| The Voyager Spacecraft Interstellar Record | |
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On August 20th and September 5th 1977, two extrordinay spacecraft called Voyager were launched to the stars. After what pormises to be a detailed and thoroughly dramatic exploration of the outer solar system from Jupiter to Uranus between 1979 and 1986, these space vehicles left the solar system - emissaries of Earth to the realm of the stars. Affixed to each Voyager craft is a gold-coated copper phonograph record as a message to possible extra-terrestrial civilizations that might encounter the spacecraft in some distant space and time. Each record contains 118 photographs of our planet, ourselves and our civilization; almost 90 minutes of the wolrd's greatest music, an evolutionnary audio essay on "The sounds of the Earth"; and greetings in almost sixty human languages ( and one cetacean language ! ), including salutations from the president of the United States and Secretary General of the United Nations. "I had monuments made of bronze, lapis, lazuli, albaster...and white limestone...and inscriptions of baked clay...I desposited them in the foundations and left for future times" _ Esarhaddon, king of Assyria, Seventh century B.C. "So deep is the conviction that there must be life out there beyhond the dark, one thinks if they are more advanced than ourselves they may come adross space at any moment, perhaps in our generation. Later, contemplating the infinity of time, one wonders if perchance their message came long ago, hurtling into the swamp muck of the steaming coal forests, the bright projectile clambered over by hissing reptiles, and the delicate instruments running mindlessly down with no report." _ Loren Eiseley. "I think an extraterrestrial message will be much more like a discipline of learned study than like a series of headlines" _ Philip Morrison. "It's gayer than a greeting and it's sadder than a sigh" _ "Aloha Oe" Don Blanding. "Be not afeard. The isle is full of noises, Sounds and Sweet airs, that give delight, and hurt not"_ Shakespeare, The tempest. "As the eyes are framed for astronomy so the ears are framed for the moments of harmony" _ Plato, Republic. "Music is harmony of heaven and earth" _ Chinese musical text yueh-chi, second century B.C. "Look here, upon this picture, and on this...the front of Jove himslef"_ William Shakespeare, hamlet, Act3, scen 4. "The Universe is a huge machine that gives life. We ignore when waves will reveal an unknown Earth and what it will look like either. But tomorrow, or within a century, something will come from up there, something different, a message written by an Intelligence unfamiliar to Mankind. I'm waiting... One day, me or my far descendants, we will have the answer." _ Jean Heidmann. The illustration at the top of this page is the gold-plated aluminum cover used to enclose the Voyager records. The etchings on the cover provide instructions for playing the record to whoever finds it. The Voyager record is secured in plain view on the outside of the Voyager Spacecraft with a spider mounting to which is also affixed the stylus cartridge used to play the disc. The record itself is actually made of two copper mothers bonded back-to-back. The side that faces inward towards the spacecraft is best protected, and contains all 122 images included on the record, as well as human and cetacean greetings, the sounds of earth, and a third of the music selections. The outer side consists entirely of music selections. NASA's Golden Record Page provides a list of the contents along with the ability to see and listen to much of the material. Note that the NASA write-up mentions only 115 images because they miscounted their listing by one and don't include the six images of text, the first two displaying President Carter's greeting and the last four displaying the names of Congress members on committees relevant to NASA. They also changed the original image of Cathy Rigby to another gymnast due to copyright issues. The late Carl Sagan headed the team that chose the contents of the Voyager record. He was also responsible for the design of the plaques included with the Pioneer 10 and 11 Spacecraft and the LAGEOS 1 Satellite.
Greetings to the Universe in 55 Different Languages Sounds of Earth Music On Voyager Record
Voyager Record Photograph Index
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This illustration
on the lower right of the Voyager record cover could be considered the
"Rosetta Stone" of the record, as it provides the key to interpreting
the remaining cover illustrations. This illustrates the hyperfine transition
of the hydrogen atom where it changes between its two lowest states. The
time interval for this is a mathematical constant equal to 0.7 billionths
of a second, or more precisely 7.04024183647E-10 seconds. The 1 between
the two states indicates the length of the transition should be equal
to a binary 1. The binary numbering system, with just two symbols, 0 and
1, is the simplest numbering system, and is more likely to be understood
by other civilizations than our decimal system adopted simply because
humans have 10 fingers. With hydrogen being the most abundant element
in the galaxy, any advanced civilization likely to encounter the Voyager
should be able to interpret the meaning of this diagram. 
This is a top-down
view of the Voyager record showing the stylus cartridge in place to play
the disc. The position of the cartridge implies the record groove is to
be played from the outside in. The symbols around the periphery of the
record are a binary representation of the time required for one revolution
of the record where a binary 0 is represented by a dash and a binary 1
is represented by the same vertical symbol used with the hydrogen transition
above. Since leading 0's are meaningless in the binary numbering system,
the number would be read off in a counter clockwise direction starting
above the stylus cartridge. This also implies the record is supposed to
spin clockwise relative to a stationary stylus, as that's the way the
illustration needs to move to read off the binary number. The number around
the periphery is 100110000110010000000000000000000 which converts to 5,113,380,864
in decimal. Multiplying this by 7.04024183647E-10 seconds yields 3.5999
seconds, the length of time for one rotation of the record. 
