Just in from Nature Communications (vol. 17):
Ryan, A. J. Ballouz, R-L. Macke, R. J. et al. Low thermal inertia of carbonaceous asteroid Bennu driven by cracks observed in returned samples 2443 s41467-026-68505-1
Thermal inertia- the ability to retain or not retain heat/cold despite night/day cycling- is one of the properties we study on asteroids and comets. It tells us of the mechanical properties of the surface regolith on the body. If a space object has high thermal inertia, it has a metallic regolith, or it is extremely dense. Both are good to know- metallic bodies are mining targets, while extremely dense bodies would be hard to defend against should they be on an Earth-impact course.
We can, to an extent, study asteroids by studying meteorites, since we assume them to be pieces of asteroids. But unfortunately meteorites are not completely representative. Fragile meteorites have difficulty surviving through our atmosphere, and landing intact to be recovered and studied. The Ryugu and Bennu samples, collected in space and landed via sealed capsules, then tell us a more complete picture than meteorites alone. Ryan et al. tell us of that new data- rocks from Bennu are full of cracks, which means they would likely not have survived as meteorites.