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The legacy of the Voyager mission.

Relevance: GS 3 – Awareness in the fields of Space.

Recent Context: Recently, National Aeronautics and Space Administration (NASA)  detected a “heartbeat” signal from the spacecraft  Voyager 2 after losing the  communication with it.

About Voyager 2 Mission:

• It is Earth’s longest-running space probe which was launched in 1977.
• Voyager 2 is the second spacecraft to enter interstellar space the region that lies outside the impact of our Sun’s constant flow of material and magnetic field. The first was Voyager 1, sent to space about two weeks after Voyager-2.
• The two probes have helped in exploring the outer giant planets of our solar system and discovered over 40 moons and numerous rings. They have provided invaluable data on planetary astronomy, and inspired many future space missions.

Why were the Voyager spacecraft sent into space?

• Voyager 2 was launched on August 20, 1977, two weeks before the September 5 Voyager 1 takeoff.
• This reversal of order took place as the two spacecraft were put on different trajectories —Voyager 1 was set on a path to reach Jupiter and Saturn, ahead of Voyager 2.
• 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 adventurers’ current mission, the Voyager Interstellar Mission (VIM), will explore the outermost edge of the Sun’s domain.

What are the features of the Voyager spacecraft?

• Voyager 1 and Voyager 2 are identical spacecraft. Each of them is equipped with instruments to carry out 10 different experiments.
• The instruments include television cameras — to take images of planets and other celestial bodies; infrared and ultraviolet sensors, magnetometers, plasma detectors, and cosmic-ray and charged-particle sensors.
• Both spacecraft feature a large antenna, 3.7 metres in diameter, which is used to receive commands from Earth and radio their findings back to the planet.
• As their mission involved going far away from the Sun, they aren’t powered by solar power, like other spacecraft are. “Instead, Voyager relies on a small nuclear power plant, drawing hundreds of watts from the radioactive decay of a pellet of plutonium.
• Each Voyager spacecraft is adorned with a golden phonograph record — a 12-inch disc, intended to be a sort of time capsule from Earth to any extraterrestrial life that might intercept the probes in the distant future.

Interstellar space:

• Scientists use the heliopause to mark where interstellar space begins, although depending on how you define our solar system it can stretch all the way to the Oort Cloud, which begins 1,000 times farther away from the sun than Earth’s orbit.

The Heliosphere:

• The heliosphere is a bubble around the sun created by the outward flow of the solar wind from the sun and the opposing inward flow of the interstellar wind.
• That heliosphere is the region influenced by the dynamic properties of the sun that are carried in the solar wind–such as magnetic fields, energetic particles and solar wind plasma.
• The heliopause marks the end of the heliosphere and the beginning of interstellar space.

What are the most notable achievements of the Voyager spacecraft?

• The most interesting discoveries made by Voyager 1 included the finding that Io, one of Jupiter’s moons, was geologically active.
• The spacecraft noted the presence of at least eight active volcanoes “spewing material into space, making it one of the mostgeologically active planetary bodies in the solar system.
• Moreover, Voyager 1 and Voyager 2 discovered three new moons of Jupiter: Thebe, Metis and Adrastea.
• While passing by the planet’s moon Titan, Voyager 1 discovered that it wasn’t the biggest moon of our solar system
• The spacecraft also noted that Titan’s atmosphere was composed of 90 per cent nitrogen, and it likely had clouds and rain of methane.
• Voyager 2 arrived at Uranus in 1986 and confirmed that the main constituents of Uranus are hydrogen and helium
• It also discovered 10 new moons and two new rings in addition to the previously-known nine rings, among other significant findings. After the Neptune encounter, Voyager entered into interstellar space.
• These exits were instrumental in enabling astronomers to determine where exactly the edge of interstellar space is, something that’s difficult to measure from within the solar system. They showed that interstellar space begins just over 18 billion kilometres from the sun.

Conclusion:

• Voyager mission of NASA, extends NASA’s exploration of the solar system beyond the neighborhood of the outer planets to the outer limits of the Sun’s sphere of influence and possibly beyond.
• Therefore, it will help in better understating and evolution of solar system.

Source: The legacy of the Voyager mission | Explained News – The Indian Express