"太空中不存在任何磨擦阻力" is also wrong. In LEO orbit, drag forces slow down space vehicle. Some years ago, a shuttle mission had a 20 km. cable attached to a probe, and the mission involved having one end of the cable attached to the shuttle orbiter and the other end attached to the probe (I forget what the probe was for). Anyway during the mission, it turned out the drag caused the cable to bend, and we had the orbiter and the probe pretty much moving in the same velocity (angular), and in between them there was a big arc due to drag.

Also, the satellite constellations that I worked on as satellite control system developers, had found something wasn't anticipated, the sunlight shining on the solar panels on those satellites got extra boosted and accelerated. We had to schedule extra burns to slow them down to maintain their orbits.

These two are just some simple facts about astronautics that there are many external forces acting on the SVs and making their orbits difficult to predict. In fact, today, in the orbit, an SV position is in a control box. We don't really know exact where the SV is, except that it is very likely to be in the control box. The bigger the control box is, the easier to control; smaller the box is, it is getting harder.

As for interplanetary, it is a chaos. Just N-body problem itself is enough make orbit calculation extremely difficult, fyi, the generalized N-body problem is impossible to solve. Don't think that is easy.