Long term evidence of civilization.

[xilman]

Originally Posted by firejuggler

if you find a nuclear reactor waste site , you may have found the last remain of a civilisation.

But you may not.

https://en.wikipedia.org/wiki/Oklo

[TommyJ]

Originally Posted by Uncwilly

You mean reporters that are not full time science reporters proclaim "WE FOUND possible EVIDENCE OF LIFE"

Originally Posted by xilman

But you may not.

https://en.wikipedia.org/wiki/Oklo

Yes, you are right. These are the reporters I mean. But that's what people see.

And yes, we may not find anything at all after the extinction of humanity or any other species.

[firejuggler]

Ok... Space elevator?

[Uncwilly]

Originally Posted by firejuggler

Ok... Space elevator?

No, because the tether is subject to erosion in the atmosphere. After it separates things go bad and the evidence goes away.
But a satellite in an orbit like the GPS system that is visible and shaped such that it is obviously artificial might be a good choice.
[edit]And if it is shaped and spun such that it would flash repeatedly when viewed from the ground, that would help. It would eventually slow down, but if it was very heavy, it would stay spinning for longer. Also, using a gravity gradient to keep it oriented would help.[/edit]

[xilman]

Originally Posted by Uncwilly

No, because the tether is subject to erosion in the atmosphere. After it separates things go bad and the evidence goes away.
But a satellite in an orbit like the GPS system that is visible and shaped such that it is obviously artificial might be a good choice.

As I noted earlier in this thread, high-altitude orbits are unstable to lunar and planetary perturbations over the course of a few megayears.

Also as noted earlier, leaving stuff on the moon is a much better bet.

[Uncwilly]

Originally Posted by xilman

As I noted earlier in this thread, high-altitude orbits are unstable to lunar and planetary perturbations over the course of a few megayears.

Also as noted earlier, leaving stuff on the moon is a much better bet.

There has to be a sweet spot area for orbits that are the most stable over long periods. Also, unstable not mean it goes away completely.

Problem with the moon is if you want to make the evidence visible from the surface of the earth, that is a major effort.

[LaurV]

Originally Posted by Uncwilly

Problem with the moon is if you want to make the evidence visible from the surface of the earth, that is a major effort.

Do you mean, a couple of solar panels that rotate periodically (face down) to get rid of the deposited dust (no air, no static, no bacterial sticking, just turn them upside down and the dust falls), and few toy laser pointers connected to a raspberry pie to paint horses and crocodiles on some nazca plateau on earth?
OTOH, wise farmer never puts all his eggs in the same basket. Unless that's a shell...

[Uncwilly]

It would have to be able to survive the 14.5 day lunar night. And after 1 mega year it would look like a piece of Swiss cheese. 1 meteor of 1 mm in size would be enough to take out the pi. The moon has no significant atmospheric shielding against impactors. Also, it has no protection against solar and cosmic radiation.

[firejuggler]

Let me try a few more space idea...
Galactic slingshot aound phobos/deimos..
Any form of Dyson swarm/ring/sphere.
Something artificial at Lagrange point...

[xilman]

Originally Posted by Uncwilly

There has to be a sweet spot area for orbits that are the most stable over long periods. Also, unstable not mean it goes away completely.

Problem with the moon is if you want to make the evidence visible from the surface of the earth, that is a major effort.

Why do you want to make it visible from the earth?

Use a few dozen nukes to dig 100-metre craters in a geometrical arrangement --- a diagram of the theorem of Pythagorus, for instance.

Then wait until the discovering civilization can get high-resolution imaging from orbit.