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As of this moment, over half a million pieces of space junk are racing in various orbits above the earth, will space also become another place that will be used without calculation like the air, the land and the sea?

We have all heard about the challenges and dangers involved in flying into space, and we in Israel have bitter personal experience in this field. In recent years, however, a new threat has been increasing for those who dare to go beyond the limits of the atmosphere.

Here's the problem. As of this moment, over half a million pieces of space debris are racing in various orbits above the Earth. I use the word 'speeding' deliberately - the speeds of these pieces of garbage range from twenty thousand kilometers per hour to thirty thousand kilometers per hour and more, and each one can be the size of a pea or more. Don't let the 'pea' illusion fool you: it's all about speed. When a piece of metal with a diameter of a single cm crashes into a spaceship that moves by itself at a speed of several thousand kilometers per hour, the energy released in the collision is enormous. The average speed of an object in low Earth orbit is around seven kilometers in one second - roughly ten times the speed of a gun bullet. The kinetic energy, the energy of movement of the object, increases according to the square of its speed. This means that if a tiny object the size of a gun bullet hits the spacecraft at such a speed, the impact will be XNUMX times harder than the impact of a normal bullet. If we look at it from another angle, an object a hundred times smaller than a projectile is enough to cause damage to the spaceship as if it had been shot at close range.

How did we get to this situation, with hundreds of thousands of potential disasters hovering over the planet? The reason is neglect that has been going on for many years. Here is a representative example.

In the XNUMXs, before the age of satellites, most secret military communications were conducted via underwater cables in the oceans. The American generals feared that in time of war the Russians would simply cut these cables, and sought an unstoppable means of communication.

Someone came up with the following clever idea: Next, millions of tiny needles will be sent into space, which will travel in a circular orbit at an altitude of about three thousand seven hundred kilometers. I think you can guess where this whole story is going. The intention was that the small needles, each one and a half centimeters long, created a sort of 'metal belt' around the earth (the 'West Ford Belt', it was called). If you transmit radio waves at a frequency that matches the length of the needles (eight gigahertz, in this case) the radio waves will scatter from the West Ford belt and return to the earth, thus enabling radio wave communication around the world without interference.

A great idea, no doubt, and it even proved itself in reality: the needles were scattered in the desired trajectory, and the Americans managed to make several successful long-range radio transmissions. At the same time, the boom in the world of communication satellites began, and a communication satellite is a great replacement for the metal belt: they do the same thing, in principle, but they are much more efficient. A satellite is an active device: it receives the radio waves from the earth, it can amplify them or change their frequency, determine the strength of the transmission and send back a quality transmission. The West Ford belt, on the other hand, is just a bunch of completely passive needles. It is quite clear, then, why this idea was quickly abandoned, and we are left with four hundred and eighty million needles to dodge. A significant part of the needles have already managed to fall to the earth since then, but God willing, there are many more in the sky.

The number I mentioned earlier, half a million pieces of garbage in space, refers only to pieces of a size of a centimeter or more, but there are millions of smaller and equally dangerous particles. Over the years, about sixty windows have been replaced in the various space shuttles due to deep scratches and dents caused by the impact of small particles. In one of the more serious cases remembered by NASA, a collision with a one-millimeter-long paint particle almost completely shattered the shuttle's window, leaving a crater several centimeters in diameter on the windshield. If that particle hit an astronaut during a spacewalk, for example, the suit would almost certainly tear.

It is not always about satellites or spaceships. Garbage in space is very diverse: the astronauts of the Mir space station threw over two hundred heavy garbage bags into space. Astronauts on spacewalks occasionally lose cameras, screwdrivers, pliers, even gloves. But what are the exceptions: most of the objects that float in space are the result of collisions and explosions that at once scatter tens of thousands of shards and fragments everywhere.

