Review: The Farthest is a compelling tale of NASA’s Voyagers - Physics-Astronomy.org

Review: The Farthest is a compelling tale of NASA’s Voyagers

Even in the era of Mars rovers and exoplanet discoveries, few scientific endeavors can match the epic scale of NASA’s Voyager mission. The twin Voyager 1 and Voyager 2 spacecraft were our first witnesses to the outer reaches of our solar system and have traveled farther than any other human-made objects. Now, 40 years after the launch of the two probes, Emer Reynolds has directed a documentary film that chronicles the mission’s history. The Farthest: Voyager in Space covers the mission’s development in the 1970s; the probes’ encounters with Jupiter, Saturn, Uranus, and Neptune; and the current quest to explore interstellar space. The beautifully put-together film weaves historical footage with interviews and interpretive imagery to produce an intimate portrait of the mission and the people who made it happen.
The story is recounted primarily by the scientists and engineers who contributed to the project during its various phases. The interviewees display strong emotions as they remember their time working with the spacecraft. Voyager project manager John Casani chokes up as he describes seeing the probes for the last time as they were prepared for launch in 1977. Reynolds made a particular effort to catch up with the remarkable women, including imaging scientists Carolyn Porco, Heidi Hammel, and Linda Morabito, who contributed to some of the mission’s biggest discoveries.NASA engineers and project managers tell viewers about their attempts to plan for the many possible hazards of the mission. The strong electromagnetic field at Jupiter, for instance, had the potential to fry the spacecraft’s circuitry. During the initial design and procurement process, engineers did not anticipate just how strong the field might be; they ultimately wrapped the finished wiring in strips of store-bought aluminum foil for additional protection.
Further challenges arose after the spacecraft were launched. The onboard computers—which planetary geologist Jim Bell reminds us are not much more sophisticated than the key fobs we now use to open our car doors—needed in-flight reprogramming so the spacecraft could perform the correct maneuvers while using the gravity of one giant planet to slingshot to the next. Communicating with the spacecraft and delivering new code over great distances required the construction of more powerful antenna arrays on Earth.
The interviews consistently remind us of the mission scientists’ extraordinary ambitions. The four gas giant planets are properly aligned for a “grand tour” of the outer solar system only once every 175 years. As NASA scientist Tom Krimigis tells it, NASA administrator Tom Paine pitched the project to President Richard Nixon by explaining that Thomas Jefferson was president during the previous such alignment, “and he blew it!” (The history here is slightly off. The proposal for the mission emerged from a 1965 meeting of the National Academy of Sciences’ Space Science Board, which concluded that sending a larger mission to four planets would be cheaper and faster than several smaller missions.) Nixon ultimately approved the mission, but only for Jupiter and Saturn. Still, NASA built the spacecraft with the capability to go farther if eventually authorized. It was.
We are also presented with the dramatic discoveries made by the spacecraft (see the article by Ellis Miner, Physics Today, July 1990, page 40). Here the enthusiasm of the now senior scientists really comes through as they (and we) see the joy, awe, and exhaustion on the faces of their younger selves in historic press conference footage. Voyager 1, although launched second, was the first to reach Jupiter, where, in addition to providing fascinating images of the planet and the Great Red Spot, it explored the moons Europa, Ganymede, and Io. While traveling away from Io, Voyager 1 recorded the first observations of an extraterrestrial volcanic eruption, a finding made possible by Morabito’s keen eye while poring over images. The spacecraft’s mission ended in 1980 at Saturn, where it observed the planet’s rings and moons, including haze-filled Titan. Thirty-two years later, Voyager 1 crossed the solar system’s heliopause and entered interstellar space.
Voyager 2 collected further data on Jupiter and Saturn and went on to Uranus, where it discovered a magnetic field that is tilted roughly 60° from the planet’s sideways axis of rotation (see the article by Bruce Schechter, Physics Today, August 1986, page 17). Voyager 2’s planetary mission ended with its 1989 encounter with Neptune, during which it discovered a Great Dark Spot, practically skimmed the cloud tops in the planet’s atmosphere, and returned striking images of the moon Triton.The Voyager spacecraft carried more than scientific instruments and cameras. One of the most iconic symbols of the mission was a golden record containing images and sounds from Earth—including an assortment of music and greetings spoken in 55 languages—mounted to the body of each craft. The film presents this record as a message in a bottle, cast out into the vastness of space.
Regardless of the probability of alien life, chances are slim that humankind’s message ever will be found by another intelligent civilization. Nonetheless, the record is a meaningful cultural artifact of the hopes of scientists like Carl Sagan and Frank Drake, who saw the simple spacecraft as emissaries of humanity. It was Sagan who persuaded NASA in 1990 to turn onVoyager 1’s camera one last time to take a family portrait of the solar system as seen from its edge. The portrait included the now famous Pale Blue Dot image, which Sagan evocatively described as “the Earth in a sunbeam.”
The Farthest premieres on PBS on 23 August at 9pm Eastern.
Matthew Shindell is a historian of science and the curator for planetary science and exploration at the National Air and Space Museum in Washington, DC. He moderated a panel about The Farthest at the AFI DOCS Film Festival in June.

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