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Comment by monocasa | Hacker News Reader

I heard a rumour that by the time they've gotten to another solar system, they will have evaporated into a metallic cloud; that's how long this next part of their journey is.

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Why would they? They will be very cold. Occasional cosmic rays aren't enough to evaporate them. They can last hundreds of thousands of years, if not millions.

And how long until they reach the next star? They're not pointed anywhere in particular. We are talking about millions of years here.

And even if they were.

Think we can point the James webb at one and get a farewell Pic?

Millions of years? Fat chance. A few days ago this post https://news.ycombinator.com/item?id=21327269 explained that during the galactic collision of the Milky Way and Andromeda in 4B years, no two stars will likely collide because of the sheer amount of empty space. Keeping that in perspective, I highly doubt that Voyager would find its way anywhere in some mere millions of years.

Space is mind boggling large and sparse. Millions of years is not a long time to be traveling through it.

* even at light speed

do you mean the plutonium batteries or the probe itself?

The whole probe itself.

Technically you're talking about sublimation rather than evaporation. And no, it won't be very likely for the Voyagers to disappear. Most likely they will be damaged by impact or get absorbed by massive object, but sublimation at 10K will take a very very long time.

I don't have the data, but if you want to calculate the rate of sublimation, you need to look at the vapor pressure of various metals at interstellar temperatures.

Some very low numbers indeed.

But they're in interstellar space. I imagine high-energy collisions (with hydrogen atoms or loose protons) would be a more likely cause of evaporation, and I don't know the numbers for that.

If there’s 1 atom per cubic cm in interstellar space, I’m finding it takes about half a million years to collide with a mole of hydrogen (at 17km/s)

Google says that's about a gram of hydrogen. Is that enough to destroy a craft? I have little intuition, but I imagine touching a gram of 55,000-degree (Farenheit) anything would be destructive.

Will the craft be radiating heat away from itself?

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