The spacecraft lost control and the space station fell. The "culprit" behind it turned out to be...

Space weather is controlled by solar activity. The electromagnetic waves, high-energy particles and high-speed plasma generated by solar eruptions propagate through interplanetary space to the Earth, inducing a series of drastic changes in the Earth's magnetosphere, ionosphere and middle and upper atmosphere, which in turn makes space weather severe. In fact, with the increase in aerospace activities and the popularization of related applications, the impact of space weather, the "sunny, rainy and snowy" in space, on the normal operation of human society is increasing day by day. At the same time, space weather can also have a destructive impact on the power grid, thus having a fatal impact on the infrastructure on which society depends.

Solar high-energy particles pose a huge threat to satellite safety

The invisible killer of spacecraft

In May 1991, my country's Fengyun-1B satellite, which had been in space for only half a year, suddenly began to flip out of control. When the control personnel discovered and took measures, the propellant on the satellite had already been sprayed out. The satellite, which was designed to have a lifespan of one year, had to be scrapped ahead of schedule after only half a year. From October to November 2003, Japan's Earth observation satellite ADEOS-2 lost contact with the ground and was scrapped. A scientific payload on the Mars Odyssey probe far away on Mars also stopped working unexpectedly and could not be restored. Many other satellites also withdrew from normal working conditions and switched to safe mode to avoid risks. All of this was caused by high-energy particles from the sun and hot plasma near the earth. In the case of severe space weather conditions, they will appear very frequently and pose a threat to the safety of spacecraft.

There are two main sources of solar high-energy particles. One is the solar flare. The high-energy particles produced by this phenomenon of rapid release of energy on the solar surface often only take tens of minutes to reach the earth, and the duration of bombarding the earth ranges from a few hours to a few days. The other is the high-speed plasma group erupting from the sun, which space weather scientists call a "coronal mass ejection." In the process of the coronal mass ejection propagating toward the earth, it will push and squeeze the plasma in the interplanetary space that blocks its progress, generating an interplanetary shock wave that propagates forward with it. The interplanetary shock wave provides an accelerator for the generation of high-energy particles. When the interplanetary shock wave reaches the earth, it will cause an increase in the flux of high-energy particles near the earth. At the same time, coronal mass ejections can induce geomagnetic storms and inject hot plasma into the earth's magnetosphere system.

A solar flare event

For microelectronic components on spacecraft, the most feared part is the part with higher energy among high-energy particles. These high-energy particles can penetrate electronic components, causing data errors, circuit function confusion or computer paralysis, causing satellite abnormalities or failures, or even completely destroying the satellite. High-energy particles with relatively low energy can cause charge accumulation in circuit boards, wires and other locations inside the spacecraft, hindering the normal operation of the spacecraft. Although the energy of a single particle of thermal plasma is not as high as that of high-energy particles and cannot invade the interior of the spacecraft, their accumulation on the surface of the spacecraft will also cause surface charging and discharging effects, interfering with the normal operation of the spacecraft and even causing damage.

For astronauts working in space, high-energy particles are also a serious threat to their lives and health. If astronauts do not take prudent protective measures according to the level of high-energy particle flux at the time when solar storms such as flares and coronal mass ejections affect the Earth, they may be exposed to excessive radiation doses. During the continuous solar storms from October to November 2003, the astronauts on the International Space Station moved to a better-protected cabin to avoid danger.

Auroras are a gift from solar storms to the Earth, but strong auroral activity also means increased risk to the power grid.

The culprit for the premature fall of the space station

The density of the Earth's atmosphere decreases rapidly with increasing altitude, and it is already quite thin at an altitude of several hundred kilometers in the LEO orbit. However, for high-speed spacecraft, the atmospheric drag here is still not negligible. If the engine is not actively used to maintain the orbit, the orbit of the spacecraft will continue to decay, the orbit altitude will become lower and lower, and eventually fall. The electromagnetic radiation generated by solar flares and the heating of the middle and upper atmosphere by geomagnetic storms induced by coronal mass ejections will increase the atmospheric density in the LEO orbit than normal. Under this influence, the spacecraft must perform additional orbit maintenance, otherwise it may encounter unexpected events.

The early fall of the US Skylab is the most typical example of this effect. Skylab is the first generation of space laboratory in the United States. According to NASA's plan, this space station launched in 1973 should have worked until the 1980s and carried out space experiments with the space shuttle. However, NASA's prediction of solar activity in the mid-1970s was biased, and it turned a deaf ear to warnings from parallel government departments such as the National Oceanic and Atmospheric Administration (NOAA). When the Apollo spacecraft visited Skylab for the last time, it did not maintain its orbit sufficiently. Under the increasingly frequent solar storms, geomagnetic storms continued to occur, and the density of the upper atmosphere on Skylab's orbit increased, causing its orbit to decay uncontrollably. At the same time, the United States' manned spacecraft was at a critical juncture: the development and testing of the space shuttle had not yet been completed, and the Apollo spacecraft had been retired. The United States was unable to launch a spacecraft to rescue Skylab, which eventually led to its early fall in 1979.

