A signal traveling from Earth to the spacecraft has to cover 13 billion miles — that's the current reality for Voyager 2. NASA dubbed this operation "Big Bang," which sounds dramatic, but what actually happened was fairly modest: simultaneously switching off a few power-hungry components, swapping in more efficient alternatives, and making sure the probe doesn't freeze in the process.
The root of the problem lies in its heart. Voyager 2 runs on a radioisotope thermoelectric generator, which converts heat from decaying plutonium into electricity. As the plutonium continues to decay, the probe loses roughly 4 watts of power every year. When it launched in 1977, it carried 10 scientific instruments on board; over the decades, they've been shut down one by one, leaving only 3 still operating today. Had NASA not made this adjustment this year, one of those remaining instruments would have gone dark in the near future.
The probe launched two weeks before its twin sibling Voyager 1, tasked with taking a close look at the solar system's gas giants. It reached Jupiter in 1979, and within a decade had visited all four of the solar system's gas giant planets. In 2018, it crossed the heliopause into interstellar space, and has since continued transmitting data on the density and temperature of plasma beyond our solar bubble.
This latest adjustment should keep the three remaining instruments running through next year. What happens after that, NASA hasn't said.
