The Gates of Eden

Despite the development of a faster-than-light drive, Earth's space program
has been in the doldrums for centuries, as has the Earth itself. Hyperspace
being impossible to navigate without beacons at which to aim, there is no
alternative but to wait for vessels sent out at sub-light speed decades
previously to find somewhere worth going. Unfortunately, when one finally
does, it doesn't take long for political conflicts to materialize over the
exploitation of the few seemingly-Earthlike world in question. When an entire
survey team dies, the problems intensify. Lee Caretta is the man most likely
to solve the problem, if his conflict-ridden employers will let him, if he
can keep his tendency to suffer unexplained blackouts under control, and if
the world really is sufficiently Earthlike not to be deadly to all who investigate. And then the humans begin dying!