This is how Aeolus has immolated itself so as not to generate any more debris around the Earth
The Spanish Isabel Rojo has literally and completely burned up the European satellite Aeolus, which cost 481 million euros to build.
It was not an unintentional mistake. She has done so quite consciously, without having the slightest qualms about setting fire to a sophisticated machine that for five years has been measuring the winds that flow around the planet and has helped meteorologists to improve their atmospheric and climatic forecasts.
From her command bridge at the European Space Operations Centre (ESOC) in Darmstadt, some 30 kilometres from Frankfurt, the financial capital of the European Union, Isabel Rojo from Madrid has been responsible for steering a 1.2 tonne spacecraft and moving it with extreme difficulty through space until it is destroyed.
The team of technicians led by Isabel Rojo has carried out a highly complex task for which there is no known precedent. Aeolus - the Greek god of the wind, Aeolus in Spanish - was launched into space on 22 August 2018 and positioned at an altitude of 320 kilometres. It had already more than accomplished its mission of acquiring accurate information from the 24 atmospheric sub-layers ranging from the ground to 30 kilometres high and was out of service.
What remained to be done was for the Earth's gravity to perform its function: to let it fall uncontrollably on its own and, in its friction with the atmosphere at 27,000 kilometres per hour, break apart, disintegrate and its pieces burn and some of its debris fall into the sea.
Five days of space manoeuvres
But the European Space Agency (ESA) wanted to be a pioneer and about a year ago planned the semi-controlled re-entry of Aeolus into the Earth's atmosphere. Semi-controlled because Aeolus had not been designed or built to head towards the Earth in a directed manner, which meant that it had to have engines attached to drive it through space in its final phase.
Isabel Rojo herself explained a few days before taking Aeolus to the atmospheric bonfire: "We used the resources at our disposal to try to make Aeolus re-entry as safe as possible and to minimise the already low risk of some of its debris falling to Earth. His colleague, Benjamín Bastida, an engineer specialising in space debris, points out that "current craft statistics tell us that between 10 and 20% of the satellite's mass survives the burn".
The responsibility of the Aeolus flight operations manager has been to conceive, sequence and direct the successive descent manoeuvres to bring the satellite to the desired area for its premeditated suicide. The green light to initiate the first orbit lowering manoeuvre was given on 24 July, when the satellite was at an altitude of 320 kilometres.
Operations from ESOC were completed on 28 July. On that day, the US Space Command's ultra-terrestrial object tracking network confirmed that Aeolus had been blown apart over Antarctica at 21:00. NASA and ESA telemetry antennas saw its tracks disappear as the wreckage of the satellite burned up in the atmosphere.
The supreme order for the incineration of Aeolus was given by ESA's director general, the Austrian Josef Aschbacher, the same man who on 5 June 2018, when he was still director of the Agency's Earth observation programmes, presented the satellite to the public after its production had been completed. It was at the Airbus Space Systems France factory in Toulouse, a few weeks before being sent to the Kourou space base for its launch into space.
The other Spaniard who brought Aeolus to life
If Isabel Rojo was the one who brought Aeolus to an end, another Spaniard, Elena Checa, was one of those who made the satellite's construction possible. An engineer specialising in thermal control and stationed at ESA's European Space Research and Technology Centre (ESTEC) in Noordwijk, the Netherlands, she is one of the key people who brought the sophisticated instrument that measures winds around the globe to life.
Weighing 1,570 kilos at launch and the size of a small van - 4 x 4.35 x 1.6 metres - Aeolus incorporated a high-energy ultraviolet laser instrument called Aladin that was considered an engineering feat. It took "more than a decade of effort" to get it up to speed. "The biggest challenge was to ensure that the high temperatures reached by Aladin did not deform the 80 optical elements that make up the laser," says Elena Checa.
Until Aeolus came into service, wind measurements could only be made in the lower atmosphere using sounding rockets, balloons and aircraft, which only provided locally useful data. But the Aeolus Aladin instrument emitted a laser beam that was reflected by the ice crystals, dust, aerosols, molecules and particles in its path.
The photons returning to the satellite were captured by the on-board telescope and the strengths and orientations of winds, tornadoes and hurricanes could be measured, providing information on a global scale. Its data and wind profiles have been a great help to meteorologists.
The results obtained by the Aeolus mission have been so important for weather forecasting that the director of Earth observation, Italy's Simonetta Cheli, has confirmed that ESA, in collaboration with EUMETSAT, the European Organisation for the Exploitation of Meteorological Satellites, has approved the upgraded Aeolus-2 version, which is scheduled for launch before 2030.