Name: SpaceX將如何讓我們上火星？ (How Will SpaceX Get Us To Mars?)
Uploaded: 2021-01-14T06:58:39.000Z
Duration: 8 min 24 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

進階形容詞比較級句型

For as long as humans have walked on this earth, we have stared into the black expanse

of space. Wondering where our place in the universe was and why we are here. The rhythm

of the moon’s phases has guided humanity for millennia, but Galileo was the first to

point a telescope towards it and identify its mountains and craters. Not just that he

saw that those distant heavenly bodies had moons of their own, a discovery that shook

the religious world’s view of our place in the universe.

Fast forward 300 years and we have landed 12 men on our moon. An achievement that was

largely driven forward in a world living in the shadow of the threat of global nuclear

war. Since that threat has subsided our race to expand into space has waned. The Mars society

put it best with their founding statement. Civilisations, like people, thrive on challenge

and decay without it. The time is past for human societies to use war as a driving stress

for technological progress. As the world moves towards unity, we must join together, not

in mutual passivity, but in common enterprise, facing outward to embrace a greater and nobler

challenge than that which we previously posed to each other. Pioneering Mars will provide

such a challenge. One man has embraced that challenge like no

other and his name is Elon Musk. Today we are going to investigate how will Space X

get us to Mars. Elon Musks ultimate goal is to reduce the

cost of space travel. He believes if he can get the cost of a ticket to Mars down to around

half a million USD, the overlap of people who actually want to go to Mars and the people

who can actually afford it will be great enough to fund a Mars colony.

The most efficient way, that is the one that uses the least amount of fuel, to get to Mars

from Earth is with the Hohmann transfer method, named after Walter Hohmann, who first proposed

the idea in 1925. With this method you wait for earth to be at it’s closest point to

the sun and then launch. Mars needs to be about 44.4 degrees ahead of earth so that

Mars will be at it’s most distant point from the sun when the vehicle arrives. This

alignment happens once every 26 months. This is not the short or fastest path to Mars,

but it requires the least amount of energy input. When getting the cost of travel down,

this is the deciding factor. As I mentioned in my last video, the Space

Shuttle could transfer one kilo to low earth orbit for 18000 dollars, the falcon 9 can

do the same for just 2700 and Space X is continuously working to reduce that cost. Let’s take

a look at the falcon 9s launch sequence to learn some of the ways Space X has reduced

the cost of operation. The Falcon 9 first stage is powered by 9 Merlin

engines. These engines have the highest thrust to weight ratio of any booster engine ever

made at 155:1. This means the engines can lift more with less fuel and do it faster.

At launch the 9 engines produce 7900 kN of thrust lifting the 550 tonne rocket of the

ground and gradually accelerating it to 5 times the speed of sound. This section, called

the interstage, houses another Merlin engine that is designed to work optimally in the

vacuum of space. The first stage now separates about 75 km above our planet’s surface and

reveals the second stage engine. It’s interesting to note that the interstage remains connected

to the first stage, after seperation. This was not the case for the Saturn V, as the

interstage needed to wait for the engines of the second stage to fire before separating

using pyrotechnic charges. This ensured a clean separation, as there were worries that

the interstage would collide with the engines as it separated. due to clearance issues.

This is not a problem with the Falcon 9, making the interstage reusable and again saving money.

The Merlin engine of the second stage is designed to be shutdown and restarted multiple times

to deliver the payload to the appropriate orbit, or increase the velocity enough to

perform the Hohmann transfer to Mars. The payload is stored inside this composite fairing,

which is big enough to fit a school bus. When the time is right, the fairing splits in half

and drifts away from the second stage. The payload is now released into orbit around

earth. Meanwhile the first stage has begun its decent

back down to earth. Cold gas thrusters fire to flip it around, once this maneovre is complete

the engines will fire again to bring the speed down for re-entry and give it an appropriate

trajectory to reach the landing site. Upon re-entry the grid fins deploy which provide

aerodynamic control allowing it to steer. These are fantastic little devices that provide

excellent control at supersonic speeds. This mesh structure provides a huge amount of control

surface area in a small amount of space, which allows them to be easily stowed away during

launch to reduce drag. Grid fins are also much shorter than conventional planar fins,

so they generate less hinge moments meaning they need smaller motors to control them in

high speed flow. As the first stage descends closer to sea

level, the cold thrusters, grid fins and merlin engines work together to control the precise

landing on the drone ship barge. The reason Space X uses this barge is another cost saving

measure. The falcon 9 launches from land towards the sea for safety reasons, when the first

stage separates it’s over open ocean and if it needed to return to land it would need

to slow down, turn around and use more fuel to get back to where it started. Instead the

drone ship can place itself at the predicted landing zone and wait for the first stage,

this way the falcon 9 just needs a little bit of extra fuel to slow itself down to land.

Most people see Space Xs true innovation in their reusable rockets, but their innovation

in the manufacturing field is just as significant. Space X was the first space company to employ

a method called vertical integration to manufacture their rockets. This means that Space X designs

and manufactures nearly all it’s components itself. The Merlin engines, the aluminium-lithium

fuel tanks, the composite fairing for holding the payloads, the dragon spacecraft, the flight

control computers and the coding that goes into them. They are all designed manufactured

by space X. Comparing this to the Space Shuttle. Rockwell

developed the orbitor, Lockheed Martin developed the external tank and ATK developed the solid

rocket boosters. Each of these companies have their own subcontractors too.. Each subcontractor

adds a markup percentage to their selling price in order to make their own profit. Manufacturing

everything yourself eliminates all of these price markups. It cuts out the middlemen,

like buying popcorn as kernals and cooking them yourself, rather than buying them from

the cinema for 10 dollars. It has the added benefit of allowing you to have full control

of your quality control and creates an efficient product development system. All of your employees

can speak and collaborate to improve and develop new designs. Elon insists on open plans offices

to remove any communication barrier. He himself works in a cubicle. This creates the perfect

environment for continual innovation and if we want to get to Mars that is going to have

to happen. So you may be wondering what is next for Space

X. They will be launching their Falcon 9 heavy

variant at the end of this year. According to Space X the falcon 9 can currently launch

1 kilo to Mars for 15400 dollars, but the heavy variant can launch one kilo for about

6600 dollars. The average American weighs 80 kg, ignoring all other costs like how you

will live on Mars and how you will survive journey there, the raw price for a one way

trip to Mars will be half a million dollars. Musk aims to bring the price of a round trip,

including all other expenses, to Mars, down to half a million total. In 2010 Space X presented

concept designs for future heavy lift rockets, that will help towards that goal. They are

also planning to replace the 9 Merlin engines of the Falcon 9 with one incredible powerful

engine, dubbed the Merlin 2, that will increase the thrust to weight ratio even more. I, for

one, am really excited to see what Elon Musk and his incredible employees have in store

Thanks for watching! As some of you may know I quit my job earlier this year with the ridiculously

ambitious goal of growing this channel so that I can spread the incredible work that

engineers do all over the world. I never thought I would be able to do it full time for long,

as I have been eating away at my savings, but thanks to this week’s sponsor I can