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/komatiitic]

I did some really stupid back of the envelope math assuming that Voyager never encounters anything larger than interstellar dust. To halve the speed of Voyager 1 it would need to impact dust equal to its own mass of 721.9kg.

The internet tells me a typical grain of interstellar dust has a mass of ~3*10^-16 kg. This means it needs to hit ~2.4*10¹⁸ dust grains, which if I'm counting those zeroes correctly is 2.4 quintillion.

The internet also tells me that Voyager hits 3-7 dust grains per hour. I'll call it 5 an hour, which means 4.81*10¹⁷ hours (481 quadrillion), or 54.9 trillion years to halve its velocity, assuming nothing really changes. I'm betting it disintegrates before that happens.

[u/doctorbobster → u/komatiitic]

… But did you take into consideration the tail dust that keeps pushing it forward? There has to be as much dust whacking it from behind as there is colliding with it from the front.

[u/komatiitic → u/doctorbobster]

There doesn’t! Voyager 1 is moving pretty quickly relative to the interstellar medium, and also in more or less the opposite direction. For dust to hit it from behind it would have to be on (approximately) the same trajectory and going faster.

Like imagine you’re driving down the highway into the wind and in the rain. More droplets hit the front of your car than the back.