The Voyager missions, consisting of twin spacecraft Voyager 1 and Voyager 2, have been instrumental in expanding our understanding of the solar system and beyond. Launched in 1977, these probes were initially designed to study Jupiter and Saturn, but their journeys took them far beyond their original mission parameters, leading to numerous shocking discoveries.

Voyager

One of the most remarkable aspects of the Voyager missions is that they are the only human-made objects to have entered interstellar space, the region between the stars. This achievement alone has provided unprecedented insights into the conditions and phenomena that exist beyond our solar system.

Here are some of the shocking discoveries made by the Voyagers:

  • Heliosphere Boundaries: The Voyagers revealed that the solar wind, a stream of particles from the sun, doesn’t gradually weaken as it travels further from the Sun. Instead, it reaches a sharp boundary called the heliopause, where its influence ceases and interstellar space begins. This boundary is not static but is constantly moving and distorted by waves.
  • Interstellar Plasma: Data from the Voyager probes showed that interstellar space is filled with denser, colder plasma, while the plasma near the solar system’s boundary is hotter and less dense. These two types of plasma interact, creating a boundary layer between the heliopause and interstellar space.
  • Interstellar Magnetic Field: The Voyagers discovered that the interstellar magnetic field is two to three times more powerful than previously thought. This means that interstellar particles exert ten times more pressure on the heliosphere than anticipated.
  • Solar Wind and Cosmic Rays: The Voyagers have provided unique insights into the behavior of solar wind and cosmic rays, phenomena which had remained poorly understood prior to the mission.
  • Planetary Discoveries: In their initial missions, the Voyagers discovered 22 new satellites, including 3 at Jupiter, 10 at Uranus, and 6 at Neptune. They also discovered Jupiter’s rings and provided additional information about the rings of Saturn, Uranus, and Neptune. The probes also found active volcanism on Io and active geyser-like structures on Triton. In addition, they observed auroral zones on Jupiter, Saturn, and Neptune.
  • Unique Planetary Features: The probes found that Uranus is an “ice giant” containing a core of rock and ice with an ocean of water, ammonia, methane, and hydrogen sulfide beneath its atmosphere, which is composed primarily of hydrogen and helium. They also discovered a “Great Dark Spot” on Neptune.
  • Unexpected Data: Voyager 2 discovered that the density of space increases as you move away from the sun. Voyager 1 also sent a mysterious signal of seemingly random data, later discovered to be a malfunction of the spacecraft’s navigation system.

The Voyager missions were originally planned to last only 4 years, focusing on Jupiter and Saturn, however, NASA designed the mission’s trajectories to allow for potential exploration of other planets. This allowed Voyager 2 to continue its journey to Uranus and Neptune, becoming the only spacecraft to study all four of the solar system’s giant planets at close range. The Voyagers have far exceeded their life expectancy and continue to send back valuable scientific data, despite having several malfunctions and the shutdown of some instruments to conserve power.

The information from the Voyagers has not only been useful for the study of the solar system, but also for the study of other stellar systems, as it is believed that they likely share the same properties and processes as our solar system. These missions continue to provide valuable data, allowing scientists to make ground breaking discoveries about space.

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