The Interstellar Age

by Jim Bell

Artisan with drill

  Factory interior

  Museum

  X-ray of hand

  Woman with microscope

  Street scene, Asia (Pakistan)

  Rush-hour traffic (Thailand)

  Modern highway (Ithaca, NY)

  Golden Gate Bridge

  Train

  Airplane in flight

  Airport (Toronto)

  Antarctic expedition

  Radio telescope (Netherlands)

  Radio telescope (Arecibo)

  Page from Newton’s System of the World

  Astronaut in space

  Titan Centaur launch

  Sunset with birds

  String quartet

  Violin with music score

  The music on the Golden Record, on the other hand, was less of a cerebral exercise. Who knew whether intelligent beings from across the galaxy would have a means for experiencing music. Could they even hear? Nonetheless, music represents the emotional side of humanity, and the pieces were chosen to convey the maximum feeling. Portraying the variety of human musical traditions was important, but when choosing a single piece from a culture, the emotion conveyed by the piece was paramount. The Golden Record’s final musical repertoire is detailed in the table on pages 96 and 97. When looking over the list of musical selections chosen to represent our world, many will feel dissatisfied. After all, music is such an individual choice. Try explaining why you are moved by Beethoven’s “Moonlight” Sonata (which I would like to have seen included, but I suppose the Fifth Symphony is also a decent choice). It is often impossible to articulate, but we can feel it in our hearts.

  Many musical experts were consulted by Sagan and Ferris when choosing the final list, and the team’s dedication to the requirement that the chosen music must touch the heart as well as the mind was striking in such scientific people. The decision to include multiple pieces by the same composer (three by Bach and two by Beethoven) is also interesting. In addition to the fact that Bach and Beethoven have produced some of humanity’s finest works, it was thought by some, Lomberg included, that the inclusion of multiple pieces by the same composer would help illuminate our intent for the music, which was ultimately to convey mood and feeling. Even so, not everyone’s personal favorites could be included. In addition to the omission of the Beatles, for example, Jon Lomberg was also disappointed that the music of Bob Marley was not represented. “At that time he didn’t have the stature he did later, but still, his was real Third World music, and we needed more of that.”

  Music on the Voyager Golden Record

  Bach, Brandenburg Concerto no. 2 in F, first movement, Munich Bach Orchestra, Karl Richter, conductor. 4:40

  Java, court gamelan, “Kinds of Flowers,” recorded by Robert Brown. 4:43

  Senegal, percussion, recorded by Charles Duvelle. 2:08

  Zaire, Pygmy girls’ initiation song, recorded by Colin Turnbull. 0:56

  Australia, Aborigine songs, “Morning Star” and “Devil Bird,” recorded by Sandra LeBrun Holmes. 1:26

  Mexico, “El Cascabel,” performed by Lorenzo Barcelata and the Mariachi México. 3:14

  “Johnny B. Goode,” written and performed by Chuck Berry. 2:38

  New Guinea, men’s house song, recorded by Robert MacLennan. 1:20

  Japan, shakuhachi, “Tsuru No Sugomori” (Crane’s Nest), performed by Goro Yamaguchi. 4:51

  Bach, “Gavotte en rondeaux” from the Partita no. 3 in E major for violin, performed by Arthur Grumiaux. 2:55

  Mozart, The Magic Flute, aria no. 14, “Queen of the Night,” Edda Moser, soprano. Bavarian State Opera, Munich, Wolfgang Sawallisch, conductor. 2:55

  Georgian S.S.R., chorus, “Tchakrulo,” collected by Radio Moscow. 2:18

  Peru, panpipes and drum, collected by Casa de la Cultura, Lima. 0:52

  “Melancholy Blues,” performed by Louis Armstrong and his Hot Seven. 3:05

  Azerbaijan S.S.R., bagpipes, recorded by Radio Moscow. 2:30

  Stravinsky, Rite of Spring, “Sacrificial Dance,” Columbia Symphony Orchestra, Igor Stravinsky, conductor. 4:35

  Bach, The Well-Tempered Clavier, Book 2, Prelude and Fugue in C, no. 1, Glenn Gould, piano. 4:48

