Since the launch of Explorer in 1958, batteries have been used in Earth orbital and planetary spacecraft to supply primary electrical power or store electrical energy generated by on-board solar or radioisotope power systems. These energy storage systems are used on spacecraft for various functions, being the most relevant ones: to provide power to the spacecraft subsystems before deployment of the solar panels, fire rocket motors for mid-course correction, meet temporary power needs during eclipse periods, provide power for payload instruments and meet peak power demands derived from data transmission or surface mobility. Primary batteries (single discharge only) are typically used in missions, such as planetary probes, that require electrical power for a period of a few minutes to several hours. Rechargeable batteries (also referred to as secondary batteries) are used mostly in solar-powered spacecraft to provide electrical power during eclipse periods and for load levelling. When considering Mars Surface Missions, the need of advanced rechargeable batteries with high specific energy, energy density, cycle life capability and low-temperature operational capability has been largely identified. Perseverance rover, for example, carries a radioisotope power system that uses the heat of plutonium’s radioactive decay to generate a temperature gradient on a thermoelectric generator. The generated power is stored in two rechargeable lithium batteries. The power generator weights 50 kg (5 kg corresponding to plutonium) and produced approx. 100 watts. The generated energy is partially stored in the batteries in order to provide power to the rover overnight. Although this solution is dimensioned to provided constant power for at least 10 years of operation, it is clear that it cannot be the sole source of power for portable/movable appliances. Yet, to meet peak power demands, the energy has to be stored in large (and therefore heavy) batteries that have to be transported to Mars in future missions. Ultimately, this turns into a heavy expense of fuel and need of space in every mission.
To ease this concern, I propose to proceed in the same way as my research group is already doing on Earth: to built-up batteries from the rough and abundant materials present on the planet surface. On Earth, we seek for identification of organic and inorganic electroactive compounds present in organic waste and test their capability to be oxidized or reduced in primary cells. Therefore, the main idea of the application is to build up a primary battery with the compounds available on Mars. In particular, Mars surface seems to be rich on Mg, which is a well-known anodic material for primary Mg-air batteries. However, as the oxygen content of Mars atmosphere is very limited (< 1%) an alternative cathodic compound must be found. In this sense, the planet is rich on iron oxides and their derivatives – which could be explored as cathodic candidates.