Measuring Martian lightning

Lightning is expected to occur on Mars within dust devils and dust storms, which are likely to discharge in the low pressure carbon dioxide environment. Despite this, radio emissions from Martian lightning have not yet been conclusively observed by remote sensing, nor have there been any in situ measurements of Martian atmospheric electricity. We report laboratory experiments to simulate Martian electrical discharges and measure the radio emissions from them, to facilitate searches of Martian lightning from spacecraft data. Voltage transients were observed in a tank in which Martian analogue simulant was allowed to become triboelectrically charged, and then fall to a sensing electrode. A plausible explanation for our results is that electrical discharges have taken place, caused by charge separation on differently sized particles as predicted by theory. Unlike in previous reports, we have been able to detect discharges without adding glass microballoons to the Martian analogue dust to facilitate the charging, although the addition of glass microballoons did enhance the transient rate.