Space weathering by micrometeoroid bombardment is a cosmic phenomenon on atmosphere-free celestial bodies, a process that is expected to particularly overprint planetesimals and cosmic dust in debris discs. We reproduced micrometeoroid impact craters by femtosecond pulsed laser irradiation on oriented enstatite single crystals (En₉₃Fs₇) to investigate the deformation behavior and its orientation dependence. All microcraters show typical bowl shaped morphologies, a glass surface layer with splash like ejecta material and subsurface layering. Although we could reproduce melting and vaporization as typical space weathering effects in the enstatite experiments, there is no formation of agglutinate particles or metallic nanoparticles (npFe⁰). The shock effects in the deformation layer consist of planar structures like microfractures and cleavages, amorphous lamellae, stacking faults and clinoenstatite lamellae. Their activation and/or orientation depends on the shock direction. In special orientations we observe the activation of glide systems along specific low indexed crystallographic planes. Due to the short timescale and the high strain rates, the most prominent effect is the failure of enstatite by microfracturing along non-rational crystallographic planes. Common deformation mechanisms reported in meteorites like the formation of clinoenstatite lamellae via shearing along [001] (100) occur less frequently. Shear is apparently the dominant mechanism in the formation of the above-mentioned effects and causes also their modification by frictional heating. The wide-spread formation of amorphous lamellae is, for example, interpreted to be the result of this shear heating along planar structures. We interpret this unconventional deformation behavior as a consequence of the small spatial and temporal scale of the experiments, resulting in a short-lived spherical shock wave with high deviatoric stresses in contrast to a long pressure pulse and quasi-hydrostatic compression in large scale impacts that produce typical shock features.

在没有大气层的天体上，通过微流星轰击进行的空间风化是一种宇宙现象，这一过程有望特别覆盖碎片盘中的小行星和宇宙尘埃。我们通过飞秒脉冲激光辐照在取向顽辉石单晶（En ₉₃ Fs ₇）上复制了微流线型撞击坑，以研究其变形行为及其取向依赖性。所有的微弹坑都表现出典型的碗状形态，玻璃表面层具有像喷射​​材料一样的飞溅和地下分层。尽管在顽辉石实验中我们可以将熔化和汽化再现为典型的空间风化作用，但没有形成凝集颗粒或金属纳米颗粒（npFe ⁰）。变形层中的冲击效应由诸如微裂缝和解理，无定形薄片，堆垛层错和斜铁辉石薄片等平面结构组成。它们的激活和/或方向取决于冲击方向。在特殊方向上，我们观察到滑行系统沿特定的低折射率晶体平面的激活。由于时间短和应变率高，最显着的效果是顽石由于沿非理性晶体平面微破裂而破坏。在陨石中报道的常见变形机制，例如通过沿[001]（100）剪切形成的斜铁辉石片晶，发生的频率较低。显然，剪切是形成上述效应的主要机理，并且还通过摩擦加热引起了它们的改变。例如，无定形薄片的广泛形成被认为是这种沿平面结构的剪切加热的结果。我们将这种非常规的变形行为解释为实验的时空规模较小的结果，从而导致了具有高偏应力的短时球形冲击波，而在较大的冲击力下则是较长的压力脉冲和准静液压压缩，产生典型的震动特征。