Feature JAP article for plasma ISRU on Mars
An international team led by IPFN researchers Vasco Guerra and Tiago Silva came up with a plasma-based way to produce and separate oxygen within the Martian environment. It holds promise to deliver high rates of production of molecules per kilogram of instrumentation sent to space.
Such a system may play a critical role in the development of life-support systems on Mars, and also feedstock and base chemicals necessary for processing fuels, building materials, and fertilizers.
The article 'Plasmas for in-situ resource utilization on Mars: fuels, life support, and agriculture,' was published in the Journal of Applied Physics (JAP) from AIP Publishing (DOI: 10.1063/5.0098011). The team presents a way to address the important space exploration concept of in situ resource utilization (ISRU) on Mars—how to harness and process local resources to generate products.
Natural conditions on Mars are nearly ideal for ISRU by plasmas, since the Martian atmosphere is primarily formed by carbon dioxide (about 96%). The article was selected as 'Featured' by the editors of the JAP.
Two big hurdles stand in the way of producing oxygen on Mars. 'First, the decomposition of carbon dioxide molecules to extract oxygen. It's a very difficult molecule to break,' says Vasco Guerra. 'Second, the separation of the produced oxygen from a gas mixture that also contains, for example, carbon dioxide and carbon monoxide.
We're looking at these two steps in a holistic way to solve both challenges at the same time — this is where plasmas can help. 'Electrons are light and easily accelerated up to very high energies with electric fields. When 'bullet-like' electrons collide with a carbon dioxide molecule they can directly decompose it or transfer energy to make it vibrate. This energy can be channelled to a large extent into carbon dioxide decomposition. And the heat generated in the plasma is also beneficial for the separation of oxygen.
Oxygen is key to creating a breathing environment, as well as the starting point to produce fuels and fertilizers for future Martian agriculture. Oxygen and carbon monoxide can be used to manufacture liquid propellants for rockets, while oxygen and nitrogen—which are also available within the Martian atmosphere—are the building blocks to synthesize nitrogen-based fertilizers. All these are essential for a future human settlement on Mars.
Aside from sophisticated plasma excitation schemes to improve gas-phase conversion and efficiency, another path toward enhanced ISRU is the combination of plasma with (solid) membrane gas-separation methods, using either non-electrochemical membranes or oxygen ionic conductor systems, the latter integrating a solid oxide electrolysis cell (SOEC) or mixed ionic-electronic conductors (MIECs).
Meanwhile, the rover Perseverance is already collecting samples to be returned to Earth. Solid fuel rockets will be used in the forthcoming Mars Sample Return missions, but local production of fuels will be important for similar future missions.
'By dissociating carbon dioxide molecules to produce green fuels and recycle chemicals, the plasma technology may also aid in addressing climate change on Earth. And at a fundamental level, the knowledge we acquire will also have profound value for planetology, in particular, to help us understand the role of lightning and other electrical phenomena in the chemistry of atmospheres containing carbon dioxide like Venus, Mars, and primitive Earth.'
The article is authored by V. Guerra, T. Silva, N. Pinhão (IPFN, IST), Olivier Guaitella (LPP, Ecole Polytechnique, France), Carmen Guerra-Garcia (MIT, USA)), Floran Peeters, Mihailis Tsampas, and Mauritius C.M. van de Sanden (Dutch Institute For Fundamental Energy Research, The Netherlands).