  Beethoven, Fifth Symphony, first movement, the Philharmonia Orchestra, Otto Klemperer, conductor. 7:20

  Bulgaria, “Izlel je Delyo Hagdutin,” sung by Valya Balkanska. 4:59

  Navajo Indians, “Night Chant,” recorded by Willard Rhodes. 0:57

  Holborne, Pavans, Galliards, Almains, and Other Short Aeirs, “The Fairie Round,” performed by David Munrow and the Early Music Consort of London. 1:17

  Solomon Islands, panpipes, collected by the Solomon Islands Broadcasting Service. 1:12

  Peru, wedding song, recorded by John Cohen. 0:38

  China, ch’in, “Flowing Streams,” performed by Kuan P’ing-hu. 7:37

  India, raga, “Jaat Kahan Ho,” sung by Surshri Kesar Bai Kerkar. 3:30

  “Dark Was the Night,” written and performed by Blind Willie Johnson. 3:15

  Beethoven, String Quartet no. 13 in B flat, op. 130, “Cavatina,” performed by Budapest String Quartet. 6:37

  THE NEXT LEVEL

  The NASA New Horizons spacecraft, launched in 2006 and headed for a flyby past Pluto in July 2015, is also on an escape trajectory out of the solar system—the first such spacecraft on an escape trajectory since the Voyagers, and following a path similar to one of the Jupiter-Pluto missions that Gary Flandro and others charted in the mid-1960s. It is destined to continue on through a zone of thousands of small, icy planets beyond Neptune called the Kuiper Belt and enter interstellar space sometime in the next few decades. But it was launched without an interstellar message like Voyager’s on board. Perhaps this is a sign of a more anxious age.

  In any case, a group of people led by Jon Lomberg are awaiting expected approval by NASA to upload a yet-to-be-determined “digital interstellar message” into the New Horizons spacecraft’s permanent long-term flash memory once the mission has completed its science objectives. More than ten thousand people from 140 countries signed online petitions to support bringing this message project forward to NASA and the New Horizons project, which no doubt helped the idea gain official approval. The contents of the message—its text, images, art, and/or music—will be crowd-sourced, a distinctively more modern way of soliciting multiple opinions through the Internet. “Previous messages from Earth, portraits of our planet and our species, have been made by small groups of experts,” Jon Lomberg noted. “This initiative proposes that this time, for the first time, the whole world can participate. The Voyager record has become an iconic image of the twentieth century, signifying our emergence as a galactic species. Now, new generations can be captivated by the incredible perspective that creating a self-portrait of Earth offers, becoming better informed citizens of the galaxy in the process.”

  I asked Jon to reflect on his motivation for taking advantage of the rare opportunity to once again include messages on an artifact being sent beyond our solar system. “Unfortunately, the New Horizons team was so busy just trying to keep their mission on track—it was canceled, then re-approved, then re-canceled, then re-approved—and successfully built and launched that they just didn’t have the time needed to create a physical artifact like a plaque or a record,” he told me. He was disappointed about that for a little while, assuming that it had to be some modern-day artifact equivalent to the Golden Record (“maybe a quantum nano superconducting Voyager record or something”). But then he thought more about it. Voyager had set the bar high for analog, physical artifacts. Later projects, like The Planetary Society’s “Visions of Mars” on the NASA Phoenix lander, or the society’s other efforts to launch the signatures of thousands of people on planetary missions, advanced that technology to CDs and DVDs. “But we have never sent o
ut a digital message,” Jon recalled thinking. “Nobody thought of putting one in the computer. So it’s kind of the next level up from the physical artifacts. Granted, the lifetime of it probably isn’t as long as the Voyager record, but again it’s still an important gesture. Every spacecraft leaving Earth will have some type of computer, and so we may be establishing a positive precedent with the New Horizons digital message, especially the crowd-sourcing aspect of it. Before, it was just a few of us who were attempting to speak for the Earth. But with New Horizons we’re making a serious effort to involve as much of the Earth as we can. And that’s certainly something I think Carl would have liked.”

