NASA’s mission to an ice-covered moon will carry a message between water worlds

NASA’s Europa Clipper spacecraft, bound for Jupiter’s ice-covered moon Europa in October 2024, will carry a laser-etched message celebrating humanity’s connection with water. The message is a tribute to previous NASA missions that released similar messages.

As president of Messaging Extraterrestrial Intelligence, or METI, International, I helped design the message on Clipper along with two fellow members of our board of directors: linguists Sheri Wells-Jensen and Laura Buszard-Welcher. METI International is a scientific organization dedicated to sending powerful radio messages to extraterrestrial life.

We collected audio recordings in 103 languages ​​and decided how to convert them into waveforms that visually represent these sounds. Colleagues at NASA etched these waveforms 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 components, 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 plates engraved with scientific and graphic messages. In 1977, two Voyager spacecraft set off for Jupiter, Saturn, Uranus and Nepture carrying gold-plated copper phonograph records. These records include lessons in math and chemistry, as well as music, pictures and sounds of the Earth, and greetings in 55 languages.

Water words

Because water is essential to life on Earth, searching for its presence elsewhere has been key to many NASA missions. Astronomers suspect that Europa, where Clipper is headed, has an ocean beneath its icy surface, making it a prime candidate for the search for life in the outer solar system.

Part of the Clipper message includes the word for water in 103 languages. We started with audio files collected online, but then we had to analyze them and find an output that could be engraved on a metal plate. Ultimately, I returned to some of the techniques I used in some of my early psycholinguistic research, which explored how emotions are encoded in speech.

The 103 spoken words we recorded represent a global snapshot of the diversity of Earth’s languages. The outward-facing side of the Clipper plate displays the words as waveforms that follow the varying sound intensity as each word is spoken.

Every person we recorded saying the word “water” in front of the waveform had a connection to water. For example, the lawyer who coined the word for water in Uzbek – ‘suv’ – organizes an annual music festival in Uzbekistan to raise awareness about the desertification of the Aral Sea.

The native speaker of the Catalan water word – ‘aigua’ – hunts for exoplanets and discovers potentially habitable planets orbiting other stars.

The Drake Equation

Clipper’s message also pays tribute to astronomer Frank Drake, the father of SETI – the search for extraterrestrial intelligence – by using the Drake Equation, his formula of the same name. Using scientific data and some best guesses, the Drake Equation estimates the number of alien civilizations in the Milky Way currently sending messages to the cosmos.

According to one widely cited estimate, there are one-tenth as many of these alien civilizations as a person’s average lifespan in years. For example, if civilizations survive for a million years, there should be about 100,000 in the Milky Way. If they only last a century on average, scientists estimate that about ten exist.

Radio astronomers study the universe by examining the radiation that chemical elements give off 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 radio telescopes can detect. During Project Ozma, the first modern SETI experiment, Drake looked for artificial signals on the same frequency, thinking that scientists on other worlds might recognize hydrogen as universally significant and emit signals on that frequency.

The water hole

As our team developed our water words message, I realized that the message would only be meaningful if it were discovered by someone who was already familiar with the content on the board. The Drake Equation would only make sense if someone already knew what each of the terms in the equation stood for.

The Europa Clipper will crash into Jupiter or one of its other moons, with Ganymede or Callisto as prime candidates. But if for some reason the mission changes and survives that fate, then people far in the future with radically different cultural backgrounds and different language conventions may retrieve the mission millennia from now as an ancient artifact.

To make sure we conveyed at least one part of the message that a scientist in the distant future might be able to understand, I also designed a graphic representation of the same frequency Drake used for Project Ozma: the hydrogen line. We engraved this on the Clipper plate, along with a frequency called the hydroxyl line.

When hydrogen (H+) and hydroxyl (OH-) combine, they form water. Scientists call the frequency range between these lines the ‘waterhole’. The waterhole represents the part of the radio spectrum where astronomers conducted the first SETI experiments.

We have shown the hydrogen and hydroxyl lines using their wavelengths in the Clipper post. The metal plate also contains diagrams showing what hydrogen and hydroxyl look like at the atomic level.

We hope that future chemists will recognize these chemical components as the ingredients of water. If they do, we will have managed to communicate at least some basic scientific concepts about time, space and language.

Waveforms allow our team to tie together the messages on the two sides of the Clipper plate. On the water words side, more than a hundred words are represented by their waveforms. On the other hand, the wavelengths of hydrogen and hydroxyl – the components of water – are etched into the plate.

METI International funded the collection and curation of the water words, as well as my design of the hydrogen and hydroxyl lines, and provided them to NASA at no charge.

As we designed the message for the Europa Clipper, we had to think about the importance of water on Earth, and consider why astronomers feel so compelled to look for it beneath the icy crust of Jupiter’s moon Europa. The spacecraft is expected to enter Jupiter’s orbit in April 2030.

This article is republished from The Conversation, an independent nonprofit organization providing facts and analysis to help you understand our complex world.

It was written by: Douglas Vakoch, California Institute for Integrative Studies.

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Douglas Vakoch does not work for, consult with, own shares in, or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

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