(单词翻译:单击)
Over the last 50 years, we've sent tons of cool spacecraft to Mars.
过去50年，我们发射了很多有趣的航天器到火星上。
Flybys, orbiters, landers, rovers, it seems like we've done everything.
近飞探测、轨道飞行器、着陆器、探测器，似乎所有的事我们都做完了。
Still, there is one kind of mission we haven't done yet:
但仍有一项任务我们没有完成：
No Mars mission has flown through the air, but that might change in just a few years.
没有在空中飞行的火星任务，但未来几年这种情况可能会改变。
Nothing's final yet, but engineers are experimenting with the idea of including a drone, called the Mars Helicopter,
事情还没定，但工程师们正在试验想法，其中就包括叫做火星直升机的无人机，
on the upcoming Mars 2020 rover.
它在未来的“火星2020”探测器上。
Mars 2020 is NASA's successor to Curiosity, and it's expected to launch in, you guessed it, 2020.
“火星2020”是“好奇号”的接班人，你猜到了，有望2020年发射。
It has a similar design to Curiosity and will study potentially habitable environments.
它的设计与“好奇号”相似，并将研究潜在的宜居环境。
It will also select and package samples we could return to Earth on a future mission.
它还会在未来任务中，选择和打包带回地球的样本。
Adding a helicopter could help this rover overcome one of Curiosity's biggest problems:
在此探测器上添加一架直升机可以帮助“好奇号”克服一个最大的问题:
It just doesn't go that far.
走得不远。
Curiosity's been on Mars for over five years,
“好奇号”在火星五年多了，
but in that time, it's only driven about 17.5 km, and average of it is less than 10 meters per day.
但那时，它只航行了17.5千米，平均每天不到10米。
Part of that is because the rover stops and studies things,
一部分原因是探测器要停下来研究东西，
but it's also because driving a rover on another planet is pretty dang hard.
但另一个原因是在另一个星球上驾驶探测器很难。
Radio communication with Mars takes anywhere from 8 to 48 minutes round-trip,
与火星的无线电通讯需要8到48分钟的往返时间，
depending on where Earth and Mars are in their orbits,
这取决于地球和火星各自的轨道位置。
so mission controllers can't just like drive Curiosity Mario Kart style.
所以任务指挥官驾驶探测器不能像马里奥赛车风格。
It can steer itself across simple terrain like a self-driving car,
它可以像自动驾驶汽车一样在简单的地形上行驶，
but it still needs to stop every now and again to get input from Earth.
但仍需要不时停下来从地球上获取输入。
And there are some kinds of rocky or difficult terrain that it just can't handle.
有一些多岩或困难的地形是无法处理的。
Picking Curiosity's path isn't always the easiest, either.
选择“好奇号”的路径也不是最简单的。
To decide where it should go, engineers rely on pictures from the rover and from satellites in orbit,
工程师们依靠探测器和轨道卫星上传来的照片来决定它的去向，
but Curiosity's cameras can only see so far.
但“好奇号”相机能照得区域有限。
And the satellites have a top-down view, so they can't always see the true shape of surface features.
而且卫星照得是俯瞰图，所以它们不是总能看到真实的地表特征。
If Mars 2020 could launch a drone to scout out the area ahead,
如果“火星2020”可以发射一架无人机来探测前方的区域，
it could anticipate obstacles and identify the most interesting things to study.
它就可以预见障碍，识别最有趣的东西来学习。
And someday, a Mars helicopter or Marscopter,
总有一天，火星直升飞机或火星探测器
might even be able to explore places a rover couldn't reach, like small channels or cliffs.
可以探索航天器无法到达的地方，比如小通道或悬崖。
This all sounds like an amazing idea, but there's a big problem: Mars is not a very good place to fly.
这听起来很惊人，但有一个不小的问题：火星不易飞行。
Helicopters stay in the air because they experience lift, or more pressure underneath them than above them.
直升机停留在空中，是因为它们有浮力，或者说是其下面的压力比上面的大。
And the more dense the air is, the more lift your helicopter can get,
空气密度越大，直升机飞得越高，
because there's more air molecules for it to push against.
这是因为有更多的空气分子来推动它。
The problem is, Mars' atmosphere is really thin, like less than a 1/60 the density of Earth's atmosphere at sea level,
但问题是，火星大气很薄，仅有地球海平面大气的六十分之一，
so it's a lot harder to create lift.
