You are not logged in.
I am currently designing a Manned Mars Mission for an AIAA National student design competition, and am trying to cut corners on mass wherever possible. Thus I was dismayed when I learned that the current means of removing CO2 from the atmosphere requires cartridges that must be replaced at least twice per day (shuttle CO2 removal system). The total mass of these systems would be insignificant if it involved a shorter mission length.
However, given the long duration of a mars mission, the weight of these cartridges builds up to a grand total of approximately 6 metric tonnes and a storage volume space of 16 meters (given 900 day mission length plus 10% safety factor in number of cartridges). Luckily, the timeframe for this mission is around 2030, so we've been authorized to use any systems with a TRL of around 4-5.
If any of you know of any methods (current, experimental or proposed) for removing CO2 that would be more effective in both mass and volume PLEASE LET ME KNOW!!!
Offline
Perhaps consider potassium superoxide (KO2) which produces oxygen as it scrubs carbon dioxide. Of course, it will only save you mass if you were going to carry something else to make oxygen.
Fan of [url=http://www.red-oasis.com/]Red Oasis[/url]
Offline
Isn't this the point where you should perhaps begin to think laterally and consider organic CO2--O2 plant conversion? Go for it!
Offline
However, given the long duration of a mars mission, the weight of these cartridges builds up to a grand total of approximately 6 metric tonnes and a storage volume space of 16 meters (given 900 day mission length plus 10% safety factor in number of cartridges). Luckily, the timeframe for this mission is around 2030, so we've been authorized to use any systems with a TRL of around 4-5.
Dick's suggestion of using plants to produce oxygen is a viable alternative. While it's true that this consumes water to produce oxygen, the mass efficiency is still higher than the use of disposable lithium hydroxide rebreather cartridges.
There is another also alternative - recycle the cartridge vanes. The half used lithium hydroxide vanes can be removed from the cartridge, baked in a kiln or steamed in a boiler at about 900 decrees celsius to reduce them back to Lithium oxide, then soaked with water to recharge them by generating fresh lithium hydroxide. The process generates additional water, which can be reclaimed, and carbon dioxide, which can be dumped or otherwise treated in its pure form. The vanes can't last indefinitely under this abuse, but you won't need six tons of them to replace the ones that crack beyond repair. With an assumed loss rate of 10%, you could probably get the job done with 500 kg of rebreather cartridge vanes. The kiln or boiler and requisite power supply necessary for this recycling operation won't weigh six tons, either - I've seen a suitable tube kiln that didn't weigh 6 kilos and only ate 2 kilowatts.
You could easily fit the scrubber and entire recycling operation - power supply, plumbing, and all - into less than 1000 kg, 500 kg of which is consumables and 450 kg is power supply.
For an even lower mass alternative, you can powder the broken plates and recast them using the same kiln, at which point your 500 kg of consumables drops to 50 kg. Unfortunately, this final reduction reflects on the robustness of the mission - kilns and presses can break, too, and all this firing and recasting (two full cartridges per day, by your count) takes time, during which backup cartridges must be constantly ready and available in rotation. And there's no real experience to draw on for powder casting operations in zero-g if you lose gravity during the transit. That's a lot of sugar for a dime.
So, while you could probably squeeze it down to about 500 kg, you should probably figure on about 1 ton for a system based on lithium hydroxide CO2 scrubbers, recycled using a kiln.
"We go big, or we don't go." - GCNRevenger
Offline
Could you point me in the direction of some research material with regards to the viability of plants for revitalizing the atmosphere? An ECLSS with a significant ecological component would be truly awesome...
Same goes for the kiln and boiler setup. Any research material regarding it would be immensely helpful.
Offline
Without a doubt, Google for it, Wikipedia source it, Space blog for it, etc. Also, consider using solar furnace techniques, adapted for LEO weightlessness as well as the other processes suggested by CM Edwards (as well as the plant processes) designed and budgeted for development oboard the ISS. Much of the criticism of the space station has been lack of usefulness. Well, I think you've hit on just the thing!
