There is no breathable air on Mars for humans. The Martian atmosphere is different from Earth’s, lacking necessary oxygen and being extremely thin. Humans venturing onto the Martian surface require advanced life support systems to survive its harsh conditions.
Mars’s Atmospheric Makeup
The atmosphere of Mars is very tenuous, averaging 6 to 7 millibars of pressure, less than one percent of Earth’s. A comparable Earth pressure is found at about 45 kilometers (28 miles) altitude. The planet’s atmosphere is primarily composed of carbon dioxide, making up 95.32% to 96% of its volume.
Trace amounts of other gases include nitrogen (2.7% to 3%), argon (1.6% to 1.93%), molecular oxygen (0.13% to 0.174%), carbon monoxide, water vapor, and other noble gases. This thin, carbon dioxide-rich atmosphere results in significant temperature fluctuations, with surface temperatures ranging from -110 °C (-166 °F) to 35 °C (95 °F) in equatorial summer.
Why Humans Cannot Breathe There
The Martian atmosphere is unsuitable for human respiration due to its severe lack of oxygen. Earth’s atmosphere contains about 21% oxygen, essential for human physiological processes. Mars offers only trace oxygen, making direct breathing impossible.
Beyond insufficient oxygen, the extremely low atmospheric pressure poses a lethal threat to unprotected humans. At Mars’s surface pressure, below the Armstrong limit, bodily fluids like saliva, tears, and lung water would spontaneously boil at normal body temperature, a phenomenon known as ebullism. This rapid vaporization causes dissolved gases in the bloodstream to bubble, leading to severe tissue swelling, loss of consciousness within seconds, and ultimately death within minutes.
Living in the Martian Environment
Human survival on Mars requires comprehensive protection against its hostile environment. Specialized spacesuits, Extravehicular Mobility Units (EMUs), are crucial for outdoor activity. These suits must maintain internal pressure significantly higher than Martian ambient pressure to prevent ebullism and provide a breathable oxygen-rich atmosphere. They also protect against extreme temperatures, harmful radiation, and abrasive Martian dust.
For long-term habitation, pressurized habitats are indispensable, designed to withstand the immense outward force of an Earth-like internal pressure. These structures often use materials like regolith for radiation shielding and can be built partially underground or as inflatable modules to enhance safety and ease of construction. Within these environments, advanced life support systems recycle air and water, creating a self-sustaining ecosystem that minimizes resupply from Earth.
The Future of Martian Air
While Mars’s atmosphere is currently unbreathable, scientific endeavors explore methods to make it more hospitable. In-Situ Resource Utilization (ISRU) is a key strategy, using local Martian resources to support human missions. The Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) on NASA’s Perseverance rover demonstrated a significant step.
MOXIE successfully produced oxygen by electrochemically splitting carbon dioxide molecules from the Martian atmosphere. This technology can generate breathable oxygen for astronauts and produce rocket propellant for return journeys. Longer-term concepts include terraforming, a hypothetical process of transforming Mars to support a biosphere by altering its climate, atmosphere, and surface. These plans involve warming the planet and enhancing its atmospheric density, but are infeasible due to immense challenges.