You may have been told by your parents that you are on another planet when you are either day dreaming or have said something silly， but have you ever wondered what it would be like to live on another world？ How different would it be compared to life here on Earth？

Out of the remaining seven planets in our Solar System， we need a world that is not too hot， not made of gas and nor so far away from the Sun that it is too cold. Can you guess which planet that is？ The answer is， of course， our red， rocky next-door neighbor， Mars. But while it is the closest planet to us， it takes a very long time to get there—just imagine a car journey with no stops that takes up to 9 months！

Mars is lighter than Earth and， because of this， you would be about 62% lighter there than you are here. That means that if you weighed 100 pounds， then you would weigh only 38 pounds on Mars. Because of the difference in gravity and the red rocky terrain1）， care must be taken when landing your rocket onto the surface of Mars. However， while you have succeeded in getting to the planet as well as landing， the hard work and watching out for your safety is not over. You need to make things more efficient and cheaper and that would require you to stay on the red planet for good. Would you and your friends be able to live up to the challenge？

Mars and Earth are not just different in color， they are made of different materials—Mars' surface is covered in dry iron oxide dust （just like the rust that you can find on an old car）， whereas our home is mostly wet with water. Since the air on Mars is thin and made of carbon dioxide—the air that you breathe out rather than breathe in—you will need to wear a spacesuit， and because the red planet hardly has an atmosphere， you would need to protect yourself from the Sun's radiation that here on Earth our thick atmosphere protects us from. Can you think of something that will give you extra protection from these harmful rays while wearing your spacesuit？

Your main task on Mars would be to make it nice and safe for your family and friends before their arrival on the red planet. But they don't want to wear a spacesuit or walk around with an umbrella to keep themselves safe from the radiation， they want to be able to live life as they do on Earth. The only solution would be to make Mars like Earth—but how？

Terraforming2） is the answer！ At the moment though， this is an imaginary process made up from a combination of real science and science fiction. Terraforming involves changing the atmosphere， temperature and surface of a planet just to make conditions much more comfortable for you， your friends and family. Playing your favorite outdoor games would be impossible on the red planet without terraforming—especially in a clunky3） spacesuit！ Because Mars was very much like Earth in the early stages of its history， astronomers believe that this planet is the easiest to transform into a world very similar to Earth. There would be two important changes that would be up to you to make. Firstly， so that you are safe from the radiation and are kept warm， you would need to change Mars' atmosphere. Since the atmosphere is made of carbon dioxide， you would need to make sure that Mars gets enough water as there is not enough water currently on the red planet. However， in order to get more water， you would need to send a search party to other places in the Solar System—icy asteroids4） and comets5）， and the icy moons6） of the gas giants Jupiter7） and Saturn8）， are really good places to look！

Getting enough water to Mars is a very hard task， but with the combination of carbon dioxide， water and heat from the Sun， you and your friends have made the pressure much higher on the red planet—this means that you are able to take your pressure suit off！ You have also melted ice on the red planet， making about half of the surface much warmer and wetter—with the plants you have brought from home， you are able to take care of them on the surface. But how can plants help us to make Mars a friendlier place？ The flowers that you might have on the window ledge9） at home or in your garden love carbon dioxide and they are more than happy to turn Mars' air into oxygen for you！

You have made the red planet much more homely for everyone， but your task is still not over. You also need to add more heat to the planet as well as another protective shield around you to stop other harmful rays from reaching you. It is time to build a home， just like your home back on Earth which you might use to stay in the shade on a hot summer day！ On your travels on the surface， you have come across volcanoes. When volcanoes drain lava10）， it often happens along a tunnel called a lava tube. Realizing that some of the volcanoes could be inactive， you head off towards the largest volcano in the Solar System， Olympus Mons， to make not just yourself at home， but the people making their way from Earth at home too！

當(dāng)你在做白日夢或是說了傻話時(shí)，父母也許會(huì)說你神游到另一個(gè)星球去了，不過你是否曾想過生活在另一個(gè)世界會(huì)是什么樣子？比起地球上的生活會(huì)有什么不同呢？

從太陽系其余的七顆行星中，我們需要找到一顆既不太熱，又不能距離太陽太遠(yuǎn)而溫度過低的非氣態(tài)行星。你能猜到是哪顆行星嗎？答案當(dāng)然是我們隔壁的鄰居——多巖石的紅色火星。不過，盡管它是離我們最近的行星，還是需要花很長時(shí)間才能到達(dá)那里——不妨想象一趟中途不停車、耗時(shí)九個(gè)月的汽車旅行吧！

