One or two surface glaciers have been detected on Mars, covered with debris to some depth. Earth-like ice should not be there, due in part to low atmospheric pressure. Hence the case for an altered ice i.e. martian rock ice, with an altered (strengthen) bond between water molecules; taking on the appearance of rock, but of a lesser density. One could drill into it, and compare densities (amperage as a proxy) with an earth ice model, and also utilize infrared spectroscopy of bond nature.
But the glaciers represent a small target, from orbit. Perhaps one could land within ~50-100 miles, and launch a large enough drone to not only get to the glacier, but also to drill into it.
Martian atmospheric pressure of 3-5 millibars would seem to preclude propellers. Instead one could utilize small rockets and/or simple non-combustible gas cartridges, since only Newton’s 3rd law applies.