The main U.S. weather satellite watching the eastern seaboard malfunctioned last month for the second time in a year, underscoring the hazards of aging satellites that monitor the planet as a threatening hurricane season gets under way.

Engineers got it running again. But the difficulties with the seven-year-old weather satellite, called GOES-13, are a symptom of a broader problem, federal, congressional and university analysts say. Scientists are losing one by one their orbital eyes on Earth, at a time when space-based sensors...