Ice in Mid-Latitude Craters

New impact craters at several sites in the martian mid-latitudes have excavated material from depths of decimetres, producing a brightness and colour strongly indicative of water ice. These impacts may have excavated completely through this clean ice, probing the subsurface to depths not previously sampled. The observations suggest significant heterogeneity in the vertical distribution of the ice deposit [Byrne et al., 2009]. With the support of Willy Benz’s group, we have been modeling these impacts using a smooth particle hydrodynamics (SPH) code to investigate whether further constraints can be placed on the vertical ice distribution and on whether the impact can result in the production of liquid water. This work is in its early stages but a preliminary result is shown in the figure below. Using an SPH code, we have modelled an impact into ice covered by an analogue for Martian dust. After 0.3 ms, the impact has produced pressures exceeding 3 GPa which is a value required to produce liquid water. Note the reflections at the dust-ice interface 30 cm below the surface.

Publications

Reufer, A., N. Thomas, W. Benz, S. Byrne, V.J. Bray, C.M. Dundas, and M.L. Searls, (2010), Models of high velocity impacts into dust-covered ice: Application to Martian northern lowlands, Planetary and Space Science, 58, 1160-1168, doi:10.1016/j.pss.2010.04.008.

Byrne, S., C.M.Dundas, M.R.Kennedy, M.T.Mellon, A.S.McEwen, S.C.Cull, I.J.Daubar, D.E.Shean, K.D.Seelos, S.L.Murchie, B.A.Cantor, R.E.Arvidson, K.S.Edgett, A.Reufer, N.Thomas, T.N.Harrison, L.V.Posiolova, and F.P.Seelos, (2009) Distribution of Mid-Latitude Ground Ice on Mars from New Impact Craters, Science, 325, 1674.