It has been recognized for over twenty years that the abundance of the light isotope 3He provides a sensitive theoretical constraint on Big Bang models of the first few minutes of the Universe. Drs. Bania and Rood propose to continue work previously supported by the NSF to determine the abundance ratio 3He/H in glowing interstellar gas clouds ("H II" and planetary nebulae) surrounding hot stars in our Galaxy and nearby galaxies. The Investigators have substantially improved radio receivers and reduction procedures in order both to detect fainter sources and to select those in which nuclear evolutionary processes in nearby stars have been minimal. It is expected that new constraints can be placed on early Universe Big Bang models as a result of this three year program.
