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#26 2017-05-04 16:34:54

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,339

Re: Industrial development on Mars

Yep, and it sits there. It's useless if you want to go exploring. If it goes wrong, you're dead...so you need to take at least two.

I'm not saying it is impossible to settle Mars with nuclear power, but I am saying it is not as desirable as PV. I am not sure why enthusiasts for nuclear power pretend it is impossible to successfully settle Mars with PV.  The MIT study shows it is.

http://systemarchitect.mit.edu/docs/cooper10.pdf

kbd512 wrote:

Louis,

A 100kW fission reactor produces power 24/7/365, no matter what the local weather conditions are, time of day, or where it's located.  No assembly is required.  On Mars, you can bury reactors in the ground and put a fence around the reactor to mark the exclusion zone.  There's no actual engineering issue with doing any of that and no EPA to stop you from doing it.  The reactor vessel itself is smaller than a 55 gallon drum and about two times as long.  It'd weigh about 760kg on Mars or 2,000kg on Earth.  If you put the reactor on wheels with 4 1kW hub motors, then two people can easily move the reactor into position, dig a hole with hand tools, and bury it.


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#27 2017-05-04 16:39:59

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,339

Re: Industrial development on Mars

I'm currently drawing up a speculative Industrial Plan for the first 20 years of a Mars settlement, which I hope to post in the next few days.  The objective of the plan is to produce within those few two decades a small but wide-ranging  industrial infrastructure which would make Mars potentially (if not actually) self-sufficient. 

If anyone has any thoughts they wish to offer on any key issues relating to such a plan I will be interested to read them. But you may wish to wait and read it.


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#28 2017-05-04 16:57:43

kbd512
Moderator
Registered: 2015-01-02
Posts: 3,110

Re: Industrial development on Mars

louis wrote:

Yep, and it sits there. It's useless if you want to go exploring. If it goes wrong, you're dead...so you need to take at least two.

I'm not saying it is impossible to settle Mars with nuclear power, but I am saying it is not as desirable as PV. I am not sure why enthusiasts for nuclear power pretend it is impossible to successfully settle Mars with PV.  The MIT study shows it is.

Colonization is not exploration, but NASA is turning to nuclear technologies to provide the power output they need in reasonably sized packages that don't require sophisticated electronics to use.  The real Mars exploration rover that's really on Mars right now is nuclear powered.  It only needed 100We to function.  For some reason, the best solar panels and batteries available were insufficient to provide the power required.  JPL is clearly capable of producing a solar powered rover, but the battery technology was the weak link in the PV power equation.  Solve the battery capacity problem and PV has more merit, but realize that we've been waiting for that solution for decades now.

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#29 2017-05-04 19:58:32

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,339

Re: Industrial development on Mars

And since Apollo... NASA has such a great track record in cost effective space exploration...not!!!

If Musk tells me nuclear is the only way to go, I will listen to him seriously.  If NASA tells me, I simply won't believe them. They have been proved wrong way too many time over the last 50 years.

You are confusing two issues with reference to larger solo robot rovers - they are quite big which means they have more scope for heat loss under difficult Mars conditions...this isn't the same as a base scenario. Nothing in a heated hab is going to be exposed to extreme cold on Mars. Absolutely nothing.  You are essentially looking at earth-like conditions within the hab. 

kbd512 wrote:
louis wrote:

Yep, and it sits there. It's useless if you want to go exploring. If it goes wrong, you're dead...so you need to take at least two.

I'm not saying it is impossible to settle Mars with nuclear power, but I am saying it is not as desirable as PV. I am not sure why enthusiasts for nuclear power pretend it is impossible to successfully settle Mars with PV.  The MIT study shows it is.

Colonization is not exploration, but NASA is turning to nuclear technologies to provide the power output they need in reasonably sized packages that don't require sophisticated electronics to use.  The real Mars exploration rover that's really on Mars right now is nuclear powered.  It only needed 100We to function.  For some reason, the best solar panels and batteries available were insufficient to provide the power required.  JPL is clearly capable of producing a solar powered rover, but the battery technology was the weak link in the PV power equation.  Solve the battery capacity problem and PV has more merit, but realize that we've been waiting for that solution for decades now.

