Voyager 1 has only 68 KB of memory on board -- far less than a smartphone, said Suzanne Dodd, Voyager project manager. Scientists communicate with the spacecraft every day.
"It's the little spacecraft that could," she said in a NASA press conference.
The probe now has a totally new mission, Stone said.
"We're now on the first mission to explore interstellar space," he said. "We will now look and learn in detail how the wind which is outside, that came from these other stars, is deflected around the heliosphere."
Wind -- made of particles -- from these other stars has to go around the heliosphere the way a water in a stream flows around a rock, Stone said. Scientists are interested in learning more about the interaction between our solar wind and wind from other stars.
Natural radioactive decay provides heat that generates enough electricity to help Voyager 1 communicate with Earth. The first science instrument will be turned off in 2020, and the last one will be shut down in 2025, Stone said.
Both Voyager probes carry time capsules known as "the golden record," a 12-inch, gold-plated copper disc with images and sounds so that extraterrestrials could learn about us. Let's hope they can build appropriate record players.
Voyager 2 will likely leave the heliosphere in about three to four years, Stone said.
Its plasma instrument is still working, Stone said, so scientists can directly measure the stellar wind's density, speed and temperature. That also means that when it crosses out of the heliosphere, Voyager 2 will send a clearer signal.
At that time, it will join its twin in the vast nothingness between stars that used to be beyond our reach.
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