[mirimir]

Impressive! Thanks for the paper link. The impact of flexible/free boundary condition is very interesting. It points to a key role for shear during compaction. Maybe grains rolling and locking?

For fibers, I wonder if asbestos would be available. Maybe too hazardous.

Edit: From the paper:

> With the flexible boundary condition, the particle motion is localized. Clearly, during compaction it is critical to allow rotation and transverse motion of Mars-1a particles, so as to maximize the effective contact area and to promote bond formation. Excessive particle motion, however, may introduce defects, which explains why the free boundary compensates with higher pressure to achieve similar R as the flexible boundary.

This is very cool. Martian regolith seems ideal for rammed earth construction.

[adrianN]

I wonder how uniform Martian soil is. We have explored only a tiny fraction of the surface with actual robots. On Earth there is a huge variation between different regions. I would expect it to be similar on Mars.

[jccooper]

Martian regolith is believed to be fairly uniform across the planet, and this is backed by analysis at several widely-scattered locations. The dust is definitely well-mixed, but coarser parts are mostly of local origin and can vary, but because of the lack of biological elements are much less varied than on Earth.