Voyager 2, which blasted off from Earth way back in 1977, has officially left the solar system and is now in interstellar space.
According to the BBC:
The news was revealed at the American Geophysical Union (AGU) meeting in Washington.
And chief scientist on the mission, Prof Edward Stone, confirmed it.
He said both probes had now “made it into interstellar space” and that Voyager 2’s date of departure from the Solar System was 5 November 2018.
On that date, the steady stream of particles emitted from the Sun that were being detected by the probe suddenly dipped. This indicated that it had crossed the “heliopause” – the term for the outer edge of the Sun’s protective bubble of particles and magnetic field.
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While Voyager 2 was launched two weeks before Voyager 1 was, Voyager 1 had a faster trajectory, which is why it left the solar system in March of 2013.
What makes this exciting is that, despite Voyager 1 beating it to interstellar space, Voyager 2 has an instrument on board that will gather “first-of-its-kind observations of the nature of this gateway into interstellar space”.
As the BBC points out, back when the pair of probes were launched, nobody really knew how long it would take for the probes to reach the edge of the solar system.
Prof Stone said that at the start of the mission the team had no idea how long it would take them to reach the edge of the Sun’s protective bubble, or heliosphere.
“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,” he added. “Now we’re studying the very local interstellar medium.
“It’s a very exciting time in Voyager’s 41 year journey.”
Scientists define the Solar System in different ways, so Prof Stone has always been very careful not to use the exact phrase “leave the Solar System” in relation to his spacecraft. He is mindful that the Nasa probes still have to pass through the Oort cloud where there are comets gravitationally bound to the Sun, albeit very loosely.
But both Voyagers certainly are in a new, unexplored domain of space.
Voyager 2 is currently moving around 9.9 miles per second (about 16 kilometers per second). Voyager 1 is moving at a blistering 10.7 miles per second (17.2 kilometers per hour).
The primary mission for the probes was to observe Jupiter, Saturn, Uranus, and Neptune. This phase of the mission was completed in 1989 (when I was just 5 years old!). After the primary mission was an incredible success, the probes were aimed at deep space. As the BBC reports:
It is expected that their plutonium power sources will eventually stop supplying electricity, at which point their instruments and their 20W transmitters will die.
The Voyager project manager, Suzanne Dodd told BBC News that she would like to see them both keep going until 2027.
“It would be super-exciting to have a 50-year mission still operating,” she added, describing the probes as “pioneers” of interstellar space.
“Every so often they phone home and say – ‘I’m still going. Don’t forget about me!'”
What makes this moment even better are the completely free, high-quality space posters that NASA just released celebrating the Voyager missions!
Been there. Done That. Got the poster. Download free print-quality #spaceposters, including this brand-new one celebrating Voyager 2’s entry into interstellar space. https://t.co/mfMwuUZRgf pic.twitter.com/jbH5yuLK9S
— NASA Voyager (@NASAVoyager) December 10, 2018
I highly encourage you to check them out on NASA’s JPL website.
It’s incredible to think that humanity has created something and sent it outside of our Solar System – twice. It’s also amazing to think that a mission launched over 40 years ago is just now passing the edge of the Solar System. If this doesn’t put the enormity of space into perspective, I’m not sure what will.