20、 Obama
Int US 131 Folder Collection
After playing the video, you can click or select the word to look it up in the dictionary.
Loading...
Report Subtitle Errors
NASA's got a new mission on the horizon.
Land an unmanned spacecraft on Titan, Saturn's largest moon, and explore the surface for evidence of potential alien life.
The billion-dollar mission will test NASA engineers like never before, because if you're going to explore Titan, there's something you need to know.
Just like our own moon, Titan orbits a planet, but it actually looks and behaves more like an Earth.
And that's why, for this mission, NASA opted for a different kind of spacecraft.
This is Dragonfly.
It's a nuclear-powered drone that's the size of a large lawn mower.
Now if NASA is going to send a space drone anywhere, it's Titan, because, similar to Earth, it has a thick atmosphere, which can keep the drone aloft.
Dragonfly is built like a helicopter, able to take short flights in between landings.
It will run on what's called a radioisotope thermoelectric generator, or RTG.
The RTG runs on radioactive decay from a reserve of plutonium-238, which not only will power the spacecraft for months on end, but will also keep it warm.
You see, the average temperature on Titan is minus 179 degrees Celsius, cold enough to freeze Dragonfly's circuits.
But a byproduct of radioactive decay is heat, which will protect the fragile electronics on board, which Dragonfly will be using to study surface composition, temperature, weather patterns, and geological activity, as well as look for water, carbon compounds, and other signs of potential life.
And NASA already has a good idea of where to explore.
Back in the 2000s, NASA's Cassini spacecraft mapped entire sections of Titan's surface, uncovering lakes of liquid methane and possible ice volcanoes.
The ice volcanoes are of special interest, because scientists think they could launch underground water to Titan's surface.
In fact, there's evidence to suggest that Titan has a vast subterranean ocean of liquid water about 80 kilometers down.
And if that water is mixed with methane-based molecules lurking in Titan's surface lakes, there's a chance for life to form, according to some experts.
And Dragonfly will have plenty of time to test that notion.
If all goes according to plan, Dragonfly will study Titan's surface for at least 2 1/2 years and is expected to travel over 175 kilometers.
That's almost double the distance covered by all the Mars rovers combined.
And whether it finds alien life or not, there's plenty more science to discover.
For instance, Titan looks a lot like how scientists think Earth looked at a young age.
So, understanding Titan may help us uncover secrets of our own planet.
What might we learn?
Well, there's only one way to find out.
NASA plans to launch the spacecraft in 2026, when it will begin its eight-year journey through the solar system towards Titan.
So mark your calendars for 2034.
    You must  Log in  to get the function.
Tip: Click on the article or the word in the subtitle to get translation quickly!

Loading…

Loading…

Int US

NASA's $1 Billion Mission To Search For Life On Titan, Explained

131 Folder Collection
April Lu published on July 10, 2019    April Lu translated    Winnie Liao reviewed

Learning Words

loading

Comments

Loading…
More Recommended Videos

  1. 1. Search word

    Select word on the caption to look it up in the dictionary!

  2. 2. Repeat single sentence

    Repeat the same sentence to enhance listening ability

  3. 3. Shortcut

    Shortcut!

  4. 4. Close caption

    Close the English caption

  5. 5. Embed

    Embed the video to your blog

  6. 6. Unfold

    Hide right panel

  1. Listening Quiz

    Listening Quiz!

  1. Click to open your notebook

  1. UrbanDictionary 俚語字典整合查詢。一般字典查詢不到你滿意的解譯，不妨使用「俚語字典」，或許會讓你有滿意的答案喔