The United States has launched 480 million copper needles into space, how is it now?

Before the 1960s, there were only two ways to establish long-distance communication: either by transmitting it through cables under the sea, or by bouncing radio signals through the ionosphere.

However, these two communication methods have many shortcomings. The submarine cable is likely to be cut off for various reasons, and the communication in the ionosphere has high requirements for the density of free electrons and the wavelength of radio waves. Only specific wavelengths meet After reaching a specific electron density, it can bounce back and forth between the ground and the ionosphere, thereby achieving the effect of long-distance propagation.

However, the electron density of the ionosphere depends on the radiation dose it absorbs from the sun and other radiation sources in the universe. If there is less radiation from the sun at night, it is basically impossible to establish communication, or it is very unstable.

For the world not long after the end of World War II, the situation in all countries was unclear, especially when the United States and the Soviet Union were in the tense Cold War at that time, and this unstable communication technology was obviously not enough.

Therefore, scientists at the time racked their brains to build a new communication system, including the fact that American scientists launched more than 480 million copper needles into space.

So why are these copper needles able to help establish communication? What about the copper needles now?

The West Ford Project: The Role of the Copper Needle

The U.S. project to launch copper needles into space, known as the "Seaford Project", was proposed in 1958 by Walter E. Morrow, a scientist at MIT's Lincoln Laboratory.

The purpose is to use hundreds of millions of tiny copper needles to build a "copper needle ring" around the earth above the earth. This ring can permanently reflect radio signals without being limited by the sun and other interference, perfectly replacing the original one. ionospheric scheme.

On October 21, 1961, they started their first test with over 100 million copper needles fired, but unfortunately the test failed because the needle copper did not spread out as planned in the orbit.

On May 9, 1963, after learning the lesson, the United States made a second attempt, and a batch of 350 million copper needles was sent into orbit again.

This time, they squeezed these copper needles tightly into a device made of naphthalene gel. The whole package of needles weighed only 20 kilograms. Then they were sent to Earth orbit along with the satellite. The naphthalene gel would quickly evaporate in space and release copper needle.

According to the original plan, 350 million copper needles will be gradually released in the earth's orbit over a period of 2 months, and then form a ring around the earth (if successful, the earth will have a ring like Saturn).

Eventually, the halo will be 15 kilometers wide and 30 kilometers thick, orbiting the Earth at an altitude of 3,700 kilometers in an orbit through the South and North Pole.

Seaford's planned copper needle is 1.8 centimeters long, 0.0018 centimeters in diameter, and weighs only 40 micrograms, which is exactly half the wavelength of a microwave at 8000 MHz.

When microwaves of this wavelength hit the copper needle, it will produce a strong reflection. In fact, the copper needle at this time acts as a tiny dipole antenna, and each antenna repeats the exact same signal they receive in all directions.

On May 14, five days after launch, scientists made their first attempt at long-range communication using the Sifford copper needle.

At this point, the dipoles (copper pins) haven't spread out completely to fill their entire orbital ring, so they're still relatively close to each other.

That day, engineers on the West Ford program used 18.5-meter microwave dishes in both California and Massachusetts to send voice transmissions at about 20,000 bits per second—about the speed of a 1992 phone modem.

However, to the engineers' surprise, as the copper needles were scattered, the data transfer rate dropped significantly, and by June 18, only 400 bits per second could be transferred.

At this time, the copper needle had not completely filled its ring, and it continued to spread. By July 2, its transmission rate could no longer establish communication, so the project was terminated.

In fact, this project seems to be very difficult to succeed now, because the copper needles are made so tiny that it will be far away from each other and lose function for various reasons.

But people at that time were so daring to think and act, and they tried it twice.

Copper needles pollute Earth's orbit

The Westford program sent a total of more than 480 million copper needles to Earth orbit twice. I don't know what you think of when you hear such a thing. Anyway, I think of the intractable sky garbage.

Although the Seaford project has been technically successful—at least briefly, the project has been met with strong opposition from all walks of life from the moment it was proposed.

Of course, at that time, humans had just sent artificial satellites, there were only a handful of man-made products in space, and there was no concept of space junk. The main concern of astronomers at that time was that these dense copper needles would affect astronomical observations.

However, at that time, the United States did not give up this doomed project because of strong opposition from others. The reason is very simple. Space exploration representing the future of mankind was obviously optional to them, and now it is possible from other countries. Threats, they believe, are the ones that need to be addressed most.

The United States fired the copper despite any dissenting voices on the grounds that the copper needles were carefully designed to return to Earth within a few years of their launch, and that the copper needles were small and far away so that they would not affect astronomical observations. Needle.

In fact, as long as a slightly sane person should know, a "copper needle ring" that is fully functional enough for reliable communication, will it be less dense? Will it return to Earth in a few years?

So, thank you for the failure of this project, otherwise the Earth's orbit would be full of copper needles.

Fortunately, these copper needles, which were only tested, did re-enter the earth's atmosphere in large numbers around 1970. Because they were so small, they were basically unscathed when they re-entered, and slowly fell to the earth's surface.

The project has received little attention now, and the only data that can be found is that as of March 2020, 36 needles are known to still be in orbit.

Known copper pins still in orbit are marked and disposed of when they are about to impact the spacecraft to avoid damage.

However, no one knows how many copper needles remain unobserved, and although these space junk are tiny, they are no small threat to the space industry.

at last

It is believed that studies in the 1970s showed that most of the copper needles fell to the Arctic highlands, about five copper needles per square kilometer.

At the time, the United States tried to find these copper needles, because it would help them understand the space environment, and they also tried to resume the project.

However, to find such tiny copper needles in billions of tons of Arctic ice and snow is tantamount to looking for a needle in a haystack, and has to give up.

In fact, by the 1970s, such a project was completely unnecessary, because almost at the same time as this project, communication satellites appeared.

Perhaps, the "copper needle ring" will be more resistant than communication satellites!