One of the solutions implemented today is passive shielding of spacecraft. 'Magan Wiffle' is one of those passive protections: the principle is simple but clever. Instead of the wall of the spacecraft being made of one solid layer of opaque material, the wall is built from several layers adjacent to each other so that there is a tiny space between them. When a small particle, like the paint particle that almost shattered the space shuttle window, collides with the wall - the encounter creates intense heat that partially melts the particle. When the particle passes the outer wall and meets the inner layer after it, it is already liquid and spreads over a larger area. The large area (don't forget, it's still only a few square centimeters) means that the pressure that the collision exerts on the wall is also dissipated, and the wall holds up. The effectiveness of a waffle shield is limited to small objects only, of course, and a piece of metal the size of a golf ball will go through it like it were margarine and probably even come out the other side of the spacecraft. I wouldn't want to be an astronaut on the space station when that happens.

Nevertheless, there is progress here in the right direction. In the past, no one devoted any effort to getting rid of satellites after their service ended - the main concern of the engineers was to make sure that if the satellite returned to Earth, it would not fall on anyone's head. It's not an easy task, and the astronauts in the first spaceships didn't know (or knew very roughly) where they would fall when they returned. John Glenn, the first American in space, took a note with him in the spaceship on which was written in several languages ​​- "I am a stranger from the stars and I say hello. Take me to your leader and you will receive a huge reward in eternal life." Glenn later explained that he was afraid that he would fall into the hands of a primitive tribe in the Pacific Ocean, and in all the movies he has seen the hero always says to the savages Take me to your leader. Today's engineers try to drop the satellites in particularly remote areas on Earth, to minimize the risk of harming civilians.

Scientist Donald Kessler came up with the theory known as Kessler Syndrome. According to Kessler's calculations, even if today we stop all spacecraft launches at once, the amount of trash that has accumulated in space has already reached a critical mass. The mechanism that is most responsible for the pollution of space is collisions and explosions, and every collision between two bodies creates masses of small fragments that scatter in space, collide with other bodies and so on. Within a few decades, Kessler speculated, the inevitable collisions between the pieces of garbage already in the sky today will fill space with countless dangerous particles. The particles would create a deadly shell around the Earth, a shell that would de facto prevent any possibility of going into space. If this dire vision is realized, we may find ourselves in a situation where entire generations of Earthlings will not be able to develop advanced space technology, and this could have a severe impact on technology in general.

Are we late? Will this be the case in the coming years? time will tell. As of today we treat the air we breathe, the drinking water in the ground and the salt water of the oceans with the same carelessness as the scientists treated the 'infinite' space outside the earth. At the very least, we learn one clear lesson from the whole thing: it's never too early to think about the future.

(The article is taken from the program 'Making History!', a bi-weekly podcast about science, technology and history at www.ranlevi.blogspot.com)

1. by Michael R. (formerly Michael) Responded:

5:
Just for fun:
The pieces of junk on Earth move at about 30 km/s around the sun and the sun itself moves at 220 km/s around the center of the galaxy (and of course I ignored their rotation speed around the earth's axis because it varies with latitude).
In short - this is actually junk that moves quite fast - at least in relation to the center of the galaxy.
The point is, of course, that the garbage speeds on Earth are synchronized with each other and with us, and thus collisions are avoided.
It will be many more years until the pieces of garbage we have seeded in space reach (due to collisions among themselves) a similar synchronization.

2. To 1 Responded:

There may be a lot more than half a million pieces of junk in God, but not a single piece flies at a speed of thirty thousand kilometers per hour.
If you intend to make proportions, put this figure in as well (however, I quite agree with your claim. Sad.)

3. lion Responded:

Here is the only solution to the problem: Let's assume that with the current amount of garbage we still manage. To prevent Kessler syndrome, all decommissioned satellites must be intercepted. This can be done by building a small dedicated rocket that will be launched at the satellite, attach to the disabled satellite and accelerate it with a rocket engine so that it falls to the ground.
The real problem is budget for such a project. In my opinion, the budget should be international, with each country participating proportionally according to the number of satellites it has in space. In the future, each new satellite must include an engine with a sufficient amount of fuel to slow it down and drop it to Earth at the end of its life.

4. י Responded:

It is possible to detonate many hydrogen bombs that will vaporize at least some of the particles

5. Vic Responded:

Amusing wording isn't it? "Exploitation of Space"
Happy holiday to all of us!

6. point Responded:

take in proportion. On the surface of the earth there are more than half a million pieces of garbage, much more.

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