The Euclid satellite will be embarking on a mission to understand the accelerating expansion of our Universe. So, it had better be sturdy! The satellite's telescope is made from four pieces of silicon carbide welded together using a sintering process patented by Leti, a CEA Tech institute. Before the satellite can be launched, the telescope's welds must first be inspected on the ground. To perform the inspection, Mersen Boostec, an expert in sintered silicon carbide, turned to another CEA Tech institute, List, which had already successfully inspected the ESA's Gaia satellite.

Silicon carbide offers some exceptional thermal properties that make it suitable for space applications. However, the material is also very stiff, which makes it difficult to probe using ultrasonic NDT techniques. Ultrasonic waves are propagated at a high speed and are reflected off of the walls of parts with complex geometries, creating parasite echoes that can make interpreting the results a challenge. To inspect the entire surface of the sintered welds through to their centers, engineers at Airbus Defence & Space worked with researchers at List to make adjustments to the geometries of the areas to be inspected. They then used CIVA simulation software to calculate and tweak the focal parameters (like the angle of the ultrasonic beam) to detect all defects measuring more than 4 sq. mm.

They tested the results of the simulations on several reference defects in the lab before successfully using them on the Euclid telescope.