Large constellations of small satellites will significantly increase the number of objects orbiting the Earth. Satellites burn up at the end of service life during reentry, generating aluminum oxides as the main byproduct. These are known catalysts for chlorine activation that depletes ozone in the stratosphere. We present the first atomic-scale molecular dynamics simulation study to resolve the oxidation process of the satellite's aluminum structure during mesospheric reentry, and investigate the ozone depletion potential from aluminum oxides. We find that the demise of a typical 250-kg satellite can generate around 30 kg of aluminum oxide nanoparticles, which may endure for decades in the atmosphere. Aluminum oxide compounds generated by the entire population of satellites reentering the atmosphere in 2022 are estimated at around 17 metric tons. Reentry scenarios involving mega-constellations point to over 360 metric tons of aluminum oxide compounds per year, which can lead to significant ozone depletion.
SpaceX has been receptive to design changes to starlink in the past to minimize impact, like decreasing reflectivity and reflection angles for astronomers. They might be receptive to moving to different alloy for the body construction.
Magnesium comes to mind that would be light but expensive. Steel alloys might be cheap and heavy options for later when starship is operational. Would those have similar effects on ozone, or is it only the aluminum oxides?
Magnesium oxides can also serve as a catalyst for lots of reactions, but I'm not sure if it will have the same effect in this specific context, I'd guess it would.
That's why I added the link to the wooden satallites, that also reduces the metal debris somewhat and reduces other effects like radio interference.
Wood is interesting, but the article doesn't address off gassing at all, which is a huge problem for communication satellites. Is there a way to keep the wood from off gassing? For 3d prints in vacuum, they metal coat them to keep the gas inside. Or maybe you could resin soak them? With hopefully an extremely UV stable resin. But I didn't know what the weight trade looks like then, resin is heavy.
But if you're looking composites anyway, carbon fiber would be another great option. Lightweight but with a few manufacturing constraints. But should burn up to carbon dioxide on reentry.
I just read an interesting research article from NASA that shows that carbon fiber survives reentry better than our previous scientific consensus claimed.
Some carbon fiber will burn up into carbon dioxide, but a good chunk of it will surprisingly survive reentry conditions. I think you are very right that it should be a better material to use for starlink.
I feel like it shouldn't even have to be said out loud that gravity and weight correlate, but their orbit would be heavily impacted by replacing aluminium with five times as much steel for the same durability. You might be able to get away with slightly less if you consider the steel has more heat resistance, but idk.
I'm not even going to answer your question, just gonna hyperfixate on you posting outright lies.
When there’s drag involved it’s different, but in vacuum there’s no relationship between weight and orbit.
There is, when a heavier object is launched: in order to maintain orbit it has to either be further away or go faster. Since the (simple newtonian) gravitational pull of the earth is GMm/r2 that means as r increases the pull of gravity decreases, a typical starlink satellite at 614 km above the earth is experiencing slightly more than 91% of the gravitational pull we experience on the surface but that is enough that it's angular momentum offsets its trajectory and and keeps it from descending. If the mass of satellite increased maybe 3 times then the force of gravity acting on then it would need to be offset by an equal amount of increased angular momentum or it would need to be further away from the earth which would defeat the entire concept of Starlink. It was made to be a net of internet connective nodes closer to the surface so that we could achieve faster speeds without worrying about the limited range as the earth's curvature blocks the operational range of the satellite as it gets closer.
Also, there is still drag in the lower exosphere.
You're welcome btw, normally people get charged for these lectures.