Africa Surveyors May-June issue 2023 digital

LASER TECHNOLOGY
Laser technology, the
real revolution of the
Aeolus mission
Aeolus, a European Space Agency (ESA) satellite launched
into Space in 2018, is now preparing to return to Earth after
successfully acquiring profiles of the Earth’s wind across the
Planet from an altitude of 30 km.
The Aeolus satellite features ALADIN (Atmospheric LAser Doppler
INstrument), a LIDAR (Light Detection and Ranging) comprising three
parts: a telescope, a receiver, and a laser transmitter, made in Italy by
Leonardo with the support of the Italian Space Agency (ASI).
It is the most powerful transmitter in the ultraviolet (UV) range ever
built for space missions. With over seven billion laser pulses emitted,
it orbited the Earth 16 times a day, covering the entire globe once a
week. It comprises over 80 optical elements aligned with micrometric
accuracy, and its manufacture involves innovative technologies
and materials never tested before. Prime examples are the laser’s
internal oxygenation system, developed to ensure that the beam is
not deformed and does not burn the internal components, and the
material used to minimise light absorption, and at the same time,
withstand the high power levels, thus avoiding energy dispersion or
damage to the optics.
Laser technology is Aeolus’ real revolution. By generating pulses of
UV light sent into the atmosphere, LIDAR detects winds worldwide.
This mission’s greatest added value was the measurement of winds in
areas inaccessible to classic surveying equipment (weather balloons or
aircraft), thereby offering a fuller and more comprehensive view of this
phenomenon.
In orbit for nearly five years, the mission positively impacted many
areas: it has helped to enhance the accuracy of weather forecasts and
improved knowledge of climate phenomena and of the consequences
of global warming and air pollution. According to the mission data,
scientists have hypothesised that, in the future, it could help improve
hurricane forecasting, and track and predict the movement of dust
emissions, e.g., from volcanic eruptions.
Between the end of operations (on 30 April) and the shutdown
of ALADIN (on 5 July), Leonardo, together with ESA and the space
industries involved, carried out further tests on the laser transmitter’s
emission capabilities, upgrading it from a power output of around 4
million nominal watts, to around 10 million watts. A record for a space
laser.
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May-June issue l 2023 33