Researchers have begun the process of identifying liquid solvents that could potentially be used to extract necessary building materials from the dust of lunar and Martian rocks. This research and development is an important part of enabling long-term space exploration. Using machine learning and computational modeling, Washington State University researchers have identified about half a dozen solvent candidates that could extract materials on the moon and Mars that could be used for 3D printing.
The work, led by Soumik Banerjee, associate professor in the School of Mechanical and Materials Engineering at Washington State University, was reported in the Journal of Physical Chemistry B.
Powerful solvents called ionic liquids are salts in a liquid state. "The machine learning work took us from 20,000 feet down to the 1,000-foot level," Banerjee said. "We were able to down-select a large number of ionic liquids very quickly, and then we were able to scientifically understand the most important factors that determine whether a solvent can dissolve a material."
Banerjee's work is funded by NASA, which hopes to return humans to the moon and then deeper into space, including Mars, as part of its Artemis mission. But to make such long-term missions possible, astronauts will have to tap into materials and resources found in these extraterrestrial environments, using 3D printing technology to create structures, tools or parts from basic elements extracted from lunar or Martian soil.
"For NASA, in situ resource utilization is a big thing in the next few decades," Banerjee said. "Otherwise, we're going to need to carry prohibitively high amounts of material from Earth."
Procuring these building materials must be done in an environmentally friendly and energy-saving manner. The method of mining the element also cannot use water, because there is no water on the moon.
Banerjee's research group has been studying ionic liquids for batteries for more than a decade, and this may be the answer.
However, testing each candidate ionic liquid in the laboratory is expensive and time-consuming, so the researchers used machine learning and atomic-level modeling techniques to sift through hundreds of thousands of candidate ionic liquids. They are looking for ionic liquids that can digest lunar and Martian materials, extract vital elements such as aluminum, magnesium and iron, regenerate themselves and perhaps produce oxygen or water as a by-product to help provide life support.
After determining the desirable qualities of a solvent, the researchers found about six highly desirable candidates. Important factors for success include the size of the molecular ions that make up the salt, the surface charge density (that is, the charge per unit area of the ion), and the mobility of the ions in the liquid.
In another study, the researchers, working with researchers at the University of Colorado, tested several ionic liquids in the lab for their ability to dissolve compounds. They hope to eventually build a lab- or pilot-scale reactor and test candidate solvents using materials obtained from the moon.
Compiled source: ScitechDaily