Unforeseen surprises are the rule in science, not the exception. Remember: Stuff happens.

There is a philosophy that says that if something is unobservable -- unobservable in principle -- it is not part of science. If there is no way to falsify or confirm a hypothesis, it belongs to the realm of metaphysical speculation, together with astrology and spiritualism. By that standard, most of the universe has no scientific reality -- it's just a figment of our imaginations.

Unless something unforeseen happens, they are going to make it if they keep up this pace.

I never make exceptions. An exception disproves the rule.

The exception which proves the rule

There is no exception to the rule that every rule has an exception