SEEING MARS WITH NEW EYES: LATEST RESULTS FROM THE HIGH RESOLUTION STEREO CAMERA ON MARS EXPRESS

The HRSC (High Resolution Stereo Camera) experiment on the European Space Agency’s Mars Express orbiter has completed its first 6 months of operations, imaging >21 million square kilometers of the surface of Mars (an area the size of Europe and Russia). The HRSC provides near-simultaneous imaging using 9 channels, including nadir, forward-looking, and backward-looking stereo, four color channels (red, green, blue, infrared), and two photometry channels. The best resolution occurs near orbit periapsis, typically 15-18 meters per pixel. In addition, a separate Super-Resolution Channel (SRC) obtains monochrome image frames embedded in the HRSC image strips at resolutions of 2-5 meters per pixel. This presentation will review some of the significant discoveries made thus far using HRSC-SRC data, and will discuss future imaging plans throughout the remainder of Mars Express’ two Earth-year nominal mission. For example, crater counts on HRSC images suggest that the caldera floors of Mars’ large shield volcanoes are as young as 100-400 million years in age, indicative of geologically-recent volcanism. HRSC imaging is also revealing evidence for geologically-recent and recurring glacial activity at Mars’ tropical and mid-latitudes, in the form of ridged lobate features indicative of ice-rich viscous flow, as well as ice-rich rock glaciers at the base of Olympus Mons and Hecates Tholus. The Olympus Mons rock glaciers could be as young as a few million years old. Unusual platy flows near the Athabasca Vallis region, originally interpreted as evidence of flood lavas, is being reinterpreted on the basis of HRSC data as being formed by the flow of pack ice. Finally, active dust devils have been detected in images north of Olympus Mon, in which stereo imaging allows the determination of the tangential velocities of the dust devils (20-25 m/s). Dust devil tracks have been detected in the Arsia Mons caldera (suggesting wind speeds of ~200 m/s to move dust at this elevation), and HRSC images have enabled detection of changes in dust devil tracks in Gusev Crater near the Mars rover Spirit landing site.