Author Topic: MOXIE payload  (Read 7395 times)

Offline guckyfan

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Re: MOXIE payload
« Reply #40 on: 04/04/2017 08:00 PM »

Secondly, the statement that both Dalhousie and myself are contesting from you is " So the required technology will have to be developed. It is not rocket science."

It is rocket science. It is not trivial like you make it out to be. Nobody is contesting what SpaceX's plans are. You brought that up on your own and nobody but you has talked about it.

I stated no more than the plans by SpaceX. Are you seriously contesting my statement "It is not rocket science" as our main difference?

So once again and for the last time building a limited mining robot is not rocket science. You keep throwing wrong accusations on me and I am not going to continue this useless conversation beyond this.

Online Robotbeat

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Re: MOXIE payload
« Reply #41 on: 04/06/2017 03:16 AM »
People keep saying CO/O2 sucks due to the crappy Isp, but the flip side of low Isp is that it takes much less energy to produce, especially considering it doesn't need to throw away so much energy with methane, Sabatier process and isn't deeply cryogenic like hydrogen. And requires no water. With a little effort, you could make a SSTO Mars RLV with it. LMO.
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Offline john smith 19

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Re: MOXIE payload
« Reply #42 on: 04/07/2017 09:07 AM »
Mining is a very difficult activity on Earth (particularly hard rock mining, aka if you're dealing with permafrost (ice + regolith). Even on Earth, mining and ore processing equipment are very prone to wear and breakdowns.  This in environments we have well quantified. What we don't have quantified well is Martian permafrost. What dissolved compounds are in it and in what ratios? How much particulate / debris, and in what size ratios, and how does that vary as you progress through a play with respect to depth and location? How does the play thickness vary? How does sublimation affect things as you work through a play? We know very, very little about what we'd be mining through.  Just making a little rock abrasion tool or sampler arm for loose material is challenging enough. And when you're talking about enough ice to make propellant for whole fleets of ITS-sized vehicles, you're talking about large scale mining. Meaning equipment with heavy parts that are hard to replace, and where if you mess up you can knock down a wall or bend important pieces of equipment. Equipment that can kill people.

Right now, the TRL for ice mining on Mars is 2-3, according to NASA analyses of the different approaches.  There's lots of different approaches proposed. None are remotely mature.
True.  Samplers have collected Martian soil since the days of Viking but IIRC the estimate is any ISRU may have to drill up to 30m to get to the water layer. While this could be fairly straightforward the problems start if anything goes wrong. On Earth commercial drilling is a fairly closely monitored process with plenty of spares on hand in case the drill bit hits trouble and humans to change them.

Then there is the doubt about what's in that water layer. Pure liquid water (implausible) to ice to very muddy ice to some ice with lots of large boulders in that will jam up any collection pipe under a metre across (or more).

BTW there is the other option of using CO2 and the trace amounts of Nitrogen to make Cyanogen. This sidesteps the whole water extraction process at the risk of even hotter combustion (it has been used in welding torches and re-entry simulation but is seriously toxic).

REL mentioned it in their Project Troy Mars project.

Attached is what i got. Methane burns hotter at stoichiometric mixture, but thats not the only difficulty. Can we maybe move this off to another CO rocketry thread ?
Except, as I'm sure you're aware, no one runs rocket engines at stoichiometric because it's actually sub optimal for Isp

People run chambers fuel rich to avoid excess oxidizer reacting with the chamber walls. This seems to be the basis of the prejudice against using LOX as a chamber coolant, despite oxidizer wall cooling being SOP for NTO and HTP engines.

The yardstick should not be absolute performance. It should be is the performance adequate to get the job done? 

High combustion temperature?  Not according to these calculations (refer to the column labeled "Ctemp").

Attached are two older papers on oxygen-CO, the second of which maps out the conditions under which the combination ignites.  There are some tricks to ignition, but it does not seem an insurmountable problem.
Thanks for that.

CO is actually quite a common industrial fuel, however as it's normally mfg in situ (IIRC mostly by the Sabatier process) you don't see tanker loads of liquefied CO being driven around the country.

It's dangerous in the way that any odourless, colourless and toxic gas is but not IIRC at the WMD levels of  the hydrazines and a respirator is quite adequate as long as the its concentration is not too high, plus CO detection is well developed and will usually give you time to evacuate (unlike the hydrazines, where if you can smell fish the chances are your lungs have already started to rupture).

