Ionic Liquids Could Help Extract Building Materials From Moon and Mars; How Can These Solvents Revolutionize Space Travel?

Over the recent years, several countries have expressed their interest in sending crewed missions to land on the Moon, and use it as a foundation for a future trip to Mars. To establish lunar and Martian colonies, new structures would be developed to provide the settlers with vital sources.

Breakthrough in Space Mining

In a recent study, experts from Washington State University (WSU) have taken the first steps toward discovering liquid solvents which could someday help extract important building materials from lunar and Martian rock dust. Their findings are discussed in the paper "Toward Metal Extraction from Regolith: Theoretical Investigation of the Solvation Structure and Dynamics of Metal Ions in Ionic Liquids".

NASA's Artemis mission aims to send humans back to the moon and to Mars and beyond. To make the long-term missions possible, astronauts will need materials and resources in those environments. 3D printing would be used to make structures, tools, or parts from vital elements extracted from the moon or Mars.

WSU associate professor Soumik Banerjee believes that in the next couple of years, NASA would rely on in situ resource utilization so astronauts would not need to carry a high payload of materials from Earth. The method of element extraction cannot use water since it is not available on the moon. Instead, they need building materials which can be acquired in an environmentally friendly and energy efficient way.

Banerjee's group thought that solvents could be the answer. They have been studying these liquids for more than a decade for use in batteries. Known as ionic liquids, these solvents are actually salts existing in a liquid state.

Lunar and Martian rocks contain pyroxene, olivine, feldspar, and aluminite are good sources of important metals like iron, magnesium, sodium, and aluminum. These metals can be extracted from an extraterrestrial environment using ionic liquids with high electrochemical stability and extremely low vapor pressure.

Selecting the Right Candidates

It would be expensive and time consuming to test each ionic liquid candidate in a laboratory. To address this concern, the researchers used machine learning and computational modeling at the level of atoms to narrow down hundreds of thousands of candidates. Their calculations provide fundamental insights into important factors that influence the solvation of metals.

As part of the selection process, they looked for liquids which could digest materials on the moon and Mars and have the ability to regenerate themselves. They should also have the ability to extract vital elements and produce water as a byproduct. Other important factors include surface charge density, the size of the molecular ions that make up the salt, and their mobility in the liquids,

After identifying the qualities that must be possessed by the solvents, the experts were able to find half a dozen potential candidates which can obtain materials on the moon and Mars usable in 3D printing. The model brought them down from the 20,000-foot to the 1,000-foot level. The ionic liquids are further tested by Banerjee's team in collaboration with the experts from the University of Colorado, hoping to build a laboratory-scale or pilot-scale reactor.