Sometimes I wonder what it would be like to climb the highest planetary mountain in the Solar System. Located on Mars, this 25 km / 82,000 ft high mountain giant makes Mount Everest seem like a hill; it would occupy the entire country of France. As someone who works in the space sector, I am quite aware of the robotic exploration of Mars, and have even participated to a crewed mission to Mars design study. But as a mountaineer, that one mountain on Mars keeps inspiring me.
So I was thinking how an expedition to climb the volcanic Olympus Mons would look like? There are several aspects to take into account. First of all, there is the travel to Mars. We can assume that people interested to climb it will already be living on Mars by that time. If not, you’re facing a 9 to 16 months travel to Mars. It is very likely that hibernation will be used to decrease the time you are active on-board (I have worked on this topic myself), but this may already mean a return-trip of two years away from your family. Then there is the travel on the Martian surface from the landing spot to the mountain to be added.
Of course there is the issue of lacking oxygen. Humans will need to wear space suites with oxygen supply at all times. This is a big difference with Himalayan 8000-ers where you only use supplemental oxygen when reaching the dead zone. The oxygen supply will need to be enormous and a large vessel to be placed as a minimum at the flanks of the mountain, preferably with an oxygen generator to refill empty bottles and ensure continuous oxygen supply to a basecamp for example, which could be used to scale the flanks of the mountain.
Then there is getting on to the mountain. Like any other mountain, several approaches are possible e.g. North, South, East, West. The East flank of Olympus Mons has several ancient lava flows, which could be used to enter the mountain crossing through lava valleys like the Barranco wall on Kilimanjaro, rather than to climb the steep walls.
The West flank would likely be preferred by the climbers who like a challenge. Its steep walls are likely to pose to biggest challenge of the entire climb. Parts of the wall are several kilometers / miles high and reaching the top of the flank would be an achievement in itself.
The climb itself however, may be disappointing. The slopes are very shallow (the Northwest side is less steep than the Southeast side), and it is a long walk: about 300 km (190 mi) to the summit caldera. While no acclimatization hikes need to be done, it may still be needed to use expedition style mountaineering to bring supplies up. With typical expected walking speed in Martian suits, the walk is likely to take several months (at least the time it takes to summit Mount Everest). Bringing oxygen and food supplies, medical equipment, water recycle equipment (from urine) etc. supplies for a full half a year for each expedition member, as well as ensuring ‘Leave no Trace’ (including human stool), is going to require an enormous amount of life support equipment and logistics planning. There could be days with strong winds (with twisters as shown on the picture below) so contingency days will need to be taken into account. Sledges with wheels could be dragged along and the heavy weight to be carried up would frighten even the most experienced Denali climber.
After this very long climb we would reach the caldera of the volcano. Like mount Kilimanjaro, we would likely need to walk along the rim in order to reach the true summit. The size of the caldera itself is also enormous ( 60 km (37 mi) × 80 km (50 mi) across ) so this is likely to be another long walk. Due to the presence of ice and dried up water streams, along with up to 6 km / 3.7 mi scarps, this walk is surely going to be more interesting than the ascent.
Reaching the summit means reaching the top of the highest planetary mountain in the Solar System. Congratulations! The view though…may be disappointing. Due to the shallow slopes and the sheer size of the mountain, it is very probable that it feels like you are standing on normal ground. It would be amazing to see the formation on the neighbor mountain Arsia Mons but the large distance (over 1700 km / 1100 mi) makes it impossible to see. And we might be in the clouds ourselves. Again, the view down the 6 km high scarps of the caldera may be far more interesting (see the water/ice flows on the Western scarp), and still provide a triumph feeling of reaching altitude. Camp could be created on the summit, which allows at least for a spectacular sunset view.
Eastern scarp detail : ESA/DLR/FU Berlin 
Western scarp detail showing water/ice flows. Credits: ESA/DLR/FU Berlin 
Cloud forming on Arsia Mons. Credits: ESA/GCP/UPV/EHU Bilbao 
Sunset as seen by Mars Pathfinder. Credits: NASA
The descent is likely to take several months again (parasailing might be possible though, requiring an enormous parasail) and now another issue needs to be overcome: Mars has a global dust storm season every 5.5 (Earth) years (or every 3 Mars years) and the expedition needs to ensure to be back in a safe haven before that happens. Local dust storms may occur every year though, and therefore it is quite possible that the expedition members get caught in a storm.
So would it be possible and would it be worth walking, instead of just taking a large mobile device which surely could find a way to drive to the Summit? Despite the fact that the ascent may not feel like an ascent at all, and Summit pictures may look boring from a mountaineering point of view, I believe that people will still be up for it. The first helicopter already touched the summit of Mount Everest and it is not unthinkable that in the future people could be placed on the Summit by helicopter, for a short e.g. half an hour stay with diving-type oxygen supply. But that surely won’t stop people from continuing to climb Everest. And as such I believe there will always be a certain type of people who would undertake this enormous endeavour to climb Olympus Mons.
These people we commonly refer to as explorers.
