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Deep Space Hardware (MARS)

Posted by: rpspeck - Tue Mar 22, 2005 4:57 am
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Deep Space Hardware (MARS) 
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Post Deep Space Hardware (MARS)   Posted on: Tue Mar 22, 2005 4:57 am
This continues a discussion of life support hardware for an ultralight Mars Mission. I have contended that a human crewmember can reach the surface of Mars (and return) starting with a single Falcon 5 launch vehicle to LEO (Low Earth Orbit). I will transfer updated details of the trip – including its orbital dynamics – to a “Mars 2006” thread in this forum. Since a primary credibility factor was my low estimate for life support systems mass, I am assembling a “zero g” compatible life support package, which I will validate by personal use. I will report progress with that, and related hardware, in this thread. Obviously, progress in this area is essential to Bigelow’s “Hotel”, and is equally essential for sustained Lunar habitation as well as the Mars excursion.

I may be able to transfer my resume information to this forum as well, as my research work in pulmonary physiology, minor and post graduate work in chemistry, and other systems development work are all applicable to my credibility in this area. I will make only passing reference to my success flying liquid fuel rockets. No one with funding authority seems interested in radically lower cost launch vehicles for atmospheric and mesospheric studies. Actually my limited experience with high altitude mountaineering seems more relevant, for it helps me understand what can actually be accomplished. Yes, I am proposing an “Alpine Style” conquest of space, including Mars itself!

Transferred from; "Can Private Space Travel Take us to Mars?"

Thank you for the Bigelow link. I am in the process of building a zero g compatible system which will sustain me (a far from compact “Astrowanabe”). A prototype Oxygen system should be operating within days, with a permanent CO2 scrubber and water reprocessing system in the next two months. I will defer the CO2 “Water Gas” “reformer” system for a bit, since it has more limited benefit. While I like the Bigelow idea (and he needs the system), I think I will be ready before he is. Other than medium term personal demonstration (with fully invertable hardware), I prefer the idea of flying a recycled rodent habitat piggyback on a SpaceX product. I suspect that the real costs of a “free” NASA launch will be excessive. I plan to post updates on this effort to a “Deep Space Hardware” thread in the Micro-Space forum.


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Post    Posted on: Tue Mar 22, 2005 7:34 pm
This recent space.com article talks about water recycling.
http://www.space.com/news/ap_050321_water_purify.html
Here are a few quotes.

"It could be two years before the water system _ as large as two refrigerators _ is loaded onto a shuttle to serve an American astronaut and Russian cosmonaut living in space. But smaller and simpler versions will soon be put to use on earth."

"Now the (ISS) astronaut and cosmonaut are living off water brought up by the Russian spacecraft, which also includes a device that catches some respiration and recycles it into limited amounts of drinking water. No urine recycler has ever been used in space."

"Although the NASA technology is virtually finished, it still must undergo several more tests to make sure it can withstand a launch."

I wonder how much smaller than 2 refigerators the ground based unit is. And how small could you make the same thing?


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Post Water Processor   Posted on: Wed Mar 23, 2005 10:11 pm
I think this is about how small the water reprocesser will get, near term. The rugged plastic case can be reduced, and a low speed motor drive added. The 6 gallon a day output is enough for my astronauts to drink. Please note that urine is about 1/5 the salt concentration of seawater. This isn’t the full picture (other filters will be added), but it fills in a key part. I actually expect to use a centrifugal evaporator for solids isolation, but this small evaporator will handle less than 400 cc per day of concentrate.

Katadyn -06 Manual Desalinator Watermaker

Water Production (+/- 15%): 1 oz/2 min (890 ml/hour)
(about 1 cup in 13 minutes or 2 pints per hour)

• Weight: 2.5 lbs (1.1 kg)
• Height: 5" (12.7 cm)
• Length: 8" (20.3 cm)
• Width: 2.5" (6.4 cm)
• Water Temperature: 33° to 120°F (1 C to 48.5 C)
• Maximum Production Height: 10"
• Salt Rejection: 98.4% average (95.3% minimum)
• Average Pump Rate: 40 strokes/minute
US Coast Guard Approval Number: 160.058/7/0


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Post OXYGEN GENERATION   Posted on: Wed Mar 23, 2005 11:51 pm
I don’t want to convey the impression that an orbital or deep space life support system is trivial. Therefore I will outline some of the requirements (and objections) as they come up. Remember, however, that SpaceShipOne is also a complex creation, but Rutan did use the X-15 drawings as a starting point, or feel constrained by it’s achieved weight or performance. In any case, it didn’t have three seats! I am equipped to start with pulmonary and metabolic physiology (as well as physics and chemistry) as a starting point, and am doing so.

