by NASA’s Europa Clipper spacecraft, which will be sent to Jupiter’s ice-covered moon Europa in October 2024, will have a laser-etched message celebrating humanity’s connection to water. The message pays homage to past NASA missions that have had similar messages.
As president of Messaging Extraterrestrial Intelligence, or METI, International, I helped design the message on Clipper with two members of our board of directors: linguists Sheri Wells-Jensen and Laura Buszard-Welcher. METI International is a scientific organization dedicated to transmitting powerful radio messages to the outside world.
We collected audio recordings in 103 languages, and decided how to convert these into waveforms that visually represent these sounds. Colleagues from NASA etched these waves into the metal plate that protects the spacecraft’s sensitive electronics from Jupiter’s harsh radiation.
I also designed another part of the message that visually represents the wavelengths of water’s constituents, because water is so important to the search for intelligent life in the universe.
Etching messages into spacecraft is not a new practice, and Clipper’s message follows a decades-old tradition started by astronomer Carl Sagan.
In 1972 and 1973, two Pioneer spacecraft went to Jupiter and Saturn carrying metal plaques engraved with scientific and pictorial messages. In 1977, two Voyager spacecraft went to Jupiter, Saturn, Uranus and Neptune carrying gold-plated records. These records contained tutorials in mathematics and chemistry, as well as music, photographs and sounds of the Universe and greetings in 55 languages.
Water words
Because water is essential to life on Earth, searching for its presence elsewhere has been essential to many NASA missions. Astronomers suspect that Europa, where Clipper is headed, has an ocean beneath its icy surface, making it a prime candidate in the search for life in the outer solar system.
As part of the Clipper message there is the word water in 103 languages. We started with audio files collected online, but then we had to analyze those and find an output that could be engraved on a metal plate. Finally I went back to some of the techniques I used in some of my early psycholinguistic research, where I examined how emotions are encoded in speech.
The 103 spoken words we recorded show a global view of the diversity of the world’s languages. The outside of the Clipper plate displays the words as waveforms that track the varying intensity of the sound as each word is spoken.
Everyone we recorded saying the word “water” to the waveform was associated with water. For example, the lawyer who gave the word for water in Uzbek – “suv” – organizes an annual music festival in Uzbekistan to raise awareness of the Aral Sea wilderness.
The native speaker of the Catalan word for water – “aigua” – is on the hunt for exoplanets, discovering potentially habitable planets orbiting other stars.
The Drake equation
The Clipper message also pays tribute to astronomer Frank Drake, the father of SETI – the Search for Extraterrestrial Intelligence – by carrying the Drake Equation, his eponymous formula. Using scientific data, as well as some best guesses, the Drake Equation estimates the number of extraterrestrial civilizations in the galaxy currently sending messages into the cosmos.
According to one widely cited estimate, a tenth of these extraterrestrial civilizations and their average lifespans are years. If civilizations last for a million years, for example, there should be about 100,000 in the galaxy. If they only live a hundred years on average, scientists would estimate that there are about 10.
Radio astronomers study the universe by examining the radiation emitted by chemical elements in space. They spend much of their time mapping the distribution of the most abundant chemical in the universe – hydrogen.
Hydrogen emits radiation at a certain frequency called the hydrogen line, which can be detected by radio telescopes. During Project Ozma, the first modern SETI experiment, Drake looked for artificial signals at the same frequency, because scientists on other worlds could recognize the hydrogen as important universal signals and broadcast signals at that frequency. .
The watering hole
As our team developed our water word message, I realized that the message would only make sense if someone who already knew the content inscribed on the plate found it. The Drake Equation would only make sense if one already knew what each of the terms in the equation stood for.
The Europa Clipper will fly into Jupiter or one of its other moons, with Ganymede or Callisto being the main candidates. But if for some reason the mission changes and it survives that fate, then people far into the future with different cultural backgrounds and different linguistic conventions can retrieve it thousands of years from now as an ancient artifact.
To make sure we had at least one part of the message that a distant future scientist could understand, I also designed a pictorial representation of the same frequency that Drake used for Project Ozma: the hydrogen line. We etched this on the Clipper plate, along with a frequency called the hydroxyl line.
When hydrogen (H+) and hydroxyl (OH-) are combined, they form water. Scientists call the frequency range between these lines a “water hole”. The waterhole represents the part of the radio spectrum where astronomers conducted the first SETI experiments.
We showed the hydrogen and hydroxyl lines using their wavelengths in the Clipper message. The metal plate also has diagrams showing what hydrogen and hydroxyl look like at the atomic level.
We hope that future chemists will identify these chemical constituents as constituents of water. If they do, we’ve succeeded in communicating at least a few core scientific concepts across time, space and language.
Waveforms allows our team to tie together the messages on both sides of the Clipper plate. As for the water words, their waveforms represent over a hundred words. On the other side, the hydrogen and hydroxyl wavelengths – the constituents of water – are etched into the plate.
METI International funded the collection and storage of the water words, as well as my design of the hydrogen and hydroxyl lines, providing these to NASA at no cost.
When designing the message for the Europa Clipper, we had to consider the importance of water on Earth, and why astronomers feel so compelled to look for it under the icy crust of Jupiter’s moon Europa. The spacecraft is scheduled to enter Jupiter’s orbit in April 2030.
This article is republished from The Conversation, a non-profit, independent news organization that brings you facts and analysis to help you make sense of our complex world.
It was written by Douglas Vakoch, California Institute for Comprehensive Studies.
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Douglas Vakoch does not work for, consult with, share in, or be funded by any company or organization that would benefit from this article, and has disclosed no affiliations relevant beyond their academic appointment.
