Because observations are never perfect, data are never complete, and gravitational interactions are complicated. The more observations you have the better you can estimate the orbit, but asteroids are hard to observe and you may not have that many data points. Mass and velocity must be estimated from observations that are compatible with different solutions. A brighter dot might mean a bigger asteroid or more reflective material, for example, and the mass depends on both. A particular speed of apparent motion is compatible with different velocities depending on whether and how much the asteroid is moving towards or away from the observer. All these kinds of factors make for uncertainty.

[+] artificialfish@programming.dev 3 points 5 months ago* (last edited 3 months ago) (1 children)

[deleted]

[–] threelonmusketeers@sh.itjust.works 5 points 5 months ago* (last edited 5 months ago) (1 children)

It's a shame you're being downvoted for genuine questions.

I thought we knew most of the stuff in our solar system to pinpoint accuracy already.

We know where all the big rocks are. Those smaller than a few hundred meters are much harder to spot.

A telescope in mars orbit vs a telescope in solar orbit vs a telescope in earth orbit could get you position and velocity very accurately id think.

It definitely could, but we don't really have astrometry telescopes beyond earth orbit. I can't wait until launch costs get low enough for us to yeet Hubble-class or Arecibo-class telescopes all over the solar system, and maybe even do interferometry between them.