[HN Gopher] Powering the Mars Base
___________________________________________________________________
Powering the Mars Base
Author : surprisetalk
Score : 87 points
Date : 2024-11-06 11:26 UTC (11 hours ago)
(HTM) web link (caseyhandmer.wordpress.com)
(TXT) w3m dump (caseyhandmer.wordpress.com)
| elif wrote:
| Besides the hilarious conflation of "mars base" and "lunar base"
| in the introduction, is there any reason this author is to be
| listened to for his authority? I have a hard time buying that
| solar and "energy beaming" are more practical power sources on
| Mars than nuclear reactors..
|
| Solar because r^2 diminishing returns
| surprisetalk wrote:
| Handmer sometimes speaks outside his core competencies, but I
| find his napkin math to be extremely insightful.
|
| You may enjoy his recent interview on Patio11's podcast:
|
| [1] https://www.complexsystemspodcast.com/episodes/solar-
| economi...
| poulpy123 wrote:
| what is his core of competence ?
| Torkel wrote:
| +1 on the podcast, it is excellent. I only wished he would
| have dug deeper on details on what they are building at
| Terraform.
| PaulHoule wrote:
| He runs a startup that is working on a methane synthesizer
| that might find uses on Earth but would be very much in
| demand on a Mars colony.
| ceejayoz wrote:
| It's not conflating, it's comparing, and draws the conclusion
| that "energy beaming" _won 't_ work on Mars. It also correctly
| discusses the challenges "nukes in space" has from a policy and
| practical standpoint.
|
| > While the Earth-facing side of the Moon can obtain
| practically infinite quantities of very cheap power if we beam
| it up from Earth, which is greatly preferable to attempting to
| engineer some sort of solar or thermal system which can cope
| with the Moon's 28-day day-night cycle, _this approach won't
| work on Mars._
| schiffern wrote:
| On Mars the r^2 scaling just means that solar panels produce
| ~half as much energy as on Earth. For dust there are
| electrostatic sweeping grids that automatically remove it.
|
| Realize that nuclear also gets more expensive on Mars, because
| there are no convenient lakes or rivers for cooling water.
| Instead you need to build a large radiator or underground pipe
| grid.
| verzali wrote:
| About 43% of the energy. But its also worse than that because
| Mars has a more eccentric orbit and slightly bigger axial
| tilt. Seasonal variations in solar energy are thus much
| larger than on Earth (at perihelion you get around 700W/m2,
| at aphelion about 500W/m2). Also seasons are longer on Mars
| and the planet moves more slowly around perihelion, so that
| it spends more time further from the Sun.
|
| You also get global dust storms enveloping the planet every
| few years for several weeks at a time. These leave a lot of
| dust on panels, but they also drastically cut the solar
| radiation received at the surface.
|
| Solar panels degrade faster on Mars too. You could replace
| them by sending new ones, but that will add up to a lot of
| mass. Or you could design panels that degrade more slowly,
| but that's not a given yet.
|
| Basically solar is not going to scale well on Mars. It might
| work for a small facility, but not for a city.
| dexwiz wrote:
| If you had a city, could you produce them locally then?
| tirant wrote:
| Yes, but you then need to have an already developed full
| supply chain, and for that you need to bootstrap your
| energy production first hand.
|
| My personal hope is that there might be some untapped
| resources of hydrocarbons or methane in Mars that could
| be used to generate energy from local sources.
| philipkglass wrote:
| Local hydrocarbons could help for making
| materials/chemicals but they wouldn't help for energy.
| Mars doesn't have free oxygen in the atmosphere so
| there's nothing to burn them with.
| schiffern wrote:
| If you choose your latitude right (roughly 10-30 degrees
| North), the variability caused by eccentricity and axial
| tilt mostly cancels out.
|
| https://images.squarespace-
| cdn.com/content/v1/61b40f74f9cdfc...
|
| As for dust storms, you need stored energy anyway --
| nuclear power goes down too! A big tank of oxygen counts as
| "stored energy," and so does a big container of desorbed
| lithium carbonate (CO2 scrubber material).
| etiennebausson wrote:
| I expect solar infrastructure for Mars would be done in
| orbit and beamed down. On earth, they are produced on the
| ground and putting them in orbit cost way too much.
