Part of this is that science isn't about experimentation, it's about observation. We perform experiments when possible so that we have more stuff to observe, or more controlled events.
Much of astronomy, atmospheric physics, geology, medicine, the "soft" sciences and I'm sure plenty of other "hard" fields are at the mercy of certain phenomena having sweet FA for data points. And I'm sure they all do what astrophysicists do: make sure that what we do have plenty of data for works; make our extrapolations with as few assumptions/rounding errors as we can; and revisit existing models anytime we find a new data point.
It's as scientific as anything it's simply going to take longer to sort out in some cases.