纪录片《火星任务》 第9期 超音速降落

If it's cold and dense¹,

若空气寒冷稠密

you slow down faster,

减速会更快

you end up shorter.

降落轨道就较短

If it's hot and low density²,

若空气炎热稀薄

you end up flying farther.

那就会飞得更远

The dangers of this unpredictable atmosphere

大气不可预知

are heightened by the speed the spacecraft

而航天器驶向火星的速度极高

has to travel at to get to Mars.

这使着陆更加危险

It will arrive

抵达火星时

at 13,000 miles per hour.

航天器的速度高达每秒5.8公里

We have enough energy

航天器高速飞行

of motion in the spacecraft

具有极高的动能

that we could vaporise the spacecraft in the atmosphere of Mars

使得只要它进入火星 与大气摩擦

just by slamming into that atmosphere

产生的巨大热量

and developing so much friction³ that the vehicle would burn up.

就足以将航天器汽化并烧毁火星车

So it's a challenge.

所以这是一个挑战

The rover will be tucked inside a spacecraft

当进入危险的火星大气层时

when it reaches the dangerous Martian atmosphere.

火星车将藏在航天器内部

Its first line of defence

它的第一道防线

will be the world's biggest heat shield.

是世界上最大的防热罩

Next, the team have to stop it

接下来 还要让它减速

from crashing head-on into the Red Planet.

以防火星车一头撞上地面

So they have designed

所以他们设计了

the biggest supersonic parachute ever made.

一张有史以来最大的超音速降落伞

1 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

2 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。

3 friction   

n.摩擦，摩擦力

参考例句：

• When Joan returned to work,the friction between them increased.琼回来工作后，他们之间的摩擦加剧了。
• Friction acts on moving bodies and brings them to a stop.摩擦力作用于运动着的物体，并使其停止。