Nyx Bikini

Maiden flight of Ariane 6. The auxiliary propulsion system (APS) failed at T+1:14, preventing the planned third Vinci upper-stage relight; instead of performing a deorbit burn over the Pacific, the upper stage and its reentry capsule payloads were left stranded in the 580 km parking orbit.

Nyx Bikini, developed by The Exploration Company in under nine months, was a 60 cm reentry demonstrator designed to survive atmospheric entry at temperatures up to 2100°C, validating low-cost avionics for the company's future Nyx cargo capsule program.