As most of the space community’s attention remains focused on the delayed Artemis rocket launch and return to the moon, two relics of the Space Age continue to cross the void between the stars, sending valuable information to scientists on Earth.
The space probes Voyager 1 and Voyager 2 were launched 45 years ago, the former on August 20, 1977, and the latter on September 5, and are now the most distant man-made objects from Earth, about three times the distance from Pluto. from the sun.
The measurements show that both probes left our solar system’s interstellar bubble a few years ago. But they are aging, so engineers are gradually shutting down their systems in the hope that their fading batteries can provide enough power for a few more years. After that, the detectors would shut down completely and could go into space forever.
“The two Voyagers became our first interstellar travelers, sending back information about a place we’ve never visited before,” said Linda Spilker, NASA’s associate project scientist for the Voyager missions at the Jet Propulsion Laboratory in Pasadena, California.
It now takes about 22 hours for radio signals from Earth to travel more than 15 billion miles to Voyager 1, the most distant probe, and another 22 hours for it to receive its reply. Spilker, who has worked on the probes since they were 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 relay 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 make the first explorations of the Solar System’s gas giants and their moons—Jupiter and Saturn by Voyager 1 and Voyager 2 in 1979 and 1981, and Uranus and Neptune by Voyager 2 in 1986 and 1989, respectively.
The high-resolution color photographs they took and the data they recorded are still vital 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 from Earth.
After their dramatic planetary flybys, however, the Voyager probes began a quieter phase of their journey, heading to the very edges of our solar system and beyond. Onboard instruments that measure charged particles in space show 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 in interstellar space – between the stars — and yet still send vital data from their onboard instruments, Spilker said.
Where the Voyager craft have gone, others will follow. A committee that will set the nation’s science priorities for the next 10 years is considering a proposal for a $3.1 billion Interstellar Probe (IP) that could reach the Voyagers’ current location in just 15 years. If approved in 2024, the probe could launch by 2036.
Ralph McNutt, who leads space science at the Johns Hopkins Laboratory for Applied Physics in Laurel, Maryland, has worked on the Voyager missions for his entire career. He witnessed the launch of Voyager 1 in September 1977 and now heads the IP project.
“We can get to about twice the speed of Voyager 1 and get about twice as far before the Interstellar Probe runs out of power,” he said.
The newer craft would be far more capable than the Voyagers, which were built with 45-year-old technology, and project planners now have a much better idea of what’s possible and what to expect on the journey.
The main 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 its outer regions. solar system, which are believed to be the origin of some comets, McNutt said.
Until the Interstellar Probe gets the go-ahead, however, the Voyagers will be humanity’s leading representatives in interstellar space. In about 40,000 years, Voyager 1 will approach 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 then, however — in just 10 years — both Voyager probes will be completely exhausted, Spilker said. Each probe is powered by plutonium batteries, but they are already starting to wear down, 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 of the instruments can continue to operate, at least until the 50th anniversary of the double’s launch in 2027.
After that, who knows?
“Fingers crossed, if all goes as planned, we could make it to the 2030s,” he said.
Whenever they run out of power, Voyager’s probes will serve as “silent ambassadors” to the stars, Spilker said. Each probe carries a disc, imprinted in gold, with sounds on Earth, including a baby crying, a whale singing, 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.