As much of the space community’s attention remains focused on the delayed launch of the Artemis rocket and the return to the moon, two space age relics continue to make their way through the void between the stars, returning valuable information to scientists on Earth.
The Voyager 1 and Voyager 2 space probes were launched 45 years ago, the first on August 20, 1977 and the second on September 5, and are now the furthest human-made objects from Earth, about three times the distance of Pluto from Sun.
Measurements indicate that both probes left our solar system’s interstellar bubble a few years ago. But they are getting older, and so engineers have progressively shut down their systems in hopes that their dying batteries can only provide enough power for a few more years. After that, the probes will shut down completely and may skirt space forever.
“The two Voyagers became our first interstellar travelers, sending information about a place we’ve never visited before,” said Linda Spilker, NASA’s deputy project scientist for Voyager missions at the Jet Propulsion Laboratory in Pasadena, California. .
It now takes about 22 hours for radio signals from Earth to cover the more than 15 billion miles to Voyager 1, the farthest probe, and another 22 hours to receive its response. Spilker, who has worked on the probes since they first launched in 1977, said maintaining contact with them was a monumental effort using the Deep Space Network’s largest radio telescopes, which NASA uses to transmit commands to its spacecraft.
The Voyagers were a big deal when they launched at the height of the space age. Their main purpose was to carry out the first explorations of the gas giants of the solar system and their moons: Jupiter and Saturn by Voyager 1 and Voyager 2 in 1979 and 1981, and Uranus and Neptune by Voyager 2 respectively in 1986 and 1989.
The high-resolution color photographs they took and the data they recorded are still crucial to scientific studies today. Their last photo was the Pale Blue Dot, a portrait of the solar system taken by Voyager 1 in 1990, about 6 billion miles away from Earth.
After their dramatic planetary flyovers, however, the Voyager spacecraft have begun a quieter phase of their journey, heading to the edges of our solar system and beyond. On-board instruments measuring charged particles in space indicate that Voyager 1 left the protective bubble of particles emitted by the sun in 2012, while Voyager 2 left it in 2018. This means that both probes are now technically located. in interstellar space, between the stars, yet they are still sending vital data from their onboard instruments, Spilker said.
Where the Voyager probes have taken, others will follow. A jury to set the nation’s scientific priorities for the next 10 years is considering a proposal for a $ 3.1 billion interstellar (IP) probe that could reach Voyager’s current position in just 15 years. If approved in 2024, the probe could be launched by 2036.
Ralph McNutt, who heads space science at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, has worked on Voyager missions throughout his career. He witnessed the launch of Voyager 1 in September 1977 and is now a leader of the IP project.
“We can reach speeds of about twice that of Voyager 1 and reach twice the speed before the interstellar probe runs out,” he said.
The newer probe would be much more capable than the Voyagers, which were built with 45-year-old technology, and the project planners now have a much better idea of what’s possible and what to expect on the voyage.
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, which they are thought to be the origins of some comets, McNutt said.
Until the interstellar probe gets the green light, however, the Voyagers will be the main representatives of humanity in interstellar space. In about 40,000 years, Voyager 1 will approach relatively another star in the constellation Camelopardalis, while Voyager 2 will approach a star in the constellation Andromeda en route to the giant star Sirius, which it will reach in about 300,000 years.
Long before then, however, in just 10 years, both Voyager probes will be completely depleted, Spilker said. Each probe is powered by plutonium batteries, but they have already begun to weaken and every few months NASA engineers order the probes to shut down some of their onboard systems. Their hope is that they can extract enough power from the batteries so that some of the tools can continue to work, at least until the 50th anniversary of the twins’ launch in 2027.
After that, who knows?
“Fingers crossed, if everything goes as planned, we could be in the 1930s,” he said.
Whenever their power runs out, the Voyager probes will act as “silent ambassadors” to the stars, Spilker said. Each probe carries a gold-stamped recording 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 some other civilization will find them and want to know more about Earth,” Spilker said.