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#51 2021-04-08 15:44:15

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,858

Re: Settlement design

Re use of robots, it's not true to say these robots don't exist. Robots are used extensively in mining. Robots are used extensively in farming.

Here are some robot miners/related vehicles:

https://www.youtube.com/watch?v=mIBz3cGKDyY

https://www.youtube.com/watch?v=79esC_pkrEs

This isn't a sci-fi scenario. The robots would be under general control of humans in visual or radio contact. 

Space X use Boston Dynamics' dog in functional roles at Boca Chica already:

https://www.youtube.com/watch?v=s6_azdBnAlU

Obviously heavy duty robot mining vehicles haven't yet been adapted for work on Mars but the principles of operation on Mars are pretty well known by now - how to deal with the temperature shifts, energy requirements, wear and tear on wheels or tracks, dust sealing etc.
I don't see any reason why existing mining robot vehicles and robot transporters can't be adapted for Mars.

I would agree that Bigelow-style inflatables won't become a permanent dominating feature of the Mars settlement but they will be v useful on Mission One I suspect. As for additional radiation shielding that can be provided by having a separate steel frame that can be assembled over the inflatable and filled with regolith or water (including along the sides) so that the inflatable has good protection from  radiation events.

Space X will have a v. good idea of where the water ice is and really, for Mission One, that is all that matters. There are features, the geological names of which I forget, which are like hillocks with ice cores - these are the features close to proposed landing locations (rock platforms) at the boundary of Arcadia and Amazonis.  The ice isn't that far below the surface - maybe 2-5 metres, something like that. All you need to do is get some diggers there and start removing the top regolith layer till you hit ice.


Oldfart1939 wrote:

Louis-
I think that Bigelow-style inflatables will serve only for a short time on the planetary surface. Too much danger from Solar flares, and wear and tear on them. You are expecting too much from a too small crew. The main reason for going there in the first place is exploration and a survey of the readily available resources. Reliance on robots is a bit fanciful, since none exist at this point that can do all that you are asking them to accomplish.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#52 2021-04-08 17:12:22

Quaoar
Member
Registered: 2013-12-13
Posts: 600

Re: Settlement design

louis wrote:

I would agree that Bigelow-style inflatables won't become a permanent dominating feature of the Mars settlement but they will be v useful on Mission One I suspect. As for additional radiation shielding that can be provided by having a separate steel frame that can be assembled over the inflatable and filled with regolith or water (including along the sides) so that the inflatable has good protection from  radiation events.

Nice idea: a steel frame holding regolith bags. It seems good for radiation shielding but even for micro-meteoroid impact

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#53 2021-04-08 17:21:36

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,858

Re: Settlement design

You're right! Could provide some protection from them as well. smile

Quaoar wrote:
louis wrote:

I would agree that Bigelow-style inflatables won't become a permanent dominating feature of the Mars settlement but they will be v useful on Mission One I suspect. As for additional radiation shielding that can be provided by having a separate steel frame that can be assembled over the inflatable and filled with regolith or water (including along the sides) so that the inflatable has good protection from  radiation events.

Nice idea: a steel frame holding regolith bags. It seems good for radiation shielding but even for micro-meteoroid impact


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#54 2021-04-08 17:23:45

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,742
Website

Re: Settlement design

Micrometeoroids do not survive Mars atmosphere. On Earth they burn up 100km above the surface, on Mars 30km. It doesn't matter how many kilometres, they still burn up. The Moon has to worry about micrometeoroids, Mars has to worry about dust storms.

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#55 2021-04-08 17:57:30

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,858

Re: Settlement design

Nope you're wrong there Robert:

"A micrometeoroid is a tiny meteoroid: a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through the Earth's atmosphere and reaches the Earth's surface. " [From Wikipedia]

So they do reach the surface.

RobertDyck wrote:

Micrometeoroids do not survive Mars atmosphere. On Earth they burn up 100km above the surface, on Mars 30km. It doesn't matter how many kilometres, they still burn up. The Moon has to worry about micrometeoroids, Mars has to worry about dust storms.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#56 2021-04-08 18:04:32

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,742
Website

Re: Settlement design

louis wrote:

Nope you're wrong there Robert:

"A micrometeoroid is a tiny meteoroid: a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through the Earth's atmosphere and reaches the Earth's surface. " [From Wikipedia]

So they do reach the surface.

Mass doesn't disappear. Micrometeoroids do burn up, break up. Then float like leaves in the wind down to the surface. Your Wikipedia article says micrometeorites ("-ite" not "-oid") reach Earth's surface. How much damage have they done to your car this year? Or the roof of your house?

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#57 2021-04-08 18:18:23

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,858

Re: Settlement design

Well the Wikipedia article suggests the two are synonymous with micrometeorites being those micrometeorids that reach the surface.

