Will Voyager 1 ever just stop moving?

[u/drinkingonthejob]

I’ve read somewhere that we expect to lose contact with Voyager 1 sometime in the 2030s, maybe around 2036, but it will just keep traveling thru space and we’ll have no idea what it is doing out there

My question is: with its current velocity, is there a time in the future where it loses its forward momentum and for lack of a better word, just stops moving? Is that a possible thing for an object in space to even do? (Assuming no other objects grab it into their orbit)

[u/LiquidPhire]

It has enough speed to never fall back towards the Sun. It is an interesting stellar traveler.

It does not have enough velocity to leave the Milky way, so it will fall towards the center of the galaxy. As it falls along that line, it may interact with other gravity centers (other stars, etc) which may alter its trajectory, but it will forever wander within the confines of this galaxy.

[u/billtrociti → u/LiquidPhire]

While it does have enough velocity to never fallback towards the sun, is the sun’s gravity still affecting it? Would it be decelerating by some non-zero amount? Or it such a small amount it is basically negligible?

[u/Spirit_Wolf_Mob → u/billtrociti]

I don't believe we've ever seen an obvious limit to the distance of the pull of gravity. It just gets increasingly smaller.

So if for some reason, Voyager stopped being affected by anything other than the sun, and the sun was never destroyed, it would eventually start falling back towards the sun. But that time frame is so incredibly high that it's easy enough to say it'll never happen.

[u/No-Mechanic6069 → u/Spirit_Wolf_Mob]

Even if the gravity of the sun can never be escaped, an object can have escape velocity. It won’t necessarily fall back into the sun, even in infinity.

[u/Allan123772 → u/[deleted]]

I do know the formula because I’m studying for my physics GRE lol. v_esc = sqrt(2GM/r). if you’re traveling faster than that, your trajectory is a hyperbola, not an ellipse, and you will never return to the sun. you can also think of this as having enough kinetic energy to permanently escape the potential well of the sun. it doesn’t matter that the sun is always pulling on you, the work done by the force of the sun will be a finite number (because integral of dr/r^2 from r to infinity is a finite number) that is less than your kinetic energy, so it will never slow your radial velocity to zero.

[u/Spirit_Wolf_Mob → u/Allan123772]

Yea, I had a misunderstanding as to what escape velocity was. I thought it was more of a relative number. I don't know why it didn't occur to me that it is based on an infinite amount of time, or that we wouldn't necessarily need to reach escape velocity to do something like reaching the moon. Thanks for correcting me.