According to the researchers, an asteroid or comet whacked a young Mars some 4 billion years ago, blasting away much of its northern crust and creating a giant hole over 40 percent of the surface.

• 根据这些调查者的调查，一颗小行星或者彗星撞击了40亿年前的年轻火星，炸掉了大部分北部的表面并且形成了一个巨大大概占火星表面百分之四十的大洞。