Picture of a porous (>90%) mantle obtained after sublimation of an intra-mixture of 0.1% tholins and H₂O ice particles, 70 μm in diameter. The sublimation lasted about 40 h at pressure <10^-5 mbar and a surface temperature of 200–220 K in the SCITEAS simulation chamber. A: porous mantle made of water-free tholins; B: bright fresh ice particles exposed to the surface after ejection of a large fragment of the mantle; C: fragments of mantle ejected from the surface of the sample and deposited onto the sample holder.