Venera

Any of a series of unmanned Soviet planetary probes sent to Venus 1965–83. Venera 2 flew to within 25,000 mi (40,000 km) of Venus in 1966; a few days later, Venera 3 crash-landed on its surface, becoming the first spacecraft to strike another planet. Later missions analyzed Venus's atmosphere, made soft landings, detected certain long-lived radioactive isotopes (chiefly uranium and thorium), sent back the first close-up photographs of the planet's surface, and mapped the surface of the northern hemisphere with radar (by Venera 15 and 16, the last two of the series).

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