Rivers are often treated as fixed features of the landscape. They bend, flood, and shift over long stretches of time, but they seem permanent enough that entire towns and economies are built around them. The Mississippi River, in particular, has long been regarded as one of North America’s defining geographical landmarks. Yet in the early…

Japan’s H3 rocket returned to flight Friday with the debut of a new low-cost variant, a badly needed success for the country’s new flagship rocket that has struggled with mission failures while facing an increasingly competitive space industry.The H3 rocket took off from the Tanegashima Space Center on a southwestern Japanese island Friday morning and…