So, everyone worrying about the Venus probe reentry: yes, it's not designed to burn up in the atmosphere, and that's bad.
But, remember Starlink? There's something like one Starlink per day reentering now, and they weigh more than the Venus probe! SpaceX says they will burn up completely, but now one Starlink piece has been discovered in my province. (And if they don't make it to the ground, that means that half-ton of metal and plastic is deposited in the stratosphere instead. Yum).
More than 7,000 Starlinks in orbit now, and they have permission for 42,000. Even conservatively, at peak operation, they'll dump 25x more aluminum into the stratosphere than falls naturally as they launch and burn up 20-25 sats PER DAY. What will that do? We actually don't know. That metal is already measurable. SpaceX is just running this experiment.
We need fewer satellites in orbit with longer operational lifetimes. THAT is the new engineering challenge in LEO.
LEO sat disposal is a new environmental disaster brewing, mostly because of the actions of a single private company, but really, it's everyone's operating procedure in LEO. Just burn those sats up in Earth's atmosphere when they're done! They just disappear! And if they don't, they probably won't hit anyone anyway.
Ok, this is turning rambly and I'm tired and need to put my goats in the barn. I hope the Venus probe reenters with no injuries, and just to be abundantly clear: fuck Starlink.
@osma @michaelgraaf You saw these two, right? https://ui.adsabs.harvard.edu/abs/2024GeoRL..5109280F/abstract
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.
Yes. The first makes the unsupported claim that "[aluminum oxides] are known catalysts for chlorine activation" incorrectly citing the SRB research. The second I reference in my post.
Aluminum oxide doesn't activate chlorine. Ammonium perchlorate does. SRB, not satellite. Basic chemistry.
@sundogplanets @michaelgraaf
Prof. Sam Lawler
Michael Graaf
Osma A 🇫🇮🇺🇦