Note that the “Fuel Cell Car and Experiment Kit” I referenced earlier is an impressive package, complete with solar cells to power the fuel cell in electrolysis mode, the assembled alkaline fuel cell assembly, a digital multimeter for testing, and the motor and car to use the cell in fuel cell mode, consuming the stored Oxygen and Hydrogen, and run the supplied car across the room. It should be good for “Gee Whiz” but also has calibrated hardware to do laboratory type analysis.

However, the unit uses water filled traps to store (and measure) the produced gasses, and these won’t work inverted, or in zero g. For the skeptic, it is necessary to replace these with plastic syringes. The generated and consumed gasses in this case will slide the syringe plungers in an out as necessary, with no help from gravity. Additionally, the electrolyte chamber has no tubing connection. Solid Potassium Hydroxide, sealed into this chamber, is dissolved in the distilled water which is added. Some excess water is consumed in the electrolysis mode (much less than 1 cc), and recreated in the fuel cell mode. Without appropriate connection to the electrolyte chamber, sustained operation in either mode is impossible.

The similarly priced (and much higher power) cell I have received from “The Fuel Cell Store” remedies this limitation. It will work well in any gravity field - or none. All fuel cells do, however, have limitations. The Alkaline cell (the type used in Apollo) has the longest history, but has a major weakness for consumer use (as a fuel cell). With Air input, rather than pure Oxygen, the Carbon Dioxide in the air will react with the Potassium Hydroxide, coating the Oxygen catalyst with insoluble carbonate, and severely degrading its operation. I AM NOT GOING TO USE THE CELL WITH AIR INPUT. Carbon dioxide dissolved in the water feed has a lesser impact, with the precipitated carbonate easily filtered out, but the water feed can also be filtered to reduce its dissolved gas level.

Zero g problems result from, 1. the lack of (gravity driven) convection, 2. the unpredictable nature of gas – liquid interfaces. With mini pumps to sustain circulation, convection is not a problem. However, the two phase situation requires careful analysis of not only the obvious (bubbles and droplets), but also the unobvious dissolved gases in liquids, and condensable vapor in gas which can create problems. By “Murphy’s Law”, read that as “WILL create problems” unless they are anticipated. This is not an unusual problem, as even the antique water siphon can be disabled by the accumulation of previously dissolved gasses at the low pressure point. This is dealt with by running the liquid stream through a semipermeable tube in an evacuated chamber. This will remove dissolved gas. As long as the dissolved gas pressure level achieved is lower than the lowest total liquid pressure elsewhere in the system, then bubbles will not form – and if injected will actually dissolve. Similarly, condensable vapor is handled with a cold trap in the gas system, which keeps the relevant vapor pressure too low to condense elsewhere (and even causes spilled drops to evaporate, and be transported in gas form to the cold trap). I am including provision to handle these factors (and demonstrate that they are working properly) in my pilot system. This thread is planned for those who want this level of detail.


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Post Re: OXYGEN GENERATION   Posted on: Thu Mar 24, 2005 3:04 pm
rpspeck wrote:
This thread is planned for those who want this level of detail.
That would be me. Could you include diagrams or pictures? I have visited your web site but didn't find any.

I see two main types of testing you need to do. First, does your system work at all. Have you considered sealing yourself into a plastic bubble or something for a couple of weeks to prove your life support system works? The second test would be to do the same thing in 0G. In that case an animal would not really work because it could probably not be trained to put it's own body waste into the right places for disposal and recycling, it would just float around the habitat. A fish would, IMO, not adequately demonstrate that the system would work in air. A person would be too heavy and would need to be recovered after the flight! So I recommend an unoccupied system with CO2 supplied from burning alcohol or something like that. Maybe a supply of stored contaminants carried up and added to the air and water automatically. The quality of the air and water would need to be measured somehow and the results transmitted to the ground. The whole thing could be small enough for a free ride on an Bigelow test flight.


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Post    Posted on: Thu Mar 24, 2005 9:44 pm
This all disturbs me very much. I think you would be better off pushing for HLLV and forget micro-space approaches until such time as established infrastructure is in place. With HLLV-launched cycler segments--maybe.

Faster Cheaper better with people on it? I don't think so.


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Post    Posted on: Fri Mar 25, 2005 1:49 am
I don't think for a second that it is even possible to go to mars with only 50 kg of life support, but I do believe that we can and should develop much lighter and simpler space flight hardware. And I am all for anyone who is making a real effort to develop that hardware and not just talking about it.
When I saw the first TV report about Burt Rutan planning a space flight, and saw the EZ rocket in the report, I though, what, is this a joke? Because I was thinking they were talking about putting a long EZ in orbit. But it turned out to be real, although not exactly in the way I first guessed. So as improbable as these extreme micro space ideas may seem, they could end up producing some amazing results.


