Asteroid surfaces break down unevenly, reshaping theories of space weathering
Scientists discovered that not all asteroids crumble the same way under extreme temperature swings—a finding that could upend plans for mining, sample collection, and long-term spacecraft durability in space. Using real-time acoustic monitoring on meteorite samples, researchers found that carbon-rich asteroids degrade quickly at first, then stabilize, while other types show delayed damage patterns.
Originaltitel: Do all asteroids break down in the same way?
<p>Thermal fatigue is considered a primary mechanism driving rock disaggregation and regolith production on the surface of airless planetary bodies, acting over millions to billions of diurnal temperature cycles. However, its long-term effectiveness has never been experimentally tested. In particular, the Kaiser effect suggests that no additional damage is expected to accumulate when a material is subjected to repeated loading at the same maximum stress level. Here, we use real-time acoustic emission (AE) monitoring to track fracture activity during 100 repeated thermal cycles of ΔT = 190 °C on three meteorites of different petrological type; CM2 Aguas Zarcas, CV3 Allende, and H3-5 Oum Dreyga. The CM2 meteorite exhibited early onset of fracturing activity as indicated by increased AE activity, whereas the CV3 and H3-5 samples showed low activity, with AE occurring predominantly during the later cycles, but ceasing towards the end. These findings suggest that the surfaces of Ch/Cgh-type asteroids, represented by CM2 material, are likely to be more susceptible to thermally driven regolith production, but this response is progressively limited due to threshold-controlled fracturing, whereas S-type bodies, linked to ordinary chondrites, may experience comparatively limited thermal fatigue under similar conditions. CV3 material, analogous to certain anhydrous C-complex/K-type asteroids, likewise appears relatively resistant to damage accumulation across repeated thermal cycles. We propose that thermal fatigue is a threshold-controlled process rather than an indefinitely acting mechanism.</p>