NASA’s Voyager at 40

The Voyager development test model, pictured at Kennedy Space Center in Florida. Voyager I and II were the first to be protected against radiation, setting a standard for engineering design still in use today. The spacecraft was the first to use a computer to control attitude and articulation and the first to be able to detect and solve its own problems.

Voyager I and II, which both drew close to Jupiter in 1979, took thousands of images of the Solar System’s largest planet and its moons, identifying its Great Red Spot as a violent atmospheric storm. Voyager I discovered active volcanoes on Jupiter’s moon Io—the first time active volcanoes were seen somewhere in the Solar System other than Earth.

The Voyagers allowed scientists to confirm that Saturn’s atmosphere is comprised almost entirely of hydrogen and helium but that the amount of helium in the upper atmosphere is less than Jupiter’s—something the scientists had not anticipated. The mission also yielded insights about Saturn’s rings and icy moons.

On Feb. 14, 1990, Voyager I had traveled beyond Neptune and more than 4 billion mi. (6.43 km) from Earth. The spacecraft turned around to capture images of six planets in the Solar System. The late astronomer Carl Sagan named the Earth’s image the “pale blue dot.”

After moving past the planets in this montage—Jupiter, Saturn, Neptune and Uranus—Voyager spacecraft embarked on the Voyager Interstellar Mission to seek the limits of the Sun’s magnetic field and solar wind. It took Voyager 12 years to move toward its interstellar mission, but it is still exploring the heliosheath, which is dominated by the Sun’s magnetic field and solar wind particles. The spacecraft continue to travel toward the end of the Solar System, where the winds from the Sun diminish and interstellar wind can be sensed. The region is thought to be 8-14 billion mi. (12.8-22.5 billion km) from the Sun, and Voyager I could be close by 2020, when it reaches the limits of its fuel supply. Voyager II will be farther away—11.4 billion mi.—at that time, but both Voyagers will continue to drift through the Milky Way.

Voyager’s lengthy mission spawned a short film chronicling the spacecraft’s journey coupled with a gold-plated record album comprising songs and sounds from Earth. The project brought Carl Sagan together with his future wife, Anne Druyan.

In addition to changing our Earthly understanding of the Solar System, NASA's Voyager spacecraft also enhanced communications with spacecraft. In California’s Mojave Desert at NASA’s Goldstone Deep Space Communications Complex, antenna dishes have been built, rebuilt and expanded. The largest is 230 ft. (70 m) in diameter. Smaller satellites are still large at 112 ft. in diameter.