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RPS: Radioisotope Power Systems
Voyager 1 & 2
Artist's rendering of the Voyager spacecraft
Artist's rendering of the Voyager spacecraft

Voyager 1 & 2


Voyager 1

  • Launched on September 5, 1977
  • Surveyed the Jupiter and Saturn systems
  • RTGs still operating
  • Currently exploring the edge of the solar system

Voyager 2

  • Launched on August 20, 1977
  • Only spacecraft to visit Jupiter, Saturn, Uranus and Neptune
  • RTGs still operating
  • Currently exploring the edge of the solar system

Each powered by: three MHW-RTGs, with heat from nine RHUs

The current power levels are about 315 watts for each spacecraft. As the electrical power decreases, power loads on the spacecraft must be turned off in order to avoid having demand exceed supply. As loads are turned off, some spacecraft capabilities are eliminated.

Goals: Voyager 1 and 2 were designed to take advantage of a rare planetary alignment to explore the outer solar system. Voyager 1 targeted Jupiter and Saturn before continuing on to chart the far edges of our solar system. Voyager 2 targeted Jupiter, Saturn, Uranus and Neptune before joining its sister probe on their interstellar mission.

Accomplishments: Voyager proved to be one of the greatest missions of discovery in history. Among their many revelations about the solar system are:

  • Rings around Jupiter
  • Volcanoes on Jupiter's moon Io
  • Moons of Saturn that shepherd its rings
  • New moons around Uranus and Neptune
  • Geysers of liquid nitrogen on Neptune's moon Triton

Voyager 2 is the only spacecraft to study all four of the solar system's giant planets at close range. The Voyagers are now exploring the outermost reaches of our sun's influence, where the solar wind mixes with the interstellar wind of our galaxy. Their long-lived power source has enabled these explorers to continue teaching us about our solar system for more than years after they left earth.

More about Voyager 1 >

More about Voyager 2 >

Images from Voyager >
Giant planets imaged by Voyager
Voyager 2 is the only spacecraft to have visited all four giant planets, and the only one to have flown past distant Uranus and Neptune.


The pale blue dot
Voyager 1 image showing Earth from 4 billion miles away, as a mere dot of blue in the vastness of space.
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Last Updated: 26 Sep 2012