by Jim Bell
EXPEDITION LEADERS
Famous ships of exploration are usually led by a famous captain or commander, like Christopher Columbus, Ferdinand Magellan, James Cook, Ernest Shackleton, or Neil Armstrong. The Voyagers, however, are led by a committee of captains—managers, engineers, and scientists from NASA’s Jet Propulsion Laboratory (JPL) and elsewhere who were tasked with overseeing the design, manufacture, and operation of the most ambitious robotic planetary exploration mission yet attempted—and a pair of equally powerful commanders, a project manager and a project scientist.
In NASA and JPL parlance, Voyager is a “Project” (capital P), run by a Project Office (capital O) and divided organizationally into a number of subsidiary offices. These include the Mission Planning Office, where the detailed spacecraft trajectories were designed; the Flight Science Office, which includes the science team and which is responsible for making sure the mission achieves its scientific objectives; the Flight Engineering Office, with the engineers and managers who designed and built Voyager’s power, thermal control, communications, and propulsion modules; the Flight Operations Office, which provides the procedures and software needed to plan and actually operate the spacecraft and its science instruments (and which includes two teams of JPL scientists and engineers: the spacecraft operations team, who directly communicate with the spacecraft and who monitor its status and health over time, and the science support team, who serve as the interface between the science team and spacecraft operations team); and the Ground Data Systems Office, which provides the hardware and software needed to send commands up to the spacecraft (“uplink”) as well as to receive and process data back down from the spacecraft (“downlink”).
The project manager leads the Project Office and is the engineering and management commander of Voyager, responsible for getting the spacecraft built and tested, keeping the mission safely operating on time and on budget, and overseeing the hundreds of contractors and several thousand engineers, technicians, and other managers on the Project. The project scientist runs the Flight Science Office and the science team—a group of scientists, engineers, technicians, managers, and students from around the world who designed, built, and operate the science instruments and who interpret the downlinked data. The project scientist is the scientific commander of Voyager, responsible for making sure the mission achieves its science goals on time and on budget and for coordinating and herding (like cats) the hundreds of scientists on the Project.
Each Voyager carries scientific instruments for eleven investigations. These include wide-angle and high-resolution cameras for imaging and spacecraft navigation; radio systems for studying gravitational fields and planetary radio emissions; infrared and ultraviolet spectrometers to measure chemical compositions; a polarization sensor for surface, atmosphere, and planetary ring composition; a magnetometer measuring magnetic fields; and four devices for studying charged particles, cosmic rays, plasma (hot ionized gases), and plasma waves. Scientists conducting each investigation are organized into instrument teams, and the leader of each instrument team is called the principal investigator (or PI). The PIs are responsible for the design, construction, and operation of each of their instruments, and together they form the Science Steering Group, which is chaired by the project scientist and which reports to the project manager.
In this kind of committee-led project, it’s critical that the two commanders at the top of the org chart, the project manager and the project scientist, are consistently on the same page and have an excellent working relationship. Each is personally responsible for the success of the mission—to NASA and, ultimately, to Congress and the taxpayers who are footing the bill. Over the course of more than four decades since the Project began, Voyager has had ten project managers. But during that entire time, the mission has had only one project scientist: Edward C. Stone.
Ed Stone is a space weatherman, a physicist who studies the ways that high-energy particles called cosmic rays travel through space and interact with the magnetic fields and atmospheres of the sun and planets. Cosmic rays are a form of high-energy radiation made of protons and the nuclei of atoms, and they travel through the universe at nearly the speed of light. Exactly where they come from is still a mystery—they could be caused by massive supernova explosions of dying stars, or by the powerful black holes in the centers of active galaxies, for example. Regardless of how they formed, scientists like Ed can use the properties of cosmic rays to understand the details of the ebb and flow of the solar wind (the stream of high-energy particles coming off the sun) and the way that wind is carried by the sun’s magnetic field and interacts with the magnetic fields of the planets. Measurements of this kind of “space weather” were some of the first scientific measurements ever made from space satellites, and Ed Stone has been a prolific scientist in this game since the beginning.
In 1972, Ed was appointed as the project scientist for Voyager. Over the course of the mission he’s had other important roles as well, including serving as the director of JPL from 1991 to 2001 and as the PI for Voyager’s Cosmic Ray Subsystem (CRS) instrument, which is making the measurements that are most closely aligned to his scientific background and interests. Project scientists have to figure out how to achieve the optimum match between the science needs of a mission and its engineering and budget constraints. They also sometimes have to make tough decisions about which experiments and which observations will or will not be done. If members of the science team can’t agree on how to carve up available resources (power, time, data volume) for competing measurements, it is the job of the project scientist to step in to arbitrate, or to just plain decide.
“It turns out,” Ed reflected, “that’s a much more critical role than I had thought ahead of time, and that’s because ultimately what science is all about is making discoveries. By deciding to make this observation rather than that one, you’re effectively deciding that that group of scientists gets to make a discovery and this group doesn’t.”
