1951 in spaceflight

The year 1951 saw extensive exploration of space by the United States and the Soviet Union (USSR) using suborbital rockets. The Soviets launched their first series of biomedical tests to the 100-kilometre (62 mi) boundary of space. Several American agencies launched more than a dozen scientific sounding rocket flights between them. The US Navy launched its Viking sounding rocket for the seventh time since 1949, this time to a record-breaking 136 miles (219 km) in August 1951.

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