  I’m a member of Jon Lomberg’s advisory board for what is being called the One Earth: New Horizons Message Project, and as we begin ramping up our public engagement in formulating what some are calling the Voyager Golden Record 2.0 message, it will be interesting to see how different today’s crowd-sourced message to the future will be from the message so carefully crafted forty years ago by a select group of people for the Voyager record. “Perhaps New Horizons will never be found and its message never read,” says Jon Lomberg, “but the very act of creating the message and sending it inspires the imagination and encourages a wider perspective in space and time. Humans have never needed this perspective more than they do today. Contemplating the vastness of the cosmos, we make our mark on it by our explorations—surely one of the most positive acts by the human species in all our history.”

  Part Two

  THE GRAND TOUR

  4

  New Worlds among the King’s Court

  NINETY-NINE POINT EIGHT percent of everything in our solar system is inside the sun, and of the 0.2 percent that is left, more than half of that is inside the planet Jupiter. Jupiter has more mass than all of the other planets, moons, comets, asteroids, and space dust out there combined, making its royal monikers from classical mythology—Zeus, Thor, King of the Planets—truly apt.

  Jupiter was the first encounter for both Voyagers, and even after the successful Pioneer flybys just a few years earlier, much was still unknown and mysterious about our solar system’s largest planet. In 1610, Galileo was the first to recognize Jupiter as a world with moons of its own, and the astronomers Robert Hooke and Giovanni Cassini were the first to recognize (separately), in 1665, the famous Great Red Spot and other colorful moving zones and belts of clouds in the giant planet’s dynamic atmosphere. Over the intervening three centuries, improving telescopic resolution and instrumentation provided more information about the speed of Jupiter’s winds and giant storm systems, of which the Great Red Spot is one, and about the chemistry of the clouds and the composition of the brightest moons. Right up until the Voyager flybys, however, those moons were still only points of light.

  The Voyagers changed all that, forever. After the flybys, Jupiter’s four large moons—Io, Europa, Ganymede, and Callisto, collectively known as the Galilean satellites after their original discoverer—became distinct worlds of their own, with features and characteristics and even personalities that now make many consider them full-fledged planets. Indeed, I believe that Voyager’s exploration of the Galilean satellites revealed a bias that we didn’t even know we’d had in our search for life beyond Earth. The only example of life as we know it exists on a planet—a large body directly orbiting the sun—and a planet relatively close to the sun at that. Life on Earth takes advantage of our inner solar system location, of our abundance of liquid water, and the ample energy of sunlight bathing our planet. Therefore, why wouldn’t we think it most likely that extraterrestrial life is planet-based as well? The only large moon in the inner solar system is our own moon, which lacks an atmosphere and thus we know is lifeless. But what if there are other moons out there that might have the right ingredients—liquid water, for example, or ways to tap into enough sunlight or other energy sources like volcanoes or tidal energy—to fuel the biochemistry of life? There are more than a dozen large moons in the outer solar system. According to the official definition, moons can be only once-removed cousins of planets because they revolve around a planet instead of around the sun. But what if that didn’t matter? What if what matters instead in the search for life “out there” is what they are intrinsically like, not who they happen to hang around with?

