Carter Dack, 2023.
Voyager - Golden Record Decoding
Overview
This article will seek to demonstrate the theory behind the Voyager Golden Record, a time capsule sent into space on board the Voyager 1 and Voyager 2 spacecrafts, intended to serve as a message to any intelligent extraterrestrial life forms that might come across it. The focus of this article will be on decoding the contents of the record, which were carefully curated by a team of scientists and researchers led by astronomer Carl Sagan, and include a wide range of images, sounds, and music. By examining and decoding the Golden Record, one can begin to uncover the messages it contains and the insights it provides into the diversity of life and culture on Earth.
Background
The Voyager Space Probes were a set of two (2) near identical scientific instruments that were launched by NASA during the Voyager program in the late 70’s. The goal of these spacecraft was to study the solar system and beyond by conducting a series of carefully choreographed planetary flybys. In doing so, the Voyager spacecraft captured high fidelity images, geological, magnetic field, and infrared spectrometer data, which were sent to earth via onboard high gain dish antennas (Figure 1.1).
FIGURE 1.1 - Voyager 1 via NASA (JPL)
While the primary objective of these spacecraft was to conduct scientific exploration within the local solar system, scientists were acutely aware that they would soon become the most distant human-made objects ever launched. Due to the trajectories and flight paths of these spacecraft (Figure 1.2), they would ultimately be slung into deep space after they perform their final flybys of Saturn and Neptune, respectively - using the gravity of Saturn and Neptune to escape the solar system at a constant 35,000 MPH.
FIGURE 1.2 - Voyager Flight Path via NASA (JPL)
Much like a message in a bottle cast out to sea, a vinyl record plated in gold was designed by NASA engineers (Figure 1.3) to be included on the spacecraft, which contained various audio samples, music, and encoded images - serving to memorialize the human race for any life form that might be intelligent enough to stumble upon these machines (assuming they do not get obliterated by space debris or pulled into any black holes). A sample of the Golden Record’s audio can be found on SoundCloud.
FIGURE 1.3 - The Golden Record via NASA
Decoding the Gold
The Golden Record contained many images and sounds which were curated to showcase the beauty, diversity, and culture of the human race. In order to even begin listening to the record onboard the spacecraft, a user will need to first understand how the onboard record player works - something newer generations on earth may not even fully understand. Thankfully for the aliens who may eventually decode the Golden Record, NASA included some helpful instructions.
On the cover of the Golden Record (Figure 2.1), there are a series of etchings which have been specifically designed to be universally decodable. At first glance, these etchings may seem ornate; however, this article will provide an explanation for each etching, starting from the bottom right and moving clockwise.
FIGURE 2.1 - The Golden Record Cover via NASA
Step 1 - Universal Constants
The first, and arguably most important etching - as it establishes constant values to be used throughout the rest of the record’s decoding - is found on the bottom right of the golden record (Figure 2.2).
FIGURE 2.2 - Hyperfine Transition of Hydrogen
For those familiar with chemistry, a Hydrogen atom - the most abundant element in the universe - may be recognizable. For those extremely familiar with chemistry, the orientation of the electrons may be enough to determine that this etching deptics the Hyperfine transition of Hydrogen. When an atom undergoes a hyperfine transition, the spin and magnetic moment of its subatomic particles have shifted in such a way that the energy level of the nucleus changes. This change happens as a result of the interaction between the magnetic field produced by the nucleus and the magnetic field produced by the electrons in the surrounding environment. During a Hyperfine transition, the change in energy can be detected as a change in the frequency of electromagnetic radiation emitted or absorbed by the atom, which will be the key to decoding this etching.
Importantly, the change in frequency that occurs during the hyperfine transition of a Hydrogen atom is ~1420.405 MHz, which corresponds to a period of ~0.704 nanoseconds (or 
, or the time it takes the frequency to complete one full wave cycle. The etching also includes a small vertical line (below the horizontal line) in the middle which is meant to represent the digit 1 in binary, representative of both the Hydrogen’s Hyperfine frequency as well as its unit of time (0.7 nanoseconds).
Step 2 - Pulsar Roadmap
The next etching onboard is found on the bottom left of the Golden Record (Figure 2.3). This etching represents the location of Earth within the broader universe.
FIGURE 2.3 - Pulsar Map
In the etching, 15 lines all extend from a single origin. Within these lines, NASA continues the pattern of binary representations in the form of “-” and “|” representing a 0 and a 1, respectively. By calculating these binary values in conjunction with the ~1420.405 MHz frequency from the previous etching, the user can begin to identify the periods of pulsars within the universe.
A pulsar is a highly magnetized, rotating neutron star that emits beams of electromagnetic radiation from its poles. Neutron stars are the incredibly small and dense byproduct of supernova explosions, with masses roughly equivalent to that of the sun.
Scientists coined the term “Pulsars” because these celestial objects emit pulses of radiation with extreme regularity, typically with periods ranging from milliseconds to several seconds. This regularity is due to the rapid rotation of the neutron star, which causes the radiation beams to sweep across the universe like light from a lighthouse.
Since these universal beacons emit radiation to the universe, their frequency values will likely be known to any space faring intelligent life, meaning that this map - once decoded - could be used to triangulate the position of our sun.
Step 3 - Girl, Put Your Records on
The next set of etchings to focus on are found on the top left of the record (Figure 2.4). These etchings may be recognizable to anyone who has used a record player before. They depict a record player from both a bird’s eye view as well as from an eye-level view. Again, there is more binary representation which when decoded, tells the user how long one revolution should take (bird eye) as well as how long the entire record should last (eye-level).
