英语听力：自然百科 行星旅行指南：火星 Mars—8
时间：2019-02-03 作者：英语课 分类：自然百科2012年
英语课
Before we take this giant leap, we need to be able to carry everything needed for a three-year -round trip with us. This is a much larger effort than getting to the moon. It’s the Apollo mission on steroids.
“At this point we know at least as much as the engineers knew at the time that they agreed to land on the moon. And they had only nine years. So I think once the nation decides they really want to land humans on Mars, the system can be designed and developed and built.”
Fast forward to the future, after six months’ crossing the blackness of space, things suddenly get a lot more interesting. The combination of a high approach speed, a thin atmosphere and twice the gravity of the moon makes Mars one of the hardest places to land in the solar system, even for robots.
“You hit the top of Martian atmosphere, you are going Mach 27, 27 times the speed of sound. And for our vehicle between when we hit the top of Martian atmosphere and when we were bouncing on the surface with the airbags were six minutes. It’s a hell of a ride. You use a hitch 1 rope to slow you down to a leisurely 2 Mach 2, twice the speed of sound and then we threw out a super-size parachute.”
Everything is complex and everything has to happen precisely 3 on time.
“The worst part is when you come into contact with the Martian surface, there is no runway, OK? There’s no nice place to land, and you can’t control very well where you are going to come down, so you are going to come down in a field of rocks like this. How do you guarantee that your $1 billion spacecraft is actually going to survive that? The approach that worked for us with our rovers was great big airbags, bounce, bounce, bounce, bounce, bounce, finally the vehicle comes to rest.
Vikings use the rocket motors, and they just touch down gently on the surface and they were fortunate. It was just good luck. They landed in a field of boulders 4 like this, but they didn’t land with one that was poking 5 through the valley and it all worked. You had to be good and you had to be lucky.”
v.免费搭(车旅行)；系住；急提；n.故障；急拉
- They had an eighty-mile journey and decided to hitch hike.他们要走80英里的路程，最后决定搭便车。
- All the candidates are able to answer the questions without any hitch.所有报考者都能对答如流。
adj.悠闲的；从容的，慢慢的
- We walked in a leisurely manner,looking in all the windows.我们慢悠悠地走着，看遍所有的橱窗。
- He had a leisurely breakfast and drove cheerfully to work.他从容的吃了早餐，高兴的开车去工作。
adv.恰好，正好，精确地，细致地
- It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
- The man adjusted very precisely.那个人调得很准。