In orbit for almost five years, ESA’s Aeolus wind mission has exceeded its design life. The satellite’s remarkable Aladin instrument beamed down seven billion pulses of UV light to profile Earth’s wind. Aeolus was never designed for a controlled reentry, but ESA is going above and beyond by attempting an assisted reentry – the first of its kind – to make the procedure even safer.
Gravity and the grasping wisps of Earth’s atmosphere as well as solar activity are dragging Aeolus down from its operational altitude of 320 km. Once Aeolus reaches 280 km, a series of commands will use the satellite’s remaining fuel to guide it towards the optimal position for reentry.
A first manoeuvre will lower the satellite to an altitude of 250 km. Four manoeuvres then usher Aeolus down to 150 km. Then the vast majority of the satellite will burn up in Earth’s atmosphere. However, some pieces of debris might reach Earth. Many months of expertise have gone into planning the optimal location for reentry to minimise the already extremely remote possibility that falling debris could pose a risk to life or infrastructure. The flight control team is aiming at a stretch of ocean beneath the satellite’s track – a long stretch of open water as far away from land as possible.
If this assisted reentry attempt has to be aborted, which could still happen, Aeolus’ natural reentry continues.
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