Ed Stone’s impeccable record as a careful and thoughtful scientist, his patient and friendly demeanor, and his ability to work fairly with ten project managers and hundreds of Voyager scientists and engineers have established him as an effective and respected project scientist, as well as a widely recognized spokesperson for the entire Project during press conferences and media appearances. Voyager is run by committee, and consensus is most often the ruling doctrine. But if things were different, I can easily envision Ed Stone as the king of Voyager, ruling benevolently over an empire that extends out to the farthest reaches of the known solar system, and beyond.
REMOTE SENSING
Astronomers traditionally study stars or galaxies; geologists typically study rock outcroppings or map oil and mineral deposits; meteorologists study the weather and climate and try to make forecasts—these are relatively traditional and established fields of scientific study. But what do you call a person who studies the science of the planets, moons, asteroids, and comets around us and has to use the theories and methods of some, many, or all those fields at once? The term “planetary scientist” is a relatively new one among academic professions, and it’s one that the Voyagers have helped establish. We’re a sort of jack-of-all-trades kind of people, thinking about science questions on scales from the planetwide (like from a mapping camera on an orbiting spacecraft), to the minuscule (like individual little rock piles or sand piles studied by a rover). Some of us are more interested in astrobiology—the study of life in space—than anything else. A common approach among planetary scientists is to use remote sensing, very remote sensing, to do our science, because except for those lucky dozen astronauts who’ve had the privilege of walking on another world, none of the rest of us can actually set foot on the places we’re studying.
We use technology to experience the place remotely. Everyone actually uses remote sensing of a sort all the time in our daily lives, using our senses to interrogate the world out of our reach to, for example, judge distances a
nd sizes or to identify objects from their shapes or colors or smells. All animals do it one way or another; plants, too. The difference for planetary scientists is the use of robotic sensors: cameras acting as eyes to provide sight, spectrometers or sampling probes acting as organs for smell and taste, arms and scoops and drills providing a sense of touch, radio antennas for “hearing” and “talking.” And even a sixth sense comes into play sometimes, one that is familiar to hikers or geologists working out in the field: a sense of place or context enabled by mobility—the ability to roam and climb and explore a place from multiple perspectives, or to leave it entirely and head for new ground. Flyby and orbiter spacecraft, and rovers on the ground, provide these essential remote-sensing capabilities for us, sending back the pictures and sensory data from remote places.
It’s easy to think of spacecraft like the Voyagers as being alive, imparting to them feelings and other human attributes. They are so far away, and it is so cold and dark. They must be lonely. Some of them, like the Mars rovers Spirit and Opportunity, are so cute with their long necks and bulging eyes! They must be plucky, intrepid, courageous, and a dozen other grand adjectives of exploration, in order to survive and thrive for so long. They are out there, working tirelessly, making discoveries and braving dangerous environments with no rest, no vacation, and no pay. We’ve got robots exploring the solar system for us!
Well, as fun (or creepy) as that is to imagine, it misses the point. They are machines, built and launched and operated remotely by smart and clever people. Spacecraft like the Voyagers are high-tech, to be sure, but not sentient or any more capable than their relatively primitive (by our twenty-first-century standards) software. “Don’t anthropomorphize the spacecraft,” Voyager imaging team member Torrence Johnson recalls Project Manager John Casani saying. “They don’t like it.”
“The sense of exploration we get with these missions is a very ‘human explorer’ kind of feeling, even though our senses are on the distant spacecraft,” my friend, planetary science colleague, and Voyager imaging team member Heidi Hammel says. “I feel like an old-fashioned mountain climber when I am making discoveries, seeing something for the first time, realizing that no human before me has ever seen what I am seeing. It takes your breath away—for just a moment you feel a pause in time as you know you are crossing a boundary into a new realm of knowledge. And then you plunge in, and you are filled with childlike joy and wonder and delight.” Like me, Heidi cut her teeth in our business with Voyager, and like me, she got hooked on the thrill of exploration and discovery. “And then you get serious again, and start thinking about how it fits into what you already know,” she continued, “and your grown-up scientist brain takes over. Those of us who have had that feeling want to keep coming back for more, and we want others to have that feeling too.”
A PLANETARY SOCIETY
The robotic exploration of space is, in fact, human exploration. It’s just that the humans doing the exploring haven’t left this planet. And that’s why the story of the Voyagers and their travels to the edge of the solar system and beyond is a story of the human drama of deep-space exploration. Voyager’s saga is one of discovery and adventure but also of risk and frustration, successes as well as sacrifices, consensus and conflict, the historic mingling with the mundane. Scientists, engineers, managers, technicians, artists, students, and countless other professionals designed the mission and built the spacecraft, guided them on their Grand Tour of the outer solar system, helped take the photos and make the discoveries that now fill our textbooks, and still help us communicate with the spacecraft today on their continuing interstellar voyages. When historians five hundred years from now look back, the accomplishments of this particular group of people will be among the most important remembrances of our time.
