NASA’s Apollo missions returned with rock samples from the near side of the Moon, but were unable to provide any from the far side or its polar regions, which have a different geological history. There are also unanswered questions about the origins of the Moon and places where ice might still be hidden.
In 2003, the European Space Agency (ESA) sent a satellite into lunar orbit to observe the Moonscape and learn more about its composition. SMART-1 (Small Missions for Advanced Research in Technology 1) was the first probe ESA had ever sent to the Moon. It orbited for three years before plummeting to the surface in September 2006.
As well as learning more about the Moon, the mission tested advanced technologies that would be necessary for future scientific planetary missions and that could be used to create smaller, cheaper probes. Two instruments measured propulsion, for example, while another looked at the efficiency of the communications systems. SMART-1 also carried two miniaturized cameras: one to take color images of the Moon and the other to map its mineral resources.
All of this equipment needed power, of course, and that was a challenge given budgetary and size constraints. SMART-1 measured just one cubic meter overall and was intended to be a low-cost space probe. The only way to resolve the concern of mass was to use a lithium-ion battery, which was not flight proven at the time. Saft supplied five cells from two of its French factories. The cells were assembled in Bordeaux and prepared and tested for flight in Poitiers. The batteries powered the ionic thrusters that propelled SMART-1 into Lunar orbit, after a journey that lasted more than a year. This was the first time a battery had been used to power ionic thrusters – previously they relied on chemical propulsion – and paved the way for the full electric satellite technology in use today. The batteries also powered the electric propulsion engine every three or four days, whenever SMART-1’s trajectory took it out of sight of the solar rays that usually powered it.
The Ariane 5 rocket that launched SMART-1 into space was also, like its predecessors, powered by Saft nickel-based batteries, giving Saft a vital role in both stages of the project. SMART-1’s mission was intended to end in August 2005, but was extended by a year so that more observations could be completed. The final stage was a deliberate crash on to the Moon’s surface that enabled scientists to study the composition of lunar dust.