Satellites at risk of impact, and climate change is to blame

A new study of the British Antarctic Survey reveals how climate change, and above all the increase of CO2 in the atmosphere, affect the permanence of satellites in Earth’s orbit. In particular, the problem is related toupper atmospherethat is the belt between 90 and 500 km of altitude, and the debris that orbit it.

If you have always wondered what happens to satellites once they are turned off, the answer is nothing short of simple: remain in orbit until their “decomposition”. In short, once they have died, they remain in orbit slowed by atmospheric resistance and gradually drop in altitude to burn in the lower atmosphere.

In March 2021 the presence of approx 5,000 satellites orbiting between active and dead, a number roughly doubled from just two years earlier. Also, within the decade numerous companies plan to launch thousands of new satellitesalso as a consequence of the increase in geolocation and communication systems.

But what does all this have to do with CO2 pollution? Well, the quantities of carbon dioxide released by man have meant that, unlike the lower atmosphere, the middle and upper atmosphere have cooled, reducing their density. At the same time this also decreased the atmospheric resistance. The satellites, therefore, deorbit more slowly and they take longer to burn.

In essence, the deceased satellites and any other space debris remain in the atmosphere longer, crowding it and creating a high risk of collision with active satellites. Ingrid Cnossen, a researcher with the British Antarctic Survey, collected her data at her disposal and simulated atmospheric change until 2070.

Cnossen then compared the results with the changes that have taken place in the last fifty years. It concluded that even in a low-emission future scenario, the average cooling and the reduction of atmospheric density will be about double compared to the past.

“Space debris is becoming a rapidly growing problem for satellite operators due to the risk of collisions, which the long-term decline in the density of the upper atmosphere is further worsening. I hope this work will help guide appropriate action to control the problem of space pollution and ensure that the upper atmosphere remains a usable resource in the future.“.