However, when they are travelling many times faster than a bullet from a high velocity rifle, the threat increases significantly. These could result in some physical damage in sensitive areas as well as electrical short circuits, plasma discharges, and computer malfunctions, which may be sufficiently serious to disable a satellite. A form of sand-blasting can erode outer surfaces such as thermal blankets, mirrors and solar cells. Large impacting particles may even knock a satellite out of its normal position, as happened to the European Space Agency's Giotto spacecraft during its 1986 flyby of Halley's Comet. However, the most likely form of damage is to vulnerable power systems.
Past evidence suggests that the risks are fairly low.
Furthermore, no spacecraft were damaged by the 1966 Leonid storm. On the other hand, there are now more than 500 spacecraft orbiting the Earth, over 10 times as many as in the mid-1960s. If this reaches 150,000 per hour, there will be all sorts of damage, but there may only be 1,800 per hour. The Space Shuttle mission that carried John Glenn was deliberately timed to avoid the Leonid shower. Cosmonauts on the Mir space station do not have the luxury of choosing their flight window.