if you set a waypoint at a planet and launch a probe (i.e. a missile with active sensor operating in flight not a buoy), to the waypoint, the waypoint orbits with the planet and the probe hits, stays with the planet a few days and vanishes as expected
if you delete the waypoint, the probe stops orbiting with the planet and stops dead in space which is unexpected, I would expect it to stay in orbit like buoys
Missile Size: 1 MSP (2.5 Tons) Warhead: 0 Radiation Damage: 0 Manoeuvre Rating: 10
Speed: 3,200 km/s Fuel: 100 Flight Time: 1,305 hours Range: 15,037.7m km
Active Sensor Strength: 0.29 EM Sensitivity Modifier: 11
Resolution: 10 Maximum Range vs 500 ton object (or larger): 2,170,967 km
Cost Per Missile: 0.484 Development Cost: 110
Chance to Hit: 1k km/s 32.0% 3k km/s 10.7% 5k km/s 6.4% 10k km/s 3.2%