Statistical Study On The High Potential Of Polar Satellite At Low Altitude

The spacecraft spends most of its time running in space plasmas,the cause of spacecraft surface charging is the difference between ambient electrons and ion fluxes.,electrons are faster than all kinds of ions due to their mass difference.Therefore,the ambient electron flux is much greater than that of the ambient ions.Spacecraft charging manifests itself in two types of effects:(1)damage to the onboard electronic instruments and(2)interference with scientific measurements.The first type is very rare but may be harmful.The second type is very common.Previous studies on spacecraft charging are very comprehensive.But there is not much research or discussion on the high potential of spacecraft when it is at low altitudes.Based on the surface voltage and satellite coordinates of Polar satellite from 1996 to 2008,here are studied on the relationship between the high potential of the satellite at low altitudes(to simplify,this situation is referred to as “abnormal events”)and solar activity,And the MLT distribution of the location where the abnormal event occurs.The main results are as follows: Firstly,solar radiation is positively correlated with the number of occurrences of the event,but solar radiation does not affect the surface potential of the spacecraft.Secondly,the solar activity positively correlate with the proportion of events.The more active the sun,the more times abnormal events occurs.And the proportion of events occurs in a seasonally changing trend.Thirdly,in the high years of solar activity,there are more abnormal events in winter and summer,and fewer events in spring and autumn.In the low years of solar activity,the number of abnormal events per month is maintained at a low level.However,there is no obvious regularity in the number of abnormal events in a month.Fourthly,in terms of distribution,there are many similarities between the northern and southern hemispheres: abnormal events do not occur in geomagnetic latitudes between 50° and 60°,but occur more frequently in the polar and faint sides.However,there are also different places between the northern and southern hemispheres: abnormal events occur more concentrated in the southern hemisphere.Lastly,even in the solar maximum year,the incidence of abnormal events does not exceed 10%.Therefore,the control of the positive potential of the satellite surface can be turned on and off with the solar cycle,and the solar energy can save the energy of the satellite to the equipment that needs more energy in the low year of the sun.