NASA’s Voyager probes have traveled through space for nearly 50 years. See the remarkable photos from their journeys.

Voyager 2, a pioneer in outer solar system exploration, left Earth for interstellar space 49 years ago, on August 20, 1977.

The twin of Voyager 1, which left Earth only a few weeks after, is the only spacecraft to visit all four of the solar system’s outer gas giants — Jupiter, Saturn, Uranus, and Neptune.

The Voyager probes were originally sent on a four-year mission to tour the solar system, but they exceeded expectations and are still going nearly half a century later. That makes them NASA’s longest-lived mission, costing the agency more than $865 million.

The two probes have had their fair share of interstellar road bumps, which have only…