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I'd be interested in seeing a deep dive analysis comparing the costs in energy / environmental impact, as well as risk profiles from space debris of maintaining

I'd be interested in seeing a deep dive analysis comparing the costs in energy / environmental impact, as well as risk profiles from space debris of maintaining clouds of lower-earth orbit satellite vs constellations of higher-earth orbit satellites. For the lower orbits I think there are some points to be made about the additional flights to maintain enough satellites, as well as the questions of what happens to all this junk as it de-orbits? If we're talking about sustainable infrastructure, what kind of new weird material/chemical build-ups are we going to be dealing with after 50 years of tens/hundreds of thousands of private satellites partially burning up and partially raining down on random spots on the planet? Perhaps this is less of an issue than I'm imagining it will be, but I tend to think we'd be better off figuring out some kind of autonomous robot LEO satellite aggregation/recapture solution for cleaning up satellites from higher stable orbits that can operate farther and live longer. We should be allocating our launches to other projects. Even without considering the emissions of launches, there is a significant resource energy/cost for each one and the noise pollution also takes a toll on surrounding ecosystem. If we're going to be ramping up launches to scale the mass to orbit, we're also going to be scaling those negative externalities. I think we really need to make sure the mass we're taking up is worth it and not just governed by whoever happens to have the most money to burn. I can imagine the very near future where people are paying to launch crypto-mining satellites for memes, or some other such wasteful nonsense.

modeless 5y ago
These satellites are designed to fully burn up on reentry, so no solid debris reaches the ground. Meanwhile, many tons of space dust burn up in the atmosphere every day, and meteors large enough to hit the ground happen multiple times a day on average as well. Space dust contains plenty of things that are more hazardous than anything in these satellites. According to [1] the abundances on this page multiplied by [2] 40000 tons per year, the stuff naturally hitting the atmosphere each year includes 0.3 kg uranium, 1.6 kg thorium, 3 kg radioactive isotopes of potassium, 10 kg mercury, 18 kg cadmium, 50 kg lead, 72 kg arsenic, and 120 tons of chromium, among other things. This stuff burns up in the atmosphere all day long, and has for billions of years. As far as emissions, one Falcon 9 launch emits 300 tons of CO2 and they've been launching one or two times per month to build out the Starlink constellation. Meanwhile commercial aviation emits 2 million tons per day and is still a small fraction of the world total. [1] https://periodictable.com/Properties/A/MeteoriteAbundance.v.log.html https://periodictable.com/Properties/A/MeteoriteAbundance.v.... [2] https://link.springer.com/chapter/10.1007%2F978-1-4419-8694-8_5 https://link.springer.com/chapter/10.1007%2F978-1-4419-8694-...
bryanlarsen 5y ago
modeless answered one of your questions well, the other has a good deep dive here: lhttps://everydayastronaut.com/rocket-pollution/ https://everydayastronaut.com/rocket-pollution/ A rocket launch powered by fossil fuels is comparable to an oceanic jet trip, surprisingly. So quantities aren't a big deal, yet. Elon Musk has promised to switch to carbon neutral fuel for his next generation of rockets, synthetic methane for Starship.
simonh 5y ago
They’re all interesting points, but I think we’re a very long way from the satellite industry being a significant environmental concern. Firstly reusable rockets cut the amount of discarded hardware massively. With expendable launchers almost all of the hardware dropped into the ocean or burned up is from the launcher. The satellite is a tiny fraction. This is a huge win. Secondly the total mass of satellite hardware burning up is dwarfed by natural meteorites, of which approximately 100 tons of silicates, metals and hydrocarbons enters our atmosphere every day. That’s an entire ISS every 4 days. That’s 600 times the mass of satellites the US launches per year. The thing is Starship may well increase mass to orbit by that much. Even so, that would “only” double the natural rate of material entering the atmosphere. Another strategy that might help, for high altitude satellites, would be to move to fewer bigger satellites, with racks for different companies instruments, and with self de-orbit capability. Treat them like orbiting data centres. Starship can certainly handle big satellites, and if launches are cheap then it could be affordable to fit such satellites with de-orbit capability. Or maybe even send a Starship to swallow it up and bring it back.

modeless 5y ago

These satellites are designed to fully burn up on reentry, so no solid debris reaches the ground. Meanwhile, many tons of space dust burn up in the atmosphere every day, and meteors large enough to hit the ground happen multiple times a day on average as well. Space dust contains plenty of things that are more hazardous than anything in these satellites. According to [1] the abundances on this page multiplied by [2] 40000 tons per year, the stuff naturally hitting the atmosphere each year includes 0.3 kg uranium, 1.6 kg thorium, 3 kg radioactive isotopes of potassium, 10 kg mercury, 18 kg cadmium, 50 kg lead, 72 kg arsenic, and 120 tons of chromium, among other things. This stuff burns up in the atmosphere all day long, and has for billions of years. As far as emissions, one Falcon 9 launch emits 300 tons of CO2 and they've been launching one or two times per month to build out the Starlink constellation. Meanwhile commercial aviation emits 2 million tons per day and is still a small fraction of the world total. [1] https://periodictable.com/Properties/A/MeteoriteAbundance.v.log.html https://periodictable.com/Properties/A/MeteoriteAbundance.v.... [2] https://link.springer.com/chapter/10.1007%2F978-1-4419-8694-8_5 https://link.springer.com/chapter/10.1007%2F978-1-4419-8694-...

bryanlarsen 5y ago

modeless answered one of your questions well, the other has a good deep dive here: lhttps://everydayastronaut.com/rocket-pollution/ https://everydayastronaut.com/rocket-pollution/ A rocket launch powered by fossil fuels is comparable to an oceanic jet trip, surprisingly. So quantities aren't a big deal, yet. Elon Musk has promised to switch to carbon neutral fuel for his next generation of rockets, synthetic methane for Starship.

simonh 5y ago

They’re all interesting points, but I think we’re a very long way from the satellite industry being a significant environmental concern. Firstly reusable rockets cut the amount of discarded hardware massively. With expendable launchers almost all of the hardware dropped into the ocean or burned up is from the launcher. The satellite is a tiny fraction. This is a huge win. Secondly the total mass of satellite hardware burning up is dwarfed by natural meteorites, of which approximately 100 tons of silicates, metals and hydrocarbons enters our atmosphere every day. That’s an entire ISS every 4 days. That’s 600 times the mass of satellites the US launches per year. The thing is Starship may well increase mass to orbit by that much. Even so, that would “only” double the natural rate of material entering the atmosphere. Another strategy that might help, for high altitude satellites, would be to move to fewer bigger satellites, with racks for different companies instruments, and with self de-orbit capability. Treat them like orbiting data centres. Starship can certainly handle big satellites, and if launches are cheap then it could be affordable to fit such satellites with de-orbit capability. Or maybe even send a Starship to swallow it up and bring it back.