Last edited by louis (2017-05-04 19:59:16)


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#30 2017-05-04 23:07:22

kbd512
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Registered: 2015-01-02
Posts: 3,110

Re: Industrial development on Mars

louis wrote:

And since Apollo... NASA has such a great track record in cost effective space exploration...not!!!

The only reason SpaceX still exists is that NASA was willing to take a chance on funding SpaceX.  Even with all of their failures, NASA stands by them because they never make the same mistake twice.  Mr. Musk didn't hire random people off the street, either.  Political decisions made in Washington DC have prevented NASA from doing what they thought needed to be done to further their exploration goals.  Even at that, no other space agency has ever sent humans anywhere but low Earth orbit.  I have faith in Mr. Musk, his team does great work, and I think he's the right man for the job of colonizing Mars, but enthusiasm.

NASA never had any desire to terminate the Saturn V or NERVA programs and the abortion that was STS was forced on the agency.  Those decisions killed space exploration, not incompetence on NASA's part.

louis wrote:

If Musk tells me nuclear is the only way to go, I will listen to him seriously.  If NASA tells me, I simply won't believe them. They have been proved wrong way too many time over the last 50 years.

Mr. Musk owns a solar panel factory.  If Mr. Musk owned a nuclear power plant factory, then fission reactors would be the only way to go.

Who "proved NASA wrong", Louis?

A lot of politicians have pulled the rug out from under NASA whenever it was politically expedient to do so, but the last time I checked NASA is the group that typically "proves things" to other people.  I just want someone at the agency to tell the politicians to screw off and let them handle the things they know how to do better than anyone in Washington DC ever will.

louis wrote:

You are confusing two issues with reference to larger solo robot rovers - they are quite big which means they have more scope for heat loss under difficult Mars conditions...this isn't the same as a base scenario. Nothing in a heated hab is going to be exposed to extreme cold on Mars. Absolutely nothing.  You are essentially looking at earth-like conditions within the hab.

The primary batteries aren't in the habitat now on any spacecraft with humans inside, for what should be obvious reasons.  I don't think that issue is very confusing.

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#31 2017-05-05 03:39:36

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,339

Re: Industrial development on Mars

Well I think time and experience has proved them wrong on the Space Shuttle concept and in terms of cost, Space X have proved them wrong on the way to get stuff to LEO. I also think they are in the process of being proved wrong on how to land stuff on Mars as cheaply as possible:  retro rocket landings were always the way to go in my view, and that appears to be how Space X are going...but a lot of time, effort and money has been spent on developing fancy landing systems (they eneded up spending billions on the MSL/Curiosity project).

I agree NASA would have done more if the budget had been there but NASA have allowed themselves to be spread too thin in my view, given the available budget. If we'd had a lunar base for the last 30 years, a lot of space exploration that takes place would already be cheaper. As it is, NASA have stuck with the most expensive way to do stuff in space. NASA's problem is that it has a multitude of things to focus on...while Space X is really a single issue company: "Get to Mars." Everything else at Space X whether it's lunar trips or satellite launches serves that purpose.

kbd512 wrote:
louis wrote:

And since Apollo... NASA has such a great track record in cost effective space exploration...not!!!

The only reason SpaceX still exists is that NASA was willing to take a chance on funding SpaceX.  Even with all of their failures, NASA stands by them because they never make the same mistake twice.  Mr. Musk didn't hire random people off the street, either.  Political decisions made in Washington DC have prevented NASA from doing what they thought needed to be done to further their exploration goals.  Even at that, no other space agency has ever sent humans anywhere but low Earth orbit.  I have faith in Mr. Musk, his team does great work, and I think he's the right man for the job of colonizing Mars, but enthusiasm.

NASA never had any desire to terminate the Saturn V or NERVA programs and the abortion that was STS was forced on the agency.  Those decisions killed space exploration, not incompetence on NASA's part.

louis wrote:

If Musk tells me nuclear is the only way to go, I will listen to him seriously.  If NASA tells me, I simply won't believe them. They have been proved wrong way too many time over the last 50 years.

Mr. Musk owns a solar panel factory.  If Mr. Musk owned a nuclear power plant factory, then fission reactors would be the only way to go.

