What were the crucial moments for SMART-1 during its journey and arrival at the Moon?
The Ariane-5 launcher put SMART-1 into an elliptical orbit around Earth. Then, in the first part of the mission, SMART-1 ‘fired’ the ion engine continuously to gradually expand its path into a spiral until its perigee was outside the radiation belts. (It did this to keep the degrading influence of the radiation on the solar panels to a minimum). Later the burn strategy became more sophisticated – designed to minimise the fuel consumption. At 200 000 kilometres from Earth, the spacecraft began to experience significant gravitational tugs from the Moon as it passed by. Once SMART-1 passed within 60 000 kilometres of the Moon, this body’s gravity was much more pronounced, in encounters known as ‘lunar swing-bys’. At about that distance from the Moon, SMART-1 passed through an invisible doorway in space called Lagrange Point Number 1, or L1 for short. This stage of the trip was called ‘lunar capture’. The gravitational effects of the Moon and Earth are in balance at L1. Beyond this point,
