gbaikie wrote:
...this could be detected by Neutron detector flying on Odyssey.

Alex writes:
It's possible, but a great deal depends on the spatial extent of any putative (frozen) water deposits throughout Cerberus Fossae and Athabasca Valles such that they could be resolved by Odyssey's High Energy Neutron Detector (HEND). This in turn is directly related to the instrument's spatial resolution and integration time vis a vis the mapping cycle/groundtrack repeat and latitudinal spacing. However, the proponents are more hopeful that landed missions such as one of the 2003 MER rovers, which can easily target the region and that will carry appropriate instrumentation, could provide in situ high resolution data to determine whether the presumed water floods permeated the volcanic deposits south of Cerberus and persist to this day as shallow ground ice. Indeed, detection of near surficial elevated hydrogen levels (which would be plausible evidence for H2O) at near equatorial latitudes would be, given the current models for the depth-to-melting-isotherm on Mars, a *significant* finding.

Alex R. Blackwell
University of Hawaii