On 05 Sept and 20 Aug 1977 NASA launched voyager 1 and voyager 2 satellites. Their mission is to explore the universe where nothing from Earth has ever flown before. At the time of writing this articles, it has been 41 years and 11 months since its launch. and they both continue to explore the interstellar space and are still sending scientific information about their surroundings through the Deep Space Network, or DSN.

The Challenge

While the mission was being designed, there was the question of how to communicate to other world beings, if ever found, and what message should be delivered to them in a way in which the beings can contemplate as much as possible about our world. The answer to this question was - The Golden Record

The Golden Record

According to NASA the golden record is:

NASA placed a more ambitious message aboard Voyager 1 and 2, a kind of time capsule, intended to communicate a story of our world to extraterrestrials. The Voyager message is carried by a phonograph record, a 12-inch gold-plated copper disk containing sounds and images selected to portray the diversity of life and culture on Earth.

The real phonograph record contents include a cover and the disk.

The golden record cover and the disk.

The Contents

The disk contains four categories of data :

The contents of the record were selected for NASA by a committee chaired by Carl Sagan of Cornell University, et. al. Dr. Sagan and his associates assembled 115 images and a variety of natural sounds, such as those made by surf, wind and thunder, birds, whales, and other animals. To this they added musical selections from different cultures and eras, and spoken greetings from Earth-people in fifty-five languages, and printed messages from President Carter and U.N. Secretary General Waldheim.

The Indian recording, which lasts for three minutes and 25 seconds is called 'Jaat Kahan Ho' rendered by Surshri Kesarbai Kerkar, a noted khayal singer of the 20th century, is one of the many songs selected by NASA among other songs from all over the world.

How is it stored?

This is probably the most interesting part. The challenge was to encode all the above information in the phonograph record. Remember that we are talking about storing information on a disk 41 years ago when there was no pen-drives and other conventional storage solutions, so storing JPEGs or PNGs as a digital format on the disk was not an option. NASA came up with this brilliant idea that they would encode all the data into the audio waveforms on the disk. So theoretically speaking, if you figured out the actually rotation and speed you should be able to play it just like any other normal record disk. But for an outsider figuring out that information can be quite tricky, which is why NASA decided to include information on the record cover which hints at how to play the record.

The Hints

NASA decided to include details like the location of our sun by encoding frequency data of pulsars from 14 known directions so that if ever found, it can lead back to the place where it came from - the solar system.

The end goal now was to provide information on how to play the disk using the right settings namely speed and rotation. For this, NASA used a fundamental clock reference which would be useful to decode all the other information on the disk, in particular, they used the transition time from one state to the other of the hydrogen atom, which is known to be spread all across the universe.

Technical Details for each symbol on the cover

Using this one piece of information which when multiplied by the binary encoded in the picture of what appears to be an outline of a cartridge with a stylus which should be used to play the disk( which was included onboard the voyager) we can now deduce the speed at which the disk should be played. The cover also has information encoded on it which says that the overall runtime of the disk would be roughly an hour.

Conclusion

Using the above data, when played using the right equipment, we can hear the following sound:

This above audioform contains all the above said data in analogue form. Among the images included, the Taj Mahal was one of them. It also has greetings in many Indian languages like Kannada, telugu, hindi among others!

With the technology available at our hands today, if you want to try and decode the data, we've included a github link which contains a computer program that helps decode the data. Go ahead, give it a try and appreciate the marvel of human creation.

The spacecraft will be encountered and the record played only if there are advanced spacefaring civilizations in interstellar space.

- Carl Sagan