Even tiny objects can do damage if travelling at speed but I think we can all agree that there are definitely  objects from outer space that might split up during entry that can do damage to Mars settlements - whatever their official title.

RobertDyck wrote:
louis wrote:

Nope you're wrong there Robert:

"A micrometeoroid is a tiny meteoroid: a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through the Earth's atmosphere and reaches the Earth's surface. " [From Wikipedia]

So they do reach the surface.

Mass doesn't disappear. Micrometeoroids do burn up, break up. Then float like leaves in the wind down to the surface. Your Wikipedia article says micrometeorites ("-ite" not "-oid") reach Earth's surface. How much damage have they done to your car this year? Or the roof of your house?


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#58 2021-04-08 19:10:43

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,742
Website

Re: Settlement design

American Meteor Society

Meteoroids enter the earth’s atmosphere at very high speeds, ranging from 11 km/sec to 72 km/sec (25,000 mph to 160,000 mph). However, similar to firing a bullet into water, the meteoroid will rapidly decelerate as it penetrates into increasingly denser portions of the atmosphere. This is especially true in the lower layers, since 90 % of the earth’s atmospheric mass lies below 12 km (7 miles / 39,000 ft) of height.

At the same time, the meteoroid will also rapidly lose mass due to ablation. In this process, the outer layer of the meteoroid is continuously vaporized and stripped away due to high speed collision with air molecules. Particles from dust size to a few kilograms mass are usually completely consumed in the atmosphere.

Due to atmospheric drag, most meteorites, ranging from a few kilograms up to about 8 tons (7,000 kg), will lose all of their cosmic velocity while still several miles up. At that point, called the retardation point, the meteorite begins to accelerate again, under the influence of the Earth’s gravity, at the familiar 9.8 meters per second squared. The meteorite then quickly reaches its terminal velocity of 200 to 400 miles per hour (90 to 180 meters per second). The terminal velocity occurs at the point where the acceleration due to gravity is exactly offset by the deceleration due to atmospheric drag.

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#59 2021-04-08 19:22:27

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,742
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Re: Settlement design

Scientific American

Even though the surface gravity on Mars is only 3.7 meters/sec (compared to 9.8 meters/sec on Earth), the thin atmosphere means that the average terminal velocity hits a nail-biting 1,000 km/hour or so, compared to about 200 km/hour back home.

Most meteorites on Earth hit at terminal velocity, but that's not enough to create a crater, just bounce on the ground. Even Mars Direct called for sand bags on the roof, and we've all talked about deep Mars dirt on the roof of a Mars habitat for radiation shielding. How much damage would a meteorite do at that speed? But again, the above article says micrometeors are "completely consumed in the atmosphere". Even if Mars has 10 times as many meteorites reach the surface as Earth, how many meteorites hit a house in the United States per decade? How many since the United States was founded?

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#60 2021-04-08 21:49:04

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,742
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Re: Settlement design

Addressing the original post, in 2005 I was invited to participate in a study to design the first permanent human base on Mars. A friend organized it, Bruce Mackenzie. I met him at Mars Society conventions. He's the founder and executive director of the Mars Foundation. He brought together a number of impressive team members; I was honoured to be asked to participate. Bruce is an alumnus of MIT. One team member was taking his master degree in nuclear engineering at MIT. And our architect was taking his master degree in architecture, our project was his thesis. I was part of Phase 1: Hillside Settlement, but not part of Phase 2: Plains Settlement.

Document Library
PowerPoint presentation: Mars Homestead Project - Overview Presentation ~10MB

Images by architect Georgi Petrov: Hillside Settlement 1 (click each image for larger view)
normal_MHP-4FC-Image002.jpg
normal_MHP-4FC-Image022.jpg
normal_MHP-4FC-Image015.jpg

Artwork by Phil Smith: Commissioned or MF Owned Artwork
normal_MHP-4FC-Image029.jpg
normal_MHP-4FC-Image026.jpg

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#61 2021-04-09 03:10:24

Quaoar
Member
Registered: 2013-12-13
Posts: 600

Re: Settlement design

RobertDyck wrote:

Micrometeoroids do not survive Mars atmosphere. On Earth they burn up 100km above the surface, on Mars 30km. It doesn't matter how many kilometres, they still burn up. The Moon has to worry about micrometeoroids, Mars has to worry about dust storms.


May be I'm wrong in calling them "micro", but some kind of meteoroid big enough to survive the atmosphere heating can reach Mars surface and a regolith bag on a steel frame might be useful to protect the habitat, like the sand bags used by soldiers.
For the dust storms, which may obscure the sun for more than a month, the only solution is a backup nuclear reactor.