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Post    Posted on: Fri Mar 25, 2005 4:07 am
I agree with your test suggestions. I plan on the operational bench test, and on something approaching your bubble test. If someone wanted to do it, I would cooperate with a “publicity stunt”, like the “DJ on a pole (in a mini kiosk)” that I remember from the sixties. Publicity and attention will be mandatory if the Public – rather than Congress – is ever going to support (or pay for) a Mars Mission.

From the technical point of view, the fish is a lot more complex (and closer to the mammal) than it sounds, and I will be posting details of this test system. I agree than the demonstration is not complete, and will not be popularly believed, without the mammal demo. I suspect that the waste disposal problem for rodents, cats or dogs has a reasonable solution (even if that solution is mini gravity). I will get serious about orbital test designs when someone (like Bigelow) offers to launch something worth testing. Personally I favor the idea of flying both (and additional) orbital tests, since they can be made light enough to be an insignificant piggyback burden, even with the Falcon 1.

I also think the mantra of “One strike, you’re out!” testing (which extends from Dr. Langley to current NASA) is one of the most destructive concepts ever created! The Wright Brothers would have failed. Dr. Goddard would have failed. The RMI founders (whose motor powered the X1 on it supersonic flights), would have failed!

By the way, it is commonly believed that there are no significant gravitational effects in a satellite. This is not true. With zero external forces (and neglecting nano forces), any object not at the center of mass of the satellite is in an independent orbit around the Earth: AND THOSE ORBITS AREN’T PARALLEL! For that matter, there aren’t any parallel orbits. Objects separated inside a quiet habitat, and spaced laterally (in any direction not just along the LEO orbital path) will float in 90 minute mini orbits about the satellite center of mass, orbital line. Objects which bump into the end walls in their path will tend to collect in “corners” (a posigrade nadir point and a retrograde zenith point). This is also true of nearby objects outside a satellite. Something that slips away from an orbiting satellite will not endlessly drift away, but will cycle back within 90 minutes and probably bump into the satellite. If the “slip” includes a significant posigrade or retrograde component, then the returning object will miss the satellite by progressively larger distances on subsequent cycles (for many days). These effects could be used to help with debris problems inside the satellite, although air circulation and filters will probably handle these.

As for Heavy Lift Launch Vehicles: GO FOR IT! Do everything you can. You will be able to read the plaque left by my astrominis when you get to Mars, but you will be able to do something more significant than making footprints.


Last edited by rpspeck on Mon Mar 28, 2005 9:54 pm, edited 1 time in total.



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Post    Posted on: Sat Mar 26, 2005 10:45 am
These people have developed a dehumidifier/water purifier unit that consumes 120W for use in offices perhaps they have smaller models or might be interested in designing something that could be used in space. The 120W model produces about 20L from an environment having 70% humidity.

http://www.treehugger.com/files/2005/03 ... olph_1.php

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Post    Posted on: Sat Mar 26, 2005 2:16 pm
Naturally it would need to be modified to work in 0G. The ground based unit depends on gravity to make condensed water drip down to a collention area.


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Post Water Condensation   Posted on: Sun Mar 27, 2005 1:27 am
I have investigated three “zero G “, condenser techniques. At least two of these will be the subject of near term bench tests, and I will report on them.

The first uses a porous membrane to separate the vapor from the liquid. I expect to use “Gore Tex” as a separator, with water on one side and air + water vapor on the other. If the water is cold enough, I expect vapor to be drawn through the hydrophobic membrane and add to the liquid captive in the membrane bag. If the water is warmer than a cold trap in the vapor side, then water should move in the other direction. Any bubbles within the membrane bag will also be squeezed (or diffuse) through the membrane to yield a bubble free liquid. This is related to “osmosis”, and the intended use of Gore Tex fabrics.

The second condenser uses a heat conducting “wick” to transport condensed water to a collection point (including through narrow tube). This is the process used in the “Heat Pipe”. In this device, a liquid boils in the hot end of a long sealed vessel. The vapor moves down the hollow core until it reaches the cold end. There it condenses on and in a stranded metallic (copper, silver) wick which covers part of the walls, and draws the heat of condensation out through those walls to external coolant. The liquid then travels by capillary action back down the outside of the long section (moving in the opposite direction relative to the vapor flow) and supplies the liquid to form more vapor in the hot end. This process uses the heat of evaporation/condensation to efficiently move a lot of heat from one point to another. Small systems of this type (where the capillary action can handle the gravitational lift) are insensitive to position and gravity. This condenser would be only the wick and cold end of this assembly, and will work well in zero g.

