英语听力：自然百科 行星旅行指南：火星 Mars—7

 A test run before attempting the fuel hungry and risky¹ trip to the planet below. 

 

Dreaming about Mars² and actually going there are two very different things. Mars may be our neighbour, but 35 million miles to the closest point is still a very long way from home. 

 

To put him on the surface of Mars, someone once joked there're only three issues: getting them there, keeping them alive while they are there and getting them back.

 

Our space age dreams of off-world colonies on the moon and Mars faded with the cancellation³ of the Apollo Program and the last trip to the lunar surface in 1972. It didn't stop us from travelling, we simply switched from astronauts to lower cost, lower risk robotic explores. And when it comes to Mars, it's probably just as well. 

 

Getting to Mars is just unbelievably hard. We've learned that the hard way before certainly it gave to go back to the days before the rovers launch two third in the missions that they fall in the Mars and fail. They fail for all kinds of reasons: rockets that blew up and spacecraft that just vanished partly without a trace.

 

Five, four, three, two, one, engine start.. Lift off.

 

If you are ever lucky enough to book a flight on the first rocket to the red planet, you'd better be sure you've packed everything. The one-way trip is at least six months with no turning back if you've forgotten something. 

 

We can go to the moon and get back in a week. It takes about three years to go to Mars and come back. You have to carry your food, you have to recycle your breathing oxygen and your water. So it's a very, very major undertake. Within about three days, your earth looks very small. And within a week, it's just another star. And you suddenly are going to realize you are in very deep space and it can be a long time before you can go back.

1 risky   

adj.有风险的，冒险的

参考例句：

• It may be risky but we will chance it anyhow.这可能有危险，但我们无论如何要冒一冒险。
• He is well aware how risky this investment is.他心里对这项投资的风险十分清楚。

2 Mars   

n.火星，战争

参考例句：

• As of now we don't know much about Mars.目前我们对火星还知之甚少。
• He contended that there must be life on Mars.他坚信火星上面一定有生物。

3 cancellation   

n.删除，取消

参考例句：

• Heavy seas can cause cancellation of ferry services.海上风浪太大，可能须要取消渡轮服务。
• Her cancellation of her trip to Paris upset our plan.她取消了巴黎之行打乱了我们的计划。