1. Space Environmental Hazards Effects of Space Weather Meidad Pariente

2. Space Environment Effects on Satellites Short Brief The environment in space hassignificant effect on satellites. Thediscussion below highlights theprincipal effects experienced bysatellites. Satellite Charging/ Deep Charging Satellite Discharging Hardware damage Electric problems 3. Satellite Charging Satellite charging is a variation inthe electrostatic potential of asatellite with respect to thesurrounding low density plasmaaround the satellite or to anotherpart of the satellite. The extent of the charging dependson both design and orbit. The two primary mechanisms 4. Deep Charging Deep charging of a satellite occurswhen cosmic ray particles passthrough a satellite and ionize atomswithin, through collisions. Some of these particles are solar inorigin, but the majority are galacticand with no preference to time orlight conditions. They do show some dependence on 5. Satellite Discharging The satellites most vulnerable tocharging/dischargingarethoselocated at geosynchronous altitude.Discharges as high as 20,000 volts(V) have been experienced. Satellites in geosynchronous orbitstypically move both in and out ofthe upper regions of the Van AllenRadiation Belts and the Earths 6. Hardware Damage Suddenelectrostatic discharge(high current or arc) can causehardware damage, such as: Blown fuses or exploded transistors,capacitors andotherelectroniccomponents Vaporized metal parts Structural damage Breakdown of thermal coatings 7. Electric Problems These discharges can result inelectrical or electronic problems,such as: False commands On/Off circuit switching Memory changes Solar cell degradation Degradation of optical sensors 8. Particle Collision High energy solar flare particles andgalactic cosmic rays can causedirect damage to the surface of asatellite. The damage can includevaporization of surface materialsand structural damage. Theseparticles can also enter star orhorizon sensors and mimicreference points. 9. Space EnvironmentalHazardsAnomalies SpaceWeather 10. Sun Index Two of the most used space weatherindex are Smoothed Sunspot Number (SSN)Geomagnetic Planetary Geomagnetic Acrivity Solar AcrivityK Index (Kp) orSSNA Index (Ap)Level KpAp Level>250Extreme7-9>100Severe Storm 150-250 Very High 650-99 Major Storm 80-150High530-49 Minor Storm40-80Moderate416-29Active20-40Low 38-15 Unsettled0-20 Very Low0-2 0-7 Quiet 11. Geomagnetic Disturbances The disturbance of the geomagneticfield may be measured by an amagnetometer. Several magnetometer data fromdozens of observatories in one minuteintervals are potentially available. The data is tracked in real-time andallows to monitor the current state ofthe geomagnetic conditions. 12. Spacequake A Magnetic Shockwave 13. Kp and NOAA G-scale Kp IndexNOAA SpaceWeather ScaleGeomagnetic Storm LevelKp =10Mewhen Kp level Solar Radiation Storm V was met; particles (number of(ions) storm days)satellites may be rendered useless, memoryimpacts can cause loss of control, may causeExtreFewer than 1S5serious noise in image data, star-trackers may 105me per cyclebe unable to locate sources; permanentdamage to solar panels possible. may experience memory device problems and noise on imaging systems; star-tracker3 per cycleS4Severe 104 problems may cause orientation problems, and solar panel efficiency can be degraded 16. Geomagnetic Activity vsNumber of Recorded Anomalies(April 2010) 17. Space EnvironmentalHazardsThe SystemsEngineer POV 18. Designing a Robust satellite Good Engineering Practice Environmental Testing is notenough ! Glitches, Faulty hardware andcomputer mishaps due toenvironmental conditions must beconsidered and anticipated. Satellites should be fully automaticfor as long as possible (no less than48 hours) 19. Designing a Robust satellite Tipsand Tricks Check, check and than double checkyour system logic for dead ends. If you have such a single pointfailure it will surly occur, henceprotect the satellites with timeouts Whenever possible perform sanitychecks, especially regarding crucialdata Critical system parameters should 20. Hardware Protection Exterior surface of satellite isexposedtochargingandovercharging, especially when usingion thrusters, hence protectionmeasured should be implementedon the outer surface as well Listen to weather reports ! When astorm is approaching shut down allredundant units, and keep only 21. The Galaxy-15 Case Study 5/4/2010 Contact with Galaxy-15 Lost Galaxy-15 team was unable to switch thepayload off, hence causing interference to othersatellites, enforcing evasive maneuvers andexposed to claims. 23/10/2010 Satellite reboot after batterydrain Satellite enters safe mode after six months ofeastward drift Currently at 121W (originally 133W anddrifted until 93W) used as a relay station forGPS signals 22. Conclusions Anomaly trend proved to be correlatedwith geomagnetic activity. Most of current satellite designs provedto be resilient to experiencedgeomagnetic activity. Still catastophric events happen duringpeak events. Galaxy 15 events to be investigated tocarefully verify repeatabilty.