A 20-kilometer metal rope was thrown into the ionosphere to harness geomagnetism in space
In 1996, the US Space Shuttle Columbia released a tethered satellite in space. A nearly 20-kilometer-long conductive rope was connected between the satellite and the space shuttle. up to 3 amps.
Electricity is one of the most important inventions in human history. The first industrial revolution relied on steam power, while the second industrial revolution can be called the electric revolution, which greatly changed our lives and is still guaranteed today. with the development of human society.
The importance of electricity is also reflected in the fact that electromagnetism is a key point in our middle school physics. There is a saying: “Electricity generates magnetism, and magnetism generates electricity.” Many people must have heard that a magnetic field can be generated near a live wire, and the change A magnetic field can also generate an electric field. Let’s not talk about “electricity generating magnetism”, so how can “magnetism generate electricity” be realized?
The answer to this question can be found in any relevant physics textbook. The key point of magnetoelectricity lies in the change of magnetic flux. In order to change the magnetic flux, the following two methods can be used:
The first is the change in the size of the magnetic field, such as letting a bar magnet pass quickly through a set of coils. For each coil, the magnetic field near it is not constant, so a current will appear in the coil. Another common way is to let the metal conductor move in the magnetic field, which is the so-called “cutting the magnetic induction line”, and then an electromotive force will be generated in the conductor, and then a current will appear when the circuit is formed.
At this time we thought, the earth under our feet is a big magnet! Can the earth be used to generate electricity?
This idea is very novel, although it is feasible in theory, but because the magnetic field of the earth is not very strong, and the metal conductor cannot move on land without obstacles (the reason here is that the magnetic induction intensity of the earth is only 5× 10 negative fifth power Tesla, very small, so if you want to generate a considerable electromotive force, you need the length of the conductor to be long enough and the speed to be fast enough, but there are many obstacles on the ground, and the long conductor cannot move continuously), so some scientists They turned their attention to space.
We all know that space is boundless. If we can put metal conductors in space and move in the orbit of the earth, then there is no need to worry about the movement of conductors. Not only will there be no obstacles, but they will be able to move for a long time.
It was the scientists from Italy who finally put this idea into action. At the end of the last century, they carried out two tethered satellite power generation experiments with the help of the US space shuttles “Atlantis” and “Columbia”. The main device is to carry a satellite tied by a conductive rope in the space shuttle, and throw the satellite out of the space shuttle. The direction of the rope is perpendicular to the earth’s magnetic force line, that is, one end of the rope points to the center of the earth.
The general principle of the experiment: the space shuttle moves above the equatorial orbit (such a position can make the direction of the rope and the magnetic force line close to vertical when cutting the magnetic field line, so that the obtained electromotive force is also the largest), and it can circle around for a long time The earth, at this time, releases the satellite tied by the conductive rope, and the rope cuts the magnetic induction line, and in order to form a loop, the space shuttle needs to release the tethered satellite in the ionosphere in the earth’s atmosphere, because the part in the ionosphere The area is in an ionized state, and the device can form a circuit between the satellite, the conductive rope, the space shuttle, and the ionosphere.
In 1992, the Atlantis was used to conduct the first power generation experiment, but the accident was that the satellite was only released about 250 meters, and it was stuck because of a device failure, but fortunately, the flying speed of the space shuttle Fast (7.5 kilometers per second, after all, the electromotive force is equal to the product of magnetic induction, conductor length, and conductor speed), this 250-meter-long conductive rope still generates a voltage of 40 volts and a current of 1.5 mA. harness geomagnetism in space
Obviously, the scientists were not satisfied with the results this time. After all, they originally planned to put a 20-kilometer-long wire, which was only 250 meters… No, so in 1996, the Columbia space shuttle performed it. This mission, this time, went much smoother. The conductor rope was released for 19.3 kilometers (this length is already very long, after all, it is hard for you to imagine that on land, how could you run with a rope nearly 20 kilometers long? , but also get a loop out).
Although the length is acceptable, but unfortunately the length is fixed at 19.3 kilometers, why? Because the rope is broken, but fortunately, 19.3 kilometers is not far from the original 20 kilometers, at least it can be regarded as half of the success, and the current generated has reached about 3 amps. If there is no accident, the power provided Still quite impressive. harness geomagnetism in space
For this rope breaking incident, at first it was thought that the tension generated in the process exceeded the limit of the rope, but in fact it was discovered after the space shuttle brought the device back to the ground that it was because the rope melted. Be careful. The melting here is not caused by atmospheric friction, but by electric current.
Although this experiment was not completed smoothly, it at least proved that it is still feasible to use the earth’s magnetic field to generate electricity in space. But unfortunately, the power supply of our current spacecraft is not in this way (it’s a bit of an afterthought), after all, why not use existing solar energy? Not only is it convenient, but compared with this kind of rope power generation, the cost and risk are also low.
In addition, there is another reason, that is, the electric current inside the rope will cause the appearance of Ampere’s force, which will continuously reduce the kinetic energy of the entire device (including the space shuttle). But on the other hand, can we use the electric energy provided by the solar panels to make the rope generate a reverse ampere force to provide the kinetic energy of the spacecraft? Speaking of this, I personally feel that this method is not as cost-effective as bringing more fuel or improving the performance of the rocket. harness geomagnetism in space
In general, this experiment may have practiced the ideas of many people. Maybe after some mature technical guarantees, it is really possible to use this method to obtain electrical energy in the future.