To establish a permanent colony on Mars or the Moon, you need oxygen. And this is obtained by splitting water into its elements with the help of electricity.However, this works much worse on the celestial bodies than on Earth, reports a team led by Bethany A. Lomax from the University of Glasgow in "Nature Communications". On the basis of electrolysis experiments on parabolic flights, in which there is very low gravity for a short time due to the special trajectory, it showed that electrolysis in lunar gravity produces about eleven percent less oxygen than on Earth.
According to the team's results, a greater tension is needed in a lower gravity to provide the same electrolysis. The reason for this increased so -called overvoltage is that hydrogen and oxygen are gaseous - that is, in electrolysis, gas bubbles form on the electrodes that displace the water. If the gravity is high, the bubbles pear up and release the electrode again for further water molecules. In contrast, in a lower gravity - as it prevails on the moon or Mars - it takes much longer for the bubbles to climb, which is why the electrodes are surrounded by a thicker coat from blisters. This contrasts the reaction resistance, accordingly the yield of electrolysis decreases.
As the team also found, the effect also depends on the properties of the electrolysis system. Thus, the importance of gravity increases with increasing current density – a feature that would have to be taken into account when designing facilities for future space colonies. Another result of Lomax's working group is that parabolic flights will probably no longer be necessary for this development. As the test series showed in different gravity – from almost weightlessness to eight times gravity« – the performance of such systems can be extrapolated from high to lower gravity.