  FLIGHT PATH

  Voyager mission designers such as Charley Kohlhase and his team of about ten colleagues at JPL had the job of figuring out how to time, align, and visualize the trajectories of each Voyager’s single pass through the Jupiter system so that the spacecraft would get the best possible views of the planet and its large moons, have a good communication geometry with the Earth, as well as have its trajectory bent and sped up by the right amount to swing the probe on to Saturn. Physicists realized long before Gary Flandro, Charley Kohlhase, and others on the Voyager team that such slingshots were possible, and that they represented the closest thing to a free lunch that one could get in the solar system. By aiming a spacecraft to pass behind a massive planet in its orbital path around the sun, the spacecraft would not only speed up as gravity draws the craft inward toward the planet, but it would also get a boost—a gravity assist—from the planet’s own orbital momentum around the sun. It’s kind of like the way a batter adds energy to a pitched softball when she hits it. The ball does not simply bounce off the bat with the same speed in the opposite direction—energy supplied by the batter is added to the ball’s energy, changing its direction and increasing its speed. A planet’s orbital momentum is a source of energy that a spacecraft can tap into to speed up (or, if passing in front of a planet relative to its direction of motion, to lose energy and slow down using the antigravity effect) relative to the sun. It seems like getting something for nothing, but it’s not. Newton’s laws of motion tell us that when it comes to forces and energies, there is always an equal and opposite reaction to any action. So for the spacecraft to speed up, it means that the planet has to slow down. Energy is conserved, never lost. The difference is, though, that because the mass of the spacecraft is so minuscule compared to the mass of the planet, the result of the spacecraft stealing some of the planet’s orbital momentum (mass times velocity) is insignificant for the planet. When the Voyagers did their gravity-assist slingshots past Jupiter, for example, they were sped up by about 10 miles per second relative to their approach velocity, but Jupiter itself was slowed down by only the equivalent of about 1 foot per trillion years.

  Setting up the flight trajectories for the Voyagers was a monumental task, sifting through what Charley describes as “10,000 possible flight paths” just for their primary mission targets Jupiter, Saturn, and Titan. Charley emphasizes that his team had to develop new software methods to quickly simulate and visualize many possible missions. One method included modeling spacecraft orbits using a centuries-old shortcut that broke the orbits down into shorter, simpler segments called conic sections (“Who was it, Kepler or Newton,” Charley asked himself, thinking back on the early history of celestial mechanics, “who first came up with this mathematical trick?”—it was Newton who discovered the shortcut), because traditional orbit-calculation methods would have taken months to complete if using the full calculations and the computer technology at the time. “I’ve got a bunch of mission constraints I’m trying to honor, like communications, navigation, and getting the trajectory to the next planet,” he recalls, adding wryly, “and I also know that the scientists would rather fly by the lit side of a planet and its moons rather than the dark side. And so we’re trying to get the flybys close to these new worlds, as close as we can, but not so close as to magnify the navigation errors.”

  That last part was important: they knew that Jupiter would bend the trajectory of the spacecraft by a given amount because the mass of Jupiter was well known. But they didn’t know the precise masses of the moons they wanted to get close to, and so they had to be careful not to get too close, lest that unknown mass bend Voyager’s path astray. “So we applied the engineering co
nstraints, then what we thought would be attractive to Science.” The team would then generate those cases in reams of plots and tables and pass them on to Ed Stone’s Science Steering Committee to look over and give feedback as to the quality and scientific value of the various moon and planet geometries that these “computer-flown missions” would yield.

  Charley positively beams with pride at his team’s accomplishment of finding the two perfect needles in the haystack of mission designs they started out with: “Winnowing through that list of 10,000 possible missions to find the best 110 to target and the 2 to launch was an effort done nearly perfectly. I should show more modesty than that, but we did that job right.”

  The final March 5, 1979, Jupiter flyby path that Charley and Ed and colleagues on the Science Steering Committee chose for Voyager 1 enabled close passes by Io, Ganymede, and Callisto, but only a relatively distant view of Europa. A more detailed view of Europa would have to wait until the July 9, 1979, flyby of Voyager 2, which made close passes by that moon, as well as Ganymede and Callisto, but allowed only distant views of Io. Thus it was only together, through both Voyager flybys, that high-resolution photos of all these worlds; movies and high-resolution photos of Jupiter’s clouds and storms; and lots of other unprecedented data on radiation, magnetic fields, and the chemistry/composition of the Jovian system could be obtained.

  Even at their super-high speeds of around 35,000 miles per hour, each of the Voyagers took about three days to pass through the heart of Jupiter’s mini solar system, traveling from the orbital distance of farthest-away Callisto to their closest approaches to the giant planet (a distance away of only about three to five times the radius of the planet), then back out again. During that time, the spacecraft was in frequent communication with the DSN, radioing the latest images and other data back to an eagerly awaiting science team and press corps at JPL, and receiving updates to the onboard sequences with the newest team estimates of the best scan-platform pointing, camera exposure times, and other parameters.