Fix a prime number p, and let X be a finite spectrum whose (n - 1)st M
orava K-theory is trivial but whose nth Morava K-theory is nontrivial,
n > 0. We prove, following a method outlined to us by M. J. Hopkins,
that, if 2p > n(2) + n + 2, the Morava module of the Brown-Comenetz du
al of the E(n)-localization of X is isomorphic to a suspension of the
Pontryagin dual of the Morava module of X. To complete this proof, we
found it necessary to develop a more canonical construction of certai
n modified Adams spectral sequences; this construction should be of in
dependent interest.