re: Something to consider before sending nano-probes speeding off into space

quote:

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So, if we send out a string of probes to transmit back data, and they don't get stopped and then all hit a planet beyond somewhere, we will be effectively bombing that planet from afar.

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The formula for relativistic kinetic energy is:

E = mc2/sqrt(1/(v2/c2)) - mc2

Assuming a 1kg probe (far more massive than those being contemplated) traveling at 0.2 c, we can plug in and get:

E = mc2/0.98 - mc2 = .02 mc2 = .02 x 90 gigajoules.

I'm guessing that some of the rest mass might also get converted too, but even total conversion to energy can't be more than 92 gigajoules.

According to LINK a MOAB bomb is about 50 gigajoules, so an impact is very roughly the size of the biggest conventional explosives. Really bad if you happen to be standing there and would destroy a city block or two.