This photo shows the reusable rocket Nebula-1, developed by Chinese private rocket company Deep Blue Aerospace, blasting off during a high-altitude vertical recovery flight test in north China's Inner Mongolia Autonomous Region, Sept. 22, 2024. (Deep Blue Aerospace/Handout via Xinhua)BEIJING, Aug. 21 (Xinhua) -- China's commercial reusable launch vehicle sector continues to make steady progress, as a company announced on Friday that it had completed a long-duration test firing of an engine for a large recoverable carrier rocket.Deep Blue Aerospace, a commercial space startup based in Wuxi, east China's Jiangsu Province, said it recently completed a 100-second static-fire test of its Thunder-RS engine, a 130-tonne-class liquid-oxygen kerosene engine designed for the company's large reusable rocket, Nebula-2.The test reached 1,297.5 kilonewtons of thrust, or about 132.3 tonnes. The company said multiple short-duration test firings had been conducted previously to evaluate engine performance, with no anomalies recorded.The recent 100‑second run was the engine's first crossing of that steady‑state duration threshold, serving as a comprehensive verification of its performance, the company said.This screenshot from a video clip shows the first stage of the Zhuque-3 Y2 rocket making its land-based recovery, Aug. 19, 2026. (LandSpace/Handout via Xinhua)Rocket reusability can greatly cut launch costs and boosts launch frequency, making it key to achieving large-scale, routine access to space.China launched the reusable rocket Zhuque-3 on Wednesday morning, achieving its first recovery of a rocket's first stage on land, marking the country's first successful land-based recovery. This mission followed the successful sea-based net recovery of the Long March-10B's first stage on July 10.More models of Chinese reusable rockets are scheduled to conduct tests this year. ■