Mars looks like a cold desert we could settle, but its surface would kill an unprotected person within minutes. The deeper problem is that nearly every basic thing Earth gives us for free, from air pressure to a radiation shield to farmable soil, is missing there. Living on Mars isn’t one problem to solve but a whole set of them, all of which have to be solved at once and kept solved for years.
The Air Is Too Thin to Keep You Alive
Water boils at a lower temperature when the air pressure around it drops. At a pressure of about 6.3 kilopascals, water boils at body temperature, 37 °C.1PubMed. Armstrong limit The air pressure on the Martian surface is far below that limit, under 1 kilopascal, less than 1% of Earth’s. So on Mars, exposed body fluids such as saliva, tears and the liquid lining the lungs would boil away without a full pressure suit.2PubMed. Armstrong limit3Eye News. Globes in space: What would happen to our globes on the globe of Mars? Blood inside your blood vessels would not boil, because the body keeps it under its own pressure.4PubMed. Armstrong limit
The first minutes would go quickly. You would lose consciousness within roughly 15 seconds as your lungs ran out of oxygen. Moisture on the tongue and eyes would bubble and evaporate. Skin and tissue would swell, but they would not burst the way some films show. Rescue within a minute or two could be survivable; much longer, and survival becomes unlikely.
Pressure is the deadly part, not the cold. Boiling here doesn’t mean scalding. The fluid evaporates because the pressure is too low to hold it as a liquid, and that evaporation pulls heat away from the tissue. Mars is very cold too, but the cold would take far longer to hurt you than the missing oxygen and pressure would.
The thin air that does exist is about 95% carbon dioxide, with only traces of oxygen. Every breath, and every room, would need oxygen supplied from tanks or made on site.
A simple oxygen mask isn’t enough, because it fixes the oxygen but not the pressure. Outside, a full pressurized suit or a sealed habitat is essential at all times.
Radiation With No Shield Overhead
Earth’s magnetic field and thick atmosphere block most radiation from space. Mars has no strong magnetic field of its own.5PubMed. Loss of atmosphere from Mars due to solar wind-induced sputtering The solar wind, the stream of particles from the Sun, has therefore stripped away much of its air over billions of years.6PubMed. Loss of atmosphere from Mars due to solar wind-induced sputtering
Radiation on the Martian surface comes mainly from cosmic rays, high-energy particles from deep space that pass through the thin air.7Icarus. The Martian surface radiation environment at solar minimum measured with MSL/RAD Solar storms add sudden strong bursts.8Icarus. The Martian surface radiation environment at solar minimum measured with MSL/RAD The Curiosity rover has measured this radiation directly on the surface across hundreds of days.9CaltechAUTHORS. Mars’ Surface Radiation Environment Measured with the Mars Science Laboratory’s Curiosity Rover The particles can penetrate shielding and damage DNA, so long stays raise the risk of cancer, memory and thinking problems, heart disease and eye damage.10New Space. Cosmic Radiation: Challenges and Innovations in Mitigating Risks for Long-Term Space Missions The harm builds up over months and years, which makes permanent living far riskier than a short visit.
Settlers could protect themselves in a few ways. Living underground or under thick layers of soil blocks much of the radiation. Water and dense materials make good shields, though they are heavy to bring. A solar storm would mean retreating to a shelter for hours or days. No shield removes the risk fully, so time on the surface would be rationed.
Brutal Cold and Toxic, Gritty Dust
The average surface temperature on Mars is about -63 °C.11Elsevier. Conceptual design and research on the thermal performance of a martian human base It ranges from around -153 °C to about 24 °C.12Elsevier. Conceptual design and research on the thermal performance of a martian human base Any habitat needs precise heating and insulation to stay livable.13Elsevier. Conceptual design and research on the thermal performance of a martian human base
Water pipes and batteries fail if they freeze, and nights get far colder than days, which stresses materials. Heating takes power, and dust storms can cut that power.
