[0x0B] Making Life Multi-planetary

Mars

Becoming a multi-planet species beats the hell out of being a single planet species. We would start off by sending a mission to Mars where it would be obviously just landing on rocky ground or dusty ground.

成为一个多星球聚居种族的感觉简直碉堡了（beat the hell out of）。我们会派一支先遣队（mission）去火星，显然（obviously）他们将登陆的是一个荒凉萧索的不毛之地（rocky & dusty ground）。

Mars Transportation Architecture | 火星运输计划

It is the same approach that I mentioned before which is to send the spaceship up to orbit, refill it until it has full tanks, and then it travels to Mars and lands. For Mars you will need local propellant production. But Mars has a CO2 atmosphere and plenty of water ice. That gives you CO2 and H2O, so therefore you can make CH4 and O2 using the Sabatier Process. I should mention that, long term, this can also be done on Earth. Sometimes I get some criticism along the lines of: Why are you using combustion in rockets and you have electric cars? Well there is no way to make an electric rocket, I wish there was, but in the long term you can use solar power to extract CO2 from the atmosphere, combine it with water and produce fuel and oxygen for the rocket. The same thing that were doing on Mars, we could do on Earth in the long term.

我们使用的方案（approach）正是我以前提到的，先把宇宙飞船送到预定轨道，加满油后（refill until it has full tanks）马不停蹄奔向火星。在火星上降落后，你需要在当地找到推进剂补给（propellant production）。火星有富含 CO2 的大气和大量的固态水（water ice）。这样你就有了 CO2 和 H2O，可通过Sabatier反应生成CH4 和 O2。不得不说的是（I should mention that），长期以来，地球上也可以实现这个反应。有时候我会受到类似这样的批评（criticism along the lines of）：“为啥你一边造电动车一边还在火箭上烧甲烷（using combustion in rockets）？” 我当然希望可以用电，但实际上根本没法（there is no way to）造一个电动火箭出来。从长远来看（in the long term），我们可以使用太阳能（solar power）从火星大气中分离（extract） CO2，然后和水一起反应从而为火箭供应燃料和氧气。我们将在火星上做的事，长期以来已经在地球上实践了。

Similar to the moon, you land on Mars, but the tricky thing with Mars is we do need to build a propellant depot to refill the tanks and return to Earth. Because Mars has lower gravity than Earth, you do not need a booster —— you can go all the way from the surface of Mars to the surface of Earth just using the ship. You need a max payload number of about 20 to 50 tons for the return journey to work, but is a single stage all the way back to Earth.

我们登陆火星和登月没啥差别。最困难的（tricky）事儿莫过于我们需要建造一座加油站（propellant depot）来给油罐加满油好让BFR可以飞回地球。由于火星上的重力比地球小得多，所以我们并不需要助推器 —— 你完全（all the way）可以只用飞船就从火星表面开回地球。你需要一个 20 - 50 吨最大载荷的燃料舱来完成返航，但是只需要一级火箭。

Mars Entry | 进入火星

For Mars entry, you are entering very quickly, going seven and a half kilometers
a second for mars there will be some ablation of the heat shield, sort of like a brake pad wearing away. It is a multi-use heat shield, but unlike for Earth operations, it is coming in hot enough that you really will see some wear of the heat shield.

进入火星阶段飞船速度达到 7.5 km/s，所以整个过程一晃即逝。飞船的隔热罩（heat shield）会有一些烧蚀（ablation），有点像刹车盘（brake pad）磨损（wear away）。BFR的隔热罩是多功能的（multi-use），但是和地球大气层不同，穿越火星大气时温度真的太高了以至于你会看到隔热罩有些磨损（wear）。

Mars Landing | 降落火星

Because Mars has an atmosphere, albeit not a particularly dense one, you can remove almost all the energy aerodynamically. And we have proven out supersonic retropropulsion many times with Falcon 9, so we feel very comfortable about that.

因为火星有一层大气，尽管不是特别浓厚（dense），你依然可以关掉几乎所有的空气动力系统（aerodynamically）。我们已经在猎鹰9上反复验证了（prove out）超音速状态下的反推进系统（supersonic retropropulsion），所以对此非常自信（feel comfortable about that）。