Mars is the only other planet in the solar system a human could plausibly stand on. It is also −63 °C on average, holds six millibars of unbreathable carbon dioxide, lost its magnetic field four billion years ago, and is covered in dust laced with perchlorate salts.
Every proposal to fix that falls into one of six problems. Each system below is a real, published answer to one of them — with what it would cost, what it would deliver, and the reason it might not be the right move. Nothing here is invented: the numbers come from Jakosky and Edwards, Kite, Wordsworth, Zubrin and McKay, DuPont and Murphy, and the 2025–2026 terraforming roadmaps.
The honest headline: the current literature says warming regions of Mars is plausible on near-term industrial scales, and converting the whole atmosphere is not.
Mars averages −63 °C. How do you heat a planet?
A mirror the size of a small country, aimed at the pole.
Glitter, nine microns long, that turns the sky into a blanket.
Deliberately building the pollution Earth spent decades banning.
Two centimetres of frozen smoke, and the ground beneath is habitable.
The planet keeps its spare atmosphere frozen at the south pole.
Six millibars of carbon dioxide. How do you build an atmosphere?
Six millibars of the wrong gas, and blood that boils at body heat.
A toaster-sized box on Perseverance already did it, 122 grams at a time.
The gas nobody thinks about is the one Mars cannot supply.
If the planet lacks air, throw air at it.
No magnetic field, no ozone, toxic dust. How do you survive the environment?
Mars lost its magnetic field four billion years ago. This is the replacement.
Measured, not modelled: a rover has been counting since 2012.
The planet is covered in a toxic powder that gets into everything.
The ice is there and it cannot be liquid. How do you get water?
Sterile rock, no soil, no oxygen. How do you make it alive?
Let something alive do the work the machines cannot afford.
Mars has dirt. Dirt is not soil, and Martian dirt is poisonous.
Resupply takes two years. The greenhouse is not optional.
Two years from resupply. How do people actually live there?
The best house on Mars is a cave that already exists.
Everything on this list is a power problem wearing a costume.
Do not bring the return trip with you. Manufacture it there.
The one variable nobody can test without going.
The planets line up every 26 months, and not a day sooner.
Cover the parts you need instead of converting a world.
Three findings define the field. Jakosky and Edwards (2018) established that every accessible source of carbon dioxide on Mars tops out near 7% of Earth's sea-level pressure. Kite and colleagues (2024) showed that engineered nanorods warm Mars more than 5,000 times more efficiently than any gas, which makes warming a decades problem rather than a centuries one. Turyshev (2026) put numbers on the rest: 3.89 × 10¹⁵ kg of gas per millibar, more than 10²⁵ joules of work to oxygenate the planet, and hundreds of terawatts to petawatts of sustained power.
Taken together they point the same way. Regional habitability — aerogel sheets, domes, buried habitats, warmed patches of ground — is achievable on industrial scales we can imagine. A second Earth is not, without volatile inventories Mars does not contain.
Not with anything close to present technology. Jakosky and Edwards showed in 2018 that every accessible source of carbon dioxide on Mars would raise pressure to at most about 7% of Earth's, and constraint analyses put full open-atmosphere terraforming at hundreds of terawatts sustained over centuries. Making regions of Mars habitable — paraterraforming — is the version current research considers feasible.
Engineered conductive nanorods about 9 micrometres long. Modelling published in Science Advances in 2024 found they warm Mars more than 5,000 times more effectively than the best greenhouse gases, and that releasing roughly 30 litres per second could raise the surface by more than 30 K within decades.
Warming enough for liquid water is modelled in decades with engineered aerosols. Producing enough oxygen for complex life by biological means is estimated at roughly a thousand years. Full industrial oxygenation runs to centuries or millennia.
Without one the solar wind strips the atmosphere, which is how Mars lost most of its air in the first place. The loss is slow — hundreds of millions of years — so a shield matters for permanence rather than for a first settlement.
Two things tie. Oxygen requires more than 10^25 joules of thermodynamic work to produce planet-wide, and nitrogen — the buffer gas that makes oxygen safe to breathe — would have to be imported by the hundred trillion tonnes because Mars has almost none.
