At the moment , about 9000 neas are known , most of them courtesy of ground-based programmes looking for bodies that might one day hit earth .

目前，大约有9000个近地行星为人所知，其中大多数在地面项目的帮助下寻找那些某天可能会撞击地球的星体。

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 .

大多数小行星位于火星语木星之间的小行星带，其中很多是近地小行星neas，它们分散于星际间，因其具有矿产资源，所以值得人类去调查研究，当然是以经济的方式。

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 .

但是已经有足够多的小行星据我们所知为近地行星，在太阳系内离人类相当近，因而非常值得把他们作为矿源来调查研究，当然，也要在经济实惠的前提下这么做。