Ers-2 satellite returned, official confirmation awaited


Ers-2 satellite returned, official confirmation awaited
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The re-entry into the atmosphere of the European Earth observation satellite Ers-2 (European Remote-Sensing Satellite 2) has been confirmed. The satellite concluded its uncontrolled return to Earth at 6.17pm Italian time, with an impact in the atmosphere on the North Pacific Ocean, in the area between Alaska and Hawaii. This was announced by the European Space Agency's office for the surveillance of space debris. There is no news at the moment on the possible fall of debris, which could have been generated due to the incomplete destruction in the atmosphere of the space wreckage which weighs 2,300 kilos, and in particular of some of its large components such as the tank and the main antenna.

Predictions regarding the time and place of impact with the atmosphere remained very uncertain until the very end, due to the variability of space weather determined by the activity of the Sun, which influenced the density of the Earth's atmosphere and therefore on the resistance encountered by the satellite on its path. The latest forecast developed by ESA close to the event indicated a possible re-entry over the Norwegian Sea at 18:05 Italian time, with an uncertainty window of around 30 minutes. An indication that did not allow us to accurately estimate the actual point of impact, considering that in a similar time frame the satellite travels approximately 28,000 kilometres.

It was a heart-stopping exit for Ers-2, after almost 29 years spent in orbit. The satellite was launched in April 1995, four years after its twin Ers-1, and remained in operation for 16 years, collecting a large amount of data on oceans, polar ice caps and soil, also useful for disaster monitoring natural events such as earthquakes and floods. Equally valuable information on the ozone hole and other polluting gases in the atmosphere was collected thanks to the Gome instrument, created by the then Officine Galileo of Campi Bisenzio, later merged with Leonardo.

The Ers-2 mission officially ended in 2011: although the satellite was still functional, it was still decided to end operations and deorbit it to mitigate the proliferation of space debris. The satellite was subjected to 66 deorbit maneuvers in July and August 2011, before being completely passivated (i.e. deprived of all internal energy) in September. The maneuvers consumed the satellite's remaining fuel and lowered its average altitude from 785 to 573 kilometers, to reduce the risk of collision with other satellites or space debris and to ensure that the orbit decayed quickly enough for it to re-enter the atmosphere terrestrial within 15 years.

And so it was, with an uncontrolled fall that first caught the attention of other satellites, which imaged Ers-2's space tumbles between January and February, and then ground-based telescopes, such as those of the European Center for Earth observation (Esrin) of Frascati, which on Tuesday evening recorded the last visible passage of Ers-2 over the European skies.

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