The third is the centrifugal condenser. This is the most complex, but also achieves pumping (circulation) of the gas, pumping of the condensate liquid, and possible gas exchange at the liquid – gas interface. I expect to try this system as part of a “carbonate solution” CO2 scrubber. With a refrigerated carbonate solution, the centrifugal bowel would both collect condensed water, and pick up Carbon Dioxide. I will detail more of this system (and its testing) soon.


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Post OXYGEN GENERATOR OPERATING   Posted on: Fri Apr 08, 2005 3:00 am
WARNING ................. WARNING .................... WARNING ..................... WARNING .................... WARNING

I have encouraged others to emulate my efforts with experimental life support systems. It has come time to warn readers that this work eventually becomes deadly serious, and that the most serious hazards – as is often the case – are the easiest to overlook. It is possible to create both poisonous and explosive gas mixtures from an improperly configured electrolysis system. BUT THE BIGGEST HAZZARD LIES WITH NITROGEN! Anyone who hooks up a breathing mask with a CO2 “scrubber”, as part of a “rebreather” system, faces this particular danger.

ANOXIA. The human body has no system to warn of impending loss of consciousness, progressing to death, from insufficient Oxygen supply. A very active physiological system responds to the buildup of Carbon Dioxide (CO2), forcing deeper and faster breathing. In normal conditions, this takes care of the hidden Oxygen need at the same time. But we are creating abnormal conditions. A CO2 absorber eliminates this biological response, allowing a person to pass into the metabolic “twilight zone” in complete comfort.

As a result, a room or chamber FILLED WITH NITROGEN GAS is one of the deadliest things known. This falls into the IDLH category: ”Immediately Dangerous to Life and Health”. To enter a space which could possibly fall into this category requires a positive pressure breathing SCBA (Self Contained Breathing Apparatus), in particular because a supplied air system (Umbilical in space) needs a backup for emergency escape. This begins to resemble a space suit.

Strapping a mask onto your face creates the same potential condition. Escape of course is easier – IF YOU HAVE WARNING – which you don’t. If no one else shows up quickly to unstrap the face mask, you are a goner.

The problem is that starting out with Nitrogen (79%) and Oxygen (21%) in your breathing system, you can take out the Oxygen by breathing it (and remove the CO2 to stay comfortable) and end up breathing increasingly pure Nitrogen. And old way to handle this was to take several deep breaths of pure oxygen to wash the Nitrogen out of your lungs before you seal your breathing mask. This kind of works, as – short term – you will suck your breathing bag empty before the Oxygen concentration falls too low. This misses the fact that your body normally holds over a cubic foot (many deep breaths) of Nitrogen which it slowly releases into your breathing system. Plus, if your experimental respirator lets air leak in, this replenishes the nitrogen you washed out. Such leaks are of course more obvious – and thus not as insidious – underwater. For diving, the problem is compounded by the need to avoid Oxygen toxicity.

The modern approach is to use Oxygen Sensors in your breathing circuit. With a proper electronic configuration you can create both a warning system and turn on an emergency Oxygen (or air) supply. The current technique, in experimental rebreathers for scuba diving, is to use three independent Oxygen sensors to control the Oxygen fed into the breathing loop, with a majority rule circuit to activate warnings, record a failing sensor, and initiate emergency procedures.

X Prize test pilots aren’t the only ones with dangerous hobbies. This life support stuff is challenging, but no more so than hypersonic flight into space in a plastic airplane.


One more quibble. Biology teachers persist in teaching that the human body does not detect or respond to low Oxygen levels. There is a slow response, which creates Acute Mountain Sickness. One part of this response is increased breathing, which, like ordinary hyperventilation, causes respiratory alkalosis. During the next couple of days at altitude, the body “compensates” for the undesired alkalosis, so the required breathing rate can be sustained with reduced symptoms. Over weeks, the body also compensates by increasing the red blood cell concentration, to allow the blood to carry more oxygen. The shorter term mechanism could result simply from the buildup of lactic acid – from anaerobic, or “Oxygen debt” metabolism in muscle tissue – or from something else. The existence of this mechanism explains why vacationers in Vail, Colorado feel bad for a couple of days (respiratory alkalosis) rather than just quietly passing out on the ski slopes. But this response is too slow to warn of the problems we can create in an experimental system!

