During this time, if an unmanned NASA spacecraft were to leave Earth, traveling at 58,000 kilometers

在這期間，如果 NASA (美國航太總署)的無人太空船以每小時 58,000 公里的速度離開地球，

per hour, it would take a little over 40 days to get to the Red Planet.

那到達紅色星球需要 40 多天。

Not bad, right?

聽起來不錯嘛？

Well, a quick trip would only be possible if the spacecraft followed a direct path, undisturbed by the wrath of the solar system and weight of life sustaining resources.

只有在太空船走直線，不受太陽系的酷熱及維生器重量的影響下，這種快速旅程才能實現。

Unfortunately, space travel is far more complicated than a straight line.

可惜的是，太空旅行遠比直線路徑複雜許多。

So ideally, how long does it take to get to Mars?

那麼理想來說，抵達火星要花多久時間？

The solar system is constantly shifting, and the orbital mechanics behind each of the planets makes space travel really complex.

太陽系時常變化，而每個行星背後的軌道力學，使太空旅行變得非常複雜。

Because Earth and Mars have elliptical orbits, the distance between them varies considerably,

因為地球和火星都有橢圓軌道，它們之間的距離變化相當大，

and in order to send a spacecraft to Mars, the planets have to line up just right.

而且為了將太空船送到火星，行星必須剛好排成一條線。

It takes Earth one year to orbit the Sun, while it takes Mars about 1.9 years.

地球繞行太陽需要一年，而火星需要 1.9 年。

So, every time Mars completes a single orbit, Earth goes around the sun almost twice.

因此，每當火星完成一次繞行，地球幾乎已經繞行太陽兩次。

Historically, for NASA, the best launch window to Mars occurs every 2 years and 2 months or 26 months.

從歷史上來看，對 NASA 來說，火星的最佳發射窗期是每兩年兩個月，或 26 個月一次。

During this time, a spacecraft can utilize what is considered the most energy efficient path to Mars known as the Hohmann Transfer orbit.

在這期間，太空船可以利用公認最有效率的路徑到達火星，稱為「霍曼轉移軌道」。

On this trajectory, the spacecraft follows an elliptical orbit around the Sun that intersects the orbit of Mars.

在這軌道上，太空船會沿著圍繞太陽的橢圓軌道行進，此軌道與火星軌道相交。

It uses fuel to increase speed and velocity to break free of Earth's gravity field.

太空船會利用燃料來增加速率和速度，以此擺脫地球的重力場。

And the spacecraft uses more fuel to decelerate in order to be captured into the Martian orbit.

而且為了進入火星軌道，太空船會使用更多燃料來減速。

Then, it can ride Mars's orbital wave until it's ready to touch down on the surface.

接著，太空船就會進入火星循環軌道，一直到它準備登陸表面。

While the Hohmann transfer is considered the most efficient trajectory to get to Mars,

雖然霍曼轉移軌道是公認最有效率到火星的軌道，

the journey is still estimated to take roughly 260 days or eight to nine months with a manned spacecraft powered by chemical propulsion,

但對使用化學推進器的人為操縱太空船來說，預估仍需要花上 260 天或 8 至 9 個月，

so NASA and private companies are trying to develop more efficient propulsion systems that can get humans to Mars faster than the chemical rockets used in the past.

因此，NASA 和私人公司正努力開發更有效的推進系統，讓人類比以往使用的化學火箭更快到火星。

Specifically, a type of electric propulsion system that propels a spacecraft by accelerating a stream of electrically charged atoms, known as ions.

具體來說，是一種電力推進系統，加速帶電原子團 (又稱離子) 來推動太空船。

And a nuclear thermal propulsion system that uses low-enriched uranium as its power source.

而核熱推進系統是使用低濃化鈾作為動力源。

But even if we do engineer a faster way to get to Mars, a round trip is still estimated to take multiple months.

但即使我們設計出更快速的方式到火星，火星的往返仍需好幾個月。

And that means we also have to solve problems of human health and resource requirements during extended deep space missions.

這也代表我們在開拓外太空任務時，必須解決人類健康和資源需求的問題。

Clearly, time is just one of many obstacles standing in the way of our Martian dreams.

顯然，時間對我們火星夢的路途來說，只是其中一個阻礙。

But still, NASA says it plans to send humans to Mars in the 2030s.

但 NASA 仍計劃在 2030 年將人類送往火星。

So do you think it's actually going to happen?

那你認為這真的能成真嗎？

Let us know in the comments below and tell us what other obstacles you want us to explain.

在下方留言讓我們知道，也說說想要我們解釋的障礙問題。

If you want to see more Space Crafts check out this playlist here.

如果你想看看更多 Space Crafts 的影片，那就看看這邊的播放清單。

And be sure to let us know in the comments what astronomical phenomena you want to learn more about.

務必在下方告訴我們你想了解的天文現象。

Thanks for watching Seeker! Don't forget to subscribe.

謝謝觀看 Seeker 的影片！別忘了要訂閱。