The Pritcher Mass

From back cover Tor paperback February 1983: EARTH WAS FINISHED... After a strange and horrible fungal growth had irrevocably contaminated the planet, humanity's only hope lay out in the farthest reaches of the Solar System where the incredible Pritcher Mass searched psychic wavelengths for living worlds. If one were found in time, a saving remnant of the race might achieve a new beginning. But, something of earth, some ancient evil, seemed bent on the destruction of the Mass...