gh SOLAR FLARES THREATEN SATELLITES AND ASTRONAUTS

The scientists from the Cosmic Radiation Department, Yerevan Institute of Physics, believe that it is important as never before to ensure the early warning of the satellites/space stations control systems about giant explosions on the Sun. In fact, the scientists are already establishing such warning system on the mountain of Aragats.

"Extremely powerful explosions in the solar corona are very rare. I would call them the 'Dorman events' after the outstanding scientist L. Dorman, who was the first to suggest the method for early forecasting of solar flares. These events take place not more than once in a 12-year cycle. However, the consequences of such explosions in the satellite era may cause a global catastrophe," says Ashot Chilingaryan, head of the International Scientific & Technical Center project for the study of solar activity. "The recent analysis of the bore pits in the eternal Antarctic ice has enabled us to determine that these solar events happen at the 80-year intervals. By quirk of fate, the beginning of the satellite era coincided with the minimum of the 80-year cycle, therefore all radiation safety assessments for the satellite electronic equipment and space station crews are based on the underestimated expectations. Now we are entering the period when the superpower solar flares will happen more often."

The streams of particles are flying from the Sun and get accelerated by the blast waves, which accompany the coronal plasma outbursts. Fast ions generate streams of neutrons when colliding with the atoms of atmosphere. The streams of neutrons are recorded by the terrestrial devices installed on the mountainside of Aragats in Armenia. There are other sources of neutrons, for instance, galactic cosmic rays which produce the background, slightly varying with time. The scientists single out a rather slight signal from solar particles against this background.

The Aragats solar neutron telescope, which makes part of the global network of similar devices, is intended to record such neutrons. To ensure early warning, it is necessary to discover very fast solar particles that reach the Earth as soon as 10 minutes after the explosion. The investigation of the two major events in the second half of the 20th century (dating back to 1956 and 1989) have proved that 25 minutes after the fast particles reach the Earth they are followed by the major stream of penetrating radiation which consists of protons. This provides sufficient time to assess the danger of the event, to generate the warning signal and to distribute it via the Internet. Having received the warning, the satellite operators will switch the satellites to the safe minimum activity mode, and the astronauts will pass to the protected ray-proof sections. On top of that, the flights near the poles will be cancelled.

The early warning system being established on the mountain of Aragats includes 5 devices covering the entire area of about 200 square meters, the devices will be installed at the height of 2,000 and 3,200 meters to record three types of particles. The three-level communications via radio modems, as well as software will allow to maintain stable solar observations throughout the year. The advantage of this Center is that it is the largest in the world set of detectors of different types, installed in the mountains, it is equipped with the sophisticated communication system and its own forecasting system based on the models of artificial neural networks. Unfortunately, the Sun can be observed from that area for not more than 10 hours a day, therefore, it is needed to involve the global network of stations located at different longitudes. "To this end we shall willingly cooperate with our colleagues from IZMIRAN (Institute of Terrestrial Magnetism, Ionosphere and Radiopropagation, Russian Academy of Sciences), thanks to whose advice we have started to create our Center 3 years ago", says Ashot Chilingaryan.

The staff of the Aragats station exceeds 100 persons, including 40 scientists. Their investigations are funded through the grants from the USA and Japan provided via the International Scientific & Technical Center. Other funds of the International Scientific & Technical Center finance the equipment which enables the Aragats mountain observatory to communicate constantly with other stations of the international network located in Japan, Switzerland, Bolivia, Hawaii and Tibet, thus providing for the 24-hour solar activity observation.

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