|
| If the panels are send from Earth to Mars, then dropping
| them in orbit mean that you don't have to account for their
| weight for landing... or don't have to land at all. Park in
| orbit, drop you payload and back to earth for the next
| delivery.
| lutusp wrote:
| > I expect solar infrastructure for Mars would be done in
| orbit and beamed down.
|
| Remember that Mars' atmospheric pressure is a tiny
| fraction of that on Earth, so the performance difference
| between a solar panel in orbit, and on the surface, is
| negligible (until a dust storm starts). So there's no
| reason to consider putting them in orbit, especially
| considering the much higher complexity and power losses
| involved in delivering power to the surface.
| inglor_cz wrote:
| "the performance difference between a solar panel in
| orbit, and on the surface, is negligible (until a dust
| storm starts). So there's no reason to consider putting
| them in orbit, especially considering the much higher
| complexity and power losses involved in delivering power
| to the surface."
|
| I wonder if you could build a space elevator on Mars
| (third of our gravity = much less demanding on materials)
| and then simply get the electricity generated by orbital
| solar panels back to the surface using ye olde cables,
| immune to dust storms.
| Yizahi wrote:
| Casey has an article why beaming energy from space to
| ground is not worth it, due to many compounding issues.
| Mars can probably only strike off one issue, about beam
| density and ramp it up, but has many more unique issues -
| far away to control and replace, less energy density per
| area, and other issues with small colony size.
|
| https://caseyhandmer.wordpress.com/2019/08/20/space-
| based-so...
| oneshtein wrote:
| Mars is very cold, so all this waste heat from nuclear
| reactor can be used to heat spaces, but nuclear reactors
| needs enriched fuel to work, which is dangerous to transport.
|
| If Petrovskite Solar Cells will work on Mars reliably, they
| can be produced directly on Mars and used together with sand
| batteries for stable supply of energy and heat.
| bryanlarsen wrote:
| It's all about the weight. Solar panels are light, nuclear
| reactors are not. Handmer correctly focuses on the metric of
| tonnes per megawatt.
| poulpy123 wrote:
| This man has 2 small self published books on the topic of mars
| colonisation. He is obviously a serious expert to listen
| airstrike wrote:
| I have no opinion on the matter but I feel it is my duty to
| point out that having written books in and of itself is no
| indication of the quality of their work so your stated logic
| does not follow, unless you dropped an /s
| lutusp wrote:
| > This man has 2 small self published books on the topic of
| mars colonisation. He is obviously a serious expert to listen
|
| Well, (a) self-publishing is free, and (b) expertise cannot
| be established by proclamation, it requires evidence. Just as
| in science.
|
| Earlier, the originator proposed an Earth-to-Moon microwave
| power supply link, which makes no sense at all for multiple
| reasons. That proposal suggests a lack of basic engineering
| knowledge.
| Yizahi wrote:
| He is one of the few (only?) person who when talks publicly
| about this or that space projects or ideas, tries to include
| ALL potential costs into big picture, even if they are very
| rough estimates.
|
| Usually when corporations or officials speak about space, they
| cherry pick some single issue, or maybe a few but not all of
| them. E.g. talk about weight but forget about cost, talk about
| weight and cost but forget about cooling. Or when companies
| talk about any complex gadgets in space and forget to account
| for them being space based, thus more complex and expensive.
| These incomplete PR statements are useless for regular people
| outside of the industry because we lack a lot of knowledge to
| fill the gaps.
|
| But reading his posts we can very quickly and reliably get
| basic understanding why some ideas are dead ends for nearest
| century despite being hyped, and why others are potentially
| interesting. Also he references a lot of sources in his posts,
| which would be hard to find but here they are linked in the
| relevant articles.
|
| And finally his roasting of the Space Disgrace System is worth
| it on it's own really :)
| slibhb wrote:
| I only skimmed it but he clearly says that "energy beaming"
| _won 't_ work with Mars.
|
| I also don't think there was any "conflation."
| Out_of_Characte wrote:
| I would love someone with more knowledge to fully explore what a
| similar sized space station could achieve compared to the arduous
| task of going down martian gravity well that has half the solar
| energy and on top of that a night cycle which halves your solar
| output again.