Last edited by Quaoar (2021-04-09 03:11:09)

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#62 2021-04-09 09:15:59

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,221

Re: Settlement design

There has been a lot of talk about the impact of humans on Mars by the Planetary Protection people. My biggest objection to using Solar Power is the visual pollution cause by hundreds of acres of solar panels. I don't wanna be in California where the Solar farms are huge. I'm a strong proponent of using Nuclear energy for it's uninterrupted supply of plenty of energy. Solar can augment and share some of the workload, but a city of a million people would simply cover the planet with solar panels if that's all we used. The impact of a year long dust storm would be catastrophic, and death would follow.

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#63 2021-04-09 09:24:38

kbd512
Administrator
Registered: 2015-01-02
Posts: 4,612

Re: Settlement design

The rosiest energy usage projections that came from Mars One were 3.7kWh of continuous power, per person, per day, for ECLSS and replenishment of O2 / N2 from the Martian atmosphere and H2O from surface ice deposits, to support a crew of 4 colonists.  That means 3.7GWe of continuous electrical power for a million people.  That equates to 32.412TWh of power per year.  That presumes all food will be imported from Earth, which would be grossly impractical for a city of a million people.

32.412TWh / 0.65TWh per Bhadla Solar Park (10km^2 of solar panels) = 49.86 Bhadla Solar Parks to keep a million people from running out of air and water.  That's 500km^2 worth of solar panels, spread out over 2,850km^2 of land area (I confirmed the 57km^2 for the Earth-based Bhadla, which spaces out the solar arrays to prevent shadows being cast by the other panels of the array, onto adjacent solar panels, and for access roads / trails to erect the panels).  That would qualify as the absolute largest solar array that humanity has ever constructed, bar-none.  The next largest array on Earth isn't 1/10th of the size, even though those arrays are clearly visible from space.  That covers basic life support only.  The real power requirements are associated with food production, construction, mining, and manufacturing.  Bhadla was considered something of a record, but it required 8,500 personnel to construct it over 8 months.  We're going to need around half a million people to do nothing but erect solar panels for 8 months.  There won't be enough power to keep them alive, though, until after the array has been built.  Minimally, we need all that excess power while the city is being constructed, to supply the power to make Sulfacrete and to construct pressurized living spaces and indoor farming spaces.  Realistically, this city will take 10 to 20 years to build, and then we need to replace the solar panels with more panels imported from Earth or made on Mars from local resources and recycled panels.

Mars One noted that they couldn't supply enough power from their mass budget allocated to the solar array during the shortest days of the year, and would have to figure out how to reduce their energy requirements by prioritizing energy usage for the most critical life support functions.  Since insufficient power was available for life support, no power for construction, food production, or manufacturing would be available, either.  Their report was published in 2015.

NASA has had six years since to perfect CAMRAS (amine swing bed CO2 scrubber / atmospheric revitalization) and IWP (grey water to potable water filtration system), which is what Mars One was relying upon on the agency to develop.  Those systems are finally slated to fly as fully operational subsystems aboard Orion later this year or early next year.  They've spent hundreds of millions of dollars on "closing the loop" and reducing power requirements.  Anyone who thinks they're going to do significantly better should stop talking and start demonstrating their flight-ready hardware aboard ISS.  CAMRAS and IWP prototypes have already flown aboard ISS, and those systems are now there to stay because they worked so well during testing.

If we can't realistically construct an array 50 TIMES the size of Bhadla on Mars, then we have to admit that a city of a million people isn't possible with solar power alone, or we have to instead rely upon our one technologically feasible alternative, which is nuclear power.

Can anyone else here appreciate the incredible energy consumption associated with building and operating our farms and cities and factories and mines and educational system to educate our people to use the available technology?

It's a truly staggering amount of power, even in a place where the air and liquid water are "free".

It could be the case that scaled-up life support systems require less power on a per-person basis, but I find that assertion to not be credible because the power consumption is based upon pumping rates and electrical heating.  Electric motors / pumps circulate the atmosphere or water through the devices that scrub CO2 from the atmosphere or produce potable water from grey water.  Pump proportionally more atmosphere through the amine swing bed of CAMRAS, and you need more power.  Pump proportionally more grey water through the ionomer membranes of IWP, and you need more power.  Absent more power, there can be no increase in pressurized living space, nor the population size inhabiting the base / city.  A million people will need something along the lines of at least 26 NRG Stadiums to live in.

This entire endeavor appears to be utterly impractical with solar power alone, marginally feasible with nuclear power even though I still have my doubts about that, and probably only truly practical and economical with nuclear fusion, on account of the material input rates to sustain fusion vs fission vs photovoltaics.  You need at least several orders of magnitude more material input with solar, and about an order of magnitude less input with nuclear fusion vs nuclear fission.  If this was going to be practical to do with photovoltaics or nuclear fission, then we should ask why we haven't already established a city or even a tiny crewed base on the moon.  We had the technology to go to the moon about a decade before I was born.  Five decades later, there's still no moon base to test out all these ideas we have about what we can or can't do, what humans can or can't tolerate in terms of gravity, etc.

