Flying over the Northern Lights

Americans hope to uncover the secrets of cosmic flashes

On Saturday, a Delta II rocket launched from Cape Canaveral, carrying five NASA research satellites into low-Earth orbit. This group will be responsible for studying solar radiation (aurora borealis), a long-known atmospheric phenomenon, the nature of which, however, scientists do not yet fully understand. The satellites will operate within the framework of the THEMIS scientific program (according to the first letters of the English name Time History of Events and Macroscale Interactions during Substorms). In Russian, this mission can be called “Themis”: this is exactly what - Themis - the ancient Greeks called their deity of justice. True, it is quite difficult to understand what exactly connects this immortal lady with scales and blindfolds and research apparatus.

Modern theories of the northern (polar) lights present them as the consequences of the solar wind - a stream of charged particles ejected from the surface of the Sun in all directions. This wind, colliding with the Earth’s magnetic field, at a distance of several hundred and thousand kilometers from our planet is slowed down and deflected to the sides. However, in the regions of the planet's magnetic poles, particles of solar plasma penetrate closer, into denser layers of the atmosphere and collide with air molecules. This is believed to cause the mysterious iridescent glow in the skies.

But this is only a general diagram of the process; the details of exactly how the magnetic field interacts with the solar wind are still not fully understood by scientists. Auroras were observed mainly from the Earth, and the data obtained “from below” was not enough for researchers. Themis' five satellites should provide additional information; scientists hope for a breakthrough in this area. The devices will pass over the polar regions of the Earth’s Northern Hemisphere once every few days; their observation data will be duplicated from the surface of the planet, from where auroras will also be monitored.

It is possible that the squadron of Themis satellites will bring quite tangible benefits to the national economy of the Earth. The beauty of Aurora Borealis, alas, is poorly compatible with modern technologies: charged particles block radio communications and interfere with a variety of electronics. The violence of the northern lights pleases the eye, but blinds radars and satellites. In order to somehow combat the elements of the solar wind, you need to at least understand the mechanism of its formation, which is what the American satellites will do.

Mikhail MANSKOY