ESA’s Aeolus satellite, which carries the world’s first space Doppler wind
lidar, has been delivering high-quality global measurements of Earth’s wind
since it was launched almost a year ago. However, part of the instrument, the
laser transmitter, has been slowly losing energy. As a result, ESA decided to
switch over to the instrument’s second laser – and the mission is now back on
top form.
Developing novel space technology is always a challenge, and despite the
multitude of tests that are done in the development and build phases, engineers
can never be absolutely certain that it will work in the environment of space.
Aeolus is, without doubt, a pioneering satellite mission – it carries the
first instrument of its kind and uses a completely new approach to measuring
wind from space.
The instrument, called Aladin, not only comprises the laser transmitters,
but also one of the largest telescopes ESA has put into orbit and very
sensitive receivers that measure the minute shifts in wavelength of light
generated by the movement of molecules and particles in the atmosphere caused
by the wind.
Aladin, works by emitting short, powerful pulses of ultraviolet light from
a laser and measures the Doppler shift from the very small amount of light that
is scattered back to the instrument from these molecules and particles to
deliver vertical profiles that show the speed of the world’s winds in the
lowermost 30 km of the atmosphere.
While scientists and meteorology centres have been thrilled with the data
produced by Aeolus, the first laser’s energy was becoming a concern – and in
June, energy levels dipped to the point that the quality of the wind data was
set to be compromised.
Tommaso Parrinello, ESA’s Aeolus mission manager, said, “With the power
from the first laser declining, we decided to turn it off and activate the
second laser, which the instrument was equipped with to ensure we could address
an issue such as this.
“Switching to the second laser appears to have done the trick so we’re back
in business. And, we are confident that the instrument will remain in good
shape for years to come.”
Aladin equipped with two lasers
Denny Wernham, ESA’s Aeolus instrument manager, added, “The great news is
that the second laser’s energy is, so far, very stable, which is what we
expected since this laser is actually better than the first. This is because we
have more scope to adjust it in orbit to retain the performance needed.
“I would like to stress that despite the first laser’s drop in energy, it
worked for nearly a year and provided a vital dataset for our stakeholders. It
accumulated nearly one billion shots, which is a record for a high-power
ultraviolet laser in space, and we can always go back to it if we need to later
in the mission.”
The European Centre for Medium Range Weather Forecasting (ECMWF) is also
enthusiastic about the data now being delivered.
Image &
info via ESA: https://www.esa.int/Our_Activities/Observing_the_Earth/Aeolus/Second_laser_boosts_Aeolus_power
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