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#64 2021-04-09 09:59:45

kbd512
Administrator
Registered: 2015-01-02
Posts: 4,612

Re: Settlement design

Word to the wise, to all would-be off-world city planners:

Energy is the true master resource.  You can't do anything else at all without it.  Technologically advanced human civilization is built upon energy input and lots of it.  In the words of that rock band from the Apollo Era, Creedence Clearwater Revival, "When you ask, how much should we give?  The only answer is more, more, more."

Determine how much power you need first, how much the power sources weighs (because it will only arrive on site after the mother of all moving jobs), what it requires in terms of continuous materials and human operator input (because this is what you're on the hook to provide, ever after), and how to resupply or repair your generating stations (because peoples' lives literally depend upon whether or not the power source is every bit as reliable as gravity).

All other requirements flow from there, as do all other possibilities.  The pair of energy requirements that you absolutely cannot ignore are what it takes to keep people counted amongst the living, namely air / water / pressurization, and what it takes to feed them.  If you want to bring in another 10,000 people to do more work, then the only way that can physically happen is if the life support system and food production capacity can support it.

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#65 2021-04-09 10:01:51

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,221

Re: Settlement design

kbd512-
Thanks for "doing the math." I was considering doing it myself, but lacked sufficient input data to start. That's the strict engineering approach, and your estimate doesn't even include any safety factor built in for energy grid problems or "power outages." I would say that there should be a 100% energy safety factor built into that estimate. So simply double everything you mentioned.

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#66 2021-04-09 12:20:10

kbd512
Administrator
Registered: 2015-01-02
Posts: 4,612

Re: Settlement design

Oldfart1939,

There was a movie where a guy was in debt to the mob.  The mobster explained to his debtor, that he didn't care if he could eat or live indoors, his response to his debtor (who couldn't come up with the money he owed) was (with less colorful language), "Screw you, pay me."  That same principle applies to providing sufficient power for life support and food production for a human civilization living on another planet.  In reality, it applies on Earth as well.  When you choose to live on Mars, you're in debt to the mob, when it comes to energy and life support.  The only valid response is to pay up, or people will die.  It's that simple.  It will always be that simple.

As you noted, my energy consumption estimates don't include much in the way of backup margin, apart from a 10% "fudge factor" that NASA, ESA, and Mars One build into their power consumption estimates.  NASA's 10kWe continuous power figure also included power for ISRU propellant production to return home, but that's about it.  Even if nobody is returning home, it's hard to figure how they won't be consuming even more power than that to produce food or to construct habitable living spaces.

All I did was simple math, based upon what the people with PhDs computed was required, which they based upon actual power consumption data from NASA, ESA, other space agencies, and the contractors who supply the hardware to make real space flight missions possible.  It takes very little work to multiply.  My calculator did all of the drudge work, to be honest.  I just punched a few buttons and did a few unit conversions.

I would absolutely love to have solar panels that are 100% efficient, work equally well in dust storms or at night as they do in broad daylight (but unfortunately simple physics seems to get in the way of this "want"), lighter than a feather, cheaper than dirt, and erected by AI-enabled robots in record time.  I don't care how the electrons are produced.  I do care about how much the complete solution weighs, how much time / effort / money it takes to construct it, whether we even have the technology to do what we're talking about, and if it can be supplied in a practical manner into perpetuity, because that is what a city built on another planet absolutely requires to function.

Mars One computed ECLSS and ISRU replenishment power requirements were 355.9kWh per day (page 50 of their reported entitled "Mars_One_Habitat_ECLSS_Conceptual_Design_Assessment.pdf").  Google it.  They assumed that NASA would fully develop CAMRAS and IWP.  That assumption turned out to be correct.  They took power consumption data for CAMRAS and IWP from NASA.  They estimated ISRU consumables replenishment power consumption based upon the known efficiency of existing pumps / cryocoolers / AC equipment, etc.  The 141.9kWh per day power consumption comes from adding the sub-totals for atmosphere management and water management.  The line item that says "atmospheric revitalization" is CAMRAS.  The line item that says "primary water processor" is IWP.  Both system are fully developed now and will fly in a fully operational capacity aboard the Orion space capsule.  They were thoroughly tested aboard ISS over the course of months and years, and represent a dramatic energy consumption reduction over the prior generation of ECLSS used aboard ISS, to the point that they are (CAMRAS) or will be (IWP) permanently installed aboard ISS.  For now, this is "as good as it gets".  Both NASA and ESA continue to develop and refine variations of these technologies in an attempt to further reduce the power demanded by the ECLSS.

