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Comment by CamperBob2 | Hacker News Reader

Photo caption: In the lab that houses the BEST experiment, fish serve as an early warning system about any leaking radiation.

Never change, Russia. Never change.

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Did you know that mussels and clams are sensitive to changes in water quality and can absorb pollutants? They are often used as bioindicators to detect harmful substances like heavy metals and toxins in the water. They are used in United States and in Europe to check if water is clean.

I remember someone creating a sensing system to see if the shells were open or closed. Given enough mussels, the odds of them all closing at once due to random chance instead of pollution drops to zero.

This Tom Scott video?

https://youtu.be/i0RkEs3Xwf0

Clams at 2:22.

I believe Tom is the second time I heard of this, as was the experience of a number of his chattier viewers.

coal miners carried canaries to warn of CO. chemical weapons workers brought bunnies in cages to monitor nerve gas leaks. it's an old tradition - it's simple, and it works.

though why not Geiger counters for radiation? there must be a reason.

If there's enough CO to kill a canary, you still have time to get to safety.

If there's enough nerve gas to kill a rabbit, you still have time to get to safety.

If there's enough radiation to kill a fish, you're a walking dead man... and the 'walking' part is temporary.

Maybe the fish get less shielding.

Maybe it's concentrated in his water

What if you have a potential worrisome alpha emitter already in water. Keeping some fish in that water might give you heads up when something is going wrong.

Then, lacking the availability of an ISO-standard fish, you should probably use a scintillator or surface-barrier detector. Like everyone else who has to deal with such matters.

If you teach a man a fish, he will eat for one lifetime. If you give a man a radioactive fish, he will eat for many half-lives.

I'm no nuclear physicist, but a theory to try out:

1. The leak scenario they're concerned about is an alpha emitter within water, which-- unlike gamma rays and Geiger counters--is harder to detect remotely, since the water serves as effective shielding for anything but microscopic distances.

2. Permanent resident fish serve as a kind of long-term accumulator for dissolved amounts that would otherwise be too hard to detect.

3. The concern isn't so much immediate risks to human health, but rather how any slow leak or discrepancy might compromise the experiment.

> though why not Geiger counters for radiation? there must be a reason.

If a detector fish moves, it works. With Geiger counter, you may not be always able to tell when it malfunctions.

You can't get them all right. To be fair, they used pencils while NASA spent time and money to have a pen that writes in 0g.

That's just a myth, you know: https://www.scientificamerican.com/article/fact-or-fiction-n...

Fischer made the space pen as a commercial product, all R+D entirely at their own expense. NASA just bought some of the pens from them.

This is a myth, using a pencil in space isn't clever or thrifty, it's a disaster waiting to happen. The graphite from pencils breaks off in small fragments while writing and the fragments can create shorts in electronics and to top it off they're also flammable. None of those are properties you want to bring into a spacecraft.

dumb question but how well do sharpies work in space? the ink diffuses through the felt tip - that doesn't require gravity. wouldn't that work pretty well?

also crayons seem like a better bet than pencils - they're still flammable and prone to flaking but at least they're not conductive.

Your question piqued my curiosity, so I did some googling... Apparently sharpies do work in space, though NASA seems to prefer the Duro brand of marker.

https://airandspace.si.edu/stories/editorial/saga-writing-sp...

Sharpies and markers generally run out waaay quicker than pens or pencils. They also dry out if you're not careful, and dry out temporarily if you use them for more than a few minutes at a time.

Crayons just aren't dark enough, and are too wide. Accurately reading numbers and symbols written in crayon at a normal handwritten size is not something I want to do. Not to mention the constant sharpening.

And we licensed the pens from a dude who spent a fortune developing them.

I wonder how graphite can create shorts, when all electronics board and components on them can be easily covered with protective nonconducting PCB varnish.

After Fisher, the pen company, spent their own couple millions to develop a pen that could write in zero gravity, they convinced NASA to use it, and a few years later the Soviets bought 100 of them for their own space program.

NASA was never involved in the development of the space pen, though they supposedly had their own effort that was quickly abandoned as it got expensive. Before that they also used pencils.

The pen is just a better writing implement in space. It cost $3 in the 60s, with wide availability.

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