Aiguille du Midi, Arete des Cosmiques

Cosmiques Ridge commences from the Abri Simond hut from where it climbs 150m to 3770m. Despite the short distance, the route usually takes about half a day. Initially the climbing is up an easy snow slope and then mixed ground. As you approach the first gendarme of the subsidiary summit (3731m), climb the inclined slabs (4b). Follow the crest of the ridge to the second subsidiary summit. Make a descending traverse (exposed, possible abseil) across two steps. Follow the steps to the end where it passes between two rock walls. Abseil 30m in two pitches via the bolted belays. Continue traversing along terraces to go round the first big tower. Climb an awkward chimney (4a) to reach a good ledge on the right. Climb back onto the ridge via a snow slope that overlooks the Cosmiques Couloir. Go right round a second tower. Alternatively skirt the second tower to the left, going through a small notch and descending a small ice couloir. Follow the ridge to the foot of the crux slab. The crux slab is only 5m and has an in-situ sling and pegs in the diagonal crack running up it but is rated 4c. Above the slab, traverse right along the narrow ledge. Climb a few metres to a terrace on the left and move onto the NW face. Gain a couloir-chimney, then climb clacks (2 pitches 3c/4a). Go up onto the final snowy shoulder and climb the metal ladder to the terrace on the South pinnacle