This is not an official answer.
The way I've chosen to interpret it, in light of the second edition rules which I also have, is thus. (Assuming strong gravity.)
On turn N you launch from planetary base (effectively, the planet hex) to a gravity hex - let's call it eastwards. Your velocity at this point was 1 hex eastwards, but you've just entered a gravity hex so it's now zero for your next turn.
On turn N+1 you can:
- Do nothing; as a special case, I rule that staying in the same hex causes gravity to be applied again. You now have a velocity of 1 west. On your next turn, if you still do nothing, you will crash (or land where you started).
- Thrust west. You crash.
- Thrust north-west or south-west. You have now entered a new gravity hex, so your velocity of (e.g.) 1 north-west gets 1 south-west added to it to become 1 west. You are in orbit.
- Thrust north-east, east, or south-east. You are now travelling freely in space.