Re:Was there a civilization on Earth before humans?
by pocketstar on Saturday April 14, 2018 @03:46PM
(#16839081)
>none of that stuff will be in orbit in 60m years.
where will it go? it wouldn't have the drag or the delta-v to reenter. i think the parent meant geostationary altitude, but "geostationary" orbits are "relatively" cyclically stable. most significant perturbations, you mentioned some, are all <100 year cycles. If there was another spacefaring civilization >60m years ago i think there would be evidence, in orbit.
Re:Was there a civilization on Earth before humans?
by acover on Saturday April 14, 2018 @12:44PM
(#16838109)
Could you move in a moon orbit?
Re:Was there a civilization on Earth before humans?
by rgbrenner on Saturday April 14, 2018 @12:49PM
(#16838138)
Same problem. I don't think it could be in orbit.
Someone else mentioned the objects we've placed on the moon. Seems to me that those would last the longest. The moon gets hit by small meteorites daily, but nothing that would destroy what's up there.
Geostationary is only stationary in relation to a specific point on earth (geo). It just means it stays above a point on earth. It requires regular minor adjustments.
L1, L2, and L3 aren't stable. L4 and L5 are... but you would still need to adjust for the earth and moon not being perfect spheres; the moon moving slowly away from earth; tidal variations; solar wind; debris; etc.
L4 and L5 would last the longest, but not 60m years.