The dust is a problem in its own right. Martian dust contains chemicals such as perchlorate and a toxic form of chromium.14PubMed Central. Potential Health Impacts, Treatments, and Countermeasures of Martian Dust on Future Human Space Exploration In lab tests, simulated Martian dust damaged lung cells and triggered inflammation.15PubMed Central. Potential pulmonary toxic effects of Martian dust simulant In mice, it caused lung inflammation and scarring that lasted months.16PubMed. Pulmonary toxicity of simulated lunar and Martian dusts in mice: I. Histopathology 7 and 90 days after intratracheal instillation Researchers have proposed iodine and vitamin C supplements to counter mild ongoing exposure.17PubMed Central. Potential Health Impacts, Treatments, and Countermeasures of Martian Dust on Future Human Space Exploration
Dust clings to suits after every walk outside, which is why airlocks and suit ports are designed to keep suits outdoors. Fine particles can still stay airborne inside a habitat, so cleaning systems would have to run continuously.
Dust also wears down technology. Dust storms coat solar panels and reduce how much power they produce.18Solar Energy Materials and Solar Cells. A study of photovoltaic degradation modes due to dust interaction on Mars Hard, sharp dust grains get into moving parts and scrape away seals and shafts.19PubMed Central. Tribological performance of mechanical face seals for Martian applications The equipment that keeps people alive would need constant cleaning and repair.
Low Gravity Wears Down the Body
Mars’ gravity is about 0.38 times Earth’s. Moving your body takes less effort there, and over time that causes bone loss, heart weakening and changes in how you move.20ICES. The Partial Gravity of the Moon and Mars Appears Insufficient to Maintain Human Health Gravity below about 0.4 times Earth’s appears too weak to keep muscles, bones, heart and lungs healthy long-term.21PubMed Central. Human Biomechanical and Cardiopulmonary Responses to Partial Gravity – A Systematic Review Settlers would likely need daily exercise routines to stay healthy.22PubMed Central. Human Biomechanical and Cardiopulmonary Responses to Partial Gravity – A Systematic Review Station crews float with no gravity but return within months, while Mars residents might never go back. No human has lived in Mars-level gravity for long, and partial gravity is barely tested.
Growing Food and Finding Water
Martian soil has no organic matter, unlike Earth soil.23PubMed. How to make the Lunar and Martian soils suitable for food production – Assessing the changes after manure addition and implications for plant growth It supplies some minerals like calcium, iron and potassium but lacks nitrogen, phosphorus and sulfur.24PubMed Central. Mars Regolith Simulant Ameliorated by Compost as in situ Cultivation Substrate Improves Lettuce Growth and Nutritional Aspects It also holds water poorly and is very alkaline, so it couldn’t properly support potato plants on its own.25PubMed Central. Assessment of Fertility Dynamics and Nutritional Quality of Potato Tubers in a Compost-Amended Mars Regolith Simulant Mixing in compost improved its structure, water holding and fertility, and crops grew better.26PubMed Central. Mars Regolith Simulant Ameliorated by Compost as in situ Cultivation Substrate Improves Lettuce Growth and Nutritional Aspects27PubMed Central. Assessment of Fertility Dynamics and Nutritional Quality of Potato Tubers in a Compost-Amended Mars Regolith Simulant Lettuce in pure simulated Mars soil grew about 20% less than in a compost mix.28PubMed Central. Mars Regolith Simulant Ameliorated by Compost as in situ Cultivation Substrate Improves Lettuce Growth and Nutritional Aspects Farming would depend on bringing or producing compost, and on removing toxic perchlorate.
Crops need a pressurized, heated, lit greenhouse. The soil must be cleaned of toxic chemicals first. Compost requires existing organic waste to start. And crops grown in space have sometimes been stunted or failed to make seeds.
