英语听力：自然百科 行星旅行：土星 Saturn—17

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Even before the mission is over, Cassini has left a thirst for a return trip. 

 

Planetary explorer Jonathan Lunan and aeronautical¹ 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 methane² 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 generator³ will provide the electrical power and the waste heat to give the balloon lift in the chilly⁴ atmosphere.

 

Titan has a dense⁵ 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 circumference⁶ 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

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