Main contents of space weather research and forecast

13.5.3. 1 scientific aspect-understanding the regularity of spatial process

Geospatial environment is a specific geophysical environment formed by the interaction of electromagnetic radiation and particle flow of the sun with the earth's atmosphere and geomagnetic field. It is a complex dynamic system composed of several coupling parts, such as the middle and upper atmosphere, ionosphere, magnetosphere, interplanetary space and the surface of the sun. The sun is the main energy and disturbance source of this system, and it is also the fundamental origin of various space weather processes. Understanding the laws of spatial processes is the central task of space physics.

People have long realized that space environment is an important part of human living environment. The conjecture about the origin of geomagnetic field variation in high-altitude current system can be traced back to 1882 Stuart's hypothesis of atmospheric generator. More than 40 years later, appleton confirmed the existence of the ionosphere through electromagnetic wave reflection. Birkeland (1867 ~ 19 17), a Norwegian, was the first scientist to associate geomagnetic changes, northern lights and solar radiation. His pioneering experiments and theoretical research have brought people's thinking to earth space.

After half a century's development, space physics has a deep understanding of the composition and structure of the earth's space and a basic understanding of the physical mechanism of the space process. Space meteorology is a new stage in the development of space physics and space exploration, which will transform human understanding of the space environment into practical productive forces to promote the progress of human society.

13.5.3.2 space activities

The importance of space weather is first reflected in space activities. Spacecraft operating in solar-terrestrial space will encounter the following space environment.

(1) neutral atmospheric environment

When the intensity of solar ultraviolet radiation and X-rays changes dramatically, the temperature and density of the upper atmosphere also change dramatically, resulting in great differences in the density of the upper atmosphere in high and low years of solar activity. Short-term changes such as solar flares can also lead to similar changes in atmospheric density.

(2) Plasma and low-energy charged particle environment

The plasma in spacecraft orbit is mainly composed of electrons and ions in the ionosphere. The difference of solar electromagnetic radiation (high year and low year of solar activity) also leads to the huge difference of electron density.

Sedimentation particles are low-energy charged particles encountered in spacecraft orbit. When the earth's magnetic field is disturbed, the binding conditions of the radiation belt particles originally bound by the earth's magnetic field are destroyed and injected into the upper atmosphere along the magnetic field lines, and the spacecraft running in low orbit will be bombarded by it. It appears in a small area, often only a few kilometers to dozens of kilometers thick, with the highest probability in the aurora belt and polar coverage area. Because it is accompanied by magnetic field disturbance, there are more opportunities in years with high solar activity.

(3) Magnetic field environment

The magnetic field in spacecraft orbit mainly comes from the geomagnetic field inside the earth. The direct influence of magnetic field on spacecraft is mainly the torque acting on the spacecraft, which changes the attitude of the spacecraft.

The variation of geomagnetic field from space current system is also an important parameter of space environmental security.

(4) high-energy charged particle environment

High-energy charged particles are important environmental parameters affecting spacecraft, which are mainly composed of solar cosmic rays from the sun, galactic cosmic rays from the Milky Way and radiation belt particles captured by geomagnetic field. In the orbit of spacecraft, particles with higher energy are concentrated in high latitudes under the guidance of geomagnetic field, showing strong regional characteristics.

Usually, only when the surface of the sun is severely disturbed will a large number of high-energy particles be released, and their components are mainly protons. The occurrence of solar proton events is very random, and shows strong spatial distribution heterogeneity and suddenness. Predicting the solar cosmic rays intensity near the Earth is an important issue in space environmental security.

The radiation belt is composed of charged particles captured by the geomagnetic field, which moves around the earth for a long time and poses a serious threat to spacecraft. In the negative magnetic anomaly region where the magnetic field intensity is lower than that of the dipole, such as the anomaly region in the South Atlantic, the height of the lower edge of the radiation belt is relatively low, and radiation belt particles appear at a height of about 200 km. The lower edge of the radiation band is above 1500 km in the positive anomaly region where the magnetic field intensity is higher than that of the dipole. The orbit of the spacecraft will inevitably pass through the South Atlantic anomaly in the radiation zone, so the high-energy charged particles in the radiation zone are an important environmental factor affecting the spacecraft.

