Flow This is a glacier on Mars, or at least it was at one point. This image was captured by the HiRISE instrument on the Mars Reconnaissance Orbiter spacecraft, which means that at its highest resolution, meter-sized boulders are visible in this camera shot. The image is sorta upside-down, as north is at the bottom side of this frame, but that’s how the spacecraft shot was oriented. The bottom side of this image is the high ground, so ice formed on that slope and flowed downhill, moving rocks and leaving streamlines with it.














