How to obtain water on Mars

One day, the humankind may decide to move somewhere else, to another planet, for example from Earth to Mars. Probably not us yet, but we cannot rule that out… Meanwhile, the differences in the appearance of the two planets are not just superficial; the Red Planet lacks available water resources. Even if the colonisation of other celestial bodies is a long way off, one thing will not change: humans will still need water to live. Where will we get it from?

Scientists from AGH University have patented a system that would allow us to obtain water from the ice hidden beneath the surface of extraterrestrial bodies, located in what is known as regolith. The term describes everything that covers the solid bedrock of planets. It is a layer of loose, crushed rock material that is the closest to the surface. It may take forms of dust, gravel, sand, or larger rock debris. On Earth, regolith is made of soil, minerals, plant and animal remnants and is affected by water, air, living organisms, and temperature.

On Mars, where traces of life have not been found yet, regolith is not that rich in organic matter. It is mainly composed of silicate minerals related to the former volcanic activity, iron oxides, responsible for the planet’s famous colour and its nickname, sulphates, perchlorates, clay and illite, as well as fine-grained and electrostatically charged dust. What is relevant in the context of the AGH University-developed patent is the fact that this layer may contain promising reservoirs of ice. At poles they are more abundant and may be found even several centimetres below the surface, whereas at mid-latitudes, although still relatively rich, they may be located slightly deeper – from several dozen centimetres to a few meters, and in extreme cases – several dozen meters below the surface. The least amount of ice is most likely found in the regolith near the equatorial regions.

Where does this ice come from? According to scientists, Mars used to have a denser atmosphere, and there was liquid water on its surface that later penetrated the regolith. When the changes caused by atmospheric rarefaction occurred, surface water vanished and persisted mainly in the form of ice below the surface.

The average temperature on Mars is around -62 °C. It can reach a maximum of 20 or 30 °C, but the minimum temperature can drop to as low as -140 °C. Due to the low temperatures and exceptionally low pressure (less than 1% of that on Earth!), obtaining water is not easy – under natural conditions, when ice is heated, water immediately sublimates, i.e. turns into water vapour.

One of the methods to restore water from the Martian regolith is to facilitate its sublimation into saturated water vapour and making it condense. The AGH University-based researchers used this concept to create their invention, patented under the name “Method of obtaining water from ice in regolith and the installation for obtaining water from ice in regolith” by the Patent Office of the Republic of Poland, reference no. PL 247201 B1.

An indispensable element of the system that is to help restore water is a borehole reaching the part of regolith that stores ice. The borehole is to consist of a column of technical pipes perforated in their lower part; these will be used to inject gas to increase the pressure in the selected area of heated regolith, and the water condensing from the regolith will flow into them. They must reach the layer rich in ice. The key to obtaining water will be achieving the right pressure – only then will the water vapour produced by heating the regolith begin to condense and thus become water that we can extract to the surface. Gases from the atmosphere of the extraterrestrial body will be used to increase the pressure – in the case of Mars, this is mainly carbon dioxide. The gas will be fed to the right place thanks to a special system consisting of a buffer tank, a compressor, a compressed gas tank, and a gas distributor.

The condensed water will enter the system through specially perforated parts of the technical pipe column and to a pump connected to the lower part of the extraction pipes found inside the technical pipe column. A movable heat source will be placed over the pipe, on the outside of the extraction pipes, to allow for the even exploitation of the selected area of ice-rich regolith. If the water reaches a high enough level in the column of technical pipes, the pump will be activated and direct the water upwards, to a water and gas separator located on the surface of the extraterrestrial body. There, the gas will be separated from the water, and the water will be transferred to a sealed tank on the planet's surface, where it will be stored ready for use. However, if it still contains some gas, there will be another separator, allowing for one more separation of the water from the remaining gas.

The system will also include specialised components such as temperature, water level and pressure sensors, as well as integrated solar-powered heating systems to ensure sustainable and efficient operation in an extraterrestrial environment.

Over the course of his academic career, Dr Tadeusz Solecki has developed numerous patents (also European ones), some of which were related to borehole technologies for water exploitation on Earth. What inspired him to take up a project on the extraction of water from regolith on Mars was cooperation with one of his students, Gordon Wasilewski. As emphasised by Dr Solecki, their success would not have been possible without an AGH University patent attorney, Robert Klisowski, who proved the validity of patent claims related to this invention before the Patent Office of the Republic of Poland.

Although the need to obtain water on Mars may seem remote, it will be one of the first essential steps to be taken when setting up a base. If we were to think about the colonisation of this planet, the transportation of water from Earth in the necessary amount would be energy-intensive and economically unviable, especially considering the large amount of water present in the form of ice in Martian regolith.

Preparing the right solutions in advance gives us time to refine and improve them before they become critical. Dr Solecki admits that he already has an idea on how to enhance the efficiency of the patented solution. Moreover, further plans can be made, including the use of water to produce hydrogen as a fuel, a likely necessity for the future colonisation of Mars.

Importantly, although the solution was designed with Mars in mind, it could also be adapted for other celestial bodies with similar conditions, i.e. regolith rich in ice and an atmosphere containing the necessary amounts of gas.