This is 2 1/2 tons, not all of it nickel. Approximately 48.5 tons of meteorites hit the earth every day https://science.nasa.gov/solar-system/meteors-meteorites

This is 2 1/2 tons, not all of it nickel. Approximately 48.5 tons of meteorites hit the earth every day https://science.nasa.gov/solar-system/meteors-meteorites/ https://science.nasa.gov/solar-system/meteors-meteorites/ and those are around 1-1.8% nickel https://sites.wustl.edu/meteoritesite/items/metal-iron-nickel/#:~:text=all%20chondrites%20have%20bulk%20(whole%2Drock)%20concentrations%20of%20nickel%20of%201.0%2D1.8%25 https://sites.wustl.edu/meteoritesite/items/metal-iron-nicke... So, there's about 1/2 a ton of nickel falling into the atmosphere every day anyway, 180 tons a year, already in the ballpark of your thousand ships.