In Cibola Burn the ships Edward Israel, Barbapiccola and Rocinante started drifting toward Ilus/New Terra once their reactors stopped working.
But if they had enough velocity, shouldn't they be able to stay in the same orbit without drifting?
Alex also mentions that he has enough battery that can put Roci so far from the planet that they will be drifting their whole life before crashing. If the velocity was an issue, why not use the battery to get the velocity to stop drifting?
As far as I understand that's how Earth satellites work, they don't need to use fuel to continuously increase velocity, so why is this an issue for the spaceships?