Example of period with big number of satellite malfunctions Upper panel – cosmic ray activity near the Earth: variations of 10 GV cosmic ray density; solar proton (> 10 MeV and >60 MeV) and electron (> 2 MeV) fluxes.
Lower panel – geomagnetic activity: Kp- and Dst-indices.
Vertical lines on the upper panel correspond to the malfunction moments. “Kosmos” satellites are marked. Here the majority of the satellite malfunctions coincides with period of magnetic storm and enhancement of high-energy electron flux.
Fig. 2.2. A big number of satellite malfunctions in April-May 1991.
Fig. 2.3. Number of satellite malfunctions per month in period 1971-1996 for high altitude (>1000 km, top panel) and low altitude (<1000 km, bottom panel). No correlation between two types of satellites.
Fig. 2.4. Increasing of malfunctions number after about one day of great geomagnetic storms SSC (for high altitude satellites).
Fig. 2.5. Increasing of malfunctions number after about five days of great geomagnetic storms SSC (for low altitude satellites).
Fig.2.6. Satellite anomalies in dependence of geomagnetic activity (Dst amplitude)
Fig. 2.7. Increasing about 10 times of the number of satellite malfunctions in the first two days after onset solar proton enhancement.
3. Data from the Past and Classification of Space Weather Dangerous Phenomena
(NOAA Classification and its Modernization)
NOAA Space Weather Scale establishes 5 gradations of FEP events, what are called Solar Radiation Storms: from S5 (the highest level of radiation, corresponded to the flux of solar protons with energy >10 MeV about ) up to S1 (the lowest level, the flux about for protons with energy >10 MeV). From our opinion, by ground level CR neutron monitors and muon telescopes it is possible monitoring and forecast (by using much higher energy particles than smaller energy particles caused the main radiation hazard) FEP events of levels S5, S4 and S3. With increasing of FEP event level of radiation will increase the accuracy of forecasting. Let us note that from our opinion, for satellite damage and influence on people health and technology, on communications by HF radio-waves more important is the total fluence of FEP during the event than the protons flux what is used now in NOAA Space Weather Scale. The second note is, that the level S5 (corresponds to the flux , or fluency for protons with ) is not maximal (as it is supposed by NOAA Solar Radiation Storms Scale), but can be much higher and with much smaller probability than S5 (Dorman et al., 1993; Dorman and Venkatesan, 1993; Dorman and Pustil’nik, 1995, 1999). As it was shown recently by McCracken et al. (2001), the dependence of event probability from fluence can be prolonged at least up to for protons with , what was observed in FEP of September 1869 according to data of nitrate contents in polar ice (see Fig. 3.1 and 3.2).
Fig. 3.1. Example on a great FEP event in September 1859 with fluency for protons with , According to McCracken et al., 2001.
Fig. 3.2. Great FEP events in the last 450 years according to nitrate data (McCracken et al., 2001).
Fig. 3.3. The dependence of FEP events probability (number of events per year) from the value of fluence according to direct satellite and NM data, nitrate in polar ice data and cosmogenic nuclide data on the moon (McCracken et al., 2001).
This type of great dangerous events is very rarely (about one in few hundred years). According to Fig 3.3 it is not excluded that in principle can occurred very great FEP events with fluency in 10 and even in 100 times bigger (correspondingly one in few thousand and one in several ten thousand years). So, we suppose to correct the very important classification, developed by NOAA, in two directions: to use fluency F of FEP during all event (in units ) instead of flux I, and to extend levels of radiation hazard. As result, the modernized classification of FEP events is shown in Table 1.
Table 2.1. Extended FEP events radiation hazard scale (based on NOAA Space Weather Scale for Solar Radiation Storms)
FEP events radiation hazard
Number of events per one year
Biological: Lethal doze for astronauts, for passengers and crew on commercial jets; great influence on people health and gene mutations on the ground
Satellite operations: very big damages of satellites electronics and computers memory, damage to solar panels, loosing of many satellites
Other systems: complete blackout of HF (high frequency) communications through polar and middle-latitude regions, big position errors make navigation operations extremely difficult.
One in few thousand years
Biological: About lethal doze for astronauts, serious influence on passengers and crew health on commercial jets; possible influence on people health and genes mutations on the ground
Satellite operations: a big damages of satellites electronics and computers memory, damage to solar panels, loosing of several satellites
Other systems: complete blackout of HF communications through polar regions, some position errors make navigation operations very difficult.
One in few hundred years
Biological: unavoidable high radiation hazard to astronauts on EVA (extra-vehicular activity); high radiation exposure to passengers and crew in commercial jets at high latitudes (approximately 100 chest x-rays) is possible.
Satellite operations: satellites may be rendered useless, memory impacts can cause loss of control, may cause serious noise in image data, star-trackers may be unable to locate sources; permanent damage to solar panels possible.
Other systems: complete blackout of HF (high frequency) communications possible through the polar regions, and position errors make navigation operations extremely difficult.
One in 20-50 years
Biological: unavoidable radiation hazard to astronauts on EVA; elevated radiation exposure to passengers and crew in commercial jets at high latitudes (approximately 10 chest x-rays) is possible.
Satellite operations: may experience memory device problems and noise on imaging systems; star-tracker problems may cause orientation problems, and solar panel efficiency can be degraded.
Other systems: blackout of HF radio communications through the polar regions and increased navigation errors over several days are likely.
One in 3-4 years
Biological: radiation hazard avoidance recommended for astronauts on EVA; passengers and crew in commercial jets at high latitudes may receive low-level radiation exposure (approximately 1 chest X-ray).
Satellite operations:single-event upsets, noise in imaging systems, and slight reduction of efficiency in solar panel are likely.
Other systems: degraded HF radio propagation through the polar regions and navigation position errors likely.