China grounds Long March 5B rockets after engine explosion

A Chinese orbital launch vehicle failed to reach orbit on Tuesday when a YF‑100 engine exploded during ascent, killing the rocket and its payload before it could clear the launch pad. The incident occurred at the Xichang Satellite Launch Centre, a key site for China’s growing commercial space industry.

The YF‑100 is a liquid‑fuel engine that powers China’s Long March 5B, a workhorse for heavy‑lift missions and a backbone for the country’s planned lunar and Mars programs. Engineers had been testing the engine in a series of static firings, but the failure suggests a deeper flaw in the design or manufacturing process. Analysts point to the engine’s complex turbopump system and the use of advanced alloys that may have introduced brittleness under the high stresses of launch. The incident comes at a time when China is ramping up its commercial launch services and eyeing a 2025 launch of the first crewed mission to the lunar south pole.

China’s space agency, CNSA, has not yet released a detailed investigation report, but officials say the incident will trigger a full review of the YF‑100 production line and supply chain. The agency has temporarily grounded all Long March 5B flights and is evaluating the safety of other rockets that use the same engine family. If the root cause is found to be a design flaw, it could delay several upcoming missions, including the Chang’e 7 lunar orbiter and the Tianwen‑2 Mars sample‑return probe. The incident also raises questions about the pace of China’s commercial space expansion and its ability to meet international launch commitments.