make methane and water. The problem is that you have to take seed hydrogen which adds launch weight and you lose most of it to boil off on the trip to Mars.
Now we're down to four from six people? Zubrin planned for four, not six. You can't take six. Six people means your consumables goes from 7 tons to 9 tons, and you have to produce more oxygen and water and have less extras. More people on Mars is not better, it's worse.
I'm not looking at any video's. I'm going to assume that it's a video of something on the Earth and not Mars. Things don't work as well on Mars that they do on the Earth.
The numbers for my WAVAR include seed hydrogen? No, they don't. You need to look up zeolite and see how it works. It doesn't use hydrogen.
Your water robots have no batteries at all, it uses an RTG and super capacitors? That's for the drill, how does the vehicle move? What causes the ball to rotate?
My WAVAR can produce about 365 gallons per year assuming it lands in a spot with twice the planetary average water vapor concentration? Correct, but we already know the higher latitudes have higher water vapor concentrations so it's not a guess. And 365 gallons a year will be enough IF the settlers don't waste it on rocket fuel.
The shelter needs to protect the crew from radiation? A Mars Hab that is thin carbon composite, 18" of hydrogen impregnated fabric, then a 6" water sack, and another 6" water sack, and some regolith on top isn't enough?
The sulfur is all over the place on Mars? Estimates say it averages about 6% of regolith. That means you are going to have to move a lot of material and use a lot of heat over and over and over again just to get a small amount of pure sulfur for a home that no one is going to leave a Mars Hab for.
Your water robot is a 250 gallon tank with a drill? What causes the ball to roll? For the tank to suck up water vapor you need a fan, then you need to pressurize the water vapor to get it to condense (so you close the intake valve and pressurize the tank somehow), then you need a pump to move the water into a separate tank to store the water.
Your robots will get water, process dirt, and build homes on Mars before a crew arrives? Okay, we'll be waiting a long time for that to happen.
I want a crew to go outside every day to move zeolite panels? One person just before nightfall. It doesn't take two people. I want a buried habitat under the greenhouse so the crew would be living inside the buried habitat and could go up to the greenhouse without having to go outside. If you're so worried that something could happen there could be a person in the greenhouse watching the person move the cart outside.
Astronauts have to prep before a space walk? They are breathing nitrogen. There won't be any nitrogen in the air in the habitats on Mars and if there is it would be in small amounts.
You've way over designed and greatly over complicated it. Get rid of the Rube Goldberg ways and keep it simple.
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OK, OK, I've heard too much misinformation about zeolites stated here. Zeolites, commonly referred to as "molecular sieves" by most chemists are produced by W.R. Grace company. They come in a wide variety of types for different applications, all based on the so-called "pore size." Want to trap ONLY water and not any CO2? You then use a 3 Angstrom molecular sieve; these can be used to dry or dehydrate alcohols, including Methanol (Methyl Alcohol). The 3 Angstrom will selectively adsorb H2O in the presence of any larger molecules, and CO2 IS a larger molecule. I used these, hundreds of pounds annually, and they weren't that pricey. But NO, they will NOT give up the adsorbed water without a struggle as Dook assumes; they have to be heated in an oven to do so, and hotter the better. In the greenhouse environment where liberated water vapor would condense on the windows/walls/whatever, a vented oven would work just fine. Just make certain the dried zeolites are promptly removed from the environment while still too hot to adsorb more water. Many times I needed ultra-dry solvents that were a PITA to obtain by any other means, and regardless of the expense, these were invaluable. So...no further discussion which exhibits ignorance and various assumptions, please.
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OK, OK, I've heard too much misinformation about zeolites stated here. Zeolites, commonly referred to as "molecular sieves" by most chemists are produced by W.R. Grace company. They come in a wide variety of types for different applications, all based on the so-called "pore size." Want to trap ONLY water and not any CO2? You then use a 3 Angstrom molecular sieve; these can be used to dry or dehydrate alcohols, including Methanol (Methyl Alcohol). The 3 Angstrom will selectively adsorb H2O in the presence of any larger molecules, and CO2 IS a larger molecule. I used these, hundreds of pounds annually, and they weren't that pricey. But NO, they will NOT give up the adsorbed water without a struggle as Dook assumes; they have to be heated in an oven to do so, and hotter the better. In the greenhouse environment where liberated water vapor would condense on the windows/walls/whatever, a vented oven would work just fine. Just make certain the dried zeolites are promptly removed from the environment while still too hot to adsorb more water. Many times I needed ultra-dry solvents that were a PITA to obtain by any other means, and regardless of the expense, these were invaluable. So...no further discussion which exhibits ignorance and various assumptions, please.
The zeolite has to be heated to get it to release water vapor? I said that. Mars daytime summer temperatures at the equator are 70 degrees F so the greenhouse should get even warmer than that. Then we'll use some tall fiberglass panels with reflective mylar on them as solar reflectors to direct more heat on the zeolite panels. Bring the wheeled cart with the panels inside the greenhouse in the morning, let them sit, after noon when the greenhouse is warmest use the solar reflectors to vent the zeolite panels for an hour or two, then take them outside once you are done.
No oven or microwave needed.
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