Humanity has long been captivated by the prospect of water on Mars, a fascination rooted in the potential for life beyond Earth and the feasibility of future human exploration. The presence of water is fundamental for sustaining life as we know it, making its discovery on the Red Planet a significant milestone. However, the central question remains: is the water found on Mars actually drinkable for human consumption?
Where Water Exists on Mars
Water on Mars primarily exists in a frozen or bound state, spread across various locations. Extensive ice caps are prominent at both the north and south poles, containing substantial quantities of water ice layered with dust. Below the surface, significant amounts of subsurface ice are present, particularly in polar regions and at mid-latitudes, often buried under regolith. Hydrated minerals within rocks and soil also hold water molecules, remnants of Mars’ wetter past. Additionally, a small amount of water vapor is detectable in the thin Martian atmosphere. While liquid water is generally unstable on the surface, briny (salty) water has been observed to flow seasonally.
Why Martian Water Isn’t Drinkable
Despite its presence, Martian water is not suitable for direct human consumption due to several factors. A primary concern is the widespread presence of perchlorates, toxic salts abundant in Martian soil and water. These compounds can cause health issues, including thyroid problems, even at low concentrations, and can also corrode equipment. Additionally, Martian water is considerably saltier than Earth’s saltiest waters.
The majority of Mars’ water is frozen due to the planet’s extreme cold, with average temperatures far below freezing. Low atmospheric pressure also prevents stable liquid water from existing on the surface, as it would rapidly freeze or evaporate. Even if melted, high salt concentrations lower the freezing point, allowing some brines to remain liquid at colder temperatures, but this also exacerbates their toxicity.
Making Martian Water Potable
Transforming Martian water into a potable resource presents considerable scientific and engineering challenges. Melting abundant subsurface ice is a primary step, with methods like thermal drilling proposed. Following melting, the water would require extensive purification. Technologies like reverse osmosis and ion exchange are being considered for desalination and removal of dissolved substances.
The removal of perchlorates is a particularly complex task, as traditional purification methods are often energy-intensive or require consumable materials. Innovative solutions include leveraging synthetic biology to engineer bacteria, like Bacillus subtilis, to break down perchlorates into harmless chloride and oxygen. This bioremediation approach offers a sustainable method to detoxify Martian water, although it remains in the experimental phase.
The Value of Martian Water for Future Missions
Access to and purification of Martian water is important for human exploration efforts. Beyond drinking, water serves as a source for producing breathable oxygen through electrolysis, splitting water molecules into hydrogen and oxygen. This process also creates rocket fuel, as hydrogen and oxygen combine to form propellants for return journeys or further exploration.
Utilizing Martian water exemplifies “in-situ resource utilization” (ISRU), a strategy focused on using local resources to reduce supplies transported from Earth. By generating consumables like water, oxygen, and fuel directly on Mars, missions become more self-sufficient and cost-effective. This approach significantly lowers the mass launched from Earth, enabling more ambitious and longer-duration human missions.