(5) Electromagnetic radiation environment

The electromagnetic radiation environment in spacecraft orbit includes solar electromagnetic radiation, the reflection of solar electromagnetic radiation by the earth and atmosphere, and the electromagnetic radiation of the earth's atmosphere itself. The total solar radiation is a solar constant, which changes very little and has little direct impact on the space environment. Ultraviolet rays, x rays and gamma rays are the opposite. Although their energy share is small, their intensity changes greatly, which has a great direct impact on the space environment. When the surface of the sun is severely disturbed, the intensity of near ultraviolet radiation will nearly double, the intensity of far ultraviolet radiation will increase several times, and X-rays may increase several times or even more. These short-wave electromagnetic radiation have a great influence on the space environment in the orbit of spacecraft. When they change, the temperature and density of the upper atmosphere will also change.

(6) Meteoroid and space debris environment

Meteorites are solid particles flying at high speed in space under the action of the gravitational field of the sun, and the maximum speed can reach 72 km/s relative to the earth. Meteorites can be divided into two parts: one part is evenly distributed in space, and the probability of collision between spacecraft and it is relatively stable; The other part is concentrated near the comet's orbit. When the earth carries spacecraft through these orbital regions, the probability of spacecraft colliding with them increases.

Space debris, also known as space junk, has a slightly lower relative velocity with spacecraft than meteoroids. From relative standstill to 16 km/s, the average relative velocity is about 1 1 km/s, and the measurement results show that the flux is very high in the height range of 300 ~ 1500 km.

Spacecraft operating and working in the above-mentioned various space environments are affected in various ways, and the form and degree of influence are related to satellite orbit and satellite function.

Satellites are mainly affected by the environment in the following aspects.

A high-energy particles from the sun, interplanetary space and the earth's magnetosphere constantly bombard the spacecraft surface. Particles with higher energy can pass through electronic equipment, changing the data bits in the electronic signal string, causing the instrument to issue chaotic instructions or provide wrong data. Such chaotic instructions will lead to a major satellite accident. If the ground controller noticed the influence of particles in advance, it could be completely avoided. Low-energy particles will cause the surface of spacecraft to be charged, especially during large-scale geomagnetic activities. In addition, high-energy electrons will cause the deep charging effect of dielectric and shorten the service life of internal devices.

B The rapidly changing solar ultraviolet intensity constantly changes the density and temperature of the atmosphere, affecting the orbit and life of satellites. Large-scale magnetic storms heat and expand the atmosphere, which strongly disturbs the orbit of low-altitude satellites and may endanger the safety of the space shuttle and crew.

C. Communication in all frequency bands will be affected by space weather, especially high frequency (HF), and the irregularity of ionosphere will often cause signal attenuation. Under the condition of strong disturbance, the ionosphere can completely absorb signals, usually near the aurora belt or when crossing the polar cover, making high-frequency propagation impossible. The ionosphere may change the signal characteristics, leading to signal quality degradation, and more importantly, it will interrupt key communications, such as search and rescue, military operations and computer networks.

These environmental impacts will cause a series of serious consequences. For example, it will affect the orbit, attitude and life of spacecraft, cause radiation damage to astronauts, radiation damage and chemical damage to spacecraft materials, electronic devices and solar cells, affect spacecraft potential, cause spacecraft software errors, affect spacecraft communication and measurement and control, and affect spacecraft thermal state.

13.5.3.3 Communication and navigation

In modern society, it is difficult to move without space communication. Various resource satellites, military reconnaissance satellites, scientific experimental satellites, meteorological satellites, communication satellites, GPS, etc. Everyone needs to transmit information, and various disturbances often occur in the space through which the transmission passes, which determines the possibility and quality of transmission.

Terrestrial radio communication depends on the reflection of radio waves by ionosphere. Space weather processes such as magnetic storms and ionospheric storms will cause catastrophic damage to wireless channels, reduce transmission quality and completely interrupt communication.

Planes and ships need the help of geomagnetic field, radar, etc. During the magnetic storm, the geomagnetic field will be greatly disturbed, leading to navigation failure.

13.5.3.4 ground technology system

When the solar wind reaches the earth's space, a series of changes will take place in the earth's magnetosphere-ionosphere-thermosphere-neutral atmosphere system. One of the most violent activities is the magnetospheric storm. During the magnetic storm, all parts of the earth's space were violently disturbed, which destroyed the normal working conditions of the spacecraft and had a great destructive impact on the ground technical system. For example, a strongly changing magnetic field will induce current in any conductor on the ground. Once there is a conductor oil and gas pipeline or power grid on the ground, there will be a strong induced current flowing in it. During the strong magnetic storm, there is an induced voltage of 6 V per kilometer of oil pipeline. When the induced current flows through the oil and gas pipeline, it will cause accelerated corrosion of the pipeline and affect the normal counting of the flowmeter. When the induced current flows through the transmission line, it will damage the transformer and memory.