356,000Wh/day for four crew members / 24 = 14,833.33Wh per hour

14,833.33 / 4 crew members = 3,708.33W/hr/crew member

3,700W of continuous power per person * 1,000,000 people = 3,700,000,000W = 3.7GW/hr of continuous power for 1,000,000 people

3,700,000,000Wh/day * 8760hrs (hours per year***) = 32,412,000,000,000Wh/yr = 32.412TWh/yr

We know quite well that the much longer wiring runs will consume even more power, every bit of our 10% "fudge factor" and at least 10% more, but we're ignoring engineering reality to simply "ballpark" the energy requirement.

*** Note: It doesn't matter in the slightest that a Martian day or year (686.98 Earth solar "days") is longer than an Earth day or year, because we computed the continuous power requirement PER HOUR (and more days in a year give us more time to both collect and consume power).  We know how much time-averaged power Bhadla Solar Park generated during the course of a year (365 Earth solar days or 8760 hours), 1.3TWh/yr.  We divided that figure by 2 because Mars is about twice as far from the Sun as the Earth is.  We're ignoring dust storms, panel efficiency with half as many photons striking each square meter of panel area, and other environmental factors that reduce the conversion efficiency of the panels.  We don't need to waste any time on that stuff, because we only want to know what the power requirement is under ideal conditions.

TSI at TOA for Earth is 1,361W/m^2.

TSI at TOA for Mars is 590W/m^2.

That means Total Solar Irradiance at Top Of Atmosphere for Mars is 43.35% that of Earth, so I over-estimated how much power we could get from the same photovoltaic panels used in Bhadla by at least 6.65%.  Even so, it doesn't mean anything at the scales we're talking about.  I'm "just" (there's that dirty four-letter word that engineers hate so much) assuming that the solar panels actually used on Mars are significantly more efficient to make up for that deficit.  Bhadla produces 1.3TWh/yr, so I divide by 2 (because it makes that math even more simple and easy to understand) and get 0.65TWh/yr for a more efficient array that manages to collect half as much power, despite all other factors working against it.

32.412TWh/yr divided by 0.65TWh/yr/Bhadla Solar Park equals 49.86 Bhadla Solar Parks.

50 Bhadla Solar Parks multiplied by 57km^2 per Bhadla Solar Park equals 2,850km^2 "Million Person City Mars Solar Park" (to keep that many humans breathing and guzzling down clean drinking water).  That means we have to erect a solar park that's 53.385km by 53.385km in size.  In reality, all the other problems I mentioned will dictate that the array is considerably larger.  The City of Houston proper, my home town in Texas, is 1,651km^2.  If you tell any engineer you're going to cover the City of Houston and the City of Dallas, and then some, with solar panels to provide power to a million people, they're going to laugh their rear end off, because that's an absurdity.

The idea of powering a city of a million people on Mars, even with 100% efficient solar panels that don't exist, is a type of thinking better known to all actual engineers as "pure bovine excrement".  The only remotely plausible engineering-based arguments that our solar enthusiasts have left is that they don't agree with the power consumption figures.  However, they also steadfastly refuse to either provide evidence of a space flight-qualified hardware set that consumes less power or to show their work when they compute the power consumption requirements.  It doesn't matter if even one other person can figure this out, even though I already know that absolutely everyone here can do it.  I already know that this is grossly infeasible in the real world, because the real world runs on engineering, not wishful thinking or ideology.  Now that we all know how ridiculous this solar powered Martian city idea truly is, based upon the simple math shown above (with no allowance made for any food production, construction of pressurized living spaces, or the mining / refining of metals or other resources for construction), can we all agree to pursue a realistic solution?

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#67 2021-04-09 12:28:24

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,858

Re: Settlement design

I think you're trying to find difficulties where there are none or there are solutions.

Firstly building huge frames to house solar panels is not necessary. There is already a technology for laying out rolls of solar panels and this could be done by robot vehicles following transponder-defined routes.

https://www.bbc.co.uk/news/uk-wales-sou … s-41443312

Secondly no one - not even Musk - is talking about building a one million city overnight. If it was done within 30 years, that would mean (using your figures) they had to build nearly 17 sq kms of PV array every (earth year) - or about 48,000 sq. metres per sol. With a working day of 6 hours that would require that 8000 sq metres per hour. I'd estimate robot rovers could lay maybe 200 sq metres per hour. So you would require a team of 40 robot rovers to accomplish the rapid rollut. You'd need other robot vehicles to transport the rolls, so let's say maybe 60 robot rovers. Obviously you'd need to transport the PV rolls from the spaceport to the PV array fields, and you'd have to lay down cables and so on. But 60 robot rovers could probably handle the installation of the PV array for a million people.