Who "proved NASA wrong", Louis?

A lot of politicians have pulled the rug out from under NASA whenever it was politically expedient to do so, but the last time I checked NASA is the group that typically "proves things" to other people.  I just want someone at the agency to tell the politicians to screw off and let them handle the things they know how to do better than anyone in Washington DC ever will.

louis wrote:

You are confusing two issues with reference to larger solo robot rovers - they are quite big which means they have more scope for heat loss under difficult Mars conditions...this isn't the same as a base scenario. Nothing in a heated hab is going to be exposed to extreme cold on Mars. Absolutely nothing.  You are essentially looking at earth-like conditions within the hab.

The primary batteries aren't in the habitat now on any spacecraft with humans inside, for what should be obvious reasons.  I don't think that issue is very confusing.


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#32 2017-05-05 08:41:17

Tom Kalbfus
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Registered: 2006-08-16
Posts: 4,401

Re: Industrial development on Mars

I think industrial development won't produce many jobs on Mars, I think that by the time we are settling Mars, industrial development won't be producing many jobs anywhere. Maybe Mars would be a great industrial park if we don't want the environmental impact here! People who love to live in cities, are going to love Mars, once we get down to colonizing the place!

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#33 2017-05-05 09:34:25

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,339

Re: Industrial development on Mars

It's an odd situation...I think the early Mars economy will be heavily automated and robotised but the small number of humans there will be fully employed.

Using Mars as a place to site polluting industries is not out of the question though perhaps far off. 



Tom Kalbfus wrote:

I think industrial development won't produce many jobs on Mars, I think that by the time we are settling Mars, industrial development won't be producing many jobs anywhere. Maybe Mars would be a great industrial park if we don't want the environmental impact here! People who love to live in cities, are going to love Mars, once we get down to colonizing the place!


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#34 2017-05-05 10:39:22

Oldfart1939
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Registered: 2016-11-26
Posts: 1,796

Re: Industrial development on Mars

OK, time for my input on this. I personally think that the biggest "industry" on Mars will be resource extraction: Oxygen, water, Nitrogen, and Methane production. This "industry" will initially be all-consuming to support construction of greenhouses and the beginnings of agriculture. The first truly "industrially manufactured" items will be greenhouse and housing components, both metal and plastic. I agree with RobertDyck that the window panels should be made from glass on the outer layer, but I also am convinced they should also have a very strong inner layer of Lexan (Polycarbonate plastic) for backup strength. Glass manufacture requires very high purity silica sand, but to date I don't know where there is any of that commodity on Mars. Maybe the windows will be entirely polycarbonate with easily replaced outer panels? At any rate, food production will be paramount importance for any thriving and growing human habitation. As a subsidiary industry will be repair facilities in order to keep the agricultural and chemical commodities coming.

As you can tell from the above comments, I have a very strong belief that a chemical industry will be the first to arise: plastics, glass, and metal refining--all over and above water extraction, Methane production, and most importantly, Oxygen production. If we can get enough Nitrogen we can also produce agricultural grade Ammonia for crop fertilization. "Better Living Through Chemistry."

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#35 2017-05-05 18:50:41

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,390

Re: Industrial development on Mars

Yup Polycarbonic plastics sure looks like the chemist dream for the symbol manufacturing from the chemical alphabet soup...

I also think that once we find more chemicals in better concentrations that we will be looking for others.

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#36 2017-05-05 20:16:04

Oldfart1939
Member
Registered: 2016-11-26
Posts: 1,796

Re: Industrial development on Mars

Does anyone here have knowledge of silica sand deposits identified on the Mars surface? Not all sand is suitable for glass manufacture. Here on the Earth, Japanese beach sand is the finest known for manufacture of optical glass.

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#37 2017-05-05 20:54:00

Oldfart1939
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Registered: 2016-11-26
Posts: 1,796

Re: Industrial development on Mars

SpaceNut-

I just did a quickie literature search online and there is a literature reference for synthesis of benzene from Carbon Dioxide and Methane. If we can get benzene, that's the key component for manufacture of polycarbonates, and polystyrenes. There are numerous patents in the literature.

