'The greatest scientists are always artists as well.'
Albert Einstein

I have always been fascinated and enthralled by the confluence of science and art. There is science in the oils squeezed onto an artist’s palette, in the flickering light that takes us to another world at the movies, and in the resonance of a violin string.

Mars and the stars sing in tones that only science reveals. Pythagoras proposed 2,500 years ago that the celestial spheres of our solar system resonated with each other in a way that touched souls. Bach and Beethoven tried to capture this music of the spheres in their work.

It is only in the last couple of centuries that we have begun to truly know the spheres of our own neighborhood: the planets, dwarf planets, moons and smaller bodies that collectively whirl about our central star. The very first emissary from Earth to reach a world past our own moon was NASA’s Mariner 2, a probe that flew past Venus almost exactly 60 years ago.

Our deeper knowledge of the solar system’s moons is even more recent, and has arrived thanks to other robotic visitors like the Voyager 1 and 2 spacecraft. They have upended previous thinking about these globes. Once expected to resemble our own pockmarked, dead Moon, we have instead learned that each of them is unique, each contains mysteries, and each has a rich story to tell us.

The planetary scientists I interact with believe these moons are more than mysterious. They are beautiful and dynamic. Forces we are still trying to understand constantly reshape the surfaces of some as they hide churning tides deep below what our cameras can see.

It was in late 2020 that I heard from two friends I admire. Linda Spilker of NASA’s Jet Propulsion Laboratory is the project scientist for Cassini, the spacecraft that orbited Saturn for 13 years. She has also recently returned to the ongoing Voyager mission that has reached the space between the stars.

Nicole Stott lived up there. She was a NASA astronaut on the International Space Station. Nicole left NASA in 2015 to become a full-time artist and science communicator.

Linda and Nicole wanted me to meet a composer they had been advising. That meeting became a lovely conversation on Planetary Radio, the podcast and public radio series I host for The Planetary Society. My interview with Amanda Lee Falkenberg, Linda, and Nicole immediately became one of my favorites across 20 years of producing the show.

Amanda took on an ambitious challenge. When Gustav Holst wrote his beloved suite, The Planets, he only attempted to capture the metaphysical and largely astrological meaning of the known worlds. Amanda set her sights much higher. She wanted to take our best understanding of the true nature of seven moons and make them come alive in her music.

She has succeeded. Along the way, she has become a lay expert on these worlds. Always an educator as well as an artist, her vision for The Moons Symphony extends far beyond the composition. I’m thrilled by her plan to use the symphony as a way to welcome young people to the cosmos.

Seven moons, seven movements. With hundreds to choose from (and more discovered every year) I think The Moons Symphony gets the choices exactly right. Each moon lends itself to an interpretation as unique as itself. Here are brief sketches of each, in the order Amanda presents them.

Io is a violent kaleidoscope of upheaval. This innermost of Jupiter’s four Galilean moons, named after their discoverer, is subjected to the full force of the planet’s massive gravity, magnetic field, and radiation. Gravity stretches and compresses poor Io like a child’s squeeze toy, generating tremendous heat. This heat turns rock into magma, making Io the most volcanically active body we’ve found. The chemicals heaved up from below the surface are bombarded by radiation that would kill a human in minutes, but these compounds also make Io one of the most colorful objects in the neighborhood. You wouldn’t expect placidity in a composition about Io. It is why The Moons Symphony begins with a bang.

Europa is just one orbit farther from Jupiter than sister Io, but what a contrast! Its cracked and crevassed surface is made of water ice. The same tidal forces that wrack Io perform magic below Europa’s skin. There is a vast ocean down there, kept liquid and warm by those tides. Look around our own planet. Wherever you find liquid water, nutrients, and a source of energy, you will find life. Could Europa have undersea vents and volcanoes like those we find at the bottom of Earth’s oceans? Biologists speculate that these well-protected locales may be where life began here. Could the same be true on Europa? NASA and its partners will begin to answer these questions with the Europa Clipper, an orbiter set to launch soon.

Saturn is our next stop. That gorgeous, ringed world’s biggest moon is Titan. Scientists hoped that the Voyagers would be able to peer through the thick, smog-like clouds that hide its surface. Sadly, they weren’t up to this task. Titan continued to guard its secrets till the arrival of Cassini. Its infrared camera and radar pierced the murk. Cassini also carried the European Space Agency’s Huygens probe that descended to Titan’s surface under a parachute.

Cassini and Huygens revealed a world that is shockingly like our own, if you ignore its shockingly cold temperature. There are lakes, rivers and seas. There are canyons carved by flowing liquid, and there is rain. But it is mostly liquid methane that takes the place of water on Titan. The surface is water ice so cold that it is as hard as rock. If there is life on Titan’s surface it is almost certainly life as we don’t know it. As you read this, NASA is preparing another visitor. Dragonfly is a flying machine, a nuclear-powered octocopter that will hop about that wondrous moon and report its findings to Earth.

Relatively speaking, Enceladus is tiny. We assumed it would be a solidly frozen ball circling Saturn. But every world we visit surprises us, and Enceladus was no exception. It hides a water ocean like Europa, but that ocean spews forth through cracks, generating what may be the highest geysers in the solar system. Cassini flew right through these fountains and tasted them. The water is salty. Could there have been critters in that cool beverage? We don’t know. Cassini’s instruments were not capable of detecting the complex molecules of life. We once again see only one solution. We must return.

