[Fudd]

And with timescales of 30+ years, you also really need to factor in Jupiters gravitational effect as well.

Do you need to include the 11-year solar maximum cycle as well? This would add a certain degree of uncertainty to the calculation, if it is significant.

[orionblamblam]

> Do you need to include the 11-year solar maximum cycle as well?

Probably not, but a 1000-foot diameter asteroid should *probably* take into account solar photon pressure. But compared to Jovain gravitational effects, it'd be a very, very, VERY minor effect.