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#38 2017-05-06 00:53:37

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 5,862
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Re: Industrial development on Mars

from my page: Plastics

Benzene
6 CH4 → 9 H2 + C6H6
Reference, a device to make it: MetaMars

Cumene
made from benzene and propylene.
Reference: Wikipedia

Acetone
made with the Hock process.
Cumene, also known as iso propyl benzene or i-propyl benzene, is oxidized to form cumene hydroperoxide. This step is mildly exothermic, 28kcal/mol. Cumene hydroperoxide is hydrogenated (with a positive hydrogen ion) to form phenol and acetone. It produces 60 kcal/mol.

An alternate process to make phenol converts toluene plus oxygen to benzoic acid plus water, then benzoic acid with oxygen to phenol and CO2. However, although this is easier because it starts with toluene instead of cumene, it doesn't produce acetone. Polycarbonate requires both phenol and acetone.
Reference: CHEM 462

Polycarbonate (PC) brand name Lexan
acetone (C3H6O) + phenol + HCl → bisphenol-A
bisphenol-A + NaOH → sodium salt of bisphenol-A
CO + Cl → phosgene (COCl2)
sodium salt of bisphenol-A + phosgene → polycarbonate

Polystyrene (PS)
Polystyrene, produced from styrene (C6H5CH=CH2), has phenyl groups (six-member carbon ring) branching off every other carbon on the backbone. The difference between styrene and ethylene is replacing one hydrogen atom with a phenyl group. Polystyrene foam is used for egg cartons and as styrofoam insulation.
benzene (C6H6) → phenyl (C6H5) + H2
ethylene + phenyl → styrene (C6H5CH=CH2)
Polymerization of styrene

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#39 2017-05-06 04:56:49

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,339

Re: Industrial development on Mars

Brilliant Robert - very informative.

Only non-technical point I would make is that we need small versatile automated machines to make our plastics, remembering that we won't need huge amounts in the early settlement period but we will need a range of plastics. It may there isn't a market for that sort of product on Earth, and so that sort of machine may not yet be produced.

RobertDyck wrote:

from my page: Plastics

Benzene
6 CH4 → 9 H2 + C6H6
Reference, a device to make it: MetaMars

Cumene
made from benzene and propylene.
Reference: Wikipedia

Acetone
made with the Hock process.
Cumene, also known as iso propyl benzene or i-propyl benzene, is oxidized to form cumene hydroperoxide. This step is mildly exothermic, 28kcal/mol. Cumene hydroperoxide is hydrogenated (with a positive hydrogen ion) to form phenol and acetone. It produces 60 kcal/mol.

An alternate process to make phenol converts toluene plus oxygen to benzoic acid plus water, then benzoic acid with oxygen to phenol and CO2. However, although this is easier because it starts with toluene instead of cumene, it doesn't produce acetone. Polycarbonate requires both phenol and acetone.
Reference: CHEM 462

Polycarbonate (PC) brand name Lexan
acetone (C3H6O) + phenol + HCl → bisphenol-A
bisphenol-A + NaOH → sodium salt of bisphenol-A
CO + Cl → phosgene (COCl2)
sodium salt of bisphenol-A + phosgene → polycarbonate

Polystyrene (PS)
Polystyrene, produced from styrene (C6H5CH=CH2), has phenyl groups (six-member carbon ring) branching off every other carbon on the backbone. The difference between styrene and ethylene is replacing one hydrogen atom with a phenyl group. Polystyrene foam is used for egg cartons and as styrofoam insulation.
benzene (C6H6) → phenyl (C6H5) + H2
ethylene + phenyl → styrene (C6H5CH=CH2)
Polymerization of styrene


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#40 2017-05-06 07:00:10

Oldfart1939
Member
Registered: 2016-11-26
Posts: 1,796

Re: Industrial development on Mars

Louis-

No--we will need LOTS of plastics for structure, but most of all, windows for greenhouses (Polycarbonate). Polyethylene also has the property desired for radiation shielding: a low molecular weight structure which is hydrogen-rich. Fortunately we have the Mars atmosphere as a resource for feedstock. One thing I learned (the hard way, and more than once!) is that a big reactor only partially full is waaay better than a too small reactor filled to the brim, which subsequently overflows.