But many other people have had an important albeit indirect role as well. As a student, I learned about and joined a new organization that my hero Carl Sagan had helped form in 1980 called The Planetary Society. The Planetary Society is the world’s largest public-membership space-advocacy organization, and its beginnings are as tied to Voyager as my own. America in the late 1970s was in a state of national crisis: high inflation, high prices (and even rationing) of oil and gas, and federal budget deficits rising to levels not seen in decades. Ronald Reagan was elected president in 1980 partly as a result of a national backlash against President Jimmy Carter’s administration’s inability to get the economy back on track. Reagan interpreted his mandate to be to recover the economy by promoting business growth (this is when the term “Reaganomics” was coined) and cutting taxes and federal spending. Specifically, that meant cutting nondiscretionary federal spending—the programs not related to defense or Social Security or Medicare and other entitlements. NASA found itself on the chopping block for massive potential budget cuts, initiated by Reagan’s chief of the Office of Management and Budget (OMB), David Stockman.
I don’t know whether Stockman liked NASA or not, but it didn’t matter—even though its fraction of the federal budget was less than 1 percent (as it is today—now less than 0.5 percent, in fact), the space agency was an easy target for budget cutters. “Why should we spend money on searching for little green men,” some in Congress have asked (really), “when we have so many other pressing needs here at home?”
Why should American taxpayers support NASA? I believe it’s because we like satellite launches, space shuttles, moon landings, Mars landings, and cutting-edge materials and computers and communications technology and products . . . even Tang, at least for a while. Most important, however, as is obvious to anyone who spends time around scientists like Ed Stone or Heidi Hammel, or science popularizers like Bill Nye or Neil deGrasse Tyson, there are critically important intangibles in this pursuit that feed our souls. Some of the intangibles of supporting NASA—results for which we cannot predict their future influence on our society or our planet—include the inspiration and education of our young people, the gathering of pure knowledge about the worlds around us and our place in the universe, and of course national pride in American leadership in exploring the greatest frontier there is.
The national debate and budget-cutting angst of the early 1980s was happening right on the heels of the spectacular Voyager flybys of Jupiter in 1979 and Saturn in 1980. These planets had been visited before, though only briefly, during flybys by the Pioneer 10 and Pioneer 11 spacecraft a few years prior to Voyager. While spectacular achievements in many other ways, the Pioneer images of the giant planets were somewhat fuzzy (not much better than telescopic images from Earth, because of the relatively far flyby distances and crude digital imaging technology that was used), and little new information was obtained about the moons or rings around those worlds.
Voyager was different.
Van Gogh–like tapestries of crazily colored, swirly clouds with vibrant tones of orange, yellow, and red on Jupiter, including the first close-ups of the Great Red Spot, began showing up on TV, on space posters, and in textbooks. The clarity of form and color and the simple elegance of Saturn’s rings were revealed for the first time, including photos looking back from behind the rings, beyond Saturn, viewing the planet from a perspective impossible to achieve from Earth. And the large moons around Jupiter and Saturn were unveiled as alluring worlds—planets in their own right—one with active volcanoes (Io), another with plates of what appeared to be floating sea ice (Europa), and another with a thick, smoggy atmosphere that may be what the Earth’s early atmosphere was like (Titan). It was a grand spectacle.
Voyager imaging team member Carl Sagan knew, from his own experience as a public speaker, educator, and TV host, that there was enormous public support for NASA, but that it was scattered across the country and not organized in any particular way. Something had to be done to combat the looming budget cuts. Sagan, along with Bruce Murray, a planetary scientist and then director of JPL at Caltech in Pasadena, and JPL space mission engineer and manager Louis Friedman, decided to try to organize a
nd focus public support. In 1980 they formed a nonprofit membership organization, a society that any like-minded people could join. Dues would be $15 per year, and they’d send out a bimonthly magazine with the latest space images and other related information. They called it The Planetary Society, and the magazine The Planetary Report.
I joined The Planetary Society as a high school student in 1980 (I think I saw the ads for membership in the materials distributed by my rural Rhode Island amateur astronomy club, SkyScrapers). Many members of the club were as excited as I was about the Cosmos TV show and thrilled about being part of a nationwide—worldwide—effort to promote space exploration. I let my membership lapse a few times in college when I was short on cash, joined again for good in grad school, and now I’m privileged to be the president of the society’s board of directors, a position once held by my mentor, Carl Sagan. Membership in the society skyrocketed to more than 100,000 people shortly after it was formed, partly fueled by Sagan’s enormous popularity and influence, but partly also because it provided a way for interested people to stay informed about and connected with the space program in the days before the Internet. Sagan, Murray, and Friedman took this public support to Congress and the presidential administrations over the years to help demonstrate the high level of enthusiasm for NASA and space exploration. Indeed, the society was instrumental in tapping into the success and legacy of Voyager to help avert the worst of the early 1980s budget slashing of NASA and to help set the stage for the phenomenal missions of exploration and discovery that have taken place since.