Forty years after they left Earth, the Voyager twin spacecraft are still chugging along, logging 35,000 miles an hour as they zoom farther and farther into the cosmos.
“I’ve had people ask me, you mean the mission is still going on?” says Suzanne Dodd, the Voyager project manager at NASA’s Jet Propulsion Laboratory. “They assumed that it had stopped after it passed Neptune.”
Far from it. After the Voyagers completed their tours of the outer planets in the 1980s, giving humanity its first real look at Jupiter, Saturn, Uranus, and Neptune, they continued on to the outer reaches of the solar system. In August 2012, Voyager 1 left the system entirely, emerging from inside the protective bubble formed by the sun’s wind and exiting into interstellar space. Voyager 2 is on its way out; the spacecraft is currently coasting through the heliosheath, the outermost layer of the sun’s bubble. Voyagers 1 and 2 are currently about 13 billion and 10 billion miles from Earth, unfathomable distances that mean little more to us terrestrials than giant numbers on a page.
And they still call home. It takes a while, but they do.
The Voyagers transmit data to Earth every day. The spacecraft collect information about their surrounding environment in real time and then send it back through radio signals. Voyager 1 data takes about 19 hours to reach Earth, and signals from Voyager 2 about 16 hours. (For comparison, it takes the rovers on Mars 20 minutes on average to call home.) The signals get picked up by NASA’s Deep Space Network, a collection of powerful antennae around the world that communicate with dozens of missions.