Voyager 1 and 2 are NASA’s iconic deep space explorers, launched in 1977 to study the outer planets—Jupiter, Saturn, Uranus, and Neptune. Now located about 15 billion miles (Voyager 1) and 13 billion miles (Voyager 2) from Earth, the spacecraft have traveled farther than any human-made objects in history.

NASA just brought Voyager 1’s dead thrusters back to life—right before the spacecraft goes quiet for nearly two years.