It doesn't matter if it's unstable - as long as it was not carefully aimed to hit something, "space is big and empty" means that a random unstable orbit is exceedingly likely not to hit anything for a very, very, very long time.
There's no way of knowing this without calculating and modeling the trajectory, but you can still be 99.99% sure that it's not going to hit anything for thousands or even millions of years even without extra information. As the parent poster said, the chance is close to 0.
There's no way of knowing this without calculating and modeling the trajectory, but you can still be 99.99% sure that it's not going to hit anything for thousands or even millions of years even without extra information. As the parent poster said, the chance is close to 0.