Surviving on Mars: Atmospheric Pressure, Breathing and Liquid Water

The Complexity of Atmospheric Pressure on Mars

On Mars, the lowest atmospheric pressure at which humans can breathe and liquid water can exist is a complex issue due to the interplay between pressure, temperature, and the presence of water. The environment on Mars is extremely hostile to both human life and the stability of liquid water, presenting significant challenges for future human missions and potential habitation.

Minimum Pressure for Human Breathing

The minimum pressure at which humans can breathe without assistance is generally considered to be around 26.5 kPa (0.26 atm). At this pressure, the partial pressure of oxygen is still sufficient for human respiration, but it would be challenging and could lead to hypoxia. This level of pressure is comfortably above the Armstrong Limit, which is the lowest pressure at which a human body can survive, around 6300 Pascals.

Atmospheric Pressure Comparison

To put things in perspective, the atmospheric pressure at the Martian surface is about 600 Pascals, while on Earth, it is approximately 101325 Pascals. This vast difference in atmospheric pressure highlights the need for advanced life support systems and pressurized habitats for human survival on Mars.

Liquid Water Stability on Mars

While the presence of liquid water is crucial for life support systems and the sustainability of future human missions, the conditions on Mars are not hospitable to maintaining liquid water. In fact, liquid water can exist at lower pressures if the temperature is sufficiently low; however, at Mars' average surface temperature of around -80 degrees Fahrenheit (-62 degrees Celsius), liquid water is unstable at pressures below approximately 610 Pa (0.006 atm) due to rapid evaporation or freezing.

Thus, for practical scenarios, a pressure between these two limits would be necessary for both human survival and the presence of liquid water. For human habitation, the ideal pressure would likely be closer to 26.5 kPa, where the temperature is low enough to maintain liquid water.

The Role of Water on Mars

The heavily carbon dioxide (CO2) laden ice caps on Mars (often referred to as dry ice) will not melt without significant intervention. Even if we could somehow melt them, creating an environment for long-term human survival would still require considerable effort. These challenges underscore the need for breakthroughs in technology and innovation to make Mars a viable habitat for humans.

Conclusion

Surviving on Mars presents a multitude of challenges, particularly related to the atmospheric pressure and the stability of liquid water. As we look to the future of human space exploration, these issues necessitate cutting-edge scientific research and technological advancements. While the current conditions on Mars make it a harsh and inhospitable environment, the potential rewards of a new world for human exploration are immense.