This is a side view
of the record and stylus cartridge, with two large bars enclosing a binary
number indicating the length of time required to play one side of the
record. Doing the math again, we have 1000010110000000000000000000000000000000000
which converts to 4,587,025,072,128 in decimal. Multiplying by 7.04024183647E-10
seconds yields 3229.377 seconds, or about 53.8 minutes to play one side.
These waveform representations of the picture signal recorded in the groove
provide an explanation for how the images are to be constructed. Someone
analyzing the signal on the record would be able to recognize the image
portion by similar looking groups of waveforms, with each group preceded
by the symmetrical waveform seen in the top left corner of this picture.
Each of these groups would be further subdivided into 512 individual signals,
the first three of which are shown here labeled in binary notation as
1, 10, and 11 (decimal 1, 2, and 3). Just below the waveform drawing is
a conceptual drawing of what they represent, again labeled 1, 10, and
11. The conceptual drawing indicates that each of the three signals represents
a "line" of the final image with each line being drawn in a staggered,
non-overlapping fashion. All 512 signals taken together constitute a single
image. This staggered line image is the same way television images are
drawn by the electron gun inside the CRT, except in the case of modern
TV the lines are arranged horizontally and interlacing is used. There
is also a binary number of 101101001100000000000000 under signal 1 which
converts to 11,845,632 in decimal. Multiplying this by the constant of
7.04024183647E-10 seconds yields 0.0083396 seconds. So it takes about
8 milliseconds to draw one line of an image. It might be a considerable
jump for someone to look at this one portion of the record cover and interpret
what the image waveforms are supposed to be, but the two images below
it provide further reinforcement of the desired interpretation. 
This drawing expands on the concepts presented in the waveform drawing
by showing what a complete image would look like. There's a binary number
1000000000 drawn vertically above the last line of the image. This converts
to 512 in decimal and indicates that the image consists of 512 lines,
which would concur with the 512 similar signals within each waveform as
described above. There is also a binary number of 10000 at the left end
of the picture that converts to decimal 16. The interpretation of this
seems somewhat cryptic, but it means that there are 16 levels of gray
within each line. In other words the image quality in terms of grayscale
is about equal to a photocopy of a photograph. The image quality in terms
of resolution would be somewhat less than a photocopy as it equals about
500 dots along each line of the image. Thus each image has about the same
number of dots along each line as there are lines in the complete image.
if you think in terms of pixels rather than lines, this ratio results
in square pixels. 
This picture of
a circle is the first image recorded on the record. It is intended for
calibration purposes to insure the signal on the disc is being decoded
properly, and the right ratio of horizontal to vertical height is used
in picture reconstruction. For example, if someone decoded this picture
and the circle instead looked like an oval that was wider than it was
tall, they would probably guess that they need to draw the picture lines
closer together. 
This picture
has nothing to do with interpreting the disc contents, but rather is a
pulsar map indicating the solar system from which the Voyager spacecraft
originated. The cover of the Voyager record also contains an ultra-pure
source of Uranium-238 to serve as a radioactive clock for determining
the record's age. This same pulsar map as well as hydrogen atom drawing
were also included on the Pioneer 10 and 11 Plaques. Each pulsar has its
own distinct and rapid pulsing radio frequency that is very slowly changing
with absolute linearity. It's likely that other civilizations of sufficient
advancement will be familiar with these and their rates of change. The
pulsar map shows fourteen pulsars and their directions from the sun along
with the current frequency of the pulsar in binary notation. The horizontal
line extending to the right with no binary number attached is a pointer
from the sun to the center of the galaxy. 
The Voyager record
contains about 20 color pictures, and at first it might seem a mystery
how these could be extracted from 16 levels of gray. This picture of the
solar spectrum is the first color image on the record, and someone recovering
the image would note that it is actually recorded on the record three
times in succession, with only the gray levels being different between
the three recordings. The black absorption lines extending through the
rainbow pattern are distinct for any G2 star like our own sun. A civilization
familiar with solar spectroscopy should be able to recognize this as the
red, green, and blue portion of a solar spectrum. They should then realize
that the color image can be reconstructed by making a composite of the
three images, one on top of the other, with the 16 shades of gray being
interpreted as 16 shades of red, green, or blue in each layer of the image.
By adjusting the color values assigned to each shade of gray, they will
be able to reconstitute this known image of a solar spectrum and then
use those color settings to properly view the remaining color images on
the record. This is the same RGB technique used with present-day computers
to determine exact colors. Sixteen levels of gray corresponds to 4 bits
(2 to the fourth power), so the color images on the Voyager record have
a combined color depth of 12 bits which permits a total of 4096 colors
(2 to the twelfth power). By comparison, a common color setting for web
browsing is 16-bit or 65,536 colors, and most computers manufactured today
can do 32-bit color. 
