The Astraeus cannot move from a medium-large sized planet to it's moon. It goes half-way there and then vanishes and re-appears back on it's starting planet. (If I ordered it to leave planet 1 and arrive at planet 2's north pole, it will arrive at planet 1's north pole.) Any one else having this issue? It can travel to other, further planets just fine.
I have had this issue also. I had two moons in orbit of a medium small planet. I could send the astraeus to the far moon but not to the closer moon. the closer moon had a really small orbit. I think the smaller orbit is causing it.
Just got out of a game, I've got to say that they need to fix this glitch, it makes moons totally unmanageable. In my game I took over a moon, made several nukes and halleys then moved into orbit of the starting planet for some mayhem. Problem was, the nukes couldn't reach the starting planet due to this bug. I tried moving the moon from one orbit to another, firing the nukes then leaving orbit so the nukes would land, but this crashed the game. This. Needs. To be. Fixed.
I noticed this in one of my own systems, and was able to resolve the issue by moving my moon(s) further away. It seemed like the gravity well of my main planet would prevent the Astraeus from getting to a moon that was orbiting too close.