|
| Any viable colonisation strategy would need to overcome the yet
| unknown downsides of lunar/martian dust and many other potential
| threats. What you get back is a rock like earth but without any
| of the useful infrastructure. I just dont see any scenario where
| a mars base would outperform a space station above
| mars/earth/moon/lagrange point with the ability to recover
| asteroids of a few metric tons. Even microgravity issues could be
| solved by making a massive rotating habitat that could serve
| hundreds of people easier than you could keep 10 people alive on
| mars.
| jandrese wrote:
| The advantage of being on Mars is that as your population
| expands you mostly need to just dig more tunnels for them to
| live in. With a space station you have to build more space
| stations or somehow add on to your existing one, which is very
| difficult with artificial gravity setups. The explosive failure
| modes of a space station are less of a concern on an
| underground Mars colony as well.
|
| But this of course raises the question as to why you would do
| either instead of staying on Earth. Elon Musk talks a lot about
| a multi-planetary species, but it's extremely unclear how long
| it would take for a Mars colony to become self sufficient. And
| anything you can do underground on Mars you can do underground
| on Earth but with fewer catastrophic failure cases. The only
| threats a Mars colony protects against are a dinosaur killing
| asteroid strike and a completely runaway greenhouse effect
| turning Earth into a second Venus. Even worse, if Elon were
| serious about the Mars colony he should have multiple fully
| self-sufficient test colonies on Earth vetting out the
| technologies now, but if he had that it negates the need for
| the Mars colonies.
| Mistletoe wrote:
| In addition the surface of Mars has lots of radiation which
| would require you to live under some sort of shielding or in a
| cave.
|
| >The average radiation level on Mars is 24-30 rads (240-300
| mSv) per year, which is 40-50 times higher than Earth's.
|
| Everything on Mars is designed to kill you. I don't understand
| the appeal either except for ultra rich on earth that are
| looking for a new exclusive neighborhood to move into, away
| from the serfs funding it.
| pyrale wrote:
| Earth is boring, Mars is exciting. Why solve the immediately
| available, mundane and sometimes hard issues we have on
| earth, rather than to entertain one's intellect in a purely
| theoretic grapple with the most interesting few of the
| distant problems we'd have on Mars?
| JumpCrisscross wrote:
| > _Why solve the immediately available, mundane and
| sometimes hard issues we have on earth, rather than to
| entertain one 's intellect in a purely theoretic grapple
| with the most interesting few of the distant problems we'd
| have on Mars?_
|
| Because Earth is boring, Mars is exciting. More pointedly:
| on Earth you're fixing problems amidst a tightly-regulated
| _status quo_. On Mars you're pioneering. We have way more
| people in the computer sciences than stewardship roles
| because human nature prefers to explore.
| redundantly wrote:
| > Earth is boring, Mars is exciting. Why solve the
| immediately available, mundane and sometimes hard issues we
| have on earth
|
| Why must they be mutually exclusive?
|
| The space race that started seven decades ago brought
| immense benefits to humanity as a whole. Any progress made
| in the pursuit of colonizing Mars would undoubtedly have
| positive repercussions for us Earthlings.
| lutusp wrote:
| > I would love someone with more knowledge to fully explore
| what a similar sized space station could achieve compared to
| the arduous task of going down martian gravity well that has
| half the solar energy and on top of that a night cycle which
| halves your solar output again.
|
| Issues:
|
| First, the solar energy at the surface is much the same as it
| is in orbit, because of Mars' very thin atmosphere -- unless a
| dust storm kicks in. This means there's no justification to use
| orbital solar with the attendant high capital costs and
| conversion losses.
|
| Second, being able to live below the surface in any of the
| existing lava tubes as protection against high surface
| radiation levels and wide temperature extremes, thus
| eliminating all the complexities of an orbital presence, makes
| the orbital option a non-starter.
|
| Third, an orbital presence would require generating artificial
| gravity to prevent known and serious health issues, less true
| for a surface colony (Mars' surface gravity is 38% that of
| Earth).
|
| Fourth, a carefully chosen lava tube site would have much
| better control over environmental temperatures than a surface
| or orbital colony. Remember that Mars surface temperatures
| regularly drop to -100F overnight. Temperature extremes would
| also be an issue in a lava tube, but with less severity if the
| site were carefully chosen.