FIGURE 2.4 - Record Player
Decoding the two images starting with the birds eye etching:
Birds Eye - Counter Clockwise from Top of the Record’s Stylus
) = 3.59982012 secondsEye-level - Left to Right
) = 3229.72435328 secondsStep 4 - Audio Decoding
Now that the user is able to play the record at the appropriate speed, the data stored within the record can begin to be decoded. Since the record contains images stored in the form of audio, the user must now begin to decode the audio to create the final image. The final few etchings on the record relate to the decoding of images. The first few etchings on the top right of the record (Figure 2.5) depict wave forms.
FIGURE 2.5 - Audio Waves
This etching serves as a representative segment of the audio data. This beginning segment of audio looks relatively consistent throughout the actual audio sample, and helps us identify the beginning of a new image. To the far left of the etching, there exists a continuous high frequency wavelength followed by three (3) relatively identical waveforms, which will be referred to as scans, since each chunk of waveform represents one horizontal line of a final image - a concept that will begin to make more sense.
Underneath the first scan there is more binary data, which in this case is representative of the length of one scan. When decoded, a user is presented with the following:
) = 0.0083405 secondsAlone, this knowledge may not give us the full picture, however with the help of the additional etchings, the user can begin to develop a better understanding of what to do with each of these scans. The final three (3) etchings (Figure 2.6) describe how to use the audio data.
FIGURE 2.6 - Waves to Images
The figure found towards the top of this final set of etchings has the same three (3) scans represented a little differently now. This etching represents the fact that a scan should begin at the top and end at the bottom of its waveform.
In this case, one scan represents one line of pixels in an image, and the binary data found to the top left and right of the middle square etching tells us that one image consists of 512 scans.
When decoded, the binary gives is the following key numbers:
Middle Etching - Top Left Corner
Middle Etching - Top Right Corner
It helps to think of these scans in the same way that an inkjet printer works, with one of those ~8 millisecond scans representing one horizontal line of the final image (if printing top to bottom). The various audio data within each 8 millisecond scan are then given a grayscale color value which represents the pixels within each line of the image. By that logic, one image will be ~4.1 seconds of audio (8 milliseconds * 512).
Finally, the last etching seen towards the bottom of Figure 2.6, is the calibration image. This is the first image in the sequence of images and it indicates that the decoding has been done properly.
Show Me the Gold
One can only imagine the profound sense of awe that accompanies the discovery of a time capsule such as this. Its creators, imbued with a deep sense of pride - having left behind a legacy of hope and tranquility for future generations to cherish. The Voyager Spacecrafts serve as just another testament to the enduring power of human ingenuity and our limitless capacity for wonder and exploration. As former President Jimmy Carter puts it:
“This is a present from a small, distant world, a token of our sounds, our science, our images, our music, our thoughts and our feelings. We are attempting to survive our time so we may live into yours.” - President Jimmy Carter
Figure 2.7 - Calibration and Beyond
The images below have been decoded using python, however there exist many different and equally effective ways of decoding this data. The first image that can be seen is the calibration image from Figure 2.6. The remainder of the images are just a sample from all that were collected.
It is important to keep in mind that these images were hand picked by a committee of scientists, artists, and educators led by astronomer Carl Sagan in order to portray the diversity and richness of human culture and knowledge. They are, for all intents and purposes, the proof to the universe that we as humans existed.
If you have made it this far - thank you. I hope that these photos resonate with you in the same way that they do for me and I invite you to take a moment to think about what you might include in your own Golden Record. I feel that reflecting on the nature of our existence inspires a deeper sense of connection and understanding with the broader universe and helps us take pride in the individual lives that we live.
Works Cited
Amazing-Rando. “Amazing-Rando/Voyager-Decoder: Voyager Probe Image Decoder/Encoder.” GitHub, https://github.com/amazing-rando/voyager-decoder.
Barry, Ron. “How to Decode the Images on the Voyager Golden Record.” Boing Boing, 5 Sept. 2017, https://boingboing.net/2017/09/05/how-to-decode-the-images-on-th.html.
“Contents of the Voyager Golden Record.” Wikipedia, Wikimedia Foundation, 30 Nov. 2022, https://en.wikipedia.org/wiki/Contents_of_the_Voyager_Golden_Record.
“Hyperfine Structure.” Wikipedia, Wikimedia Foundation, 25 Feb. 2023, https://en.wikipedia.org/wiki/Hyperfine_structure.
“Pioneer Plaque.” Wikipedia, Wikimedia Foundation, 8 Nov. 2022, https://en.wikipedia.org/wiki/Pioneer_plaque.
“Voyager - the Golden Record Cover.” NASA, NASA, https://voyager.jpl.nasa.gov/golden-record/golden-record-cover/.
“Voyager Golden Record Images Decoding (Step by Step - the Simplest Way).” YouTube, YouTube, 27 Nov. 2022, https://www.youtube.com/watch?v=HWXHIfou3pw.
“Voyager Golden Record.” Wikipedia, Wikimedia Foundation, 26 Feb. 2023, https://en.wikipedia.org/wiki/Voyager_Golden_Record.
“Voyager Golden Record: Encoded Image Data.” SoundCloud, https://soundcloud.com/user-482195982/voyager-golden-record-encoded-images.
