Dunno where I got the idea that millimeter-range was the only way to go back that far in time. But this piece implies that UV scatters enough that it is still around from back then.

Unless I'm reading this wrong. Anybody?

"By choosing targets carefully, we can get more easily interpreted data, allowing stronger conclusions regarding the nature of interstellar dust. The observed cosmic background is not fully understood and possibly is of new cosmological importance. We are confident that with FUSE and carefully implemented further observations, we can answer many questions for the first time."

If so, that is pretty exciting!