|
| I think a Mars colonization project at scale will choose a
| surface colony over an orbital presence on multiple grounds.
|
| > I just dont see any scenario where a mars base would
| outperform a space station above mars/earth/moon/lagrange point
| with the ability to recover asteroids of a few metric tons.
|
| If the mission is to collect or mine asteroids, that would
| change everything. All the above assumes some other purpose --
| for example, Mars surface mining.
| Out_of_Characte wrote:
| >If the mission is to collect or mine asteroids, that would
| change everything. All the above assumes some other purpose
| -- for example, Mars surface mining.
|
| If we had the ability to mine mars, that would change
| everything. But this is precisely why I'm suggesting that a
| station in space might be superiour to any mars base. A
| station doesn't have to be near mars, lots of locations,
| asteroids and points of interest are closer to us than the
| surface of mars. Even going to mars will be easier if you
| have the station first.
|
| >there's no justification to use orbital solar with the
| attendant high capital costs and conversion losses
|
| Are you talking about orbital solar for a non-existent mars
| base? A space station can have 100% uptime of their solars
| cells without the problems dust brings. Mars is the one with
| conversion losses if they need to store any power for any
| length of time.
|
| >being able to live below the surface in any of the existing
| lava tubes as protection
|
| Radiation protection is just a cost figure for a station.
| Converting lava tubes into something we could use seems like
| a herculean effort without even knowing any safety aspects.
| You're just limiting your own space on a dead planet.
|
| >artificial gravity
|
| We could spin the habitat. It would be easier than testing
| lava tube methods of engineering.
|
| >Remember that Mars surface temperatures regularly drop to
| -100F overnight. Temperature extremes would also be an issue
| in a lava tube, but with less severity if the site were
| carefully chosen.
|
| Stations win again as we've already solved this.
| perihelions wrote:
| - _" For example, if we need a gigawatt of energy (10,000 people
| at 100 kW each) and space reactors weigh 150 T/MW, we'll need to
| salami 150,000 T of reactors between 1500 Starship flights..."_
|
| This is not a good estimate because the scaling laws you should
| be looking at are very strongly sub-linear. It's a major error to
| take a 10 kW design and flatly multiply it by 100,000x.
|
| This[0] is what mass-optimized, gigawatt-scale space nuclear
| reactors look like. They don't need 1,500 starships; they would
| fit inside one--they were _designed_ to fit in one, because they
| are rocket propulsion engines.
|
| [0] https://en.wikipedia.org/wiki/Project_Rover
|
| ([late edit]: Anticipating the strongest criticism: _these_ weren
| 't electricity-generating reactors, true--but those subsystems
| can be highly miniaturized as well. The power density of gas
| turbines is incredible. A single Starship has 2 gigawatts of
| turbopump shaft power, distributed between its 30-something
| engine fuel pumps).
| ceejayoz wrote:
| > This is what mass-optimized, gigawatt-scale space nuclear
| reactors look like.
|
| A nuclear _rocket_ and a nuclear _power plant_ are vastly
| different things, for the same reason a jet engine and an oil
| power plant look quite different.
|
| The reactor itself is a spatially small part of everything -
| the little doughnut in the middle.
| https://commons.wikimedia.org/wiki/File:EPR_1_EPR_2_perso.pn...
| perihelions wrote:
| I'm aware of that. But your commercial power plant example is
| also far from optimized for the requirements of a space power
| plant.
|
| ((edit): Your jet engine analogy is apt: a turbojet is a
| highly miniaturized version of the same type of turbine used
| in gas power plants. It'd be quite a mistake to look at a
| power plant turbine and analogize from that that jet
| airplanes are _impossible_ , because, well, just _look_ how
| huge those turbines are!)
| ceejayoz wrote:
| An in-space power plant isn't the proposal, though. It
| would be on Mars, and have similar requirements for
| containment, cooling, maintenance, etc. We are unlikely to
| want to spew radioactive hydrogen all over the landscape.
| perihelions wrote:
| It's a fascinating topic, isn't it?