However, I don't really accept your power demand estimate. Power demand for the early colony will be very different and much higher I think than will be the case later on.

In the early colony, the first three or four missions at least, everyone needs to return to Earth, and so you need to fuel up a big old Starship. By the time you have a one million person city most people will be emigrating to Mars on a permanent or long term basis. Fuelling Starships is a huge call on the per capita energy resources in the early stages. This will decline and it is quite possible we will find a methane source on Mars that means we don't need to use Sabatier to get our methane. 

In the early colony we will rely on artificial light for farming. Later, we will have natural light farming.

To begin with, oxygen will have to be produced by electrolysis, but later on oxygen will be produced by plants and trees - no need to input energy.

Initially we'll  be manufacturing things from scratch but later on recycling of materials will become a much more important part of the economy. Yes, recycling requires energy input but is even more economical on Mars than on Earth.

I also don't think in reality we'll be relying 100% on solar.As mentioned, methane sources might be located and so methane could be used to generate electricity. There is also obvious scope for a differential heat engine of some description.

kbd512 wrote:

The rosiest energy usage projections that came from Mars One were 3.7kWh of continuous power, per person, per day, for ECLSS and replenishment of O2 / N2 from the Martian atmosphere and H2O from surface ice deposits, to support a crew of 4 colonists.  That means 3.7GWe of continuous electrical power for a million people.  That equates to 32.412TWh of power per year.  That presumes all food will be imported from Earth, which would be grossly impractical for a city of a million people.

32.412TWh / 0.65TWh per Bhadla Solar Park (10km^2 of solar panels) = 49.86 Bhadla Solar Parks to keep a million people from running out of air and water.  That's 500km^2 worth of solar panels, spread out over 2,850km^2 of land area (I confirmed the 57km^2 for the Earth-based Bhadla, which spaces out the solar arrays to prevent shadows being cast by the other panels of the array, onto adjacent solar panels, and for access roads / trails to erect the panels).  That would qualify as the absolute largest solar array that humanity has ever constructed, bar-none.  The next largest array on Earth isn't 1/10th of the size, even though those arrays are clearly visible from space.  That covers basic life support only.  The real power requirements are associated with food production, construction, mining, and manufacturing.  Bhadla was considered something of a record, but it required 8,500 personnel to construct it over 8 months.  We're going to need around half a million people to do nothing but erect solar panels for 8 months.  There won't be enough power to keep them alive, though, until after the array has been built.  Minimally, we need all that excess power while the city is being constructed, to supply the power to make Sulfacrete and to construct pressurized living spaces and indoor farming spaces.  Realistically, this city will take 10 to 20 years to build, and then we need to replace the solar panels with more panels imported from Earth or made on Mars from local resources and recycled panels.

Mars One noted that they couldn't supply enough power from their mass budget allocated to the solar array during the shortest days of the year, and would have to figure out how to reduce their energy requirements by prioritizing energy usage for the most critical life support functions.  Since insufficient power was available for life support, no power for construction, food production, or manufacturing would be available, either.  Their report was published in 2015.

NASA has had six years since to perfect CAMRAS (amine swing bed CO2 scrubber / atmospheric revitalization) and IWP (grey water to potable water filtration system), which is what Mars One was relying upon on the agency to develop.  Those systems are finally slated to fly as fully operational subsystems aboard Orion later this year or early next year.  They've spent hundreds of millions of dollars on "closing the loop" and reducing power requirements.  Anyone who thinks they're going to do significantly better should stop talking and start demonstrating their flight-ready hardware aboard ISS.  CAMRAS and IWP prototypes have already flown aboard ISS, and those systems are now there to stay because they worked so well during testing.

If we can't realistically construct an array 50 TIMES the size of Bhadla on Mars, then we have to admit that a city of a million people isn't possible with solar power alone, or we have to instead rely upon our one technologically feasible alternative, which is nuclear power.

Can anyone else here appreciate the incredible energy consumption associated with building and operating our farms and cities and factories and mines and educational system to educate our people to use the available technology?

It's a truly staggering amount of power, even in a place where the air and liquid water are "free".

It could be the case that scaled-up life support systems require less power on a per-person basis, but I find that assertion to not be credible because the power consumption is based upon pumping rates and electrical heating.  Electric motors / pumps circulate the atmosphere or water through the devices that scrub CO2 from the atmosphere or produce potable water from grey water.  Pump proportionally more atmosphere through the amine swing bed of CAMRAS, and you need more power.  Pump proportionally more grey water through the ionomer membranes of IWP, and you need more power.  Absent more power, there can be no increase in pressurized living space, nor the population size inhabiting the base / city.  A million people will need something along the lines of at least 26 NRG Stadiums to live in.

