China on Friday successfully landed a reusable rocket for the first time — a milestone for the country’s space programme that will challenge American companies’ dominance in the technology. The Long March 10B rocket — which can carry a payload of up to 16 metric tons to low Earth orbit — lifted off from the Wenchang Commercial Space Launch Site in Hainan, Southern China around noon (local time). Low Earth orbit is a region between 160 km and 2,000 km above the Earth. Six minutes after liftoff, the rocket’s booster — the part that houses the engine and provides the initial thrust — separated from its upper stage and began a controlled descent to a floating platform on the sea. There, it was caught by a net. Before China, only Elon Musk’s SpaceX and Jeff Bezos’s Blue Origin demonstrated the ability to launch and land rockets. So how does China’s technology differ from previous reusable rockets and what strategic implications does this step have? We explain. The mechanics of re-entry  All rockets lift off in …