|
| The hydrogen exhaust in nuclear thermal rockets isn't
| actually radioactive (well, in practice it was, because
| the rockets they actually built had a tendency to fall
| apart and eject bits of their nuclear fuel in the
| exhaust, but on paper that shouldn't happen). But the
| power-plant versions are closed gas loops anyway--you're
| driving the hydrogen or helium through a turbine, it's a
| sealed system.
|
| I don't think you'd choose to build any serious
| containment building on Mars. The baseline risk of death
| on Mars is extremely high; nuclear accident risks don't
| appreciably move the needle. My understanding is what
| you'd actually do is put a biological shield--maybe a
| pile of Martian rock--on the line-of-sight between the
| reactor and the astronaut base, and, simply, never walk
| that way.
|
| Cooling is substantially easier on Mars than in space,
| since there's an atmosphere that functions as a heat
| sink. The space version (i.e., in the nuclear electric
| propulsion context) has a more difficult challenge, with
| radiation as the sole heat dissipation mechanism.
|
| You're right that a space reactor would have to be
| designed for zero maintenance, else it'd be a non-
| starter.
| PaulHoule wrote:
| In theory you can build a low capital cost and compact
| nuclear reactor that operates at high temperature with a
| closed-cycle gas turbine powerset
|
| https://ntrs.nasa.gov/api/citations/20140016755/downloads/2
| 0...
|
| It could be a molten salt reactor or a liquid metal fast
| breeder reactor or a high temperature gas cooled reactor
| (carbide fuel in prismatic or pebble form) It could be
| highly competitive with solar as a carbon free energy
| source for terrestrial use but it is not a bird in the
| hand.
|
| (I think the robots in Gundam use a power plant like that
| which is why Zakus blow up when you hit them)
|
| I imagine the reactor, powerset and all, would be packed up
| into one Starship load but would have some civil works
| (cooling system) assembled on site. In another comment I
| point out Casey is accounting for 1 Starship launch of
| powerplant for 1 Starship load of colonists so this could
| scale OK from that point of view.
|
| Presumably they use a closed fuel cycle which is more like
|
| https://www.youtube.com/watch?v=KEfhx5ovuYk
|
| than Sellafield.
| perihelions wrote:
| - _" but it is not a bird in the hand."_
|
| Kind of amusing to read this in the context of a "city on
| Mars" discussion :)
|
| - _" Presumably they use a closed fuel cycle which is
| more like"_
|
| I doubt this. Nuclear fuel reprocessing is a very
| invasive thing--a difficult industrial process that's
| hard to get working even on Earth, let alone resource-
| constrained environments like a putative Mars settlement.
| I doubt metal-fuel reprocessing like what you linked with
| the EBR changes the equation much.
|
| Reliability and maintenance would be the top drivers
| here. You'd end up with something like the nuclear
| submarine solution: tiny, self-contained systems that (in
| the sub case) are just replaced once every 30 years for
| refueling. This drives you to choose 90% HEU as your
| fuel. Beyond what submarines have as their requirements,
| you're, in addition, critically constrained on mass.
| That, I think, strongly drives you to unmoderated fast
| reactors: small, dense cores with lightweight coolants
| like sodium. From memory, I believe all of the 30+ space
| reactors that were _actually_ built were HEU fast
| reactors with Na or NaK coolant. (There 's actually
| droplets of radioactive NaK in Earth orbit right now,
| according to Wikipedia, because one of them leaked).
|
| (This is not my field of expertise; I just spend a lot of
| time reading NTRS).
| PaulHoule wrote:
| It's hard to say.
|
| HEU cores can go to a high burnup in a fast reactor (and
| leave very little actinide behind) but the burnup is
| limited because U235 depletion will drop reactivity. If
| you are breeding new fuel that reduces the reactivity
| drop.
|
| Modern FBR cores can get maybe 30% burnup of fertile
| material without reprocessing. Rather than the low-
| latency reprocessing cycles that people thought about
| 1950-1970 martians might not think of reprocessing for 20
| years or so.
|
| If they really need to ship 1000+ Starship sized reactors
| they are going to have a different attitude about
| reliability (e.g. a 5% failure rate that don't make a
| mess is no problem)
|
| I could be wrong but I think space colonists would be
| fanatical about a circular economy. If they had 1.5
| million people on the ground they could not count on
| getting a new reactor for every citizen every 25 years.
