Artificial photosynthesis for production of oxygen and fuel on the Moon and Mars

Image of ice in a crater on the Martian plain Vastitas Borealis captured by the European Space Agency’s Mars Express orbiter. Credits: ESA/DLR/Freie Universitat Berlin (G. Neukum)

When we establish outposts and eventually, settlements on the Moon or Mars it would be economically beneficial if we did not have to create supply chains from Earth for water, breathable air and the fuel we will need for our rockets. This is why sources of water ice in the permanently shadowed craters at the lunar poles and in glaciers in the equatorial regions on Mars are so attractive as early destinations. Once we get there what equipment will we need to process this valuable resource? The typical way envisioned for cracking water in situ on the Moon or Mars to produce oxygen and hydrogen is through electrolysis. But this method requires a lot of power. There may be a more efficient way. New ESA sponsored research by scientists* in the UK and Europe examines a novel method that mimics photosynthesis in plants using a photoelectrochemical (PEC) device. The findings were published June 6 in Nature Communications.

PEC reactors are currently being studied on Earth for water splitting to produce green hydrogen from sunlight. Since they only rely on solar energy for power they are ideal for space applications. One type of device consists of a semiconductor photocathode immersed in an electrolyte solution that absorbs solar energy for a reaction to split hydrogen from water molecules. Oxygen is produced at the anode of the cell. PEC devices can be fabricated as panels similar to photovoltaic arrays. For use on Mars, the authors analyze another similar PEC technology using a gas-diffusion electrode to reduce atmospheric carbon dioxide in a reaction producing methane for rocket fuel.

The authors modeled the performance of these devices subjected to the expected environmental conditions on the Moon and Mars. Specifically, they looked at attenuation from the accumulation of dust on the PEC cells caused by micrometeorites pulverizing the lunar surface, coupled with the solar wind inducing an electrostatic charge in the resulting dust. And of course dust storms are relatively frequent on Mars which could significantly degrade performance. To address this problem self cleaning coatings are suggested as a solution. Solar irradiance was also considered as it would be reduced at the orbit of Mars. It was concluded that the PEC performance could be significantly boosted with solar concentrators by a factor of 1000 enabling higher production rates and power densities, especially on Mars.

An added advantage for space-based application of this technology is the elements needed to construct PEC devices are readily available on these worlds obviating the need to transport them from Earth and thereby significantly reducing costs.

“…in-situ utilization of elements on both, the Moon and Mars, is feasible for the construction of PEC devices.”

The technology is ideal to augment the production of oxygen in environmentally controlled life support systems of habitats that may not initially be 100% closed and cannot easily be resupplied with consumables from Earth. A competing technology for oxygen production which was recently demonstrated on Mars is the Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) which functions via solid oxide electrolysis of carbon dioxide. This process requires high temperatures and therefore, more energy presenting a challenge when increased production of oxygen will be required for large settlements. The author’s analysis show that the PEC devices are more energy efficient and can easily be scaled up.

“Oxygen production via unassisted PEC systems can … be carried out at room temperature … suitable to be housed in temperature controlled space habitats.”


* Authors of the Nature Communications article Assessment of the technological viability of photoelectrochemical devices for oxygen and fuel production on Moon and Mars: Byron Ross at the University of Warwick, UK; Sophia Haussener at Ecole Polytechnique Fédérale de Lausanne, Switerland; Katharina Brinkert, University of Bremen, Germany


Tired of messy lunar dust? Take an electron beam shower

Lunar dust caked on an astronaut’s space suit. Credits: NASA

Researchers at the University of Colorado at Bolder have discovered a promising method for cleaning lunar dust off of space suits and other surfaces likely to be contaminated on the Moon. The solution could be zapping the nasty grit with an electron beam.

Lunar dust sticks to just about everything because it acquires an electrostatic charge from the solar wind. By directing an electron beam at the surface contaminated with dust particles, an excess negative charge will build up resulting in the grains repelling each other and leaping off the surface where the beam is applied. Taking an electron beam shower may be how lunar settlers clean off before coming inside after walks on the Moon.

Lunar Cruiser: JAXA and Toyota name their rover

JAXA/Toyota Lunar Cruiser. Credits: Toyota

In a recent press release, the Japan Aerospace Exploration Agency (JAXA) and Toyota announced that they will name their crewed pressurized rover “Lunar Cruiser”. There have been some updates since we initially covered this topic. For instance, work this year progressed on simulations modeling power and heat dissipation while driving and the use of virtual reality to determine the layout of equipment in the vehicles’ cabin. In addition there have been discussions among over 100 partners in various industries of a “future lunar surface-based society” in an effort to “…gather the knowledge, experience and technological capabilities of enterprises from across a variety of industries in their attempt to realize their dream of sustaining continuous activities on the surface of the moon…”

Hopefully “Team Japan”, as the consortium is called, will take into consideration mitigation of the risks caused by lunar dust in the design and use studies of the Lunar Cruiser, as discussed in my presentation at the Moon Society’s Lunar Development Conference. At some point we hope to see the Lunar Cruiser navigating the network of roads that will hopefully be constructed as proposed by the Space Development Network. It may look like this:

Mitigation of the risks and challenges of lunar dust

Astronaut Gene Cernan covered in Lunar dust after an EVA during the Apollo 17 mission. Credits: NASA

Catch my presentation at the Moon Society’s Lunar Development Conference that took place on July 19 and 20 in which I describe the hazards posed by lunar dust and several solutions needed for space settlement. This is definitely on the critical path for large scale operations on the moon.

There were a couple of technical glitches in the presentation, one of which was playing a simplistic animation of deploying a dust-free landing pad beneath an initial lunar lander using telerobots. You can view the animation here. Hat tip to Doug Plata and the Space Development Network for the source material used in the presentation. Many of the conference presentations are available on the Moon Society’s YouTube Channel.