Increased solar activity will prematurely de-orbit satellites

(ORDO NEWS) — At the end of 2021, operators of the European Space Agency’s (ESA) satellite constellation Swarm, which has been observing the geomagnetic field since 2013, noticed a disturbing trend: the devices began to plunge into the earth’s atmosphere at an unusually high speed – an order of magnitude faster than before.

These changes coincided with the beginning of a new solar cycle, and experts believe that this could be the beginning of difficult years for spacecraft orbiting the planet, writes Space.com.

“In the past five to six years, satellites have been submerging about 2.5 km per year into the atmosphere,” said Anja Stromme, ESA Swarm mission leader.

“However, since December of last year, they have been practically diving into it. The rate of sinking from December to April is 20 km per year.

Satellites orbiting close to Earth always encounter increased drag from the rarefied atmosphere, which gradually slows the spacecraft down and eventually causes it to fall back to the planet usually burning up in the atmosphere in the process.

This phenomenon forces, in particular, the International Space Station controllers to perform regular “orbit boost” maneuvers, burning fuel, in order to maintain the station’s orbit at a level of 400 km above the Earth.

A similar phenomenon also helps to clean the near-Earth environment from space debris. Scientists know that the intensity of atmospheric drag depends on solar activity – the intensity of the solar wind emanating from the Sun – which varies with the 11-year solar cycle.

The latest cycle, which formally ended in December 2019, has been fairly benign, with below-average sunspot numbers and an extended low of any activity.

But since last fall, our star has been slowly waking up, sending out more and more solar wind and generating sunspots, solar flares and coronal mass ejections with increasing intensity. And the upper layers of the Earth’s atmosphere have already felt the consequences of all this.

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