Could the moon serve as an oxygen ‘petrol station’ for rockets in the future?

The moon is dry, dusty and uninhabitable yet it may prove to be very useful as a source of oxygen in outer space. Scientists have been studying the moon for decades through Apollo missions to try and get a grasp of what it is made of and what processes it is responsible for. Samples of rocks have been brought back and upon analysis it was confirmed that moon soil has approximately 40-45% oxygen by weight. This is a striking difference to Earth where oxygen makes up only 21% of the air in the atmosphere. Oxygen is actually the most abundant substance on the moon’s surface.

What are the uses of oxygen on the moon?

If it could be converted to gaseous oxygen, future human visitors would have a breathing supply. Another use is called in-situ resource utilisation which makes use of the natural resources present rather than astronauts having to carry them from Earth. The liquid oxygen present on the moon could be used as a propellant in rocket fuel. This is extremely helpful when the liquid oxygen needed for a propellant is very heavy. If this system were made efficient enough, it could make the moon like a cosmic petrol station where rockets can fuel up for their missions to Mars and beyond!

A cosmic petrol station where rockets can fuel up for their missions to Mars and beyond

The difficulty in getting the oxygen out of the soil largely comes down to the fact that it is tied up in chemical compounds which need lots of energy to be broken. Researchers, at the European Space Agency in the Netherlands, used a replica of the moon soil which was made from terrestrial materials but had the same composition. This is because the actual samples are too valuable to experiment on. The technique trialed is called salt electrolysis which is used to separate the oxygen from the compound. The end result sees the oxygen separated and migrating to the anode where it can be captured. This experiment has proven to be quite successful. The researchers were able to extract 96% of the oxygen in a space of 50 hours, or 75% of the oxygen in just 15 hours. Although this still may seem like a long time, it saves using resources that would otherwise need to be taken from Earth. Also, the mixture of metal alloys left behind after the extraction of oxygen could also be of use, although the exact use in space missions is not clear yet. The process would produce no waste and hence the moon could function as a non-polluting petrol station.

Oxygen is actually the most abundant substance on the moon’s surface.

This is a big improvement from previous experiments which have also extracted oxygen but have either been of extremely low yield or simply too complicated. Science is moving forward and with a perfected technique of oxygen extraction, the moon may soon be the first cosmic petrol station for rockets travelling far and wide.