From Nautil.us, December 3:
Voyagers Ready to Go Dark
When the two Voyager probes launched into space in 1977, they were headed to uncharted territory. It was the first time humanity had sent robot spacecraft to study up close the four giant outer planets of our solar system: Jupiter, Saturn, Uranus, and Neptune. Stunning images and scientific data captured by the probes over the next few decades altered our understanding of the cosmos.
Through the Voyagers, we learned of Jupiter’s turbulent atmosphere, the tilted magnetic field of Uranus, a rotating storm on Neptune called the Great Dark Spot, and Saturn’s dynamic rings. We also discovered 23 new moons of the outer planets and found that these moons were not the dead, frozen worlds scientists had suspected. Saturn’s moons appeared to be composed mostly of water ice, while active volcanoes on Jupiter’s moon Io spewed lava dozens of miles high. Eventually, the two spacecraft would explore not just the four giant planets, but 48 of their moons, as well as the rings, atmospheres, and magnetic fields those planets possess.Once the Voyagers’ tour of the four planets was complete in 1990, the world’s attention faded; but the probes continued to provide remarkable insights into the dynamics of the solar system, including ultraviolet sources among the stars and the boundary between the sun’s influence and interstellar space. Even today, both probes continue sending back data about the interstellar medium, the space between the stars, says Linda Spilker, NASA’s project scientist for the Voyager missions—including precise measurements of the density and temperature of the thin ionized gases it contains and the incidence of high-energy cosmic rays.
More than 45 years after they first launched, the Voyagers are now NASA’s longest-lived mission and the most distant human-made objects from the Earth—but they will one day soon go offline and drift silently into the final frontier, perhaps for eternity. NASA has been progressively shutting down the instruments and cameras on the spacecraft for decades, to extend their working lives to the limit by using as little electricity as possible. One of Voyager 1’s last photographs, for example, was the famous “Pale Blue Dot” taken in 1990, shortly before its cameras were powered off forever. And since the late 1990s, engineers have commanded both Voyagers to shut down instruments related to plasma science, the strength of electromagnetic fields, and the analysis of starlight.
Some experts give the Voyagers only about five years before we lose contact. “There’s been a big push to try to keep the mission going until the 50th anniversary of their launches,” in 2027, says Johns Hopkins space scientist Ralph McNutt, who witnessed the Voyager 1 launch from Florida’s Cape Canaveral in 1977 and has been involved with the Voyager missions throughout his career. “We’ll see.”According to NASA, Voyager 1 is now more than 15 billion miles from Earth, about three times the average orbit of Pluto, where radio signals take about 23 hours to reach it; while its twin Voyager 2 is almost 13 billion miles away....
....MUCH MORE
Although one might experience a twinge of something (sadness?) as the two Voyagers exit our terrestrial lives, that twinge is nothing as compared to that elicited by the Mars rovers.
And we'll be back with more on the Voyagers on December 31.
