Voyager 1 Maybe Didn't Leave the Solar System Yet (Again, Again, Again)

This is all getting to be a bit too much to bear.

Jul 23 2014, 5:35pm

Image: NASA

Voyager 1, the furthest manmade thing from Earth, is still plodding along. It has become the spacecraft that cries "interstellar space" every six months or so, all the while traveling even further-er from this pale blue dot. But has it actually left the solar system? Finally? Who the heck knows. 

There have been more false alarms from astronomers and scientists on this thing than any other scientific-based inquiry in recent memory. 

Voyager was "leaving" the solar system, NASA said back in June, 2012. Then, it "left the solar system" in October, 2012. Then it maybe didn't leave the solar system. Then it reached the "last leg" of the solar system in December of that year. Then, in March 2013, there was a "consensus" that it hadn't left the solar system. Then, it "officially" became the "first human-made object to venture into interstellar space" in September of last year. Then, earlier this month, it encountered a "tsunami wave" of energy from our sun, which further confirmed the earlier finding. And now, maybe it hasn't again.

Two Voyager team scientists suggested today that we won't know for roughly two years whether or not Voyager has actually passed into interstellar space. In a paper published in Geophysical Research Letters, the scientists suggested that the spacecraft will eventually detect a shift in the polarity of the magnetosphere. If it does, it means it's still in the heliosphere. If it doesn't, then it's already passed into interstellar space.

The confusion surrounding Voyager is certainly understandable. The spacecraft is using technology developed in the mid 1970s to explore our solar system, and it's now sending signals back to Earth from beyond Pluto. That's insane, and it's very cool. Meanwhile, it's exploring parts of the solar system (or interstellar space) that we know very little about. 

Still, it doesn't really help anyone to have to renege the interstellar space story every couple months. Amy Shira Teitel covered the subject quite well for Motherboard last year with her article, "Stop Saying Voyager 1 Has Left the Solar System:"

"Unfortunately, there's no clear line in space that demarcates the beginning of interstellar space. It's a murky line that's not really a line, which is why we've seen so many false alarm announcements. The 'line,' as it were, is a change of plasma, the ionized gas that permeates space. The material that comes from the Sun in the form of solar wind is a plasma and it only stretches so far, creating the bubble known as the heliosphere. Once the solar wind material no longer dominates and material from distant stars does, that's interstellar space. 

So to say that Voyager 1 is in interstellar space in this case means it's reached an area where the Sun's solar wind and plasma no longer have the dominant influence. It's a definition that takes into account particles and fields, not distance." 

Hence the confusion. There's great disagreement about what the heck is going on out there, and it's going to continue until Voyager can prove it's found something else out there. George Gloeckler, a researcher who worked on the Geophysical Research Letters paper, as well as on the spacecraft itself, says the "controversy will continue until it is resolved by measurements," which makes sense, considering that this is science.

Hopefully we'll have them soon, so we can focus on the research Voyager is still doing all these years later, instead of worrying where it is.