When asked what was the significance of the results, Eke added they were "still a little bit too tantalizing" because the ice depth was not defined as precisely as he would like. Eke said he plans to use the final MESSENGER MLA data to provide better sampling of the polar regions, allowing him to see more craters - perhaps including smaller ones - to give a tighter constraint on the ice depth.
Failing that, there's another Mercury mission called BepiColombo that is headed to Mercury in the 2020s. The European mission should be carrying a laser altimeter, and Eke said he is hopeful the methods in his team's paper could improve the constraint on the ice thickness.
"If BepiColombo flies low over the south pole, rather than the north pole like MESSENGER, then this would also be helpful to increase the number of well-measured polar craters. I'm not sure that the orbit has yet been decided," he said.
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"The limiting factor is not how accurately an individual altitude is measured, because both the MLA and [BepiColombo laser altimeter] do this to better than 1 meter. However, craters have departures from axisymmetry of up to 100 meters due to subcratering impacts. We need to average over enough craters to ensure that the height difference we're measuring is caused by ice, rather than just being intrinsically rough craters."