THIS DAY IN HISTORY: Mariner 2 First to Explore Venus 60 Years Ago
By Space Coast Daily // December 14, 2022
(NASA) – On Dec. 14, 1962, Mariner 2 completed the first successful close-up observations of another planet when it flew by Venus.
Managed by NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, the spacecraft made several important scientific discoveries not only about the planet but also about interplanetary space during its transit. The road to Venus, however, proved anything but easy.
Scientists knew relatively little about Venus at the time. Because of similar size as Earth, scientists often called the two “sister planets.”
Since it orbited closer to the Sun, most scientists assumed Venus had a warmer surface, with a climate similar to Earth’s tropics.
A young scientist named Carl E. Sagan, then at the University of California, Berkeley, however, proposed that the known high concentration of carbon dioxide in Venus’ atmosphere created a runaway greenhouse effect, leading to extremely high temperatures at the surface.
JPL planned, developed, and executed the first mission to Venus in about one year. To save development time, JPL adapted the Ranger lunar probe then under development to build the Venus explorer.
The 447-ppound spacecraft carried seven scientific instruments weighing 46 pounds to study Venus’ atmosphere and temperature, to search for a possible magnetic field, and to study cosmic rays, the solar wind and cosmic dust during the trip to the planet.
Mariner 2 sent data back to Earth at the then-blistering rate of 8-1/3 bits per second.
The instruments included:
A crystal microphone for measurement of the density of cosmic dust.
A proton detector for counting low-energy protons in the solar wind.
Two Geiger-Müller (GM) tubes and an ion chamber, for measuring high-energy charged particles in interplanetary space and in the Venusian equivalent of Earth’s Van Allen Belts (later shown not to exist).
A special-purpose GM tube for measuring lower energy radiation, particularly near Venus.
A three-axis fluxgate magnetometer for measuring the Sun’s and Venus’ magnetic fields.
A microwave radiometer for measuring the temperature of the planet’s surface and its cloud tops.
Two infrared optical sensors for parallel measurement of the temperature of Venus.
