This image from ESA’s Mars Express shows Aganippe Fossa, a fascinating groove at the foot of Mars’s colossal Arsia Mons volcano. Credit: ESA/DLR/FU Berlingraben
This image shows Aganippe Fossa, a snaking groove found at the foot of Mars’s giant Arsia Mons volcano, in a wider context. The area outlined by the larger white box indicates the area imaged by the High Resolution Stereo Camera aboard ESA’s Mars Express orbiter on December 13, 2023, during orbit 25189, while the smaller white box shows the part of the surface featured in these new images.
These terrains are characteristic of Arsia Mons’s ring-shaped ‘aureole’, a 100,000-square-kilometer disc around the base of the volcano, possibly associated with ancient glaciers. Intriguingly, this aureole has only built up on the northwestern flank of the volcano, likely due to prevailing winds from the opposite direction controlling where ice settled over time.