  We study the Laplace spectra of the intrinsic instantaneous metrics on the
event and cosmological horizons of a Kerr-Newman de Sitter space-time and prove
that the spectral data from these horizons uniquely determine the space-time.
This is accomplished by exhibiting formulae relating the parameters of the
space-time metric to the traces of invariant and equivariant Green's operators
associated with these Laplacians. In particular, an interesting explicit
formula for the cosmological constant is found.