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#41 2017-05-06 07:48:48

Dave_Duca
Member
From: Oconto, WI usa
Registered: 2017-03-15
Posts: 92

Re: Industrial development on Mars

This is where Gen-4 Power Systems could shine (previously: Hyperion Power)
"Negative Impacts for a Positive Return" is a good criteria to remember, yeah?

"Industrial Development"
I've received little response from the Voxeljet people.
They specialize in Silica Sand Molds for Metal Casting.
And use a Furan Resin for the bonding.

Mars Sand Dunes have Olivine that could replace the Silica
and an "anaerobic adhesive" in place of the Furan.

An interesting process... and much less energy-throughput.
VOXELJET_dot_COM

Last edited by Dave_Duca (2017-05-06 07:49:23)

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#42 2017-05-06 07:51:11

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,390

Re: Industrial development on Mars

http://www.nss.org/settlement/manufactu … orMars.pdf
page 8 brings up to organization of what we need to derive. The table also contains sulfur, Chloride, Potasium, phosphorous, Salts Ca, Mg, Al, Fe, Na, K -

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#43 2017-05-06 07:51:45

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,339

Re: Industrial development on Mars

Yes, depends on your conception of how to grow the settlement.  When I sketched an industrial plan for Mars...

http://newmars.com/forums/viewtopic.php?id=7715

...I became more and more alarmed at the amount of material required for ambient light farming structures (assuming  you are serious about feeding your colonists rather than just importing food). To me it doesn't make sense to put all that effort in when you can have much more concentrated indoor hydroponic farming with artificial lighting in what are basically cut and cover trenches (so requiring much less construction effort).   

How many tonnes of plastic, glass, concrete and processed soil would be required to provide the 400,000 sq metres of farmland you will probably require to feed 100 people? It could easily be several hundred thousands of tonnes.

I'm not saying never but you'd probably need a community of tens of thousands before you started tackling such a gigantic project, given all the other priorities that demand your attention. Greenhouses on Mars are a bit like road bridges and tunnels on Earth - hugely beneficial but hugely expensive.

It's ironic that Musk started with the idea of building a greenhouse on Mars...should have been the last thing on his mind! smile 

Oldfart1939 wrote:

Louis-

No--we will need LOTS of plastics for structure, but most of all, windows for greenhouses (Polycarbonate). Polyethylene also has the property desired for radiation shielding: a low molecular weight structure which is hydrogen-rich. Fortunately we have the Mars atmosphere as a resource for feedstock. One thing I learned (the hard way, and more than once!) is that a big reactor only partially full is waaay better than a too small reactor filled to the brim, which subsequently overflows.


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#44 2017-05-06 07:56:41

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 17,390

Re: Industrial development on Mars

The trade assement for above ground or below from start of supplied equipment to insitu created has not been done as a comparison for cost or mass but I got a feeling that it all comes out very close.... once we build up the list for each....

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#45 2017-05-06 09:10:11

Oldfart1939
Member
Registered: 2016-11-26
Posts: 1,796

Re: Industrial development on Mars

I suspect the pre mission hypotheses will be tested during the first landings. Conversion of collected solar output vis a vis batteries will demonstrate that there's many a slip twixt the cup and the lip. Solar power collection at a ~ 30 % efficiency; storage in Lithium ion batteries and recovery of the power at  "X" %; conversion to light by LED lighting at "Z" %. Hydroponics and artificial lighting sound good until the enormous additional infrastructure required is considered. There's an old saw in the physical sciences worth repeating here: Theory guides but Experiment decides.

My thoughts have been tempered on this topic by Robert Zubrin's comments (There's THAT name again!), in his book "Entering Space." In Chapter 5, he examines the problem of artificially lighted crop production. He points out that crops are enormous users of energy, and proceeds to state the number 3,000 kW per acre. This translates into capture and subsequent conversion of ~ 12,000 kW from PV panels, storage by batteries, and then reconversion of the energy to spectrally suitable light. That's for ONE ACRE, and a single acre doesn't feed a colony of 10 astronaut-settlers very long. My conclusion based on a strictly thermodynamic model is we'll be forced to use passive-solar greenhouses, perhaps supplemented by SOME artificial lighting in order to feed the proposed colony. Either that or continuing subsidies of food from Earth.

