Hi Gary,
There are a handful of references in your later-era AD&D writing to space travel -- in the description of Celestian in the WoG, in some notes in Dragon articles, and perhaps a reference or two in spell or item descriptions in UA -- that were never developed and I'm curious what you envisioned this aspect of the game being like. How, for instance, would the play-experience of traveling to different planets have differed from traveling to different planes? How would you have avoided a 'sci-fi' feeling (or is that something you would have embraced)? Was this notion inspired by Jack Vance's story "Morreion" (the same story that gave us IOUN stones)? How close would a Gygax "D&D in space" supplement have looked to TSR's "Spelljammer"

?