Name: 冷戰如何讓我們擁有谷歌地圖 (How The Cold War Gave Us Google Maps)
Uploaded: 2021-01-14T08:55:34.000Z
Duration: 5 min 18 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。

It's one of the most important technologies of the 20th century.

第二類條件句型

If it failed tomorrow, banks would crash, planes would get lost

情態副詞

and you'd probably struggle to find your way around the city

It's called GPS and it was designed to defeat the Soviet Union.

This is how a Cold War technology went from guiding bombs to guiding your Uber.

GPS is a network of satellites which allows you to open your phone and know where you

But its roots can be traced back to the world's first satellite.

"Today a new moon is in the sky. A 23 inch metal sphere, place in orbit by a Russian

In October 1957 The Soviet Union launched Sputnik.

The Space Race between the USSR and America had begun and the U.S. was losing.

"All over the world people are tuning in to the bleep bleep of the satellite, which carries

aboard the complex mechanism necessary to transmit secrets of the universe"

As the beach ball sized satellite flew above, American scientists noticed that the radio

frequency it was transmitting increased as it approached and decreased as it moved away.

It's called the Doppler Effect, and it could be used to locate the satellite.

This was a Eureka moment. If a satellites position was known, the position of a receiver

In 1978, over twenty years after Sputnik, the U.S.A. launched its first Navstar satellite.

"They will provide highly accurate and continuous global coverage

Unlike earlier navigation satellites , Navstar would give a constant positioning service

Each satellite carried an atomic clock which broadcasts its location with a time stamp.

By using the location and time data from at least four satellites, a GPS receiver can

tell you where you are, your altitude and the speed and direction you're moving in.

24 satellites are needed to cover the globe.

This was cutting edge technology, run by the military, for the military

But that all changed when tragedy struck.

"My fellow Americans, I'm coming before you tonight about the Korean Airline massacre"

On September 1, 1983, a Russian fighter jet shot down a Korean Airline's plane on its

The plane had deviated from its original route and flown through Soviet airspace.

Radio technology couldn't track the plane because of its limited range.

Just two weeks after the attack, President Reagan made GPS available for civilian use

But the U.S. military was concerned. They didn't want to give away

The decision was made to restrict GPS's accuracy by purposefully messing with the

It would take another decade, several more GPS satellites, and a war, for the technology

In August 1990, the U.S. and it allies launched Operation Desert Storm to remove Iraqi forces

This was GPS's first full military test and it passed with flying colours.

It allowed troops to navigate and direct fire with unprecedented accuracy.

While cruise missiles were guided to their exact locations

The Department of Defence paid million to U.S. manufacturers to provide troops with

After the war, manufacturers quickly found ways to market the new technology.

Then in 2000 GPS's accuracy restrictions were lifted

Since then the technology has become intertwined with our modern lives

GPS is the global time keeper. Its atomic clocks are accurate to within 40 nano seconds

that's four thousand-millionths of a second.

Banking systems rely on it to timestamp transactions, including withdrawing money from ATMs.

It is used to keep our trains running on time and reduce farm wastage

Not to mention all the apps that rely on GPS.

Today the civilian satellite navigation market is worth nearly thirty five billion dollars

And is expected to grow to more than eighty three billion by 2022.

Compare that with the global military market and civilian uses now dwarfs it

It may have been born out of the Cold War, but GPS services are now a critical part of