So how big an impactor would it take to make a 180-kilometer diameter crater on the earth?

多大的撞击物才能在地球上留下直径180千米的陨石坑呢？

The last is the Kinetic Impactor technique.

最后是动能冲击器技术。

The impactor's kinetic energy would be some 10,000 times too high.

撞击器的动能会高出大约 10,000 倍。

Mars got hit with an impactor and you and I are a descendent of Martians?

火星被撞击器击中，你我是火星人的后裔？

But luckily  for us, the vast majority of these impactors are small and they just burn in the atmosphere.

但对我们来说幸运的是，这些撞击物中的绝大多数都很小，它们只会在大气中燃烧。

He told The Associated Press that to get the second set of samples in July, Hayabusa2 used an impactor to blast below the asteroid's surface.

他告诉美联社，为了在7月获得第二组样本，隼鸟二号利用撞击器在这颗小行星的表面以下爆炸。

The size of the impactor isn't quite known, but we think it might be on the order of about 60 kilometers or so.

撞击物的大小并不确定，但我们认为大概是60千米（的直径）。

At that time, a 10-kilometre impactor is going to vaporize, melt and displace something like well over 10,000 cubic kilometers of the surface of the earth.

那时，这10千米的撞击物将要使地球表面上超过一万立方千米的东西被蒸发、融化和被撞飞。

And it deposited a fair number of meteorites in  the ground and I happen to have a piece of the Chelyabinsk impactor right here  in my hand.

它在地下沉积了相当数量的陨石，而我手上恰好有一块车里雅宾斯克撞击器的碎片。

Scientists say the chance of this rock hitting Earth is about four tenths of one percent they don't expect it to have a major impactor to disrupt the U.S. election the next day.

科学家们称这颗小行星撞击地球的几率大约是4%，他们预计这不会对第二天的美国选举产生重大的影响。

Mercury has weaker gravity, so it doesn't pull in impactors as hard as the Earth does, but it orbits the Sun far faster than Earth does, so asteroids and comets tend to hit at higher velocity.

水星的引力较弱，所以它不像地球那样强烈地吸引撞击物，但它的公转的速度比地球快得多，所以小行星和彗星往往会以更高的相对速度撞击。

And because the asteroid is so tiny, and the impactor spacecraft will crash into it at breakneck speed, " I think the biggest concern is that they completely destroy the asteroid, " says Dr Agrusa.

而且因为这颗小行星如此之小，撞击器航天器将以极快的速度撞向它，“我认为最大的担忧是他们会彻底摧毁这颗小行星，” 阿格鲁萨博士说。