Solar because r^2 diminishing returns
You may enjoy his recent interview on Patio11's podcast:
[1] https://www.complexsystemspodcast.com/episodes/solar-economi...
> 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.
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.
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.
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.
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).
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.
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.
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.
https://caseyhandmer.wordpress.com/2019/08/20/space-based-so...
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.
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.
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 :)
I also don't think there was any "conflation."
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.
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.
>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.
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.
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.
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.
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.
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).
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...
((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!)
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.
https://ntrs.nasa.gov/api/citations/20140016755/downloads/20...
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.
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).
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.
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.
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.
- 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...
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.
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.
If you send up a wafer per person, which can be laser cut and placed into more easily constructed electronics locally, you've got hundreds of years to solve the fab problem in a worst case, Earth no longer exists situation.
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.
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.
I passed on that because both options require a lot of mass transfer -- either solar panels or microwave antennas.
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.
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
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)
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...
Why climb a mountain?
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.
That said I think I'd prefer they kept it more as national park / site of special scientific interest rather than a construction site.
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)
https://boardgamegeek.com/rpgitem/49409/fire-fusion-and-stee...
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.
Has it?
Or will it?
Or might it?