So, Voyager 2 has slipped past the edge of the heliosphere:
Nasa’s Voyager 2 probe ‘leaves the Solar System’
So where are they headed? are they keeping in roughly the same direction, or have their paths diverged? and are there any stars that we can identify that they’ll pass near at some point?
These two spacecraft are travelling in different directions. Voyager I will pass nearby to the star Gliese 445 in about 40,000 years, while Voyager 2 will pass by Ross 248 at very roughly the same time. By a cosmic coincidence, both of these stars are themselves travelling towards the Sun due to their so-called ‘proper motion’, so they will be closing the gap as well.
Neither approach is really very close - Voyager 1 will be 1.7 light years from Gliese 445, while Voyager 2 will be about the same distance from Ross 248.
They’re headed to different directions.
Voyager 1 is going towards the constellation Ophiuchus. There’s several nearby stars in that constellation, including Barnard’s Star. However, the star it’s going to approach next is Gliese 445, which is currently in Camelopardis and about 17 ly away. However, that star is rapidly approaching the Sun and V1 will pass about 1.6 ly from Gliese 445 in 40,000 years. At that time, the star will be one of the closest stars to the sun at 3.45 ly and no longer in that constellation.
Voyager 2 is going towards the constellation Telescopium, which is in the southern hemisphere. Also in 40,000 years, it’ll pass by Ross 248 at a distance of 1.7 ly. At that time, Ross 248 will be the closest star to the sun. Currently, Ross 248 is about 10 ly away and in the constellation Andromeda, which is in the far north. V2 will later make a distant pass to Sirius (4.3 ly, about half the distance Sirius is to us now).
According to this chart Ross 248 will be closest to the Sun between 33,000 and 42,000 years. Gliese 445 will be closest from 42,000 to 50,000 years. Alpha Centauri will still be quite close during that period as well.
ETA: took a long time to research my answer, so it’s not too surprising someone ninja’d me.
Is it really fair to say they’ve left the solar system if they haven’t passed the Oort Cloud?
As always, there’s an xkcd for that. The mouseover text reads:
Which is to say that there is a lot of room for interpretation on the point of where the “solar system” ends.
Although the Heaviside layer is a real thing (no, it’s not Cat Heaven) and the Voyagers have in fact passed through it once each, it’s a mighty peculiar choice for “boundary of the Solar System”, given that it doesn’t even contain the Sun. It’s one of the layers of the Earth’s atmosphere.
I don’t recall a lot of my ancient Greek astronomy, but I think it’s on par wrt distance to where the crystal spheres holding the fixed stars resides. 
Both the Pioneer 10 and the Pioneer 11 space probes are also heading out of the solar system. Pioneer 10 is heading in the direction of the Aldebaran star system. I’m not sure what direction Pioneer 11 is headed.
IIRC, they are going to have to start shutting down some instruments in the next year or so of the mission due to the weakening of the nuclear power source on board. Supposedly, the last instrument to go will be the transmitters, which will die sometime in the next decade…between 2020 and 2030 (maybe a tad longer if they are lucky). Kind of sad, but it’s also kind of unreal that they are still going after 40 years.
What kind of usable data are they getting anyway?
To my layman mind, the only thing Voyagers are transmitting back is: “Yeah, there ain’t shit out here”.
Next you’ll be telling me that the crystal sphere containing the fixed stars is a poor choice for the boundary of the Solar System too.
Naw, it’s (well, they I guess are) generating good data still on the instruments still working. Stuff about the magnetic fields in the outer solar system, cosmic ray information in the same region, . I know they discovered via Voyager that the shockwave of the sun moving through the interstellar media is a lot different than they thought (it has two tails, IIRC, instead of one large one for instance).
And even when the only thing getting power is the transmitters themselves, that’ll still be useful information, as it’ll let us see precisely where in the sky they are, and their radial speed. Remember the “Pioneer Anomaly”? That was discovered just from the transmission data, not from any of the instruments (incidentally, it was explained a few years ago, and it’s not anything like a modification to Newton’s laws or any of the other super-sexy explanations, but it’s still interesting in its way).
Of course, all of this data we’re still getting from the Voyagers is gravy. Their primary mission was to get close-up views (including with non-camera instruments, like magnetometers) of the outer planets. At that mission, they succeeded superbly, and if that were all they did, we’d have already gotten our money’s worth just from that (heck, the EPO value of the pretty pictures was probably enough to justify the price tag). But hey, they’re still out there, and still working, and still collecting data, and it doesn’t cost much marginally to keep on collecting that data and analyzing it, so we might as well.
The Voyagers’ transmitters will be dead long before they get out of the Oort Cloud.[sup]1[/sup] And it’s not like the Oort Cloud has a well defined boundary, so it’s impossible to say a spacecraft left it with any exactitude. So they may as well go with something that does have a defined boundary.[sup]2[/sup]
[sup]1[/sup] The investigators will be dead too.
[sup]2[/sup] And happens while they’re still alive.
Voyager mission status shows 4 instruments on Voyager 1 and 5 on Voyager 2 are operating. These measure cosmic rays, charged particles and magnetic fields. These are incredibly valuable measurements. Inside the solar system, the charged particles mostly stream from the Sun. And in space dominated by plasma, magnetic field is a tangible thing sustained by the charged particles but also affecting the paths of those charged particles. But both Voyager 1 and 2 are now past the point where the flow of particles from the Sun (solar wind) hits the interstellar medium - so they have now provided measurements through that whole layer and are now directly measuring the properties of interstellar space.
Fascinating stuff! Thanks for the answers, everyone.
Seems like Voyagers have nuclear power source on board and not dependent on solar panels to power their instruments.
Lets say for the sake of argument they did have solar panels which as they got further and further away from our sun were unable to supply it’s batteries till the guys fell silent.
They then traveled on and on silently alone through empty space for years and years till they started to approach another star system and started to get their batteries recharged by the new sun and slowly waking up 40 thousand years later send a message home “Hi Remember Me?”
How cool would that Be - Yea!
wasn’t that the theme of the first star trek movie
Well kind of. “Star Trek the Movie” had the Enterprise crew discover a Voyager that had mutated into something else, forget the details now. Memory not what it was :rolleyes:
https://www.youtube.com/watch?v=gxAaVqdz_Vk
Even once you get out to the vicinity of the gas giant planets, it’s tough to get a usable amount of power from solar panels (hence, of course, why they had the nuclear power sources to begin with). And they’ll probably never get that close to any other star, ever again.
