[VadeRetro]

However, orbital mechanics are based upon fairly stable equilibria and are not easily degraded to the point of catastrophe except when big things start banging into each other.

I don't mean to imply that persistent drag effects don't matter. Skylab was supposed to be in a long-term stable orbit. However, in the mission planning stage (early 60s) when we calculated that orbit we didn't yet know that the Earth's atmosphere swells outward during peaks of the 11-year solar cycle. We had made measurements during a quiet phase and didn't appreciate the changeable nature of what we had measured. When the next peak came, Skylab proved to be skimming gas, its orbit decaying rapidly.

But I suspect the meteor imbalance drag effect is too small to do much, never mind that it swamps your solar sail.

[Fish Hunter]

True,

You do seem to be open my doubt that anything in the solar system can remain stable for a billion years. The solar system is very active and a billion years is an incredibly long time, almost inconceivable to the human mind. Any constant perturbation of any size would effect things over a billion years. That was where I was going with my calculations, but I messed up when I did not throw the solar pressure into my initial condition for my exercise.

In my heart I just can't bring myself to believe in absolute constants, because the universe is dynamic and changing.

F H