| I've done some modelling of an asteroid colony where I'd
| expect people to not waste a wisp of carbon dioxide, for
| instance, martians on the other hand would have no
| problem venting it to the atmosphere because they will
| source it from the atmosphere.
| gamblor956 wrote:
| Westinghouse recently announced a mini-nuclear reactor capable
| of powering several hundred homes
| (https://info.westinghousenuclear.com/news/first-canadian-
| evi...). The reactor itself is the size of small apartment and
| would fit aboard a spaceship (the now defunct Space Shuttle)
| and is light enough that a large rocket (like the Saturn) could
| carry it into space. The reactor plant would be constructed
| around the reactor at its final destination (in this particular
| case, Saskatchewan Canada, but for purposes of this discussion,
| Mars).
|
| As a side benefit of the design, it uses the heat of the
| reactor to provide heating, which a Mars colony would need a
| lot of.
| PaulHoule wrote:
| His cost numbers for reliable supply from either nuclear are
| solar are in the $150B per GW range. A reactor like that might
| serve 1.5M terrestrial customers. The thing is martians use
| electricity for everything while flatlanders use a variety of
| energy sources. Also martians use electricity to provide services
| that are provided by the ecosystem on Earth such as breathable
| atmosphere, climate control, prevailing oxidization states, etc.
| His chart says martians use 100x as much water, methane and other
| primary resources so that can support 150,000 martians which also
| take 1500 Starship flights at a cost of $150B. Solar has the
| advantage is that it can be deployed as scalable modules to
| support the first 1,500 martians as well as the next. However 20
| or 30 years in the future those martians need a new power plant.
| If they were serious about establishing a durable presence on
| Mars they'd also be reproducing and growing in population.
|
| Eric Drexler gave up on the Gerard K. O'Neill vision because he
| foresaw the problem of that kind of economy being dependent on
| the Earth for some high-leverage aspects of technology. A Mars
| colony has to expect that terrestrial sponsors may give up on the
| project someday so they have political reasons to develop self-
| sufficiency. (e.g. it's hard to see how a Mars colony would be
| profitable to the Earth as a whole) Some radical advanced in
| manufacturing that allows a small group of people to manufacture
| everything they need for their survival on a strange world seems
| necessary.
|
| Sooner or later the martians will need to build their own solar
| panels, batteries, nuclear reactors, whatever. Today I think it
| is a profitable research area to look into manufacturing
| techniques that might let a colony of 15,000 martians be largely
| self-sufficient in that this research could pay off here on
| Earth.
| ttepasse wrote:
| Some other stuff martians will need:
|
| - Replacement rubber caskets for airlocks and the kilometres of
| plumbing. Synthetic rubber seems petrol based; natural rubber
| trees seem to need a lot of space.
|
| - A source of fabric for clothes and other cloth stuff.
| Presumably natural fibres like hemp or cotton or plastic
| fibres. Sheep, I think, will be right out. Mars is vegan.
|
| - An enormous amount of greenhouses (a lot of glass) or grow
| houses (energy, insulation) for growing the vegan diet. I
| assume a Martian colony will look something like this:
| https://earthobservatory.nasa.gov/images/150070/almerias-sea...
| PaulHoule wrote:
| I am not that worried that petrol can be replaced for
| "petrochemical" applications. Somewhere there is going to be
| a carbon processing system that harvests CO2 from the
| atmosphere and either feeds it to plants or cracks it into CO
| + O2 and builds up larger molecules. Between Fisher-Trospch
| type chemistry, pyrolysis of waste products and other
| methods, not to mention advanced biotech, quite a bit should
| be possible. If we're ever going to have carbon neutral
| chemicals we'll have to figure this out for terrestrial use.
| aziaziazi wrote:
| Nice! Would that fit (unmounted/folded) inside a reasonable
| number of rockets?
|
| Wonder also what's the plans to process those chemicals to
| finite products, in quality high enough to leverage auto-
| production for those facilities (some) spare parts.
| AlotOfReading wrote:
| It's basically the same stuff the rockets themselves are
| made of. Large towers with miles of plumbing and
| corrosion resistant tanks.
| codesnik wrote:
| for a lot of stuff we make from rubber various types of
| silicone polymers would probably work too.
