Space Weather Effect of Space Meteorology

Solar high-energy particles, coronal mass ejections or solar flares are also important driving forces of space weather, because they will destroy spacecraft electronic equipment and threaten the lives of astronauts.

The charge accumulation on the exposed outer surface of spacecraft is called spacecraft surface charging. Surface charging includes absolute charging and uneven charging. If the surface of the spacecraft is all metal, then the whole spacecraft will be charged with the same potential, which is called absolute charging. Absolute charging can only be realized instantly, and the characteristic period is in the order of milliseconds. If dielectric materials are used on the surface of spacecraft, different parts of the surface may have different potentials, which is called uneven charging. Unbalanced charging has a time scale of seconds to minutes. Dielectric materials are poor distributors of accumulated charges, so they keep the charges stored in them in a certain part. The change of charged particle flux makes these surfaces reach different floating potentials. The sunny side and the shady side of the spacecraft are typical cases of uneven charging. The further development of floating potential difference between two surfaces will cause the development of electric field between them. Unbalanced charging may produce strong electric field, which will affect the absolute charging level of spacecraft. From the point of view of abnormal effect, uneven charging is more effective than absolute charging, because it will lead to surface arc discharge or electrostatic discharge (ESD) between different potential planes of spacecraft. This kind of arc discharge or spark discharge directly causes the damage of spacecraft components and produces serious interference pulses in electronic components. In synchronous orbit, spacecraft anomalies are basically caused by unbalanced charging.

The surface potential of spacecraft changes with the state of space plasma. During the substorm, the high-density and low-energy plasma was replaced by the low-density plasma cloud with the energy of 1 ~ 50 kV. In this case, the dielectric surface of the spacecraft can be charged to a very high potential, and even electrostatic discharge breakdown occurs.

Spacecraft internal charging

The internal charging of spacecraft is produced by high-energy electrons with energy of 0. 1 ~ 10 MeV penetrating the shielding layer of spacecraft and depositing in the dielectric. When the charge accumulation rate is higher than the charge leakage rate, the electric field generated by these charges may exceed the dielectric breakdown threshold, resulting in electrostatic discharge, which will damage some parts of the spacecraft and eventually lead to the complete failure of the spacecraft, bringing serious economic losses and social impacts. For example, on May 1998 and 19, the US "Galaxy -4" communication satellite broke down, resulting in the closure of 80% of pagers, cable TV and broadcast transmission, credit card authorization networks and corporate communication systems in the United States. In order to restore satellite service, many satellites must be moved and thousands of ground antennas must be relocated manually. There are many similar incidents. According to the data provided by the database of the American Geophysical Center, most of the 46 satellite anomalies from March 7 to March 3, 1989 were diagnosed as ESD. It can be seen that ESD caused by high-energy electrons poses a serious threat to satellites. Because of this, high-energy electrons are called "killers" of satellites.

Single event in spacecraft

When high-energy heavy ions or protons hit the chip of electronic components, the charge generated on the P-N junction of the chip causes the abnormal potential of the logic circuit to flip, lock or breakdown, which is called a single event. The single event probability is closely related to the high energy proton flux. If a single event happens occasionally, it can be corrected by coding correction device, but frequent single events will lead to spacecraft failure.

radiation effect

The molecular structure of materials is damaged by radiation, which is called radiation damage. Radiation damage is mainly caused by two modes of action: one is ionization, and the other is atomic displacement, that is, relatively low-energy atomic particles stay in matter. These stopped particles knock silicon atoms out of the correct lattice position, resulting in defects in the lattice structure and increasing the resistance of the device. This problem is particularly important for solar cells. Because with the accumulation of displacement damage, the resistance gradually increases and the output power will decrease.

High energy protons and heavy ions can produce ionization and displacement. These effects lead to the deterioration of the performance of various materials and electronic devices on spacecraft, which will be damaged in serious cases. For example, glass materials will turn black and darken after intense irradiation; The film became blurred; The output of the solar cell is reduced; The performance of various semiconductor devices is degraded or even completely damaged.

The total damage effect is the total effect of long-term accumulation of various radiations. Total radiation damage usually limits the life of spacecraft electronic components. When exposed to radiation, the electronic characteristics of solid parts will change. Due to the accumulation of damage, these changes make the parameters of the components deviate from the design values of the normal operation of the circuit.

High-energy electromagnetic radiation or particle radiation penetrates human cells and ionizes the molecules that make up the cells, which can destroy the normal functions of cells. The most serious damage to cells is when DNA is damaged. DNA is the heart of a cell and contains all the structures that produce new cells. There are two main forms of radiation damage to DNA: one is indirect. When the water molecules in the human body absorb most of the radiation and ionize, they will form highly active free radicals, which will damage DNA molecules. The other is the direct way, that is, radiation collides with DNA molecules, ionizing them or directly damaging them.

Symptoms of radiation sickness include severe burns, infertility, tumors and other tissue damage. Serious injuries can lead to rapid (days or weeks) death. Variation in DNA can be passed on to future generations.