If a sealed world makes restraint, honesty and located responsibility into survival requirements, then the qualifying condition for a multiplanetary species is not propulsion. It is character — and character can be specified.
CLOSED-LOOP ETHICS
The practised assumption that nothing is outside. Not a belief — a habit of accounting, learned before departure because it cannot be learned after.
TRUTHFULNESS UNDER COST
The capacity to report your own error immediately, while it is still embarrassing. In a habitat, the interval between concealment and consequence is short.
RESTRAINT AS REFLEX
Tapas, made ordinary. The ability to want something available and not take it, repeatedly, without supervision and without resentment.