Offline
Could you point me in the direction of some research material with regards to the viability of plants for revitalizing the atmosphere? An ECLSS with a significant ecological component would be truly awesome...
Same goes for the kiln and boiler setup. Any research material regarding it would be immensely helpful.
I would recommend going to the library. Your local college or university library is bound to have a good reference, and many public libraries can call up an interlibrary loan for you if they don't. And, of course, there are several online libraries if you don't want to leave your computer.
For example, I found this little gem in the Digital Book Index, accessible from The Internet Public Library:
The second chapter, starting on Page 53, discusses the efficiency of photosynthetic processes, and the chapter on chlorella looks interesting as well. (One interesting note: because photosynthesis sequesters the entire CO2 molecule and produces its free oxygen from water, many plants actually produce slightly more moles of oxygen than they absorb in CO2. Cool! 8) )
"We go big, or we don't go." - GCNRevenger
Offline
If any of you know of any methods (current, experimental or proposed) for removing CO2 that would be more effective in both mass and volume PLEASE LET ME KNOW!!!
Yttria stabilised zirconia cells ?! What else ?
For example, read this
There are also a lot of PDF papers out there. There was even an experiment with such a cell, I believe at Arizona Univ. Very small, but very effective. Also, I think YSZ acts like a catalyst, thus you need a very small amount.
Just search google for something like "ISRU Yttria stabilised zirconia", "Mars Yttria stabilised zirconia" etc.
Offline
Yttria stabilised zirconia cells ?! What else ?
For example, read this
There are also a lot of PDF papers out there. There was even an experiment with such a cell, I believe at Arizona Univ. Very small, but very effective. Also, I think YSZ acts like a catalyst, thus you need a very small amount.
Ooooh! I like that! The prospect of manufacturing oxygen from the Martian atmosphere with only power input could save up to 0.9 kg/day per crewman. If you can get the mass of these cells + power supply under 300 kg per crewman (entirely possible), it becomes a viable alternative to bringing all of the oxygen along for a surface stay of one year or more. We'll want to strongly consider this completely aside from bobwd40's project.
The only consideration I have is: I can't find any successful demonstrations of this technology for CO2 scrubbing at the low concentrations expected inside the crew cabin. If it could work with CO2 partial pressures that low, it wouldn't necessarily require a compressor to produce oxygen from the Martian Atmosphere - it could just work at ambient pressure. But I find no indication that this is possible.
This is still a fantastically promising technology. I just don't know if it's going to take all of the Lithium Hydroxide off of the ship.
"We go big, or we don't go." - GCNRevenger
Offline
Uhmm, you are right about this one. My mistake. The OGS developed by Arizona Univ does not work at low pressure. :oops: I think it needs at least 1 atm, better 5 atm.
But, even if the OGS can't be used during flight time, maybe it can be used on Mars, in a open-loop type of life support system, thus reducing mass. Maybe...
@bobwd40, have you read this ?
BTW, the main site for OGS should be here:
http://stl.ame.arizona.edu/mip-ogs/, and another publication here:
http://stl.ame.arizona.edu/publications … o_2000.PDF, but it seems the site is not working right now, at least for me.
Also, some kind of slide show here:
http://www.hq.nasa.gov/office/apio/pdf/ … s_isru.pdf
There are also a lot of papers out there, just waiting to be read.
Offline
You should also add these to the list of available:
MHP Gas Production & Storage Systems Concept Presentation
ISRU Atmosphere Harvesting Presentation
On another note:
The techniques and technology for the plan can help mother Earth with its fight against global warming.
Now here is a first for one that likes to win prizes to now giving them away. $25 million climate prize offered by Branson
Scientists must 'put their minds to it today,' he says of removing emissions
British tycoon Sir Richard Branson on Friday announced a $25 million prize for a way to extract a billion tons or more of carbon dioxide from the atmosphere each year.
The winner will have to come up with a way of removing one billion tons of carbon gases a year from the atmosphere for 10 years with $5 million of the prize being paid at the start and the remaining $20 million at the end.
Online