The Interstellar Age: Inside the Forty-Year Voyager Mission

  • Author: Jim Bell

  • Published: February, 2015


The Interstellar Age by Jim Bell tells the incredible story of mankind’s grandest exploration. How else to describe the journey of the twin Voyager spacecraft (Voyager 1 and Voyager 2) launched by NASA all those years ago? It is a journey that took mankind on an awe-inspiring trip through our solar system, and beyond. At times it reads like science fiction, but the photos and data collected by Voyager would be hard for any imagination to top. Planetary scientist and professor Jim Bell plays the ultimate tour guide. His broad yet comprehensive prose provides the reader with a thorough overview of the mission, team and journey without getting bogged down in the technical or tedious. Just turn the page, and you have lift off.

Launched in 1977 in order to take advantage of a rare celestial alignment of the planets (such opportunities occur only once every 175 years), Voyager 2, followed shortly by Voyager 1, was on a mission to give us all “our first detailed, high-resolution, glorious views of the solar system beyond Mars, revealing the giant planets Jupiter, Saturn, Uranus, and Neptune, and their panoply of rings and moons, in all their awesome wonder.” The vision for a Grand Tour was conceived in the late 1960’s by aerospace engineer Gary Flandro, when he discovered the outer planets would be in a rare alignment, allowing a space probe or robot to utilize “gravity assists” from each planet (in essence, enter their field of gravity and whip around them, charging towards the next destination at peak velocity). Such assists would reduce the duration of the mission from 40 years to 10 years. The race was on. 

The Voyager spacecraft were outfitted with all of the instruments and gadgets needed to gather data and communicate with Earth while zooming around the solar system. Hundreds of scientists, engineers, technicians and physicists contributed. As Bell puts it, “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 ultra-violet 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.” Think of a flying laboratory, meant to withstand extreme, speed, cold and radiation, and you get the idea. 

It’s safe to say the final addition on each spacecraft was of least interest to the project scientists, but captured the public’s attention like no other part of the trip. Such was the intrigue and bafflement behind the famous Voyager Golden Records. Each spacecraft was outfitted with a physical phonograph record, or more accurately, a time-capsule. The records were made ofgold-plated copper, covered in aluminum and uranium, and filled with images and songs that display the diversity of culture and life on Earth. The records were “bottles launched into the cosmic ocean”, as Carl Sagan put it, (who headed the committee that chose the record’s contents). Sagan acknowledged, “The spacecraft will be encountered and the record played only if there are advanced space-faring civilizations in interstellar space.” The odds of any aliens discovering the Voyagers and their records are astronomically small (which is why many scientists considered it a sentimental waste of time), but Sagan insisted it “said something very hopeful about life on this planet.” As usual, Sagan, much like his heir-apparent Neil DeGrasse Tyson, possessed a way of stimulating the public’s interest in the cosmos in ways no other scientist was able to do. With more interest, comes more funding, comes more discoveries, comes the betterment of mankind. Sagan was playing the long game. Right now, floating out there in the cold vastness of space, are two golden records filled with calculations, pictures of animals, and cuts by Chuck Berry and Beethoven. They are two tiny blinking dots, extending their hands, with a song on their lips. 

In the years following their launch, the Voyager spacecraft did their jobs well, capturing awe-inspiring images that redefined our understanding of our solar system. Each flew by Jupiter, and the Galilean satellites orbiting it (Jupiter’s four large moons). For hundreds of years, these moons were nothing more to mankind than simple points of light, but Voyager turned them into “distinct worlds of their own, with features and characteristics and even personalities that now make many consider them full fledged planets.” From the deep subsurface oceans of Europa, to Io’s over 400 active volcanoes, to Callisto’s battered and cratered surface, to the massive Ganymede’s mammoth magnetic field, Jupiters moons are simply astounding. Voyager 1 went on to inspect Saturn’s mysterious orange moon Titan, which sent it off it’s planetary course and hurling towards interstellar space. Voyager 2 continued the journey through our solar system, and collected photos and data from the ringed ice giants Uranus and Neptune, before also moving on towards an interstellar trajectory. The details and mysteries uncovered by Voyager dazzle the imagination and whet the appetite to know more. The discovery of conditions for life right here in our own solar system (I’m looking at you Europa), is an amazing and profound realization. For those people who still don’t believe in “aliens”, odds are good that they haven’t given the subject much thought, or are ignorant of mankind’s latest missions into the stars.

Amazingly, both Voyager missions continue today. Scientists now believe Voyager 1 has passed beyond our suns cosmic rays, and has officially entered interstellar space. Voyager 2 is currently exploring the heliosheath (the area that defines the limit of the sun’s influence) and will soon follow, providing critical data to help explain many of the signals currently being sent back by Voyager 1. You can even go on NASA’s website and see live odometers, updating in real time, as each Voyager propels through the boundless void of space. Bell writes, “Even though the plutonium on the Voyagers has decayed by only about 25 percent of its starting amount, the spacecraft are already starting to feel the pinch of looming power limitations.” While many instruments are starting to be shut off, scientists predict the Voyagers will have enough power and thruster fuel to stay in touch with Earth until about 2025, which is when they’ll officially sign off, and truly become, messages in a bottle. 

Magellan, Columbus, Marquette and Joliet, Lewis and Clark - none of them can compare to the the forty year Voyager mission through our sun’s backyard and beyond. Bell, like his hero Carl Sagan, is an able ambassador to the stars for earthlings from all walks of life. His prose conjures up a feeling of awe and gratitude for sharing his enthusiasm and wonder at what we’ve been able to accomplish. 

There’s something undeniably lonely and poignant about each Voyager as they near the end of their missions and drift further into the black vacuum. After more than 40 years, they are surely weary travelers. They have seen new worlds, new moons, and traveled unimaginable distances, all while beeping back data to the scientists and people who created and cared for them. Eventually that tiny, feint signal will disappear, leaving them floating through space for what could be an eternity of silence. With the discovery of so many exoplanets in recent years (Earth-like world’s orbiting other stars), we retain hope that they’ll be scooped up, and given a final resting place. Bell himself writes movingly when he envisions these battered machines at the center of some wonderful alien atrium, displayed for all to see and surrounded by light. My hope is simply that before they disappear, on to a future no one can predict, we’re able to send a simple reply back. “Thank you. Mission Accomplished.”