THE STORY BEHIND THE 4Oth ANNIVERSARY OF THE VOYAGER SPACECRAFT: SAGAN´S “GOLDEN” DISC.

BACKGROUND

The Voyager 1 probe is the farthest human made object released from the Earth and now has reached interstellar space abandoned the boundaries of our solar system. The Voyager 1 is a space probe launched by NASA on September 5, 1977.  Having operated for 40 years and 2 days as of September 7, 2017, the probe is still communicating and exchanging data with the Deep Space Network to receive routine commands.

Voyager 1 and Voyager 2 were launched with a message aboard with an intended time capsule, enabling the spacecraft to communicate itself to extraterrestrials showing how the earth brings a story of humans among other species, live and behave on Earth. Carl Sagan envisioned that the spacecraft if encountered with intelligent ET beings, they will be capable to “play” this one and bring a compelling story about our planet.

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The Golden Record. Photo credit: NASA
HOW THE CONTENTS WERE SELECTED AND CURATED

The way the contents were selected was under the management of an specific NASA committee led by Carl Sagan from the Cornell University and took almost a year to be concluded. Consisted in 115 images with an assortment of sounds of the nature such as the wind, thunder, several animals mixed with musical selections from different cultures, backgrounds and ages plus spoken greetings in 55 different languages. The record also includes the inspirational message Per aspera ad astra in Morse code which means “through hardships to the stars” and other human sounds including laughters from Sagan.

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Image of Jupiter with the correspondent scale. Photo credit: NASA

Regarding the images, many of them are of scientific interest such as mathematical and physical quantities, the Solar System and its planets distribution, the DNA configuration, the human anatomy and how the reproduction works. Diversity was taken into consideration to include not only pictures of human species, but also animals, insects, plants and several landscapes. Scales of time, size, mass and chemical composition are taken into account in the pictures assuming that are likely to be consistent anywhere in the universe. To add some curious contents, the golden record also carries an hour long recording of the brainwaves of Ann Druyan.

HOW TO PLAY THE GOLDEN RECORD

In the upper left corner is a drawing of the phonograph record and the stylus carried with it. The stylus is in the correct position to play the record from the beginning. Written around it in binary arithmetic is the correct time of one rotation of the record, 3.6 seconds, expressed in time units of 0.70 billionths of a second, the time period associated with a fundamental transition of the hydrogen atom. The drawing indicates that the record should be played from the outside in. Below this drawing is a side view of the record and stylus, with a binary number giving the time to play one side of the record – about an hour.

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Diagram of the Voyager golden record cover explained, as provided by NASA.  Photo credit: NASA Jet Propulsion Laboratory.

The information in the upper right-hand portion of the cover is designed to show how pictures are to be constructed from the recorded signals. The top drawing shows the typical signal that occurs at the start of a picture. The picture is made from this signal, which traces the picture as a series of vertical lines, similar to analog television (in which the picture is a series of horizontal lines). Picture lines 1, 2 and 3 are noted in binary numbers, and the duration of one of the “picture lines,” about 8 milliseconds, is noted. The drawing immediately below shows how these lines are to be drawn vertically, with staggered “interlace” to give the correct picture rendition. Immediately below this is a drawing of an entire picture raster, showing that there are 512 (29) vertical lines in a complete picture. Immediately below this is a replica of the first picture on the record to permit the recipients to verify that they are decoding the signals correctly. A circle was used in this picture to ensure that the recipients use the correct ratio of horizontal to vertical height in picture reconstruction. Color images were represented by three images in sequence, one each for red, green, and blue components of the image. A color image of the spectrum of the sun was included for calibration purposes.

LENGTH OF TRAVEL

Was launched in 1977, passed the orbit of Pluto in 1990 and left the solar system in November 2004. It is now in the Kuiper Belt but in about 40,000 years, it and Voyager 2 will each come to within about 1.8 light-years of two separate stars: Voyager 1 will have approached star Gliese 445, located in the constellation Camelopardalis; and Voyager 2 will have approached star Ross 248, located in the constellation of Andromeda.

In March 2012, Voyager 1 was over 17.9 billion km from the Sun and traveling at a speed of 3.6 AU per year (approximately 61,000 km/h), while Voyager 2 was over 14.7 billion km away and moving at about 3.3 AU per year (approximately 56,000 km/h).

On September 12, 2013, NASA announced that Voyager 1 had left the heliosheath and entered interstellar space, although it still remains within the Sun’s gravitational sphere of influence.

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Artist conception of the Voyager 1. Photo credit: NASA

 

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Author: Jesus Padilla

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