Note how much less of a problem exists if, as on Apollo, low pressure Oxygen is used alone for breathing. The mixed gas systems not only add complexity and hazards, they make spacesuit use a very time consuming and difficult process. Space suits have never been practical without transitioning to pure Oxygen breathing.


OXYGEN GENERATION HARDWARE
In line with the above warnings, I have my Oxygen sensor systems, with warning modes, in operation. I have a prototype Hydrogen sensor in operation, since a lot of Hydrogen is present in the electrolytic process (and in addition to explosive mixtures, this gas can create the same anoxia problem that Nitrogen does). I have a metabolic range CO2 sensor to use with the experimental scrubber systems. And I am considering one of the more comprehensive gas analysis systems I have worked with.

Our Fuel Cell, Oxygen generator is now churning out Oxygen (and Hydrogen) as planned. This, as described previously, is an “Alkaline” type fuel cell, of the same technology used in Apollo to produce power. Nothing in the basic system involves gravity or bubbles. (Although I am bubbling the gasses through water as a cheap flow meter and filter. This has Phenolphthalein added to see if the cell “spits” hydroxide electrolyte – which hasn’t happened yet). I have started this evaluation with a single fuel cell element – for reduced cost. It is possible that this particular cell chemistry and design will not be adequate. I am also working at reduced input current until I am satisfied with my Hydrogen dumping system. Thus I should now be getting only about one sixtieth of my expected O2 supply from this single cell. Actual production seems about right.

As soon as I am sure that the cell is in stable operation, I will measure the Oxygen generation rate carefully. As expected, the cell is instantly reversible, and sucks up the Hydrogen and Oxygen it has produced when the power supply is replaced with a load resistor. The combination of cell with stored gas makes this work like any rechargeable battery. In a spacecraft this reverse mode could provide emergency power, or power when the craft, with its solar cells, passes through a planetary shadow. At rated current, this one cell should allow me to collect (in 24 hours) enough Oxygen to breath for two hours. Since this is sixty times as long as I can hold my breath, this will be an adequate test.

A next step will be to order the planned, multicell unit. This is the described, 1 kilogram unit, producing all my Oxygen needs (or that of two petit astronauts).

Meanwhile, as described earlier, I need to understand the actual gas mixtures in both outputs, including water, and the dissolved gasses in the circulating electrolyte. A consistent handling of these will be necessary for a reliable zero “G” product. Of course it is also necessary to show that the fuel cell element can run for many thousands of hours without problems.

It should come as no surprise that advanced development slows down when one moves from talking about doing something, to actually making it work! But the first step is completed, I have a working, zero “G” compatible oxygen source, initial rebreather chemicals and hardware, and the sensor systems required to make these experiments reasonably safe.


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Post Re: OXYGEN GENERATOR OPERATING   Posted on: Fri Apr 08, 2005 1:49 pm
rpspeck wrote:
Note how much less of a problem exists if, as on Apollo, low pressure Oxygen is used alone for breathing. The mixed gas systems not only add complexity and hazards, they make spacesuit use a very time consuming and difficult process. Space suits have never been practical without transitioning to pure Oxygen breathing. .
I have heard that extended breathing of pure oxygen has undesirable health effects, even at low pressure. That is why the ISS and shuttle don't use it. What are the effects, or why do we need all that nitrogen anyway?


rpspeck wrote:
I have a working, zero “G” compatible oxygen source
Are you really sure? Even testing upside down or at random orientations will not accurately simulate zero "G". I understand that you believe the design SHOULD work in zero "G", but I also assume that the Russian and US engineers (some of who actually worked on Apollo) know all about this design too. Yet they still claim that zero "G" is a big problem. What do you know that they don't? Or more to the point, what might they know that you and I don't.


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Post Re: OXYGEN GENERATOR OPERATING   Posted on: Fri Apr 08, 2005 4:10 pm
campbelp2002 wrote:
I have heard that extended breathing of pure oxygen has undesirable health effects, even at low pressure. That is why the ISS and shuttle don't use it. What are the effects, or why do we need all that nitrogen anyway?

Well spotted. Lung damage can occur with prolonged exposure to 50-100% Oxygen.
100% Oxygen can cause damage and onset of oedema in about 24 hours, at normal atmospheric pressure.

Oxidation injury to membrane component molecules. Dries them out, sort of.

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Post    Posted on: Fri Apr 08, 2005 6:23 pm
I guess my confusion is that 3 psi pure O2 causes damage but 14 psi mixed air with O2 partial pressure of 3 psi does not. How does that 11 psi partial pressure N2 prevent the damage?
And I do remember hearing that pure O2 was a problem, but I never heard about any problems with Apollo astronauts. Where symptoms detected in the Moon travelers after they got back?


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