Well clearly at the beginning of the solar system, Mars and the Earth were bombarded by giant asteroids and comets, and there were ejecta from these impacts all over the place.
我们知道，太阳系刚诞生的时候， 火星和地球被巨大的 小行星和彗星撞击过， 这些强力撞击形成的 喷出物到处都是。