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#46 2017-05-06 17:08:02

louis
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From: UK
Registered: 2008-03-24
Posts: 5,339

Re: Industrial development on Mars

I would approach this from a very different angle.

I would say: what can you do with per capita electrical energy usage of say 0.58 Kw constant (that's a recent UK figure)?  Answer: you can do a hell of a lot.  But with Mars we are talking about much larger electrical energy usage...probably more like 16 Kws constant for Mission One...30 times what affluent Brits consume. But our Mars residents are going to be much more frugal than your average Brit - they  won't be demanding their own private energy-guzzling private cars, or huge TV screens, or cooking Sunday roasts or heating the water for baths or generous living space.

So we can allow for a lot of what is thought of as energy inefficiency in how we use the energy that will be available on Mars.

The most important point really  is that it is easy to import energy generation equipment from Earth - whether PV or nuclear.

But it is NOT easy to build huge greenhouses on Mars spanning tens of thousands of square metres.  What we won't have on Mars is copious amounts of human labour to build, organise, manage and monitor huge greenhouses.

So though Zubrin is a "Hero of the Mars Union", he can be wrong. 

In terms of Mars we need to factor the total energy input of

(a) artificially lit indoor farming with hydroponic systems

(b) ambient light greenhouse farming

(c) ambient light greenhouse farming with auxillary lighting.

(d) down time from dust storms in ambient light systems

(and for (b) and (c) we need to look at variants involving fertile soil and hydroponics - there are also alternatives such as aeroponics that need to be examined).

Regarding (a) I believe we can develop v. low energy input construction techniques i.e. simple cut and cover construction.

It may be that with experience we can perfect (a) to incorporate solar reflectors and light piping so as to improve efficiency.

I also think we can improve efficiencies for (a) with surrounding reflective surfaces within the interior space (such reflective surfaces don't exist in nature - a lot of light bounces off plants and back up into space). 

Probably best to start up a new thread on this topic and really get to grips with it. smile

Oldfart1939 wrote:

I suspect the pre mission hypotheses will be tested during the first landings. Conversion of collected solar output vis a vis batteries will demonstrate that there's many a slip twixt the cup and the lip. Solar power collection at a ~ 30 % efficiency; storage in Lithium ion batteries and recovery of the power at  "X" %; conversion to light by LED lighting at "Z" %. Hydroponics and artificial lighting sound good until the enormous additional infrastructure required is considered. There's an old saw in the physical sciences worth repeating here: Theory guides but Experiment decides.

My thoughts have been tempered on this topic by Robert Zubrin's comments (There's THAT name again!), in his book "Entering Space." In Chapter 5, he examines the problem of artificially lighted crop production. He points out that crops are enormous users of energy, and proceeds to state the number 3,000 kW per acre. This translates into capture and subsequent conversion of ~ 12,000 kW from PV panels, storage by batteries, and then reconversion of the energy to spectrally suitable light. That's for ONE ACRE, and a single acre doesn't feed a colony of 10 astronaut-settlers very long. My conclusion based on a strictly thermodynamic model is we'll be forced to use passive-solar greenhouses, perhaps supplemented by SOME artificial lighting in order to feed the proposed colony. Either that or continuing subsidies of food from Earth.


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#47 2017-05-06 20:16:20

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 17,390

Re: Industrial development on Mars

The above ground greenhouse would use supplemental lighting to extend the levels for a longer growing period into some of the mars night and for climate control and for brightening the levels for those crops requiring a higher intensity to grow as well, where as the underground would use it for the full duration of time that we are giving the crops light and still for the climate control as well.

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#48 2019-11-28 13:17:57

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,390

Re: Industrial development on Mars

Calliban wrote:

Regarding steel making, a good place to start is embodied energy, which includes estimates of energy needed in all activities to produce the material.  In the case of steel, it is dominated by smelting.

https://en.wikipedia.org/wiki/Embodied_energy

Something like 70% of all steel in the EU comes from recycling now, so only a third of steel is virgin steel that requires metal oxide reduction by carbon monoxide.  Modern steel furnaces rely on electric induction for achieving the required temperatures.  On Mars, we would likely do the same.  Direct electric would bring the furnace to temperature, whilst methane, hydrogen, CO, etc. will serve as reducing agents.  That reduces the fuel requirements substantially.

