Fission source as "rocket"

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Looking at a humble smoke detector - a metal plate with some alpha source on one side. I guess the fission products / apha etc emitted in one direction are absorbed into the metal, and the opposite direction go into space. So there should be a minute net force ? Would that be useful as a "sail" in space ? It seems to me it would be simpler than a thermoelectric generator and ion engine (?)
 

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  • #2
berkeman
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Looking at a humble smoke detector - a metal plate with some alpha source on one side. I guess the fission products / apha etc emitted in one direction are absorbed into the metal, and the opposite direction go into space. So there should be a minute net force ? Would that be useful as a "sail" in space ? It seems to me it would be simpler than a thermoelectric generator and ion engine (?)
Why are you calling alpha decay "fission"?

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

https://en.wikipedia.org/wiki/Alpha_decay
 
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  • #3
anorlunda
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Looking at a humble smoke detector - a metal plate with some alpha source on one side. I guess the fission products / apha etc emitted in one direction are absorbed into the metal, and the opposite direction go into space. So there should be a minute net force ? Would that be useful as a "sail" in space ? It seems to me it would be simpler than a thermoelectric generator and ion engine (?)
Yeah a minute force would be expected, but far too small to be useful. To estimate how small it is, figure out how much mass loss the smoke detector experiences in a year, and then use ##E=mc^2## My guess is that after 100 years, the mass loss would still be far too small to measure by ordinary means.

By contrast, the Deep Space 1 probe carries 36kg of fuel for the ion thruster.
 
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