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Comment by irq | Hacker News Reader

Does anyone have details? Like what is the nominal voltage, power density, etc?

Here's the best I can find, from Eikka's comment on Phys.org:

"Carbon-14 has a mean decay energy of 49 keV or 7.85e-15 Joules and activity of 165e+9 bq/g which gives you a power output of 0.0013 Watts per gram.

So a gram-sized lump of carbon-14 - about half a teaspoon - assuming perfect conversion, will produce 1.3 Milliwatts, or about 1/20th of what it takes to light up a common red indicator LED."

http://phys.org/news/2016-11-diamond-age-power-nuclear-batte...

That would actually be perfect for long range interstellar probes. A constant source of energy for thousands of years, even that small, would propel a craft to reasonably high speeds. Give a spacecraft a few pounds and you'd have something really great.

https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...

(Because it's relevant, not as agreement or disagreement with any particular point.)

But if it's for interstellar probes, we could use just carbon-14 and keep the diamond...? Unless we're wrapping it in a diamond to protect the electronics.

The diamond is the carbon-14.

I would love to place my comment in a block of coal right now and then set the coal on fire.

would that be a block of C-14 coal? Dirty power! Dirty bomb!

So given that, assume you put an array of batteries together, what is the formula for Batteries of qty=N allowing a range of Z AU comm ability to earth / current-AU-distance == distance-from-earth before we will not be even able to receive said comms...??

So how far can they get on N batteries before we cant hear them?

Is there such a thing as "solar-syncronous" and "galactic-syncronous" orbit such that we can deploy a TON of little relays that would speed up comms to each probe to the Earth?

I.E. we have however many in a sphere around the solar system, then at some AU distance out, that the extending probes can contact more efficiently?

Assume that the little diamond batts can only reliably transfer a signal by AU/.00X - then we need to create grids of these little guys at AU/.00X intervals to relay the signals within the power capabilities of the probes...

or is this a stupid thing to say?

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This begs the questions; what is the best method/technology for sending messages between sensors through space?

We can still hear the Voyagers, how long do their signals take to get here? How much data do they send? How long will their batteries last? How far until they go dark? (they are already like 34 times as far from us as we are from Jupiter.)

How well could these little batteries power the new EM/ION drive: https://www.nasaspaceflight.com/2015/04/evaluating-nasas-fut...

How much power does that need?

If you put a radio at ~10X the distance of Pluto, you can use the sun as a gravitational lens, and communicate with another star using milliwatts of power:

http://www.centauri-dreams.org/?p=10123

You're still bound by the speed of light, unfortunately.

There are far far far better choices for long range interstellar probes. In particular you want a material with much better power density.

The type of decay used by this device (beta decay) is one of the least energetic types.

Assuming linear scalability, size that up to a 100kg power source, and you've got enough power to run radio repeaters that could outlast civilization.

Some microcontrollers use under 0.2 watts, which would be 153 grams of this material. So there are at least some potential applications. If you combined that with a bistable LCD display, could you make a clock/thermometer/whatever that would run almost indefinitely (until the Carbon-14 ran out, that is)?

0.0013 Watts per gram would be about 1 kilowatt per ton.

If there were enough of this stuff and it would be easy enough to manufacture, maybe slabs could be installed under peoples' houses as the foundation. How much heat does it take to make a diamond? Would Americium be a more practical source of radioactivity, considering how much infrastructure is already in place for smoke detectors? I'm not really sure what they mean by "radioactive field", there are several different modes of radioactive decay (gamma, beta, alpha). Carbon-14 undergoes beta decay so I assume this is the only decay mode that will work. That would make sense since beta minus decay creates an electron. Americium undergoes alpha decay so if that's how this works, Americium would be no good.

This could be used to make ever-luminescent things like road signs or something. Very interesting.

"assuming perfect conversion" is important. It seems unlikely that the conversion is 100% efficient. It may for example only be 1% efficient, so you may need to multiply all power and weight estimates by 100.

radioisomer batteries would provide much much higher power densities, but they're currently more of a theoretical thing.

https://en.wikipedia.org/wiki/Nuclear_isomer#Applications

It may be 1/20 of what it takes to light a LED, but it's 100 times what it takes to power a watch. A watch that lasts 5,000 years between batteries sounds attractive.

There are an lot of things you can do with 15 joule per day budget. Being able to do it using an failsafe energy that lasts for millennia using a would be amazing. We could literally blanket the planet with sensors that never die.

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