The idea of a rocket robot getting around Mars sounds idealistic, and there is the issue of having to find a way so that it is capable of refueling itself. The ESA has then set out to make this happen, where their idea is to rely on a rocket which will use carbon dioxide as a propellant. After all, this makes plenty of sense, considering how there is plenty of carbon dioxide over on Mars. This rocket robot will obtain all the CO2 it needs from the surrounding atmosphere by using a radioisotope thermal generator as a power source, before liquify it gradually. Once a critical mass of CO2 has been achieved, the thermal generator will heat up a hollow tube that has plenty of pebbles which were made from beryllium and boron carbine. Once said tube becomes extremely hot, CO2 will be injected within, firing out via a nozzle underneath the rocket robot to keep it going.