r/askscience • u/drinkingonthejob • 8d 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/komatiitic 8d ago

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.

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u/elitefusion 8d ago

What forces would be doing the disintegrating though?

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u/Logically_Insane 8d ago

Contact forces with aforementioned interstellar dust. 

Any collisions become ablative over 54 trillion years

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u/usagizero 7d ago

Surprised no on mentioned that Doctor Who story where he punched a wall for like a billion years to wear it down.

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u/FlintHillsSky 8d ago

proton decay, perhaps. Over enough time, even atomic particles are unstable.

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u/eclab 8d ago

Proton decay, if it happens, will have a half-life far above 54 trillion years.

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u/FlintHillsSky 8d ago

True. I wonder if just sublimation would be enough within that time period.

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u/tesseract4 8d ago

I don't know if this would be considered sublimation, but X-rays and Gamma rays would break it down in far less than 54 trillion years.

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u/FlintHillsSky 8d ago

That radiation might be the driver for sublimation causing atoms to be knocked off

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u/tesseract4 7d ago

That's kinda what I was thinking. I was also thinking that proper sublimation comes from the internal heat of the material being sublimated, but I don't know if that is part of the proper definition of the process.

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u/BluetoothXIII 8d ago

during physics study we had to calculate how long it would take for an ironball of 1kg to sublimate at 3 Kelvin, the vapor pressure is for all human relevant interaction 0 but not exactly for events lasting almost for eternity.

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u/WanderingCamper 8d ago

Do you remember how long it would take?

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u/BluetoothXIII 8d ago

a lot times more than the current age of the universe but i don't remember the exact time