Skylab

In addition, the impact of space weather will make the density of the middle and upper atmosphere more difficult to predict. For operations such as rendezvous and docking that require precise orbital control, if the actual value of the atmospheric density deviates greatly from the predicted value, the actual flight trajectory of the spacecraft may deviate greatly from the predicted orbit, and it will take longer to continuously correct the orbit in order to complete the docking.

Sources of interference in satellite positioning and radio communications

In the area 60 to 1000 kilometers above the ground, there is an ionosphere composed of charged particles. Whether the radio signal can pass through the ionosphere and the changes in the signal parameters when passing through the ionosphere are all related to the properties of the ionosphere. For example, shortwave signals can be transmitted across continents by utilizing the reflection of radio signals in this frequency band by the ionosphere; when communicating between the ground and satellites, high-frequency signals that can penetrate the ionosphere must be used. The properties of the ionosphere are mainly affected by solar activity. Once a flare occurs, the properties of the ionosphere will change immediately at the same time as the flare occurs. When a coronal mass ejection hits the earth, the geomagnetic storm caused will also induce changes in the properties of the ionosphere.

When ground equipment receives positioning signals transmitted by satellite positioning systems such as Beidou and GPS and calculates position information from them, it has already taken into account the properties of the ionosphere under normal circumstances. However, once the properties of the ionosphere change due to space weather, the actual changes in the positioning signals will differ from the preset conditions in the equipment, and the positioning accuracy of the positioning equipment will decrease. For mobile phone positioning in daily life, since the positioning accuracy requirements are not high and poor positioning can be achieved with the help of the location of the mobile phone base station, the impact of space weather will not be significantly felt. However, for high-precision field operations such as directional drilling and the new generation of aviation navigation and instrument landing systems achieved with the help of GPS, the reduction in positioning accuracy caused by ionospheric changes is enough to interfere with their normal work.

In 2001, the radio communication of our troops searching for the China-US plane collision was suddenly interrupted for two hours, which had a certain impact on the search and rescue work. After analysis by experts, it was found that the cause of this problem was the change of the ionosphere due to the solar storm. Although long-distance radio transmission is difficult to be used in the daily life of ordinary people, this communication method affected by the ionosphere is still irreplaceable in the military and some other professional fields. For departments that use long-distance radio communication, space weather conditions are information they must pay attention to.

Solar storms blow the magnetosphere formed by the Earth's magnetic field

The man behind the destruction of the high-voltage power grid

During the Vietnam War, the U.S. military deployed a large number of mines to block Vietnam’s ports. One day in 1967, 40 U.S. mines deployed in the waters near Fangchenggang, Vietnam, suddenly exploded without any ships passing by. The chain reaction of the explosion eventually detonated more than 4,000 mines.

The explosion of these mines was not the "masterpiece" of Vietnamese agents, but was caused by changes in the Earth's magnetic field caused by coronal mass ejections. The solar magnetic field contained in the coronal mass ejection can "cut" the magnetic field lines of the Earth's magnetic field when the direction is right, inject plasma into the Earth's magnetic field system, and pull the magnetic field lines of the Earth's magnetic field from the side facing the sun to the side facing away from the sun. In this process, the entire Earth's magnetic field will undergo drastic changes. Space meteorologists call this phenomenon a "geomagnetic storm." The U.S. military's mines use the changes in the magnetic field caused by the passage of ships to detect enemy ships. Once the speed of the magnetic field change exceeds a certain threshold, they will detonate themselves. However, when a geomagnetic storm occurs, the mines mistake the changes in the magnetic field caused by the geomagnetic storm for changes in the magnetic field caused by the passing of ships, and thus detonate.

Combined observation of a coronal mass ejection using various wavelengths

The greater threat of geomagnetic storms to contemporary society lies in the damage they may cause to the power grid. The drastic changes in the magnetic field caused by geomagnetic storms will generate strong geomagnetic induction currents in long-distance high-voltage transmission lines, causing unstable power supply or complete collapse of the power grid. The geomagnetic storm in March 1989 paralyzed the power grid in Quebec, Canada, and millions of people spent the night without electricity in the cold. If a stronger solar storm hits and burns the large core transformers of the power grid, the power grid will be paralyzed for a long time. This is because these large core transformers are mostly specially customized products, and there are no ready-made shelf backups to replace them. Once damaged, spare parts cannot be found in a short time. Electricity is the basic condition for the operation of modern society. Once the power supply is lost, the operation of the entire society will stagnate. According to the conclusion of risk assessment research, a major power outage caused by a super-strong solar storm will cause huge losses of trillions of dollars to North America.

A transformer burned out during the Quebec blackout

In the United States' National Space Weather Strategy and Action Plan, the National Science and Technology Council proposed the concept of a "spaceweather-ready nation", which pointed out three key directions for national-level actions to respond to space weather: First, it is necessary to strengthen the protection capabilities of national security, homeland security (i.e., U.S. domestic security), and commercial facilities and operations that are vulnerable to space weather; second, to develop timely and accurate space weather monitoring and forecasting capabilities, and provide key information and guidance for the whole society to respond to space weather events; third, to formulate post-disaster recovery plans after space weather events, so that after suffering from irresistible space weather disasters, relevant departments can respond to the damage caused by the disaster in an orderly manner according to the plans and action steps that have been studied and verified in advance.