| ptek wrote:
| >Today I think it is a profitable research area to look into
| manufacturing techniques that might let a colony of 15,000
| martians be largely self-sufficient in that this research could
| pay off here on Earth.
|
| I don't know how they will be able to manufacture CPUs on Mars,
| I'm guessing 8-bit CPUs will be more possible than modern day
| CPUs. I think even Motorola 68K will still require advanced
| manufacturing equipment to transport to manufacture.
|
| I guess with close to 50 years of CPU design knowledge they
| would be able to design a decent 8-bit CPU with 16-bit address
| space. Maybe they would use first 512 bytes as a data/code
| cache to speed up certain calculations (trig functions) (Not a
| EE, studying Mechanical). Although there is a lot of code
| available for Z80, 6502, 8080 CPUs.
| lutusp wrote:
| > [ ... ] The second reveals that beaming power to the lunar base
| region with microwaves from Earth is by far the cheapest, most
| flexible option - for operations on the Earth facing side of the
| Moon.
|
| Sorry, this fails several tests of common sense. Compare the
| alternatives: * A suitably large solar array
| near the Moon's north or south pole, with DC transmission lines
| to the point of use, able to provide continuous power during all
| lunar phases. * A solar array on Earth, then a
| microwave converter, then a phased-array beam of microwaves to
| the moon, then an equal-sized phased-array microwave receiver on
| the moon, then a converter from microwaves to DC, finally a lunar
| transmission line of some length to (a) avoid the area
| immediately beneath the microwave high-flux area and (b) convey
| the power to the point of use.
|
| The second option is a non-starter on multiple grounds, starting
| with the antenna sizes that would be required -- on both ends --
| to avoid spilling the majority of the microwave energy outside
| the beam path. Then there's the issue of multiple conversion
| losses: Earth solar collector -> DC to microwave loss -> losses
| while being beamed to the moon -> microwave to DC loss -> to
| point of use.
|
| Let me re-emphasize this one line: "... beaming power to the
| lunar base region with microwaves from Earth is by far the
| cheapest, most flexible option ..."
|
| Well, no. Not really. Not remotely. Even geostationary microwave
| power stations have multiple-conversion and beam-width power loss
| issues, and that's a small fraction of the Earth - Moon distance.
| JumpCrisscross wrote:
| You're ignoring the mass-transmission losses of moving heavy
| panels to the Moon. Concluding the author's back-of-the-
| envelope math is a "non-starter" with zero numbers, just hand
| waiving, is heavy with hubris.
| lutusp wrote:
| > You're ignoring the mass-transmission losses of moving
| heavy panels to the Moon.
|
| I passed on that because both options require a lot of mass
| transfer -- either solar panels or microwave antennas.
| nanna wrote:
| It looks great, I hope Musk moves there soon.
| londons_explore wrote:
| Earth solar cells are thick and heavy mostly because of the
| protective glass, frames, etc.
|
| The actual silicon is under a millimeter thick, and presumably
| could be made even thinner.
|
| On Mars, with a super thin atmosphere, there may be no need to
| protect the cells. Just laying plain cells on the ground might
| prove cheapest. Sure, they'd be super fragile (imagine potato
| chips the size of a person and how hard they would be to lay flat
| on the ground without breaking) and you'd probably have to come
| up with special techniques to lay them whilst breaking as few as
| possible.
|
| Wiring is probably the next heaviest component. But with no
| atmosphere, there is no need for wires to be waterproof or have
| insulation. Wires could be bare aluminium.
| pohl wrote:
| It's probably the martian dust and not the thickness of the
| atmosphere that creates the need for protection.
| micromacrofoot wrote:
| absolutely need dust protection on Mars, more than on earth
|
| wind speeds are generally lower, but the dust is
| thermostatically charged, tends to stick to everything, and is
| incredibly abrasive -- wires would also need to be insulated
| from Mars dust because it's conductive
|
| it's a very hostile environment for solar, dramatic temperature
| changes are also a factor
| londons_explore wrote:
| mars dust is conductive? Thats news to me.
| RandallBrown wrote:
| News to me as well, but it makes sense at least on the
| surface. Mars is red because it's covered in rusty iron.
