Episode 159Water is the dominant agent of destruction of rocks on Earth. Mars has vanishingly small amounts of water, so wind erosion dominates, but that ca...
The thermal cycling hypothesis for erosion has been advanced for Mars since the 1960s - before we had landed even a single mission on the surface - but personally, I’m not convinced. The effect should be ubiquitous and would apply to every clast/rock a rover can see, but just about any landscape shot shows that there are plenty of rocks without the network of cracks you’d expect. Paul Hammond is correct in pointing out that rocks preferentially fracture along planes of weakness (the direction/face where a mineral is naturally weakest), and the composition of the rocks should have a lot to do with it, but I still think that the process would be a lot further along after billions of years.
The potholes you see (…feel) in places with sub-zero winters show us exactly how good freezing/thawing water is at breaking and flaking hard surfaces, so Mars Guy isn’t wrong to point that out first in the video.
The thermal cycling hypothesis for erosion has been advanced for Mars since the 1960s - before we had landed even a single mission on the surface - but personally, I’m not convinced. The effect should be ubiquitous and would apply to every clast/rock a rover can see, but just about any landscape shot shows that there are plenty of rocks without the network of cracks you’d expect. Paul Hammond is correct in pointing out that rocks preferentially fracture along planes of weakness (the direction/face where a mineral is naturally weakest), and the composition of the rocks should have a lot to do with it, but I still think that the process would be a lot further along after billions of years.
The potholes you see (…feel) in places with sub-zero winters show us exactly how good freezing/thawing water is at breaking and flaking hard surfaces, so Mars Guy isn’t wrong to point that out first in the video.
Maybe it’s the same process with dust acting as water on mars? It might not expand as much but with bigger temp differential maybe it’s similar?