This entire endeavor appears to be utterly impractical with solar power alone, marginally feasible with nuclear power even though I still have my doubts about that, and probably only truly practical and economical with nuclear fusion, on account of the material input rates to sustain fusion vs fission vs photovoltaics.  You need at least several orders of magnitude more material input with solar, and about an order of magnitude less input with nuclear fusion vs nuclear fission.  If this was going to be practical to do with photovoltaics or nuclear fission, then we should ask why we haven't already established a city or even a tiny crewed base on the moon.  We had the technology to go to the moon about a decade before I was born.  Five decades later, there's still no moon base to test out all these ideas we have about what we can or can't do, what humans can or can't tolerate in terms of gravity, etc.

Last edited by louis (2021-04-09 12:30:42)


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#68 2021-04-09 12:49:21

kbd512
Administrator
Registered: 2015-01-02
Posts: 4,612

Re: Settlement design

Louis,

CAMRAS is space flight-qualified.  IWP is space flight qualified.  No other system that provides a breathable atmosphere or clean drinking water, that also consumes less power, is space flight qualified.  I showed you my math and my sources.  I've repeatedly asked you to do the same thing.

There is no grass on Mars.  If you dump solar panels in the dust there, they get thoroughly coated with dust in short order, due to static electricity build-up on the face of the array, and then they quit producing power, so that's not a practical solution, certainly not a long-term solution.  We've been over this before.

If you're specifying new pieces of hardware that use less power to provide life support functions, then name the hardware and the test data source showing that it works and how much power it consumes.

I'm done responding until you show your work.

Edit:

One last note.  We don't build cities based upon "what we might find when we get there".  We build based upon what we know we have to work with, that's physically sitting in our inventory stockpile.  We know that we're building absolutely everything from scratch on Mars.

Last edited by kbd512 (2021-04-09 12:58:19)

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#69 2021-04-09 15:51:35

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,858

Re: Settlement design

Kbd,

My maths suggests there is somewhere you've gone wrong in your calculations.

53.38 kms x 53.38 kms = 53380 metres x 53380 metres = 2,849,424,400 sq. metres.

2,849,424,400 sq. metres divided by 1 million gives a per capita figure of 2,849 sq metres per person.

On Mars with maybe 25% efficiency this per capita PV panel figure could maybe generate 1424 Kwhes per person per sol (assuming 0.5 Kwh being generated per sq. metre). Assuming a 25% reduction for energy storage, that would give a useable 1068 KwHs per sol per person. That would equate to about 43 Kwes constant per person, not the 3.7 Kwes you mention.

You figures might be about by a factor of ten as far as I can see.

I have other observations...

For some reason you appear to be using figures for keeping people alive in space or in early missions as a subsitute for thinking about energy requirements in a city of one million on Mars.

Take just one example. A million person city is going to be its own heat island, much more than an orbital space station. Heat loss from one unit will go to another unit and so on, the overall heating requirement will be reduced on a per capita basis.

I don't know why you are ignoring the fact that plants produce oxygen. Surely that is highly relevant.

Mars is not uniformly dusty. There are areas that have relatively low dust amounts.

You don't have to lie the PV roll flat. We'll have to see if the dust issue is as bad as you make out, remembering just how well PV panels have worked on Mars in reality. If it is a problem, it can be hung on wires held taut between poles. That won't add much to the infrastructure requirement. My hunch, though, is that with robot cleaning this won't be a requirement .

We already have PV power producing 2% of the world's electricity on Earth - the equivalent of electricity for 140 million people, not 1 million. Just because all the PV panelling is currently spread out all over the globe, is irrelevant, it could just as well be concentrated in one location e.g. Sahara or SW USA, if that was a needed solution.

I accept electricity requirements will be substantial on Mars but you have at least 30 years - probably more like 100 years - to put the solutions in place for your million person city. My own view is we will be doing very well if we have 100,000 people on Mars in 30 years' time (and many perhaps most won't be permanent settlers).

Land area usage on Mars is irrelevant. If we need 2850 sq kms plus that's not an issue. There is pretty much the same land surface on Mars as on Earth,  but as things stand the land on Mars is unproductive and unoccupied, so to lose the land is not an economic cost.

Last edited by louis (2021-04-09 15:53:08)


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#70 2021-04-09 15:59:17

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,221

Re: Settlement design

Louis--

I applaud your optimism. On another planet, optimism will get a lot of people killed.
I'm a professional scientist by trade, and I have always gone with "just the facts." kbd512 has satisfied me with his basic math calculations. Sooner or later, Elon will also wake up to the need for nuclear power, in spite of selling solar panels for (Part of) his living.
There are lots of other people besides myself who abhor the idea of he entire landscape covered with solar panels, as the fantastic Mars landscapes are part of their reason for going there in the first place.

