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I’m Indigenous Canadian and I still have friends or new people I meet who joke with me about Native stuff, like do I know what time it is, what’s the weather forecast, can I read the stars? Where are the animals? How’s the fishing?
I tell them that there is a traditional way of being able to tell which way is north.
I tell them to look for the nearest satellite TV dish … they always point south.
Obviously, this only works in the northern hemisphere … if you are a Native person in the southern hemisphere, the dishes point north.
if you are a non-native person in the Southern hemisphere the dishes still point north
Are you sure about that? Thousands of years of ancient knowledge might disagree
are geostationary orbits stable? they must be too far from the atmosphere to degrade.
wonder how will they look in a few million years?
Will they aggregate into a new tiny moon?
imagine a future civilization, whom only indication that we existed it’s mysterious layer of micro plastics in their geological record, then when they reach space they find all our satellites.
They’re stable over human-lifespan time frames, but not million-year time frames. There’s a lot of things up there to disrupt orbits other than atmosphere; solar photon pressure, solar wind pressure, and tidal effects from the Moon and Sun are the main ones. This is why Earth doesn’t have rings now despite there having been plenty of impacts in the past that would have contributed dust to them. There might still be a few satellites in scattered orbits, though, so you could still find some for archaeological analysis.
There’d also be plenty of non-plastic artifacts in the geological record. Ceramics last forever, they’re basically rock. Same with glass.
so no geostationary satellite’s, would the satellites placed on a Lagrange orbit be more stable?
follow up question, how hard would it be to find a dead satellite in a Lagrange point?
let’s use James Webb, would it show on a survey? or we could only find it if we know exactly where it is?
would the satellites placed on a Lagrange orbit be more stable?
Probably not, it would still be perturbed over time by those forces (not Lunar tides, though, so perhaps a little more stable).
Orbital dynamics are really a lot more jumbly and chaotic than intuition might suggest, over long timespans. The current arrangement of the solar system only seems stable because it’s had billions of years for all the really unstable stuff to get shaken out. Unoccupied regions of space are usually unoccupied because there’s some mechanism that disturbs anything that tries to hang around there long-term.
Finding defunct satellites would probably not be too difficult for a civilization at our level. They’re small, but they’re always nearby so there’s plenty of opportunity to catch them in surveys. You probably wouldn’t want to use the James Webb, though, for a couple of reasons:
- James Webb is in the Earth-Sun L2 point, so to observe objects in the vicinity of Earth it’d have to point toward the Sun. That would wreck its ability to keep itself cool, which is vital for an infrared telescope, and blind the optics if you weren’t being extra careful when pointing it.
- James Webb is designed to look at distant objects with high resolution, so its field of view is very small. It’s like looking through a straw, you’re going to have a hard time catching things that you don’t already know where to aim for.
Something like the Simonyi Survey Telescope is better suited to this. It’s designed to have a wide field of view so that you can regularly blanket the sky with photographs, then compare the photographs from different times to see if anything’s moved relative to the distant stars. Those moving things are likely to be stuff like asteroids and satellites.
Ironically, geostationary satellites would be the hardest type to detect like this since they don’t move relative to the distant stars. But since they’ll get pushed out of geostationary orbit over time by the perturbations I mentioned, that future civilization will still be able to find them if they’re still somewhere nearby.
Sorry, I meant the James webb as a target, not as a telescope to do the survey.
and would a survey by Simonyi be able to detect something so small like the James Webb?
I doubt it, but when it comes to astronomy things have so much precision that I would not be surprised if it was trivial.
Oh, I see. I think James Webb wouldn’t be a good target, either. The L2 point isn’t stable at all; once James Webb loses station-keeping ability it’ll just be a matter of years before it’s drifted off and fallen into a generic solar orbit. That’ll keep it quite far away from Earth, I doubt it’d be detectable to telescopes with our current technology.
that’s what I feared, so “space artefacts” wouldn’t be a thing for a future civilization. :(
One story I can’t write
No, you’re over-generalizing from a special case. The vast majority of the satellites we put up are orbiting close to Earth, the L2 point is only useful for a handful of scientific probes. Same with the L1 point, where Sun-observing satellites get placed.
The satellites orbiting in LEO and MEO will have their orbits decay due to atmospheric friction over the course of thousands or millions of years and will be gone. But HEO and GEO orbits won’t have meaningful amounts of atmospheric friction to deal with. Those are the ones that may still be around in a million years. They won’t be in the same orbits, though - they’re going to be perturbed by the other forces I mentioned. So nothing will really be GEO any more at that point.
Wait long enough and they’ll probably all end up scattered, their orbits will become elongated enough that either they’ll dip into the atmosphere or get far enough out for the Moon to give them a fling out into solar orbit. But a civilization at our level of capability will probably still be able to find a few of them orbiting Earth after a million years.
They may also be able to find a few things left on the Moon. It’ll be hard to spot them against the Lunar surface after a million years, everything will be eroded by micrometeors and covered in dust, but since they’ve been clued in to the existence of a prior civilization they’ll probably look harder for such things earlier on than we would. And if you want to give them a little boost to help things along, it’s not inconceivable that something with writing on it could last a million years on Earth if it gets buried in exactly the right way - a page from a children’s textbook would have all sorts of important Lunar sites marked on it. I’d look into how various “deep storage” companies around the world use old salt mines as places to store archives of data for customers, your future archaeologists could find one of those and it’d be an absolute jackpot.
My understanding is they don’t degrade like low-earth orbit but still require station keeping to maintain their precise location, so as they run out of fuel they get moved to a “graveyard” orbit that’s out of the way. At much larger time scales I think the orbits can still get unstable but I don’t think earth’s atmosphere contributes much to that.
it’s fine if they shift a bit, as long as they stay in orbit.
been obsessing about a post human civilization doing archaeology on us
They degrade all the time
As far as I understand there aren’t actually that many satellites in geo stationary orbit, when compared to Leo at least.