Miranda is as far as Amanda’s tour takes us. This moon of Uranus is … odd. It looks like it was assembled from parts that weren’t designed to fit together. It has canyons that make our Grand Canyon look like a backyard ditch. It has the solar system’s highest cliff, a feature that has made the more adventurous wonder what it would be like to leap from it in Miranda’s low gravity. There are other features not found anywhere else. We know all this because of one brief visit. Voyager 2 glanced at the moon as it flew past Uranus in 1986. The spacecraft saw only one side. What wonders await us when we see the other hemisphere? This year the National Academies made a Uranus orbiter their highest recommendation for a new planetary mission. Don’t hold your breath. Planetary science is only for the most patient—scientists who are willing to play the very long game. I love Amanda’s melodic tribute to Voyager 2 contained in the fifth movement.

We return to Jupiter for the sixth movement. Ganymede would surely qualify as a planet if it weren’t under Jupiter’s spell. It’s bigger than either Mercury or Pluto. It is also the only moon we have discovered that has a substantial magnetic field. A magnetic field is one of the factors that has made Earth so hospitable to life, and Mars so much less so for the lack of one. The Galileo orbiter long ago found that Ganymede is yet another water world, hiding a liquid ocean like Europa and Enceladus. Our best bet to learn more will come with the arrival of the European Space Agency’s JUpiter ICy moons Explorer, or JUICE. In the meantime, NASA’s Juno spacecraft has turned its instruments toward the Galilean moons as it continues to circle Jupiter.

Amanda saved our nearest and best-known neighbor for last. The Moon has been our companion and protector for far longer than there have been humans on Earth. We have walked on it, crashed into it, flown around it and analyzed it, and we still don’t know everything we’d like to. With the possible exception of the Sun, no other celestial body has had so many stories and myths spun about it. And no other body has captured our minds, hearts and imaginations as it has.

After no human visitors for more than five decades, the Moon is about to become a very popular destination. China and the United States are assembling multi-national programs that will put 'the first woman and the next man' on the surface, and a host of new robots are about to head that way. Some look to the Moon as a commercial opportunity, while others see a window on our own past.

When we look outward, when we learn about the other worlds we travel with, we inevitably learn more about ourselves. We also find inspiration and awe. It’s in this spirit that I treasure our explorations. And it is in this spirit that I have grown to love The Moons Symphony. Thank you for joining this journey. May it bring you wonder and joy.

Mat Kaplan © 2022
Planetary Radio host and producer, The Planetary Society

I had just spent two hours researching crescent moons when suddenly I stood up after stumbling across an article. I was transfixed. My hands shook with excitement. The title read: 'Ten of the weirdest moons of our Solar System'.

I instantly disagreed with the author’s description. Those moons were not weird; they were fascinating. However seeing them locked in the vacuum of space, I yearned to break them free from that eternal vault of silence and two thoughts quickly crossed my mind: 'These moons need music, these moons need emotion.'

I thank my roots as a film composer where we are acutely aware of music’s emotional abilities to catapult stories and manipulate the direction of thought.

I was curious to unleash the moons’ secrets and communicate their stories through a musical lens to transport us to experience their exotic habitats in the cold, far-flung, expansive regions of our solar system.

Scientific research was the next evolutionary step after consulting with the world’s most outstanding planetary scientists where scientific data drove the entire creative process for the first six moons.

Then finally, along came consultations with astronauts and meeting NASA’s ISS astronaut Nicole Stott. And so, it’s emotional data that drives the narrative of the seventh moon as experienced from the hearts of astronauts after seeing our planet united and whole.

In this final movement, we stand together on the surface of our moon to experience earthrise and its powerful message for humanity. This story forms the crowning moment of this symphonic spaceflight.

Clair de lune
Nothing quite captures images of a dreamy moonlit sky more than Debussy’s evocative musical tableaux Clair de lune. After traveling to moons in outer space, we now turn our attention to inner space, where the gentle sound of a piano serenades our thoughts 'back to Earth'.

Debussy’s simple melody follows the rich symphonic sounds from our previous moon adventures allowing our imaginations to drift to sights of lunar-lit oceans as we contemplate the cosmic shores from which we have just traveled.

Reflections on Symphonic Space Flight
A poem by Amanda Lee Falkenberg
read by NASA ISS Astronaut Nicole Stott, author of 'Back to Earth'
Following Debussy’s moonlit scenes, we enter the final chapter of lunar travel presented through a poem. There is something earthy about a poem and it felt appropriate that the delivery came from the voice of an astronaut.

Combining the authority of someone who has flown to space there is a resonance, an acoustic alchemy attached to this poem. A poem crafted to bring our journey 'Back to Earth'.

But the journey has only just begun. We have a vision and are on a mission.

The hope is this symphony will offer a chance to reflect on who and where we are in this place and through the awe and wonder of spaceflight, we wish to celebrate Earthrise, together.

And so it is, through the persuasive and dynamic forces of symphony and song, we return from a journey from those stars, and contemplate the cosmic dust which we came from.

Amanda Lee Falkenberg © 2022