A 4 decade journey

And no, I am not turning 40. No where close enough!

NASA’s Voyager 2 was in the news recently because the agency announced that the probe had crossed into interstellar space in the outer edges of our solar system in Nov 2018.

The Voyager program is a NASA program that launched two robotic probes, Voyager 1 and Voyager 2, to study the outer Solar System in 1977. Surprisingly, the Voyager 2 was the first to be launched and the more robust of the two; Voyager 1 was launched on a shorter trajectory and the first to cross the interstellar space.

The twin Voyager 1 and 2 spacecraft are exploring the interstellar space where nothing from Earth has flown before. Continuing on their more-than-40-year journey since their 1977 launches, they each are much farther away from Earth and the sun than Pluto. In August 2012, Voyager 1 made the historic entry into interstellar space, the region between stars, filled with material ejected by the death of nearby stars millions of years ago. Voyager 2 entered interstellar space on November 5, 2018. Both spacecraft are still sending scientific information about their surroundings through the Deep Space Network.

The primary mission was the exploration of Jupiter and Saturn. After making a string of discoveries there — such as active volcanoes on Jupiter’s moon Io and intricacies of Saturn’s rings — the mission was extended. Voyager 2 went on to explore Uranus and Neptune, and is still the only spacecraft to have visited those outer planets. The current mission, the Voyager Interstellar Mission (VIM), will explore the outermost edge of the Sun’s domain and beyond.

The Voyagers now explore the outer boundary of where hot solar wind meets cold interstellar space – a place which is called as heliosphere. Their mission has been extended three times and they continue to transmit useful scientific data back to NASA.

However, just because the probes have left the heliosphere doesn’t mean they have left our solar system. That boundary is located at the outermost edge of the Oort Cloud, a group of small objects influenced by the gravity of our sun. Scientists believe it would take Voyager 2,300 years to reach the inner edge of the cloud, and 30,000 years to fly past it completely.

The particles of solar wind and of the interstellar space wind mix when they spill across the boundary. The interstellar wind is created by stars that went supernova millions of years ago. The mixing of these particles creates a layer between the heliopause and interstellar space.

Even though the Voyager 1 crossed this boundary in 2012, the amount of information received on the flyby was limited due to damaged instruments onboard. Voyager 2 continues to send data back to earth but it takes 16.5 hours for the data transmitted to reach the earth.

The Voyagers also were the source of some of the most intricate photos of the outer planets of the solar system including Jupiter, Uranus & Saturn.

The Voyagers also optimistically carry within them, records containing  115 images and a variety of natural sounds, such as those made by surf, wind and thunder, birds, whales, and other animals as well as musical selections from different cultures and eras, and spoken greetings from Earth-people in fifty-five languages, and printed messages from President Carter and U.N. Secretary General Waldheim in the hope of communicating with advanced civilizations in the universe that we are currently unaware of.

The data gathered by the probes has helped in the scheduled launch of NASA’s Interstellar Mapping and Acceleration Probe in 2024.


  1. https://voyager.jpl.nasa.gov/
  2. https://solarsystem.nasa.gov/missions/voyager-2/in-depth/
  3. https://edition.cnn.com/2019/11/04/world/voyager-2-science-results-scn/index.html

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