13.5.3.5 national defense security

Since the first artificial satellite was launched into the sky, the application of satellites in military reconnaissance and future wars has been regarded as a main goal in all countries. The most representative applications of space technology in the military field are strategic missiles and military satellites. Military reconnaissance satellite is the most powerful space weapon to see through the battlefield situation of high-tech war.

There are two problems in the operational application of missiles and military reconnaissance satellites. First, the accuracy of attacking or solving the target; The second is reliability. With the development of science and technology, the hit accuracy of missile weapons and the target resolution of reconnaissance satellites are constantly improving, and the reliability of space flight safety is also constantly improving. However, it is not uncommon to fail to achieve the expected results and unexpected failures, even fiasco accidents.

There are three reasons, that is, the influence of design (including materials), operation and use, atmosphere and space environment. The accuracy and reliability problems caused by the first two types of reasons are gradually decreasing through the continuous research and improvement of applied technology. The third reason is that improvement depends on the understanding of the space environment.

At present, the most concerned military issues are: the influencing factors and mechanism of space environment on missiles and satellites, space thermal environment, electromagnetic environment and radiation environment, meteor and debris environment and upper atmosphere environment.

Space environment is a factor that must be considered in spacecraft design, but catastrophic space weather events are abnormal and have great deviation from the normal model. In order to improve the reliability, rationality and adaptability of spacecraft design to space environment changes, it is required to describe the parameters of disastrous space weather process as accurately as possible and evaluate its harmfulness.

The four-dimensional combat space makes the space environment one of the important combat environments in modern warfare, and the guarantee of the space environment will inevitably become one of the basic military support elements in future wars. Space climate and space weather will inevitably enter all stages and levels of the whole process of strategic planning, decision-making and war.

2 1 century, more military systems such as command, control, communication, navigation, reconnaissance, early warning and missiles will enter the stratosphere and above. The design, development, life cycle management and use of these systems need the support of space climate and space weather.

Understanding and understanding space weather is also the need to make use of space weather, seek advantages and avoid disadvantages, attack the enemy and protect ourselves.

With the expansion of the operational space of modern warfare, the issue of military meteorological support in the vast space from the troposphere to the ionosphere, which originally belongs to the category of military meteorological support, has not been implemented in the past and has not been paid attention to, will be gradually put on the agenda. These spaces are the most practical space fields that intersect with space weather research spaces. With the increasing demand for military meteorological support, the solution of some difficult problems in conventional meteorological support also needs to broaden the research field and support space weather research.

The development of modern war and modern military science constantly puts forward new requirements for space weather support. For example, high-altitude wind and high-altitude wind shear, middle and upper atmospheric density and its change, ionospheric electron density and its change, geomagnetic interference, solar proton events, solar X-ray events, solar radio bursts, satellite orbit high-energy particle flux and so on.

Therefore, the development of space weather is very important for strengthening national defense construction and enhancing resilience.

natural disaster

Geomagnetic activity has a good correlation with solar activity, atmosphere and biosphere, so geomagnetic activity can be used as an "indicator" of the relationship between solar weather. The data of solar activity, geomagnetic activity and various meteorological parameters in the last hundred years are analyzed and studied, and the relationship between geomagnetic field and lower atmospheric pressure, temperature and rainfall is revealed.

1974, J.W.King, a British solar-terrestrial physicist, suggested that the research field of the relationship between meteorological phenomena and related earth's magnetic field should be called "magnetometeorology".

National health

Studies have shown that the onset and death of heart disease, cerebrovascular disease and malignant tumor are related to some unexpected events in nature, such as solar activity and geomagnetic field interference, and it is likely that some external factors have induced or accelerated the onset and death of these diseases to some extent.

13.5.3.8 National Education

Space weather is a new field of knowledge. On the one hand, it closely depends on the understanding of space laws between the sun and the earth in space physics. On the other hand, it is based on high technology such as aerospace and communication. It is very basic and practical. The publicity and education of space weather knowledge is conducive to improving the basic quality of citizens and enhancing the public's understanding of space weather and its impact. In particular, it can make young students know and understand the role of basic research and high technology in today's society, inspire and guide them to care about this cause that has a great impact on mankind today and in the future, and create conditions for constantly supplementing high-quality scientific research and engineering talents in the field of space weather.