Unconventional resources (oil, gas, and geothermal) are often buried deep underground within dense rock strata and complex geological structures, making it increasingly difficult to create volumetric fractures through conventional hydraulic fracturing. This paper introduces a novel method of supercritical energetic fluid thermal shock fracturing. It pioneers a CO2 deflagration impact triaxial pneumatic fracturing experimental system, using high-strength similar materials to simulate deep, hard rock masses. The study investigates the rock-breaking process and crack propagation patterns under supercritical CO2 thermal shock, revealing and discussing the types of thermal shock-induced fractures, their formation conditions, and discrimination criteria. The research indicates that higher supercritical CO2 thermal shock pressures and faster pressure release rates facilitate the formation of radial branching fractures, circumferential cracks, and branch cracks. Typically, CO2 thermal shock generates 3-5 radial main cracks, which is significantly more than the single main crack formed by hydraulic fracturing. The formation of branched cracks is often caused by compression-shear failure and occurs under relatively harsh conditions, determined by the confining pressure, rock properties, peak thermal shock pressure, and the pressure sustained post-decompression. The findings are expected to offer a safe, efficient, and controllable shockwave method of supercritical fluid thermal shock fracturing for the exploitation of deep unconventional oil and gas resources. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

The extremely hot and dense environment on Venusian surface will degrade almost any material via atmosphere-surface interactions, therefore the exploitation of its soil and atmosphere is very challenging. Exploring rovers are designed with mostly mechanical parts, and the knowledge of the effect of Venusian exposure on mechanical and tribological systems is very important for the longevity of the missions. Herein, we studied the effect of 3-day Venusian exposure on selected interfaces. It was found that diamond-like carbon (DLC) and Ti-doped molybdenum disulfide (TiMoS2) experienced negligible morphological changes, whereas polycrystalline diamond (PCD) and PS400 (plasma sprayed Ni-alloy) formed few-microns thick sulfur-containing reacted surface layers after exposure. Also, PCD retained its structural integrity, while the mechanical properties of DLC deteriorated the most, manifested as 49% decrease in hardness. The hardness of PS400 and TiMoS2 degraded to a lesser degree, with 8 and 26% decrease, respectively. The above coatings could be candidate materials to coat structural and bearing systems in the rovers, probes, and drills for future missions to Venus. (c) 2024 COSPAR. Published by Elsevier B.V. All rights reserved.