Where the Voyager probes have led, others will follow. A panel to determine the country’s scientific priorities for the next 10 years is considering a proposal for a $3.1 billion interstellar probe (IP) that could reach Voyagers’ current location in just 15 years. If approved in 2024, the probe could be launched in 2036.
Ralph McNutt, chief of space science at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, has spent his career working on the Voyager missions. He witnessed the launch of Voyager 1 in September 1977 and is now the leader of the IP project.
“We can reach speeds about twice that of Voyager 1, and get about twice that far before the interstellar probe runs out of power,” he said.
The newer probe would be much more capable than the Voyagers, which were built with 45-year-old technology, and the project’s planners now have a much better idea of what’s possible and what to expect during the journey.
The key transmitter on the new probe and its instruments, including magnetometers and spectrometers, would be many times more powerful than their 1977 equivalents. And the IP could also visit some of the mysterious Kuiper Belt objects in the outer reaches of the solar system, some of which are believed to be thought to be the origin of some comets, McNutt said.
Until the Interstellar Probe gets the green light, however, the Voyagers will be the most important representatives of humanity in interstellar space. In about 40,000 years Voyager 1 will get relatively close to another star in the constellation Camelopardalis, while Voyager 2 will approach a star in the constellation Andromeda on its way to the giant star Sirius, which it will reach in about 300,000 years.
Long before that, however — in just 10 years — both Voyager probes will be completely without power, Spilker said. Each probe is powered by plutonium batteries, but they’re already starting to weaken, and every few months, NASA engineers instruct the probes to shut down a few more of their onboard systems. Their hope is that they can draw enough power from the batteries so that some instruments can continue to work, at least until the 50th anniversary of the twins’ launch in 2027.
Who knows after that?
“Fingers crossed, if everything goes according to plan, we could reach the 2030s,” she said.
When their power eventually runs out, the Voyager probes will serve as “silent ambassadors” for the stars, Spilker said. Each probe carries a plate, printed on gold, of sounds on Earth, including a baby’s cry, a whale’s song, music by Mozart and Chuck Berry, and greetings in 55 different languages.
“Maybe another civilization will find them and want to know more about Earth,” Spilker said.