It's a fallacy that you have to go into debt to get an advanced degree in the sciences. I don't know any American student in my department (at a graduate level) who's paying tuition. Most of us have assistantships that pay a stipend. I'm in CS, but I understand it's the same way for many of the science fields.
Of course, if you want a Ph.D in, say, English Literature, be prepared to pay through the nose. When they take away my stipend, then I'll think that maybe we don't have a demand for Ph.Ds any more.