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#71 2021-04-09 16:57:11

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,858

Re: Settlement design

There's no way a mature colony will need 2,849 sq metres of PV panel per person . There's something gone wrong with kbd's calculation in my view.

Let's see if kbd maintains that is the amount of PV panel required per person, first.

Oldfart1939 wrote:

Louis--

I applaud your optimism. On another planet, optimism will get a lot of people killed.
I'm a professional scientist by trade, and I have always gone with "just the facts." kbd512 has satisfied me with his basic math calculations. Sooner or later, Elon will also wake up to the need for nuclear power, in spite of selling solar panels for (Part of) his living.
There are lots of other people besides myself who abhor the idea of he entire landscape covered with solar panels, as the fantastic Mars landscapes are part of their reason for going there in the first place.


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#72 2021-04-09 18:22:38

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,078

Re: Settlement design

I think its time to slow down so that Noah can get caught up and give insight into what might not be of concern in his proposal to enter the forum....

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#73 2021-04-09 21:00:05

kbd512
Administrator
Registered: 2015-01-02
Posts: 4,612

Re: Settlement design

Louis,

I've been over this before.  I've stated it more than once in various posts in this very thread, some of which you responded to.  Whether you actually read what I wrote, or not, is on you.  The Bhadla array covers 57km^2 (actual land area), with a solar panel area of 10km^2 (the area covered by the solar panels themselves, according to the "Interesting Engineering" article I posted a link to).  If you multiply 10km^2 by 50, that's 500km^2.  However, the actual array, which includes service roads (for both the vehicles and autonomous intelligent self-replicating machines, aka "humans", to build and service the array) and gaps between strings of panels to prevent the panels from casting a shadow over the other panels in the array, works out to 57km^2.  The Bhadla array provides 1.3TWh of electricity per year in India.  If it's 2 times further from the Sun, as it would be on Mars (and it's a bit further away from the Sun than that during certain times of the year), that means the same array would produce 0.65TWh per year.  Multiplying 57km^2 by 50 is where that 2,850km^2 figure comes from, because 57km^2 is the actual land area that the array and associated equipment covers.  It would be foolish to think that casting a shadow on a photovoltaic panel on Mars works any differently than it works here on Earth.

By merely observing what everything we send to Mars looks like after a few months on the surface (thoroughly caked in dust), it would also be foolish to think that locating the panels right on top of the dust source would help keep them clean, but even more foolish to think you could effectively clean them by either blowing CO2 across them or kicking up a giant dust cloud with a feather duster when all the other panels are laid out in neat rows right next to them.  Mars may not be uniformly dusty in all areas, but during the last major dust storm the surface of the planet was uniformly obscured in its entirety.  You don't get to dictate whether or not minimal dust, subsurface ice, and Sulfur to make Mars bricks / concrete, all coincide in the same happy spot.

The Bhadla array also includes a single-axis tracking mechanism to maximize the power produced by the panels, hence the steel structure that was built to mount the panel strings, so that fewer electric motors can be used to track the Sun as the Earth rotates.

Regarding photovoltaics providing 2% of the power for humanity, that was only achievable by devoting copious quantities of fossil fuels to making the panels.  Unfortunately for us, those same fossil fuel sources may not exist on Mars.  If they do, then maybe we can burn enough gas to produce enough panels, but that remains to be seen.

Edit:

The admonishment from NASA (JPL, actually; you know, those people who actually built every single solar powered or nuclear powered robot that's survived on the surface of Mars for a significant period of time), specifically stated that the solar panels were to be kept at least 1 meter from the surface to avoid even worse problems with static electricity caking the panels in dust.  I posted a link to that info, which came from a NASA document explaining "lessons learned" from the design of the Spirit and Opportunity rovers.

Edit #2:

Here's a picture of the Bhadla Park Solar Array from space with a kilometer scale marking applied for reference purposes.  Feel free to argue with it, but you're wasting your time.

Last edited by kbd512 (2021-04-09 23:06:21)

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#74 2021-04-10 03:50:42

Noah
Member
From: Zurich (Switzerland)
Registered: 2020-07-28
Posts: 38

Re: Settlement design

I saw some misconceptions about the size, so I determined a goal:
goal

The number of people is not fixed, it is only to create a rough framework.
The goal can and should change over time.

Last edited by Noah (2021-04-10 05:12:51)

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#75 2021-04-10 04:03:51

Noah
Member
From: Zurich (Switzerland)
Registered: 2020-07-28
Posts: 38

Re: Settlement design

Comments

First of all, big thanks for all the comments. There are many new and interesting ideas (for me, anyway).

The topic of settlement design is very broad. If you write a longer comment, please add a heading/subheading to keep the thoughts clear (especially for people who join later).

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