Ten years ago, there were about 1,200 satellites in orbit around the earth. Now there are about 12,000 and the numbers are growing rapidly. Starlink alone has 9,000 satellites in its communications swarm and may in a few years have as many as 42,000. By 2040, there may be more than 100,000 active satellites circling Earth.
People worry about the physical dangers of collisions between satellites and the possibility of space debris raining down on Earth or crashing into airplanes, but there is also the alarming increase of satellite-generated pollution.
Satellites don’t stay up indefinitely. When they are deorbited, they burn up in the upper atmosphere. The vaporized materials include tiny particles of a wide variety of elements, but especially lots of aluminum. The effects of aluminum oxide nanoparticles on the Earth’s protective ozone layers are unknown.
Rocket launches are a separate pollution issue. The global annual total of orbital launches is nearly 300. The result is increasing amounts of the byproducts of rocket fuel combustion. Currently, that is primarily black carbon particulates. How those absorb solar radiation in the upper atmosphere is not well known, but some researchers believe the effect could be significant warming of the upper atmosphere.
Debates about the effects of the growing number of orbital satellites is a high-altitude analog of the general discussion of climate change. Many of the same forces driving the two sides of the debate are the same: taking care of the planet vs. taking care of business.
