stock here: sorry for the A-Eye blast out. Have a Look-See
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so do a deep dive on solar energy on mars, and what would it take to exist there for humans, to grow food using solar energy (its like 1/6 right?) and being “sustainable”. Seems very shaky to me, like it would be expensive, and why….like Musk likes to think it is a backup to sustain the human species if something happened to earth. Do an energy balance,,,,,Thought for 56s
Yes — the backup-species pitch gets shaky fast once you run the energy balance.
The first correction is this: Mars is not at 1/6 of Earth’s sunlight. Mars sits about 1.5 AU from the Sun, so sunlight at Mars orbit is about 43% of Earth’s before you even account for the dusty atmosphere. NASA plant researchers use that same 43% figure, and Mars solar-power work emphasizes additional losses from suspended dust, dust deposition on panels, and low temperatures.
A second correction: solar on Mars is not just a “lower output version of Arizona solar.” It is a storage and survivability problem. Mars has a 24.6-hour day, big seasonal swings because of its elliptical orbit, and an atmosphere whose mass changes by about 30% annually. Dust storms and background dust reduce sunlight further, and NASA’s Mars power work treats those as central design constraints.
My bottom-line view: a Mars outpost can use solar, but a genuinely sustainable human settlement cannot sensibly rely on solar alone. It would need nuclear baseline power, solar as a supplement, very large storage, and aggressive recycling/ISRU. NASA’s own current Mars surface power framing points the same way: even a short two-crew mission needs about 10 kW minimum practical power, while power can rise toward megawatt class for ISRU-heavy architectures; NASA is also explicitly advancing 40-kW-class fission surface power because it provides continuous power regardless of environmental conditions.
Start with the solar resource
At Earth orbit the Sun delivers about 1,360 W/m²; Mars, at about 1.5 AU, receives much less, which is why NASA and NASA-affiliated Mars agriculture work refer to roughly 43% as much sunlight. On top of that, Mars’s atmosphere and dust cut surface irradiance further, and panel dust accumulation matters enough that NASA has treated it as a major system issue for Mars photovoltaics.
So the usable picture is:
Earth orbit: ~1360 W/m²
Mars orbit: ~590 W/m²
Mars surface: lower still, often materially lower, depending on sun angle, season, latitude, and dust.
That means the “nameplate” problem is already hard, and the continuous-power problem is much harder because half the sol is night and dust events can hammer output for days or weeks. NASA’s Mars solar and dust-storm literature has been explicit about dark days and large performance swings under storm conditions.
What a small solar base would actually need
Take a deliberately modest crewed outpost and ignore return-propellant production for the moment.
Assume a small base wants a continuous 100 kW electric average. That is not crazy-high once you include habitat systems, water processing, oxygen systems, food systems, tools, mobility, thermal control, comms, and margin. NASA documents show even conceptual Mars missions quickly rise well above the bare-minimum human-habitation figure, and older mission studies showed around 50 kW just for a cargo mission supporting propellant plant, life support cache, and habitat needs.
Now do rough PV sizing.
Use these simplifying assumptions:
- Mars peak sunlight at array level after geometry/dust losses is not the raw 590 W/m² all day.
- Good PV efficiency might be around 25%.
- Effective capacity factor on Mars for fixed or lightly tracked arrays in real conditions might land roughly in the 0.2–0.3 band once day/night and environmental losses are accounted for.
That gives average delivered power per square meter on the order of about 30–45 W/m².
So:
- 100 kW continuous needs roughly 2,200 to 3,300 m² of active PV just in favorable conditions.
- Add dust degradation, aging, seasonal margin, and operational reserve, and you are soon more in the realm of several thousand square meters, not a cute little rooftop. This is inference from the cited Mars solar constraints plus standard PV arithmetic.
That is before the real killer: storage.
The storage problem is what breaks the “solar-only civilization” idea
Night alone is manageable with batteries if your base is small.
For 100 kW continuous, one 12-hour night is about 1.2 MWh.
For 24 hours of reserve, about 2.4 MWh.
For 7 sols of poor production, about 16.8 MWh.
For 30 sols, about 72 MWh.
That is only for the base load. It does not include big episodic loads like heavy excavation, large-scale electrolysis, or industrial food production under artificial light.
And Mars dust events are not hypothetical. NASA’s own Mars solar literature treats high optical depth and “dark days” during global storms as design realities, while dust storms can substantially reduce flux to the surface.
So the core objection is strong: solar can run a base on Mars; solar alone is a bad bet for guaranteeing human continuity on Mars.
Food changes the math a lot
This is where “sustainable” gets slippery.
