So this is a book I read 25+ years ago.
Its set on a world which eventually gets wiped out and a handful of inhabitants escape in a shuttle/spaceship/rocket to find a new home.
They stop on a moon/asteroid and the book ends there. The way it ends makes me certain there is a continuation
Cant remember what causes the catastrophe. One of the main character survives getting assassinated as it has two hearts or something like that. The killers didn't realise about this anatomic feature and presumed they had killed him for good.
Sorry, I know its not much to go and its so vague.