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Right now, as of 2021, Voyager 1 has left the Solar System. If it has reached such a great distance, is it possible for it to reach the Andromeda Galaxy? Also, will we be able to still be in contact with Voyager 1 in case it reaches the Andromeda Galaxy?

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    $\begingroup$ If Voyager 1 won't go to Andromeda, Andromeda must come to Voyager 1. Which in fact it will. $\endgroup$
    – pela
    Nov 12, 2021 at 13:11
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    $\begingroup$ It's funny, I have to upvote both answers, one with 'yes', the other with 'no'. Both are correct. $\endgroup$ Nov 12, 2021 at 20:30
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    $\begingroup$ Leaving the Solar System is "such a great distance" only if you compare it to going down the road to the chemist's. But if you compare it to the distance between galaxies, even neighboring ones, it's just peanuts. $\endgroup$
    – vsz
    Nov 13, 2021 at 10:33
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    $\begingroup$ Obligatory xkcd. $\endgroup$ Nov 13, 2021 at 11:10
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    $\begingroup$ Distance aside, Voyager 1 would also need to be headed towards the Andromeda Galaxy (which does not encircle the Milky Way, so unlike Rome, not all roads lead to it.) $\endgroup$
    – chepner
    Nov 13, 2021 at 22:08

3 Answers 3

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Technically, yes

While Voyager 1 lacks the velocity necessary to escape the Milky Way galaxy, it doesn't actually need to. Because the Milky Way galaxy itself will collide and begin to merge with the Andromeda galaxy within about 4.5 billion years. It's unlikely any objects within either galaxy will collide with something in the other. But it's pretty likely a lot of dust and some stars will get ejected from them, which could even conceivably include the Voyager spacecraft itself (or even our own Sun).

This is many billions of years longer than the projected lifespan of Voyager's batteries, however. And it is within a billion years or so of the projected lifespan of our own sun, at which point Earth's surface is expected to be too hot to have liquid water. So we would not be able to communicate with it due to lack of battery, and also not being able to exist any more (short of settling other worlds, possibly other star systems). However, some modelling suggests that the Voyager craft, and indeed their golden records, may still be meaningfully intact by the time of the merger/collision.

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    $\begingroup$ But would Voyager 1 itself still exist after about 4.5 billion years? $\endgroup$ Nov 12, 2021 at 19:05
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    $\begingroup$ @DaddyKropotkin exist is a tenuous concept. Neither matter nor energy can actually be created or destroyed, it just changes form. So in that sense, yes, Voyager 1 will still exist. Of course, not even a good lab will be able to positively identify even one atom of its material, but that does not mean it won't exist (tl;dr: no. it will run into something, get blown up, eaten by a star, or recycled by Watto the Toydarian's Deep Space Salvage Junkers, a long, long time before then.) $\endgroup$ Nov 12, 2021 at 19:13
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    $\begingroup$ @DaddyKropotkin The only thing to threaten the craft is dust. Which definitely isn't meaningless over these timescales, but the golden disks they carry were designed to last a billion years or more in space in the worst case scenarios for dust encounters. Here's an article covering research that suggests the records would be at least partially intact and readable for some 5 billion years, enough for the merger/collision to begin. $\endgroup$ Nov 12, 2021 at 19:34
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    $\begingroup$ This answer is technically correct, the best kind of correct. $\endgroup$ Nov 12, 2021 at 22:08
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    $\begingroup$ Technically it may not be correct. 4.5 billion years might be a time of closest approach, but the Galaxy centres could be separated by as much as 50-100 kpc at that time, and merger may not occur for 10 billion years or more. $\endgroup$
    – ProfRob
    Nov 13, 2021 at 8:29
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no.

Voyager 1 is currently orbiting the center of the Milky Way, which has an escape velocity of $550 \ \text{km}\ \text{s}^{-1}$ at the Sun's position, while the Sun orbits at $\sim 220 \ \text{km}\ \text{s}^{-1}$. Voyager was ejected at $\sim 17 \ \text{km}\ \text{s}^{-1}$, like @user438383 said in a comment, and in the prograde direction, which means, at best, Voyager 1 will be traveling at $237 \ \text{km}\ \text{s}^{-1}$, which is $313 \ \text{km}\ \text{s}^{-1}$ short of ejection, so it cannot escape toward the Andromeda galaxy.

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    $\begingroup$ ... and even if we ignored that - it would need 3.3 billion years for the journey at the current distance. And that's just 3,299,999,980 years after the power supply ran out. $\endgroup$
    – asdfex
    Nov 12, 2021 at 17:22
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    $\begingroup$ And a good argument can be made that the slow pounding of CBR will have reduced it to slag by then. $\endgroup$ Nov 12, 2021 at 20:23
  • $\begingroup$ Humm... I wonder how many gravity assists from stars would be needed for it to reach galactic escape velocity? $\endgroup$
    – jamesqf
    Nov 13, 2021 at 2:23
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    $\begingroup$ Note that 17 km/s is approximately c/17635. So at that speed it takes around 17,635 years to go 1 light-year. $\endgroup$
    – PM 2Ring
    Nov 13, 2021 at 14:12
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    $\begingroup$ Well, it could get lucky and get one or more gravity assists from (sufficiently cold) massive objects, in order to achieve galactic escape velocity. That also allows it to change direction. After all, it couldn't have achieved Solar System escape velocity without gravity assists. $\endgroup$ Nov 13, 2021 at 17:59
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As already answered, the Voyager spacecraft (both 1 & 2) lack the velocity required to escape the Milky Way (assuming either is even headed in the right direction), so would only encounter Andromeda when the two galaxies merge in several billion years. As of this writing, the two spacecraft have been operating for some 44 years; there is a limit to how much longer their RTGs can provide adequate power for even the most minimal of spacecraft operations. According to a NASA FAQ here, it appears unlikely that radio contact can be maintained beyond about 2036. By that time, they will technically still be within our solar system (well inside the Oort cloud), thus still far closer to the Sun and the Earth than the distance to even the nearest neighbor star.

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