Most asteroids dwell between the orbits of mars and jupiter . But enough of them , known as near-earth asteroids , or neas , come within interplanetary spitting distance of humanity for it to be worth investigating them as sources of minerals-if , of course , that can be done economically .
But enough of them , known as near-earth asteroids , or neas , come within interplanetary spitting distance of humanity for it to be worth investigating them as sources of minerals-if , of course , that can be done economically .