CO is probably a lot more common industrial fuel than people realize (it's the ultimate oxidizer in steel making) but it's not noticed because it doesn't cause trouble and that's because the technology and procedures to handle it (in an industrial environment) are well developed.
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Offline john smith 19

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Re: MOXIE payload
« Reply #43 on: 04/07/2017 09:29 AM »
I've seen little analysis about actually using that carbon monoxide as fuel. It seems people either are unaware it's possible, or they're aware but only remember "it has low Isp," dismiss it out of hand as such, and aren't actually aware of a serious trade that incorporates carbon dioxide as a fuel
Then i can only conclude you are not actually interested in the subject. Like i mentioned, CO based rockets have been discarded like 10-15 years ago. Easily the most referenced comprehensive study:

http://www.niac.usra.edu/files/studies/final_report/340Rice.pdf
This is a NAIC study, which by it's nature tend to consider radical concepts. In this case trading the simplicity of mfg of a CO ice/LOX rocket engine (low chamber pressure, close to ambient Mars temperatures) versus it's pretty poor performance. The upside is no one has to design a CO pump and work out how to power it.

All reports have biases. The more honest ones will set them out up front.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline Rei

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Re: MOXIE payload
« Reply #44 on: 04/07/2017 09:50 AM »
CO is probably a lot more common industrial fuel than people realize (it's the ultimate oxidizer in steel making) but it's not noticed because it doesn't cause trouble and that's because the technology and procedures to handle it (in an industrial environment) are well developed.

CO is really neat stuff in general, not just a waste product.  It's quite stable at ambient temperatures and pressures, but at elevated temperatures and pressures becomes unstable, even to the point of decomposing to carbon and CO2. Which makes it a natural precursor to the generation of hydrocarbons, since the carbon generated would rather join to almost anything else (hence CO + H2 forming syngas for the production of synfuels). If you want a petrochemical industry on Mars, you want CO.

Offline Dalhousie

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Re: MOXIE payload
« Reply #45 on: 04/07/2017 10:23 AM »
CO is probably a lot more common industrial fuel than people realize (it's the ultimate oxidizer in steel making) but it's not noticed because it doesn't cause trouble and that's because the technology and procedures to handle it (in an industrial environment) are well developed.

CO is really neat stuff in general, not just a waste product.  It's quite stable at ambient temperatures and pressures, but at elevated temperatures and pressures becomes unstable, even to the point of decomposing to carbon and CO2. Which makes it a natural precursor to the generation of hydrocarbons, since the carbon generated would rather join to almost anything else (hence CO + H2 forming syngas for the production of synfuels). If you want a petrochemical industry on Mars, you want CO.


CO can also be used in a fuel cell and internal combustion engines, both turbines and diesels.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline john smith 19

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Re: MOXIE payload
« Reply #46 on: 04/07/2017 07:59 PM »
CO is really neat stuff in general, not just a waste product.  It's quite stable at ambient temperatures and pressures, but at elevated temperatures and pressures becomes unstable, even to the point of decomposing to carbon and CO2. Which makes it a natural precursor to the generation of hydrocarbons, since the carbon generated would rather join to almost anything else (hence CO + H2 forming syngas for the production of synfuels). If you want a petrochemical industry on Mars, you want CO.
For a lot of people Carbon Monoxide is just what badly adjusted heating furnaces put out but in industrial environments its a very useful chemical intermediate.

You're probably right about needing it for petrochems on Mars. The trouble is that they are used to coal and oil as mass Carbon sources.

CO can also be used in a fuel cell and internal combustion engines, both turbines and diesels.
True. In fact the MOXIE cell is effectively a fuel cell in reverse.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline savuporo

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« Last Edit: 06/20/2017 08:40 AM by savuporo »
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Offline jongoff

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Re: MOXIE payload
« Reply #48 on: 06/21/2017 03:52 AM »
As a fun little side note, Altius got to do the vacuum bakeout on some of the MOXIE hardware a few weeks ago. The company building the motors for the scroll compressors is the same company we selected to do the actuators for the RCS thruster gimbal we're doing for ULA, and they didn't yet have the facilities to do vacuum bakeout in-house, so they paid us to do that for them. Kind of cool to say we had Mars hardware in our facility.

~Jon

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