bladeelover429 t1_j9rlkmr wrote on February 24, 2023 at 1:35 AM

Well, from purely a chemistry standpoint, aluminum metal burning up in the atmosphere would mostly create aluminum trioxide. The EPA doesn't consider it to be a dangerous substance, and I can't come up with other reactions with Atmospheric gasses that would form anything significant.

Now from a climate standpoint- large amounts very tiny particles do have a measurable effect on global warming. If we're burning up a mass of aluminum on the same order as all of the meteorites that enter the atmosphere, then the effect is probably negligible, however. But I only say this because I haven't yet seen any climate models that consider particles added by meteorites. This could mean that it's either too difficult to model or its just not important enough. Climate change is notoriously difficult to model, unfortunately.

CoffeeFox t1_j9seco7 wrote on February 24, 2023 at 5:29 AM

>Now from a climate standpoint- large amounts very tiny particles do have a measurable effect on global warming. If we're burning up a mass of aluminum on the same order as all of the meteorites that enter the atmosphere, then the effect is probably negligible, however.

That's a good point to add to the discussion. Micrometeorites are believed to enter the Earth's atmosphere at a rate of many tons per year. One study estimates roughly 10^6 kilograms yearly

So the Earth has already long had massive amounts of metallic elements entering the atmosphere and vaporizing.

bladeelover429 t1_j9t16nf wrote on February 24, 2023 at 10:16 AM

Also, another thing that can be done to get an idea of how problematic the materials the satellite is made of might be depends on this pretty convenient chart of common spacecraft metals and their thermal conductivity: https://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html

If an object starts in space and you assume it's at an ambient temp of 2.7K, you can test different values of the distance travelled through the atmosphere, m. Then you have the amount of energy absorbed per degree, so factor in the energy absorption rate of the metal, and you have how long it takes for it to aerosolize. In this case, if the particles added by the object do end up being problematic to the climate, we would want to make sure that they're being aerosolized as close to the surface of the earth as possible.

So best case scenario, it exits the atmosphere before the amount of light being blocked can do any harm. (Ref. https://www.nesdis.noaa.gov/news/the-dirt-atmospheric-dust)

Worst case scenario, it subtracts a few years from the time left we have to solve this problem before getting sent into an ice age.