Weapons testing with high-speed projectiles helped prove that material exchange between the planets is not so limited as had once been thought: in fact, some 500 kilograms of rock from Mars are estimated to land on the earth each year.

• 武器实验中发射的高速射弹也有助于证明行星际的物质交换并不像以前认为的那样有限：事实上，每年约有500公斤火星岩石溅落到地球上。