Water is locked underground. Large deposits of ice lie beneath the surface in Mars’ middle latitudes.29AIAA AVIATION FORUM AND ASCEND 2025. Advanced Deep-Drilling Technology for Subsurface Ice Melting and Water Extraction on Mars Reaching it is difficult because of its depth, the unpredictable ground above it and the harsh conditions.30AIAA AVIATION FORUM AND ASCEND 2025. Advanced Deep-Drilling Technology for Subsurface Ice Melting and Water Extraction on Mars Water for drinking, oxygen and rocket fuel would require drilling and melting equipment that doesn’t yet exist at scale.31AIAA AVIATION FORUM AND ASCEND 2025. Advanced Deep-Drilling Technology for Subsurface Ice Melting and Water Extraction on Mars
Life Support and Getting There
A system that recycles air, water and food with plants for six people on a 780-day mission was estimated at about 18 tonnes.32PubMed Central. Supplementing Closed Ecological Life Support Systems with In-Situ Resources on the Moon That is about four times heavier than a space-station-style system that relies more on stored supplies.33PubMed Central. Supplementing Closed Ecological Life Support Systems with In-Situ Resources on the Moon The plant system still lacked enough oxygen, which would have to come from local ice.34PubMed Central. Supplementing Closed Ecological Life Support Systems with In-Situ Resources on the Moon Growing food only pays off for missions longer than about 2 to 3 years.35PubMed Central. Supplementing Closed Ecological Life Support Systems with In-Situ Resources on the Moon
Landing is its own obstacle. A crewed Mars mission needs to land roughly 20 to 100 tonnes of cargo.36IEEE Aerospace Conference. A Survey of Supersonic Retropropulsion Technology for Mars Entry, Descent, and Landing The parachute-based methods used since the 1970s can’t scale to those sizes.37Journal of Spacecraft and Rockets. Development of Supersonic Retropropulsion for Future Mars Entry, Descent, and Landing Systems38IEEE Aerospace Conference. A Survey of Supersonic Retropropulsion Technology for Mars Entry, Descent, and Landing The thin air gives little drag, and parachutes can’t be made big enough.39IEEE Aerospace Conference. A Survey of Supersonic Retropropulsion Technology for Mars Entry, Descent, and Landing So engineers are developing ways to fire rockets against the direction of travel at supersonic speed to slow down.40Journal of Spacecraft and Rockets. Development of Supersonic Retropropulsion for Future Mars Entry, Descent, and Landing Systems There’s no runway or ocean splashdown, so every landing must be fully automatic and precise.
Resupply can’t rescue a failing colony either. Launch windows to Mars open only about every 26 months, and the trip takes many months. Broken equipment must be fixed with what’s on hand.
Isolation and Delayed Calls Home
A message to Earth and back can take up to 44 minutes when Mars is farthest away.41NASA Technical Reports Server. Assessment of the State of Communication Delay Research in Preparation for Missions Beyond Low Earth Orbit Live conversations and real-time help from mission control are impossible.42NASA Technical Reports Server. Assessment of the State of Communication Delay Research in Preparation for Missions Beyond Low Earth Orbit These delays add stress and frustration and reduce how well people perform.43NASA Technical Reports Server. Assessment of the State of Communication Delay Research in Preparation for Missions Beyond Low Earth Orbit In an emergency, crews must have the skills to act completely alone.
Isolation takes its own toll. In Antarctic winter crews, loneliness, paranoid thoughts and conflict grew over time while team cohesion fell.44PubMed Central. Social interactions in isolated, confined, and extreme environments: A study of Antarctic winter teams using wearable sensors A small Mars crew would face similar or stronger strain, without the chance of leaving.
Why We Can’t Just Make Mars Like Earth
Terraforming means warming Mars and thickening its air enough to make it Earth-like. The main idea is releasing carbon dioxide trapped in ice and rock to create a greenhouse effect. But Mars doesn’t hold enough carbon dioxide to cause significant warming.45Nature Astronomy. Inventory of CO2 available for terraforming Mars46NASA. Mars Terraforming Not Possible Using Present-Day Technology – NASA Most of what remains is locked away and can’t readily be released.47Nature Astronomy. Inventory of CO2 available for terraforming Mars Making Mars Earth-like isn’t possible using present-day technology.48Nature Astronomy. Inventory of CO2 available for terraforming Mars49NASA. Mars Terraforming Not Possible Using Present-Day Technology – NASA Even a success might not last, because Mars lacks a magnetic field and any added air would slowly leak away again.
Protecting Mars From Us
More missions to Mars raise the risk of carrying Earth microbes there.50PubMed. Assessment of the Forward Contamination Risk of Mars by Clean Room Isolates from Space-Craft Assembly Facilities through Aeolian Transport – a Model Study Mars may be the best place to search for life beyond Earth, and international space agreements since 1964 call for keeping it uncontaminated until that search is done.51The National Academies Press. Preventing the Forward Contamination of Mars A human settlement would bring trillions of microbes, making that search much harder.
Robots can be sterilized, but people can’t. Humans shed microbes constantly through breath and skin, and habitat leaks and waste could spread them across the surface.