An artist's concept of Mariner 2 near Venus. *
Image: NASA * 1962: Mariner 2 passes within 21,000 miles of Venus and begins transmitting data back to Earth, making it the first successful interplanetary spacecraft.
The spacecraft was the second in NASA's Mariner series, a program designed for conducting planetary exploration by gathering as much data as possible in the course of a carefully choreographed flyby. Mariner 1 failed shortly after launch on July 22, 1962, when its rocket veered off course and the craft was deliberately destroyed.
Mariner 2, launched a month later at Cape Canaveral atop an identical Atlas-Agena rocket, took three-and-a-half months to reach Venus.
The spacecraft, more accurately described as a probe, was a small (just over a meter wide, with a mass less than 500 pounds), hexagonally shaped box with an array of panels and an antenna attached. Other scientific instruments were packed inside the probe, including sensors for measuring temperature distribution and atmospheric conditions on Venus.
Due to the heavy cloud cover blanketing the Venusian surface, Mariner 2 was not equipped with a camera.
During its voyage to Earth's closest neighbor, Mariner 2 conducted experiments to measure the density and velocity of the solar winds emitted by the sun. The data sent back helped establish that solar winds stream continuously in interplanetary space. On Dec. 14, the attention turned to Venus.
Scanning with infrared and microwave radiometers, Mariner 2 found that the clouds enveloping the planet are quite cool, but that the surface temperature is very hot: around 900 degrees Fahrenheit. It also obtained improved estimates of Venus' mass.
Mariner 2 failed to turn up any evidence of a magnetic field, although its existence was confirmed in later visits to the planet, including the European Space Agency's current Venus Express mission.
Mariner 2's signal was tracked until Jan. 3, 1963, after which contact was lost. The probe eventually entered into orbit around the sun, where it remains to this day.
(Source: NASA, Wikipedia)
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