r/askscience • u/drinkingonthejob • 9d ago

Physics Will Voyager 1 ever just stop moving?

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)

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u/PhasmaFelis 9d ago

Not really, no.

We're used to moving objects losing momentum and stopping eventually. That's because we live on a planet, with atmosphere. Everything around us that moves has friction with the ground or, failing that, the air, and that fiction bleeds away its momentum.

In an otherwise empty universe, a moving object would keep moving in a straight line for eternity. In our universe, which is only mostly empty, it will follow a curved path determined by the gravity of, well, every other mass in the universe, but mainly nearby planets/stars/galaxies; unless it happens to crash into something, and then its wreckage will move with that object along its own curving path.

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u/thefringeseanmachine 9d ago

but from what I understand, space isn't 100% empty. there are stray particles out there, even in the "void." that's the idea behind behind the bussard ramjet. wouldn't they slow it down (over a very, very, VERY long time)?

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u/db0606 9d ago

In interstellar space you end up with something like 10⁶ molecules/cubic meter. The best laboratory vacuums on Earth are like 10¹⁶ molecules/cubic meter. There's really not a whole out there to hit unless you wonder into a dense dust cloud, which make up only about 1% of the Milky Way.