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Comment by revnode | Hacker News Reader

> evidenced by the fact that they did not leave behind any space junk

Whatever space junk we leave behind will be gone 100 years from now. https://www.nasa.gov/news/debris_faq.html

That’s really not what that means. The 4th satellite Vanguard 1 was put into orbit in 1964 and it’s expected to have a 240-year orbital lifetime despite getting to within 657.3 kilometers of earth. https://en.wikipedia.org/wiki/Vanguard_1

Geosynchronous satellites 35,786 km (22,236 mi) are going to be up there for a very long time.

PS: If you’re interested https://aiaa.kavi.com/apps/group_public/download.php/3172/IS...'

And anything that went to solar orbit will be the more or less for ever, subject only to the slow erosion of thermal cycles over the eons. And all Pioneers, Voyagers and New Horizons will not have to sustain even that, just comic rays.

BTW, it's a bit mind boggling how big and empty even just interplanetary space is - there could be wrecks of an unlucky discovery fleet paying a visit couple milion years ago and we might never find them unless they come really close to Earth or other sensor rich human inhabitted place or possibly still produce some active emissions (outgassing, sporadic radio signals, abnormal heat absorption/radiation, weird albedo variations, etc.).

I think that’s just for lower orbits, I was under the impression our geosynchronous satellites will be up there for millions of years (unless future humanity cleans up the geosynchronous graveyard orbit)

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