If you mean:
- some salad, herbs, psychological benefit, and oxygen recycling, that is plausible;
- full calorie autonomy for a permanent settlement, that is much harder.
Greenhouse crops such as lettuce need a daily light integral of about 15–20 mol/m²/day just as a benchmark crop. Purdue’s greenhouse guidance uses lettuce as a moderate-light example. NASA plant work says many low-latitude Mars regions receive enough sunlight to grow plants, but that does not mean unprotected, low-maintenance, field-style agriculture. Mars crops would still need controlled conditions.
The problem is that Mars greenhouses are not Earth greenhouses. They must also solve:
- pressure containment,
- thermal control,
- radiation shielding,
- dust exclusion,
- water recovery,
- nutrient recycling,
- often supplemental lighting.
The atmosphere is so thin that liquid water is not stable on the Martian surface, which is why NASA treats buried ice as a vital resource and why water handling must be enclosed.
And if you abandon sunlight and go to indoor LED farming, the energy burden jumps. Recent plant-factory modeling puts lettuce around 6.2–12.0 kWh/kg, with many studies clustering around 10–18 kWh/kg in current practice. That is lettuce — a poor calorie crop. It is good nutrition, not a civilization-saving staple.
So a Mars settlement that wants to survive on local food would likely do some combination of:
- sunlight-assisted greenhouses for bulky biomass and psychological benefit,
- tightly controlled indoor production for sensitive crops,
- imported food for years,
- and eventually selected staple crops grown in highly optimized systems.
But that is not “cheap solar farming.” It is industrial life support that happens to include plants.
Water, oxygen, and fuel are possible — but energy-intensive
Mars does offer one huge advantage: CO₂-rich atmosphere plus accessible subsurface ice in some regions. NASA’s SWIM maps show likely water ice within the upper 1 meter in large areas, and NASA explicitly says this buried ice would be vital for drinking water and rocket fuel.
Oxygen production from the atmosphere is real, but MOXIE shows both promise and scale limits. MOXIE produced up to 12 grams of O₂ per hour at high purity and made 122 grams total over its Mars mission. That is a successful technology demo, but it also shows how far there is to go from “it works” to “it supports a settlement.”
So yes, you can envision:
- mine ice,
- purify water,
- electrolyze water,
- use Sabatier chemistry with CO₂ to make methane and oxygen,
- recycle crew waste streams.
But each step costs power. NASA’s ISRU roadmaps and Mars mission power studies have long treated these systems as major electrical loads, not side chores.
Radiation makes “surface greenhouse homestead” less attractive
Mars is not just dimmer; it is also harsher. Curiosity’s RAD measured a surface dose rate around 210 micrograys per day from galactic cosmic rays alone during its observations, and NASA notes solar particle events remain a major uncertainty for human exposure. Another NASA educational summary puts average surface dose near 0.7 mSv/day.
That pushes serious habitat design toward:
- bermed or buried habitats,
- regolith shielding,
- shielded storm shelters,
- and possibly partly buried agriculture.
Once you bury habitats and grow spaces, you lose direct sunlight and start paying the electricity bill for lighting. Again: this pushes the system away from “solar settlement” and toward power-intensive underground life support.
So is Mars a backup for humanity?
As a small scientific or strategic outpost, yes, maybe eventually.
As a true backup of human civilization, not remotely in the near term.
A real species-backup location should be able to survive:
- long supply interruptions,
- local equipment failures,
- low-sun periods,
- medical emergencies,
- industrial spare-parts shortages,
- and multi-year crop or power problems.
Mars fails that test unless you build an enormous industrial stack:
- redundant power,
- mining,
- metallurgy,
- pressure-vessel manufacturing,
- electronics repair,
- chemicals,
- medicine,
- radiation shielding,
- heavy storage,
- agriculture,
- and transport.
That is not a colony in the romantic sense. It is a high-maintenance off-world industrial bunker.
My practical energy-balance verdict
If you forced me to summarize it in one line:
Mars solar is good enough to supplement a base, bad as the sole foundation of a self-sustaining civilization.
A plausible long-duration Mars architecture looks more like:
- nuclear baseload for habitat, life support, and critical ISRU,
- solar augmentation for daytime and noncritical loads,
- large energy storage for ride-through and resilience,
- buried or shielded habitats,
- greenhouses plus controlled-environment agriculture,
- aggressive recycling and ice mining,
- years of imported spare parts and food buffer.
That is why NASA is pursuing fission surface power for future Moon and Mars operations, not because solar is useless, but because survival systems hate intermittency.
So your instinct is basically right: the economics are brutal, the energy margins are thin, and the “Mars as easy backup Earth” story is much more marketing than engineering.