| micromacrofoot wrote:
| it's incredibly dry so not hugely conductive, but any
| moisture will cause perchlorates within it to dissociate
| into ions
|
| I wouldn't want to bury a bunch of unshielded wire in it,
| especially if the wires ever get hot (which can produce
| moisture given the presence of specific minerals)
| hnuser123456 wrote:
| There are folding camping solar panels that are designed to
| balance portability with reasonable durability.
| lialopx wrote:
| ?
| lpapez wrote:
| One thing I never understand with these terraforming startups is:
| instead of terraforming Mars, isn't it much more economically
| valuable to terraform chunks of Earth?
|
| At the end all of this boils down to economics, and instead of
| spending trillions to terafform Mars, you can buy large swathes
| of unproductive land on Earth and try to develop that...
| carabiner wrote:
| It's nothing to do with economics. Was landing people on the
| moon economics?
|
| Why climb a mountain?
| tete wrote:
| > Was landing people on the moon economics?
|
| No it was an investment. Military and civil research (in so
| many fields), as well as propaganda (to USSR, US and the
| world). It was the cold war.
|
| See also: https://en.wikipedia.org/wiki/National_Aeronautics_
| and_Space...
|
| > Why climb a mountain?
|
| Sports, hobby, in some cases I am sure also inferiority
| complex.
|
| Neither were done by companies though, so the question still
| holds, when there appear to be more viable options.
|
| I am not going to judge what makes economic sense, but these
| questions really don't seem related.
| ianburrell wrote:
| There is a difference between climbing a mountain and living
| on top of a mountain. Going to Mars and exploring it is a
| good goal. Colonizing Mars is a bad idea because it is so
| hard.
| tim333 wrote:
| I'm not sure there's much of an economic case for terraforming
| Mars so much as it seeming kind of cool to be multiplanetary.
| I'm not sure what the startups are selling.
|
| That said I think I'd prefer they kept it more as national park
| / site of special scientific interest rather than a
| construction site.
| ketzo wrote:
| The author of this blog is also very into terraforming Earth!
| https://caseyhandmer.wordpress.com/2024/10/26/we-can-terrafo...
| perihelions wrote:
| - _" For example, if we need a gigawatt of energy (10,000 people
| at 100 kW each) and space reactors weigh (
| https://en.wikipedia.org/wiki/Kilopower ) 150 T/MW, we'll need to
| salami 150,000 T of reactors between 1500 Starship flights..."_
|
| The example he's drawing on (NASA's Kilopower concept) is a
| 10-kilowatt sized reactor and it's probably a bad extrapolation
| to scale from that to the 1-gigawatt scale, linearly.
|
| This is at least a 50-fold overestimate of mass. From nuclear
| electric propulsion literature [0], the mass budget for space
| electric power plants at the 15- _megawatt_ scale optimizes to
| around 3 tons / megawatt. (I couldn't find serious engineering
| studies at the gigawatt scale).
|
| [0] https://inldigitallibrary.inl.gov/sites/sti/sti/2688772.pdf (
| _" Multi-Megawatt Power System Analysis Report"_ (2011))
|
| (Mainly, the closed Brayton power systems summarized in table 4,
| on page 26)
| CapricornNoble wrote:
| As an aside, post-2000 research like your link really makes me
| wanna dive into notoriously-crunchy sci-fi RPG & wargame
| systems and validate/update their construction rules to account
| for advances in the science. Mostly thinking GURPS: Vehicles
| and Traveller's Fire, Fusion, and Steel....
|
| https://boardgamegeek.com/rpgitem/49409/fire-fusion-and-stee...
| tim333 wrote:
| >10,000 people at 100 kW each... 150,000 T of reactors ... 1500
| Starship flights...
|
| It would seem much more practical, given the way AI and robotics
| are going, to send a bunch of robots down there to build the Mars
| base. Then subsequently humans could go visit to avoid an
| asteroid or take selfies or whatever.
| jimnotgym wrote:
| > A growing Mars base has a prodigious need for power.
|
| Has it?
|
| Or will it?
|
| Or might it?
| nickdothutton wrote:
| ~200MWt reactors are common in large nuclear submarines and
| weight about 2000 tons, not sure how much of that (if any) is
| shielding, but the figures for reactor weight sound high. I'd
| imagine for joules/kg nuclear would be hard to beat.
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