火星比地球輕，因此，你在火星上將比你在地球上輕62%左右。也就是說，如果你重100磅，那么你在火星上將只有38磅。由于重力的差異和火星表面布滿紅色巖石的地形，你乘坐火箭在火星表面著陸時(shí)必須小心。不過，即使你已經(jīng)成功抵達(dá)火星并安全著陸，艱苦的工作并沒有結(jié)束，安全意識也不能放松。你需要讓這里的生活更有效率、費(fèi)用更加低廉，這就要求你永遠(yuǎn)留在這顆紅色星球上。你和你的朋友們能夠經(jīng)受住這個(gè)挑戰(zhàn)嗎？

火星跟地球不只是顏色不同，它們的物質(zhì)構(gòu)成也不同：火星表面覆蓋著干燥的氧化鐵塵埃（就跟你在舊汽車上看到的鐵銹一樣），而我們的地球表面大部分被水覆蓋。由于火星上空氣稀薄，而且是由我們無法吸入、只能呼出的氣體二氧化碳構(gòu)成的，所以你需要穿上宇航服。而且因?yàn)檫@顆紅色行星幾乎沒有大氣層，所以你需要保護(hù)自己免受太陽的輻射——在地球上有厚厚的大氣層為我們阻擋這種輻射。你還能想出有什么東西能夠在你穿著宇航服時(shí)為你提供額外的保護(hù)，以阻擋這些有害射線嗎？

你在火星上的主要任務(wù)將會(huì)是在你的家人和朋友來到這顆紅色行星之前，把它改造成一個(gè)安全、宜居的地方。但是，他們可不愿意為了保護(hù)自己不受輻射傷害而穿著宇航服或者打著傘走來走去，他們希望能像在地球上那樣生活。唯一的辦法就是把火星改造得像地球一樣——但是怎么改造呢？

答案就是“地球化”！但是在現(xiàn)階段，這還只是一個(gè)結(jié)合了現(xiàn)實(shí)科技與科幻小說的假想過程。地球化包括改造行星的大氣、溫度和地表，使那里的環(huán)境讓你、你的家人和朋友感覺更為舒適。如果不對這顆紅色星球進(jìn)行地球化改造，你就不可能玩你最喜歡的戶外游戲，尤其是穿著笨重的宇航服玩！因?yàn)榛鹦歉幱谧陨戆l(fā)展史早期的地球非常相像，天文學(xué)家相信這顆行星最容易被改造成與地球高度相似的星球。有兩項(xiàng)重要的改造工作需要你來完成。首先，為了保暖和免受輻射的傷害，你需要改造火星的大氣。由于火星的大氣由二氧化碳構(gòu)成，而這顆紅色的星球上現(xiàn)在沒有充足的水，所以你先要確?；鹦巧嫌凶銐虻乃２贿^，為了獲取更多的水，你得派一個(gè)搜索小組前往太陽系的其他地方，冰封的小行星和彗星，以及氣態(tài)巨行星木星和土星的冰封衛(wèi)星都是非常理想的搜索地點(diǎn)。

讓火星上有充足的水是一項(xiàng)非常艱巨的任務(wù)，但是在二氧化碳、水和太陽熱能的共同作用下，你和朋友們已經(jīng)讓火星上的氣壓大幅提高——這就意味著你可以把增壓服脫下來了！當(dāng)你再把運(yùn)到火星上的冰融化時(shí)，火星表面大約有一半的地方會(huì)變得溫暖和濕潤得多——現(xiàn)在你可以把那些從地球上帶來的植物種在火星表面。但是植物怎么幫助我們將火星打造成一個(gè)更宜居的地方呢？你可能會(huì)在自家的窗戶壁架上和花園里種植一些花草，喜歡二氧化碳的它們會(huì)非常樂意地為你把火星上的空氣轉(zhuǎn)化成氧氣。

你現(xiàn)在已經(jīng)為大家把這顆紅色行星改造得更有家的感覺了，但你的任務(wù)依然沒有結(jié)束。你還需要再多加一重為你阻擋有害射線的防護(hù)屏障，并且讓這顆行星變得更加溫暖。是時(shí)候安一個(gè)家了，就像你在地球上的家一樣，在炎熱的夏日你可能需要它為你提供陰涼。你在火星表面旅行時(shí)，曾經(jīng)碰到過一些火山?；鹕絿姲l(fā)排出熔巖常常會(huì)形成一條通道，叫做熔巖隧道。你發(fā)現(xiàn)一些火山可能并不活躍，于是便朝太陽系最大的火山奧林匹斯山進(jìn)發(fā)了，不僅為自己，也為正在從地球前往火星的人們安一個(gè)家。