To make 1kg of steel from 70% recycled steel, takes about 20MJ.  For virgin steel, about 30MJ/kg.  That reflects the extra fuel needed to chemically reduce the iron(ii) oxide into pure iron.

On Mars, to produce 10MJ of hydrogen for reducing iron oxide, will take about 15MJ of electricity.  So 1kg of low carbon steel on Mars will cost a minimum of 35MJ.  This energy assumes a scale economy that we may not be able to achieve on Mars (smaller furnaces are less efficient) but it allows a baseline cost for now.

Suppose we need to produce 100 tonnes of steel per day to manufacture a pressure dome.  That is an energy cost of 100,000kg x 35MJ = 3.5million MJ.  That is a continuous power input of 40.5MW – a lot of juice.  The temperature of the refractory lining is about 1200C.  The thermal expansion at those temperatures is so great, that thermal cycles inevitably result in cracking, which damages the lining.  Once you start a blast furnace, you don't want to shut it down unless absolutely necessary.  You need baseload power to make steel, although the power used to make the hydrogen, methane or CO reducing agent, could be variable, at least to a point.

We will need a lot of steel to make any pressurised structure on Mars that isn't underground.  That includes steel pressure struts for things like greenhouses, in which to grow food.  I worked out previously that producing 3000m2 of cropland on Mars (the amount needed for 1 person), would require 36.7tonnes of low carbon steel for pressure resisting frames.
http://newmars.com/forums/viewtopic.php?id=9187&p=2

So, producing enough farmland for one person would require continuous power of 40kW for one year.  Then you have the energy cost of water (1MJ/kg) and heating.  Living on Mars will be an energy hungry activity and most of that energy must be baseload.  That means lots of nuclear power.  And it need to be cheap.

http://newmars.com/forums/viewtopic.php?id=9197


As we are crossing into this topic with the talk of pressure vessels, pipelines and ore procesing we are doing more than staying we are building a future.

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#49 2019-11-28 19:27:18

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,339

Re: Industrial development on Mars

We need to find, eventually, the right way to farm on Mars.

Initially I think intensive underground units (or rather trench and cover units) with artificial lighting will suffice.

Later on, I think we can experiment with:

1. Low pressure CO2 domes that have aerogel panels (to allow light through but help trap heat).

2. The domes will benefit from additional insolation provided by surrounding reflectors.

3.  The domes might be smallish "pop up" inflatables, mass manufactured and with connecting tube tunnels to other farm domes (so allowing humans with breathing apparatus to pass with ease from one to another.)  Keeping them small will minimise issues of structural support.

4. We could use thermogenic plants (plants that generate and release heat at night) to help keep the domes warm at night.

5. A portion of the crops could be bio-fuel. The bio-fuel could be used with oxygen harvested from the domes to act as boilers to heat water that could be circulated around the domes.

6. The domes could maybe have a light rail system (very narrow gauge) for easy movement of harvested crops and humans.

I say "domes" but it is possible they might be more like the plastic polytunnels used in farming on Earth.#

If we could use this, what I would call, Augmented Heat and Light  system of farming, the need for nuclear power or vast solar arrays would not arise. Also, we would not need to build huge, resource-intensive domes (nice though they look in artist's illustrations).

Last edited by louis (2019-11-28 19:30:05)


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#50 2019-11-30 12:36:05

Oldfart1939
Member
Registered: 2016-11-26
Posts: 1,796

Re: Industrial development on Mars

I become very frustrated by those claiming underground farming to be "the answer." I again refer everyone so interested in Robert Zubrin's "Entering Space," and his commentary re: energy requirements to do so. Green and growing crops thrive by capturing and converting energy (photons), into carbohydrates and some proteins. Basing this analysis on thermodynamics is the only conceivable way to do any meaningful calculations. Light is the "driver" of these growing plants, since the entire photosynthetic pathway depends upon solar irradiance. Producing enough photons by artificial methods is a distinctly losing proposition. I'm not going to spout the numbers here, because no one would take them seriously enough to matter. They are all in Zubrin's books; note that that final word is PLURAL! He discusses this problem in excruciating detail.

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