Looking at my google news the other day I saw an article titled “Voyager 2 Spacecraft Approaches Interstellar Space.” I was thrilled but in the spirit of full disclosure I have to admit, I had forgotten about the voyagers until I saw this headline. Out of sight out of mind, right?
For those of you who don’t know or may have forgotten: The Voyager 2 and it’s twin, the Voyager 1, are sedan-sized, unmanned spacecrafts that were born and launched into space in the late 1970s. Their original mission was to explore Jupiter and Saturn, but after having such wonderful success NASA decided to see how far they could push these explorers. Voyager 2 went on to see Uranus and Neptune, and Voyager 1 shot off towards the great wide open.
Originally, these little spaceships were only built to last for 5 years; That means NASA assumed that both the Voyagers would be obsolete by 1982! I think the moral here is to not underestimate a flying saucer. Now they expect them to stay in contact with the Deep Space Network (DSN) until 2025 and remain functional until 2036. NASA has already turned off most of their extraneous equipment and will lose that remote access once the ships get out of range, but with none of that pesky friction up there in space both of the Voyagers should theoretically continue moving along until they hit something.
After the Voyagers were done exploring our solar system, NASA set their sights on interstellar space. The Voyager 1 made history when it left our solar system in September of 2012 and now very soon the Voyager 2 is getting it’s day in out of the sun.
So my biggest question was: How do they know? I mean, it’s not like there is a border wall on the edge of the solar system (yet). I saw the drawing of the heliosphere and understood the concept, but after I read the original article on NASA’s website and they defined all of the “helio’s” then I comprehended.
“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.”
This instantly reminded me of seeing freshwater meet saltwater. Obviously it’s all water but the differences in density and salinity keep each body suspended separately. It’s also not unlike a droplet of oil in a glass of water, for a more microcosm comparison. Well apparently, space stuff works the same way! Who knew, right? As our sun burns, it puts off a certain combination of “stuff” (very scientific, I know) that radiates out from all directions and then hits up against the interstellar space around it, which is putting off a different combination of “stuff” that doesn’t mix with our heliosphere.
Just like the oil droplet, the heliosphere shifts and flows dynamically but doesn’t ever mix with the rest of space. The solar magnetic field stays inside and the cosmic rays from deep space stay out. And that is precisely how they know; by measuring these cosmic rays around the Voyager 1, NASA was able to track it’s approach towards open space and predict when it would cross through the heliopause.
Fast forward to the present and the Voyager 2 is starting to pick up more cosmic rays, leading NASA to believe that it will soon join it’s twin out in the void. That’s what is happening at the moment. So the Voyager 2 isn’t in interstellar space yet, and there isn’t a way to definitively say when it will be, but we do know that it is getting close.
The real question now is, what happens now that they’ve actually gone where no man has gone before? At this point do they serve as less of an exploration effort and more of a testament to how far the human race has explored beyond what we thought was our farthest reach? They were built in the 1970s after all. And if that is the case, is that necessarily a bad thing? I think I can accept that sentiment. Even when they are out of reach of our most advanced equipment, when they are lifelessly drifting into the stars, even if the golden records are never found by alien civilizations, the Voyagers’ discoveries and legacy will live on forever.
I highly recommend checking out the galleries of all the photographs taken by the two Voyagers of our outer planets. (Jupiter is my personal favorite.) They also took several other photos not just of the planets and moons such as the famous “Pale Blue Dot” photo that was taken right before they turned off their cameras on Valentine’s Day of 1990.
Voyager Image Galleries:
https://voyager.jpl.nasa.gov/galleries/images-voyager-took/
https://voyager.jpl.nasa.gov/galleries/
The original article I read:
Voyager 2 spacecraft approaches interstellar space
The official NASA article:
https://www.nasa.gov/feature/jpl/nasa-voyager-2-could-be-nearing-interstellar-space
My other references: (What, you thought I pulled all that stuff out of thin air?)
https://www.space.com/39161-fate-of-the-voyager-spacecraft.html
https://voyager.jpl.nasa.gov/mission/science/thirty-year-plan/
https://www.nasa.gov/mission_pages/voyager/images
https://www.space.com/22797-voyager-1-interstellar-space-nasa-proof.html
Also, a fun fact for my fellow December babies out there: the Voyager 2 is actually headed right towards the constellation Sagittarius! The Voyager 1 is headed for the star Alpha Centauri in the Little Dipper, which is pretty cool too. Alright, I’m finished geeking out now.
-Emily
Dabbling Adult 