所以很难创造浮力。
But good news: There's less gravity so that's one thing working in favor for us
但好消息是：火星重力较小，这是有利于我们的一件事，
but it is not enough to counteract just the lack of molecules to push against.
但这不足以抵消缺乏分子推动的作用。
For this to work, engineers would have to give their Marscopter extra long rotor blades.
为此，工程师们必须给他们的火星探测器增加额外的旋翼桨叶。
Basically, this would let the helicopter push against more air molecules at once,
它基本上能让直升机同时推动更多的空气分子，
even if they're spread farther apart.
即使它们相距较远。
To carry just 1 kilogram across the Martian surface,
为了在火星表面携带1公斤重的物品，
the Mars Helicopter would need rotors more than a meter across,
火星直升机需要超过一米的旋翼，
which is a lot bigger than your neighbor's photography drone.
这比你邻居的摄影无人机要大得多。
And that doesn't mean the drone could carry one kilogram of samples, either.
不过，这不意味着无人机可以携带一公斤的样本。
Everything, from the rotors to the flight computer to the solar panels, would have to add up to a kilogram of mass.
从旋翼到飞行计算机再到太阳能电池板，所有东西加起来必须有一公斤的质量。
But amazingly, getting airborne might actually be one of the easiest parts of a Mars helicopter.
但令人惊讶的是，空中飞行实际可能是火星直升机最简单的部分。
Remember that communications delay between Earth and Mars?
还记得地球和火星之间的通信延迟问题吗？
Well, unlike a rover, which can sit around and wait for instructions,
火星直升机不像探测器，可以坐等指令，
once the Mars Helicopter is airborne, clock's ticking.
它一旦在空中飞行，时钟就会滴答作响。
It would probably fly for 2 to 3 minutes and could cover up to a half a kilometer of terrain
它可能会飞2到3分钟，覆盖半公里的地形，
but since we wouldn't be able to steer it in real-time, every second of that would have to be on autopilot.
但由于我们无法实时驾驭它，期间的每一秒都必须是自动驾驶。
It would have to take off, judge the wind speed, fly in the right direction, take pictures,
它必须起飞、判断风速、飞向正确的方向、拍照，
and find a safe place to land, all in 180 seconds or less.
找到地方安全着陆，所有的一切都在180秒以内。
That might seem like a ton of work, but it could come with a big payoff.
这似乎是一大堆工作，但可能带来的回报也很大。
NASA engineers estimate having a Mars Helicopter could help a rover like Mars 2020
宇航局工程师估计，一架火星直升飞机可以帮助“火星2020”这样的探测器
travel three times farther than Curiosity in a day,
比“好奇号”的路程一天之内多两倍。
and when you're talking about multi-billion dollar missions, tripling efficiency is a pretty sweet deal.
当你谈论数十亿美元的任务时，三倍的效率是个相当不错的交易。
As a bonus, all those extra near-surface images would be really helpful for scientists studying Mars.
作为奖励，所有这些额外的近地表图像将对研究火星的科学家们非常有帮助。
You'd get a mission that could study not only more targets,
你在一个任务中不仅研究多个目标，
but better ones, and that's a heck of a good thing for exploration.
但更好的是，这对探索来说是件好事。
So far, NASA has already tested a prototype of the helicopter design,
到目前为止，宇航局已经测试出了直升机设计的原型，
but they'll need to do a lot more work before we're ready to start zooming around.
但在他们准备开工之前，还需要做更多的工作。
Since Mars 2020 is expected to launch in less than three years, hopefully we'll be hearing more about it soon.
“火星2020”预期三年内发射，希望到时候我们能了解更多内容。
Thank you for watching this episode of SciShow Space,
感谢您收看本期的太空科学秀，
which was made possible by our Patrons on Patreon who pay,
同时也感谢Patrons的大力支持，
so that everybody gets to watch it for free, except for them.
这样才使得人们能够免费观看。
That's a wonderful thing that you do. We really appreciate it.
你们做了一件了不起的事，我们很感激。
If you would like to help make episodes like this and be one of those people,
如果你想继续帮助我们制作这样的节目或成为这样的人，
you can go to patreon.com/scishow.
请登录patreon.com/scishow。
And if you want to help us out by watching and by sharing that's also great,
如果你想通过观看和分享支持我们也不错，
we're at youtube.com/scishowspace.
我们在youtube.com/scishowspace哦。
