When these satellites burn up in the atmosphere, what happens to all the particles? Do we have lots of likely toxic material just constantly being burned and circulating around?
We estimate that the amount of dust and meteorites entering earth's atmosphere is about 100 metric tons per day. Combine that with emissions from volcanoes, many of which are highly toxic, and vaporised satellites are really insignificant.
The proportions remind me of another somewhat common space-related misconception, which is that rocket launches are big polluters.
With each launch emitting roughly as much as a single commercial flight and typically around 100 launches happening globally per year, even a tiny change in the tens of millions of commercial flights per year has a far larger impact on emissions than launches will for the foreseeable future.
> With each launch emitting roughly as much as a single commercial flight
It's one of those "connective" facts that puts so many distinct things into perspective. When I first learned it a few years ago, I became simultaneously very relieved that a rocket launch doesn't really have that big of a carbon footprint, and horrified by how much emissions a single passenger plane can make. It's a lesson about how visuals can be misleading: a plane looks tiny and doesn't really seem to be doing anything, while a rocket is big and rises to heavens on a pillar of flame, propelled by the anger of hell itself - and yet it turns out they're roughly the same, emissions-wise.
An easy way to compare the amount of CO2 they release is looking at the size. They only can burn the fuel they carry, and the density of the fuel is similar. The best images I got are
To make the calculation more difficult, like the 80% of the volume of a Boeing 747 is room for humans, and like 50% of the volume of a Falcon 9 is room for Oxygen and thrusters.
Some of the propellants (especially the hypergolics) are pretty toxic. However, Soyuz, Long March 5 (and later), Falcon 9, and Delta III (first stage) all use high-grade kerosene (RP-1 or its Russian equivalent) and liquid oxygen. Jet-A isn't too far from high-grade kerosene. Ariane 5 uses liquid hydrogen and liquid oxygen in its first stage. Many of the smaller players use RP-1/LOX, and some of the next-generation rockets will use methane/LOX propellants.
Though, the Delta III and Ariane 5 boosters do contain ammonium perchlorate, which is worse for the environment than jet fuel.
No, we have very small amounts of likely toxic material circulating around.
Earth's atmosphere is around 5 x 10^18 kg. All the satellites put together are not going to increase the amount of toxic material enough to matter whatsoever.
If you are concerned about metal oxide dust, then you would want to shut down every blast furnace in the world, and also pave over the Sahara, since it throws millions of tons of iron oxide dust into the air every year: https://en.wikipedia.org/wiki/Saharan_dust
> Also pave over the Sahara, since it throws millions of tons of iron oxide dust into the air every year
And at the same time fuck up our planet in a major way. There is a lot of life dependent on the plant on that dust. Everything from micro organisms in the sea, the Amazon gets its phosphorus from it, etc (it is a long list of things).
