 What are the Levels of High-Velocity Electrons in Near-Earth Space Right Now? |
About the Image: | Appearance of Dangerous Levels of High Speed Electrons in the Magnetosphere |
The SAMPEX spacecraft has documented the association between high speed solar wind streams and the appearance several days later in the magnetosphere of large numbers of very energetic electrons. This particular sequence of data documented the build up of electrons during an event that occurred in January 1997. Courtesy of Dan Baker, LASP and NASA | High speed electrons appear deep in the magnetosphere several days after high velocity solar wind streams blow past the Earth. The exact reasons for this association are still not understood. These electrons are extremely dangerous to satellite operations because they have so much energy that they can bury themselves inside dielectric materials deep within the spacecraft. Dialectric materials are used to make coaxial cables, circuit boards and other electronic components in the spacecraft. |
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Spacecraft Damage | |
| If the deeply-penetrating electrons build up, faster than charges are able to leak out of the material, the charge inside the dielectric can create potentials that exceed the breakdown potential for the material. When this happens, a discharge can result that is capable of damaging semiconductors and sensitive devices. Whether or not this happens depends both on the design of the particular spacecraft (some are more susceptible than others) and the total amount of high velocity (> 1 MeV = 1 million electron volts) electrons that have hit the spacecraft during the event. One widely-publicized example where deep-dielectric discharges were thought to have crippled two Canadian communications satellites occurred in January 1994 . |
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