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n. A tiny particle of meteoric dust, especially one of many that fall to the surface of the earth or moon.

n. an extraterrestrial particle, less than a millimeter in size, that has survived entry into the atmosphere without melting

n. A meteorite so small that it drifts down to Earth without becoming intensely heated in the earth's atmosphere.

n. a meteorite or meteoroid so small that it drifts down to earth without becoming intensely heated in the atmosphere

"The shuttle astronauts will use the laser- and camera-tipped boom one last time late Wednesday night to check for any signs of micrometeorite damage to Endeavour's heat shield."

meteorite   

micrometeoroid   

meteoritic    ecotoxicological    sack-like    tinpot    orsubstantial