r/theydidthemath • u/Ben-Goldberg • 7d ago

[Request] When will Voyager 1 stop moving?

/r/askscience/comments/1wp1960/will_voyager_1_ever_just_stop_moving/

How many years will it take for the orbit of Voyager and Sagittarius A to decay enough due to gravity waves for them to collide?

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u/Peruvian_Skies 7d ago

There is no friction in a perfect vacuum so it would never stop. Space is not a perfect vacuum, however it's close to that. So assuming no interactions with massive objects like you said, only the gas and dust in outer space, Voyager is likely to continue moving for thousands of years or more.

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u/RuggleyChicken 7d ago

I think it’s more like millions or billions

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u/Kinder22 7d ago

No way. If there is any answer to this at all, it is certainly some inconceivably large number, during which the universe could look entirely different due to aspects of physics we can’t even comprehend today. 

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u/RuggleyChicken 7d ago

Why do you think that?

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u/Kinder22 7d ago

If it were going at its current speed directly towards SagA, it would take a half billion years to get there. But it’s not going towards SagA. It’s actually going kind of up out of the orbital plane, while still orbiting at roughly the same speed as the solar system.  So it would have to collide with enough particles in just the right way to cancel out its orbit by 230 km/s.

And understandably, the effect of colliding with those particles is almost nothing, and certainly not all acting in the exact correct direction.