Tuesday, February 08, 2011

Communication with Extraterrestrial Intelligence #3


Pioneer plaque

The Pioneer plaques are a pair of gold-anodized aluminium plaques which were placed on board the 1972 Pioneer 10 and 1973 Pioneer 11 spacecraft, featuring a pictorial message, in case either Pioneer 10 or 11 are intercepted by extraterrestrial life. The plaques show the nude figures of a human male and female along with several symbols that are designed to provide information about the origin of the spacecraft.[1]
The Pioneer spacecraft were the first human-built objects to leave the solar system. The plaques were attached to the spacecraft's antenna support struts in a position that would shield them from erosion by stellar dust.

Physical properties

  • Material: 6061 T6 gold-anodized aluminum
  • Width: 229 mm (9 inches)
  • Height: 152 mm (6 inches)
  • Thickness: 1.27 mm (0.05 inches)
  • Mean depth of engraving: 0.381 mm (0.015 inches)
  • Mass: approx. 0.120 kilograms

At the far right, the bracketing bars (1) show the height of the woman compared to the spacecraft.  The figure indicated by (2)
 represents a reverse in the direction of spin of the electron in a hydrogen atom. This transition puts out a characteristic radio 
wave 21 cm long, so we are indicating that 21 cm is our base length.  The horizontal and vertical ticks (3) are a representation
of the number 8 in binary form. Therefore, the woman is 8 x 21 cm = 168 cm, or about 5'5" tall.  The human figures 
represent the type of creature that created Pioneer. The man's hand is raised in a gesture of good will. 
The radial pattern (4) will help other scientists locate our solar system in the galaxy. The solid bars indicate distance, with the 
horizontal bar (5), denoting the distance from the Sun to the galactic center. The shorter solid bars represent directions and 
distances to various pulsars from our Sun, and the ticks following them are the periods of the pulsars in binary form. Pulsars 
are known to be slowing down and if the rate of slowing is constant, an other-world scientist should be able to roughly 
deduce the time Pioneer was launched.  Thus, we have placed ourselves approximately in both space and time. The 
drawing at the bottom (6) indicates our solar system.  The ticks accompanying each planet are the relative distance in binary
 form of that planet to the Sun. Pioneer's trajectory is shown as starting from the third planet, Earth.
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