The answer to a lot of the pollution problems is probably, and perhaps counter intuitively, "even more mass even cheaper, combined with regulations that are enabled by that". The key identified current concern is very specific to aluminum reentry, not just generic "whatever mass". Around 15000 tons of space dust hits the Earth each year no problem, but the chemical composition is quite different from what present typical satellites produce on reentry.<p>But in turn the composition of present satellites and the nature of their use/lifespan/safety systems has itself been driven heavily by economics. We don't make satellites out of steel or other safer materials not because they don't work, but because of the cost the extra weight imposes. We haven't put satellites in VLEO not because being lower is bad for communications or imaging (it's the opposite, lower is better) because it'd need more satellites, more fuel per sat, and higher cadence, all increasing cost beyond the historic ROI. But Starship or other future fully reusable methalox designs will give us vastly more mass budget and cadence for the same cost. Some of that could result in more trouble with existing designs made for a low cadence/high $/kg environment, because some externalities that were previously acceptable due to lack of scale stop being so at scale. But the same increased budget also means increased budget to ameliorate that. We can trade some of the gains for materials that burn up harmlessly in the atmosphere, designs for lowering apparent magnitude to the ground, for better self-destruct and end of life systems, more fail-safety, more redundancy in general, etc etc. And if that requires more regularly replacement that too is made easier but order of magnitude or more lower cost.<p>Some of this may happen naturally just due to self-interest, but other parts like pollution may require thoughtful regulation. But such regulation will be a much easier lift when it's affordable, so it's worth it to try to maintain an appropriately thoughtful mindset on the benefits vs tradeoffs and how to keep the former while reducing the latter.