Sci-tech

NASA's Voyager 2 reaches interstellar space

December 12, 2018 23:59·
This illustration shows the position of NASA’s Voyager 1 and Voyager 2 probes outside of the heliosphere a protective bubble created by the Sun that extends well past the orbit of Pluto

This illustration shows the position of NASA’s Voyager 1 and Voyager 2 probes outside of the heliosphere a protective bubble created by the Sun that extends well past the orbit of Pluto

It's official! The Voyager 2 probe has entered interstellar space, making it just the second human-made object to do so. The twins are the only two spacecraft ever to venture so far from home.

NASA has confirmed that Voyager 2 crossed the heliopause, the boundary of the Sun's solar wind, though there are a few other conflicting ways to measure where exactly the Sun's influence (and, by extension, the Solar System) "ends". However, on 5 November, the instrument went silent, showing it had exited the bubble. The devices were launched in October 1977 and now they are the most tenacious NASA. Interstellar space is the vast emptiness between star systems.

The probe's present location is some 18 billion kilometres from Earth. Both of them were initially heading pretty much in the same general direction, on a path towards Jupiter and Saturn. As a comparison, Pluto's average distance from the sun is "only" 40 AU!

Chief scientist on the mission, Prof Edward Stone said: "We didn't know how large the bubble was, how long it would take to get there and if the space craft would last long enough". Here are some of the known cosmic landmarks the Voyagers could meet in their relatively near futures.

The twin Voyager spacecraft were launched in 1977 on a mission to explore the solar system's gas giant planets.

Zero solar wind flow has been observed with the instrument following November 5, underscoring Voyager 2's milestone.

Voyager 2's new environment is strikingly different from anything it would have encountered before.

The nearest star beyond the sun, Proxima Centauri, is about 4.2 light-years or 268,770 AU away.

At its current velocity, it will take Voyager 2 another 300 years or so to reach the inner boundary of the Oort cloud and possibly 30,000 years to move beyond it.

Not only could Voyager 2's continuing journey tell us about our own neighborhood, but its insights may also shape how we understand exoplanets.

Find out more in the video above. In terms of the reach of heliospheric particles or particles from the Sun, both spacecraft are effectively outside of it but they still have a long way to traverse for them to escape the influence of solar gravity. It discovered five moons, four rings, and a "Great Dark Spot" that vanished by the time the Hubble Space Telescope imaged Neptune five years later.

The Voyager Interstellar Mission is a part of NASA's Heliophysics System Observatory, sponsored by the Heliophysics Division of NASA's Science Mission Directorate in Washington.

"Both spacecrafts are very healthy if you consider them senior citizens", Voyager project manager Suzanne Dodd said.

But until then, long may the explorations continue.

Although neither Voyager's instruments will last forever, the two spacecraft themselves will continue their plodding course across the solar system.

"There is still a lot to learn about the region of interstellar space immediately beyond the heliopause", said Ed Stone, Voyager project scientist based at Caltech in Pasadena, California.

"That's an incredible journey for this unbelievable little ... spacecraft". Plus, gravitational encounters with things like wandering, starless planets could bounce the probes around like billiard balls.

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