英语听力：自然百科 行星旅行：土星 Saturn—17
时间：2019-01-22 作者：英语课 分类：自然百科2012年
英语课
These are just bold first steps on a journey that's just begun.
Even before the mission is over, Cassini has left a thirst for a return trip.
Planetary explorer Jonathan Lunan and aeronautical 1 pioneer Julia Nod think they know the perfect way to do it---a robotic hot air balloon.
So where we are flying over now is very much like the Huygens landing site.
And I love to see those ravines on Titan though steep valleys where the methane 2 is flowing and covering all the hills very much like what we are seeing now.
The dream is to return to Titan and drop a robotic / balloon into the atmosphere.
A radioisotope generator 3 will provide the electrical power and the waste heat to give the balloon lift in the chilly 4 atmosphere.
Titan has a dense 5 atmosphere. It’s cold, the gravity is low, the winds are gentle, so ballooning is very easy.
I think this flight just makes the point so beautifully. Why a balloon is a wonderful way to explore Titan?
If you're over an interesting area, very easy to come down, maybe even land on the surface, lower instruments down.
One could cover with a robotic hot air balloon, the entire circumference 6 of Titan in a space of perhaps six months.
You shouldn't think of Titan as a place just for robots. With a thick protected atmosphere and plenty of frozen water, Titan could be a more user-friendly destination for earthlings than Mars.
When humans do finally move out into the solar system, and I think Titan will be seen as a somewhat distant but very attractive place to go play.
You don't need a pressure suit on Titan, you don't have the feeling as the astronauts described, trying to work with a beachball between your arms
adj.航空（学）的
- Many of the pilots were to achieve eminence in the aeronautical world. 这些飞行员中很多人将会在航空界声名显赫。 来自辞典例句
- The advent of aircraft brought with it aeronautical engineering. 宇宙飞船的问世导致了航天工程的出现。 来自辞典例句
n.甲烷，沼气
- The blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
- Methane may have extraterrestrial significance.甲烷具有星际意义。
n.发电机，发生器
- All the while the giant generator poured out its power.巨大的发电机一刻不停地发出电力。
- This is an alternating current generator.这是一台交流发电机。
adj.凉快的，寒冷的
- I feel chilly without a coat.我由于没有穿大衣而感到凉飕飕的。
- I grew chilly when the fire went out.炉火熄灭后，寒气逼人。
a.密集的，稠密的，浓密的；密度大的
- 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。
n.圆周，周长，圆周线
- It's a mile round the circumference of the field.运动场周长一英里。
- The diameter and the circumference of a circle correlate.圆的直径与圆周有相互关系。