A Historical Study of Space Weather

For centuries, people have noticed the aurora caused by space weather, but they don't know about it. Medieval European navigators used natural magnetic compasses. Navigators noticed that the direction of stones sometimes deviated from the magnetic north pole. This was described in the book De Magnete in 1600, but it was not known until 19 century that it was caused by space weather. The space weather of 1840 affected the first telegram in different time periods in various regions. The huge solar storm of 1859 interrupted the global telegraph service and was reported by many major newspapers at that time. Richard carrington correctly associated the interruption with the solar flare observed a day ago and the large geomagnetic field deflection (magnetic storm) that occurred at the same time as the telegraph interruption. According to this connection, space weather has become an academic research topic within the scope of solar physics. KristianBirkeland explained the physical process of aurora and predicted the existence of solar wind by artificially making aurora in his laboratory. With the application of radio in commercial and military fields, people have noticed extreme calm and periodicity of noise. During the 1942 solar event, radar was seriously disturbed, which led to the discovery of another aspect of space weather: solar radio burst (radio waves covering a wide frequency range generated by solar flares).

In the 20th century, because both military and commercial systems depend on the influence of space weather system, people became more and more interested in space weather. Communication satellite is an important part of global trade, meteorological satellite system provides ground weather information, and satellite signals of global positioning system are widely used in various commercial products and processes. Space weather phenomena will interfere or destroy these satellites or interfere with their radio uplink and downlink signals. Space weather phenomena will produce harmful surge currents in long-distance transmission lines, and will also cause radiation to passengers and crew on the plane, especially on polar routes.

The International Geophysical Year (IGY) has greatly promoted the study of space weather. The ground data obtained during IGY show that the auroras occur in the auroral elliptic belt with a width of 5-20 degrees from the magnetic pole latitude 15~25, which is a permanent luminous area. 1958, Explorer I satellite discovered the Van Allen Belt, that is, the area where radiation particles are bound by the earth's magnetic field. 1In June 1959, the Soviet satellite Luna 1 directly observed the solar wind for the first time and measured its intensity. 1969, Yinjiang 5 (also known as Explorer 40) directly observed the ionospheric electric field at high latitudes of the earth brought by the solar wind for the first time. In the early 1970s, Triad data showed that there was a permanent current between the auroral elliptical belt and the magnetosphere. Because of these and other important discoveries, space weather research has developed rapidly.

In our solar system, space weather is mainly influenced by the speed and density of solar wind and the interplanetary magnetic field (IMF) carried by solar wind plasma. Many physical phenomena are related to space weather, including geomagnetic storms and substorms, energy enhancement of Van Allen radiation belt, ionospheric disturbance, satellite-ground radio signal flicker, long-distance radar signal flicker, aurora and geomagnetic induced current on the earth's surface. Coronal mass ejections and related shock waves are also important driving sources of space weather because they can compress the magnetosphere and cause magnetic storms. Solar high-energy particles accelerated by coronal mass ejections and solar flares are also important driving sources of space weather, because they will damage the electronic equipment in spacecraft (such as the failure of galaxy 15) and threaten the lives of astronauts.

In the 1990s, the influence of space environment on human system made people more and more clearly feel the need for a more coordinated research and application framework, and the term space weather was also used by people. The purpose of the National Space Weather Plan of the United States is to focus on the needs of commercial and military groups affected by space weather, connect research groups with user groups, coordinate commercial data centers, and better define the needs of user groups. This concept was transformed into an action plan in 2000, an implementation plan in 2002, an evaluation in 2006 and a strategic revision in 20 10. The revised action plan will be released on 20 1 1, and the revised implementation plan will be released on 20 12. Part of the national space weather plan is to let users know that space weather has affected their business.

As early as 1994, the United States approved and implemented the National Space Weather Plan, and the inter-departmental cooperation including government departments, research institutions, universities and enterprises strengthened and consolidated the leading position of the United States in the field of space weather.

What is particularly interesting is that the US military has always occupied a dominant position in space weather research, and space weather detection facilities and products involving national security have always been under military control. For example, in terms of solar observation, the US military has a solar ground-based observation network, which is distributed in Australia, Italy, Massachusetts, New Mexico and Hawaii, and continuously observes the sun, which is called "the sun never sets"; In terms of ionospheric detection, the US military has an integrated ionospheric detection network all over the United States and major regions of the world; In satellite orbit space weather detection, the US military has a space-based space weather detection network deployed on a series of satellites such as GPS. They also pay special attention to the commercial transformation of research results. For example, the famous 55th Squadron of the US Air Force is a professional unit specializing in space weather business.