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Hey Chris, it’s a really cool question about different types of rocket engines
嘿 克里斯 这个关于各种火箭引擎
and whether there might be a rocket engine coming in the future that uses very little energy.
以及未来是否会出现只需极少能量的火箭引擎的问题问得很好
One of the big challenges of getting anything into space right now
现阶段 把任何东西送入太空所面临的最大挑战是
is you need to get it up out of the Earth’s gravity,
你得让它摆脱地球引力
and really the only way we had to do that is with fairly traditional rockets
而我们实现这一点的唯一途径就是使用相当传统的火箭
that use either solid rocket fuel or liquid rocket fuel,
这些火箭用的要么是固体火箭燃料 要么是液体火箭燃料
but it takes a huge amount of energy to get off the surface of the Earth.
但它需要耗费巨大的能量才能脱离地表
Right now we don’t really have any better way to get things off the surface of the Earth,
目前 我们还没有让物体脱离地表的更佳方式
but things change once you get up into space.
但到太空以后 情况就不一样了
And one of the things that I’m really excited about is something called an ion drive,
让我很激动的是一种叫做离子驱动的东西
and NASA uses these right now.
目前NASA正在使用这种技术
And an ion drive generates a tiny little bit of thrust,
离子驱动会产生极少量的推力
I mean it’s almost similar to just taking your hand and blowing on it, it’s about that much thrust.
相当于你在手上吹了一下 就是那么微弱的力量
But you can turn an ion drive on and you can leave it on for years!
但是离子驱动打开以后 可以持续好几年
So even though it’s a tiny little bit of thrust some of the fastest spacecraft that NASA now operates use ion drives.
所以即便它的推力很小 但NASA一些速度最快的航天器现在用的都是离子驱动
One of my favorite missions is the Dawn Mission, which is actually surveying the larger asteroids in the asteroid belt.
我最喜欢的一个任务是“黎明号”任务 它在小行星带测量比较大的小行星
It went out to the asteroid Vesta and Vesta is about 300 miles across.
它去测量了维斯塔小行星 维斯塔的直径大约有300英里
It took wonderful pictures of Vesta and then it went onto the asteroid Ceres,
它拍下了维斯塔特别好看的照片 然后它又去测量刻瑞斯小行星
which is actually the largest of the asteroids—it’s actually close to 700 miles across—
刻瑞斯是最大的小行星——直径接近700英里——
and the images it returned of Ceres were absolutely amazing.
“黎明号”发回的刻瑞斯的照片美艳惊人
And it was able to go from one asteroid to another because it had this ion drive that it could leave on for years.
它还可以在不同的小行星之间穿梭 因为它用的是离子驱动 可以持续很多年
And even though the thrust is tiny, keep that thrust going day after day,
即便这种推力很小 但让它日复一日
month after month, year after year you can get up to many, many tens of thousands of miles an hour.
月复一月 年复一年的持续下去 每小时也能走上成千上万英里
So the way an ion drive works is—it basically can even use just electricity—
所以离子驱动的工作原理就是——它基本上只需要用到电力——
It creates ions by actually ripping apart molecules into charged particles
它会把分子离化为带电粒子 从而产生离子
and then accelerating them out the back of the spacecraft.
然后让它们在航天器尾部加速释放出去
And really all you need is electricity.
你需要的就只有电力而已
You can even run this on solar panels if you want.
如果你愿意的话 甚至可以用太阳板来操作这些
So you can actually have an entire rocket engine up in space that is powered simply by solar energy
这样你就可以在太空中 仅仅使用太阳能来给整个火箭引擎提供动力
and accelerating ions out the end of the spacecraft.
在航天器尾部加速释放离子
The problem is we don’t know how to use an ion engine to actually launch something into space.
问题是 我们还不知道如何用离子引擎把物体发射至太空
For that you need a lot of thrust, you need to actually get out of this strong gravity well of the Earth.
这需要很大的推力 需要完全摆脱地球引力
So right now we sort of have these dual strategies for rocket engines,
所以现在我们对火箭引擎采用的是双重策略
one that gets you up off the Earth (and those are pretty traditional),
其一是让它脱离地球（这方面还比较老套）
but then once you get into space turn on your ion drive, leave it on,
其二是进入太空后 打开离子驱动 让它一直开着
get yourself going 30,000 miles an hour a little bit at a time, and you never need to turn it off.
每小时一点一点地走上3万英里 而且永远都不需要关闭
