Wikipedia:Today's featured article/September 25, 2019
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SOLRAD 1
SOLRAD 2 was a surveillance and scientific satellite developed by the U.S. Naval Research Laboratory. Like the similar SOLRAD 1 satellite (model pictured), it was intended to measure solar X-rays and ultraviolet radiation while conducting a covert surveillance mission, mapping the Soviet Union's air defense radar network with its onboard Galactic Radiation and Background electronic surveillance package. SOLRAD 1, launched in June 1960, had been the first satellite to observe solar X-rays, confirming the connection between increased solar X-ray activity and radio fade-outs, and the first to conduct surveillance from orbit, revealing a Soviet network that was more extensive than had been expected. SOLRAD 2 was launched along with the Transit 3A satellite atop a Thor DM-21 Ablestar rocket on November 30, 1960, but both satellites failed to reach orbit when the booster flew off course and was destroyed. Debris rained down over Cuba, prompting protests from the Cuban government. (Full article...)