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  • Have you ever wondered what Earth would be like if it had a big, gorgeous ring like Saturn's?

  • Well, in the 1960s, we did almost put a ring on Earth.

  • Starting in 1961, the US military tried to launch hundreds of millions of tiny copper

  • needles into space to create a reliable boost for their communications systems.

  • They called it Project West Ford.

  • At the time, if the US wanted to send long-range messages to their allies on the other side

  • of the Atlantic, they had two main options:

  • They could send them through undersea cables, or by bouncing radio signals off of the ionosphere,

  • a layer of the upper atmosphere that stretches from about 50-1000 kilometers up.

  • The ionosphere is full of charged particles like ions and electrons, which means you can

  • sometimes use it as a kind of long-range, signal-boosting antenna.

  • When radio waves hit electrons in the ionosphere, they vibrate at the same frequency as the radio wave.

  • And as they vibrate, they emit radio waves of their own, bouncing the signal back down to Earth.

  • The problem was that neither of these approaches are fool-proof.

  • Undersea cables can be sabotaged, and since this was the Cold War, sabotage was business as usual.

  • And the ionosphere is really unpredictable.

  • The number of electrons available to carry a signal changes with the seasons, solar weather,

  • and plenty of other factors that we still don't understand.

  • So, the US military wanted a system that was reliable and beyond sabotage.

  • They decided that if the ionosphere wasn't reliable for sending messages, well, they'd

  • just make something that was.

  • And so Project West Ford was born.

  • The idea was to launch 480 million copper needles into space where they would fill the

  • orbit they were placed into, creating a ring.

  • The needles were each 1.28 centimeters long, and about as thin as a human hair.

  • During the testing phase, each of these copper needles would help boost the signal for a

  • receiver dish in the town of Westford, Massachusetts.

  • But eventually, other sites would be able to use the communications ring, too.

  • The needles would work by acting as little dipole antennas.

  • At its simplest, a dipole antenna is basically a wire that's exactly the right length to

  • boost signals with a specific frequency.

  • When you carefully match the signal to the antenna this way, it creates a standing wave,

  • where the vibrations of the electrons in the needle bolster one another to produce a strong radio wave.

  • That stronger radio wave can then be picked up by other needles, or by stations on the ground.

  • The first batch of needles was launched on October 21, 1961.

  • The needles were in a cylinder, embedded in naphthalene, otherwise known as mothballs.

  • But they didn't choose that compound because they wanted the needles to smell like your

  • grandmother's closet; naphthalene was convenient because it would evaporate in the near-vacuum of space.

  • The idea was that when the cylinder was released, it would spin, creating a force on the needles

  • that would push them out into space.

  • That force, combined with the evaporation of the naphthalene, would disperse the needles.

  • Andit didn't work.

  • The test failed because even though the needles were pushed out of the cylinder, there were

  • so many crammed into such a tight space that they clumped together into about a half dozen big clusters.

  • But in May of 1963, the military tried again, putting 350 million more needles into 5 smaller

  • cylinders instead of one big one.

  • And that launch was successful.

  • The needles transmitted radio signals much more reliably than our natural ionosphere,

  • and it would've been pretty tough for the Soviet Union to go up there and destroy the ring.

  • So if the test was successful, and the idea worked, why aren't we constantly bragging

  • about our awesome metal space ring?

  • Well, the main reason is that satellites became a thing pretty soon after that.

  • And they were a way better solution than Project West Ford.

  • Satellites are easier to put into orbit, can transmit and relay a much wider range of microwave

  • and radio wave signals, and can be actively controlled and pointed at different things.

  • Plus, it's a lot easier to fit a camera on a satellite than on a tiny copper needle.

  • The other reason we don't use a giant ring of needles anymore is that there was a lot

  • of protest from other scientists.

  • Interference from the needles would've messed with sensitive telescopes, and there were

  • a lot of people accusing the U.S. ofdirtying space”.

  • So the military shelved Project West Ford, and Earth doesn't have a ring of tiny needles.

  • But some leftovers from the project are still out there.

  • The needles they launched were meant to fall to Earth within a few years, but dozens of

  • batches of them are still being tracked by NASA, including plenty of clumps from that

  • first failed test.

  • Which is a lot of debris from just a couple of early tests.

  • If nothing else, Project West Ford helped to shape how we treat the space around our

  • planet, and made us much more aware of the debris we put up there.

  • Today, the project stands as a both ridiculous and wonderful testament to our capacity to

  • think beyond the obvious.

  • And as the time humanity tried to turn Earth into a mini-Saturn.

  • Thanks for watching this episode of SciShow Space, brought to you by our patrons on Patreon.

  • If you want to help support this show and join our Patreon community, jgo to patreon.com/scishow.

Have you ever wondered what Earth would be like if it had a big, gorgeous ring like Saturn's?

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B1 中級

那次我們給了地球一個由幾百萬根小針組成的戒指 (That Time We Gave Earth a Ring Made of Millions of Tiny Needles)

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    林宜悉 發佈於 2021 年 01 月 14 日
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