Japan's H3 rocket, the country's first new medium-lift launcher in three decades, failed to lift off on Friday because two secondary booster engines strapped to the side of the space vehicle didn't ignite. During the live-streamed event, the H3's main engine cut off after the launch countdown had reached zero, leaving the 57-metre (187ft) rocket on its launch pad at the Tanegashima spaceport along with its payload.