Hazards of Hypervelocity Impacts on Spacecraft

Hypervelocity impacts by space particles, such as meteoroids and debris, pose hazards to spacecraft. The limits of velocity of meteoroid and debris are derived. Characteristic properties of hypervelocity impacts are momentum transfer, penetration, plasma production, localization, and suddenness. Using McDonnell's empirical formulas derived from laboratory experiments, impact penetrations and plasma production rates in the space environment are calculated. When the critical temperature theorem for Maxwellian space plasmas is used, the energy of the plasma generated is shown to be too low to induce any significant spacecraft charging. The plasma generated, however, can induce a transient, sustained or avalanche discharge between differentially charged surfaces. The discharge current depends not only on the plasma density generated but also on the neutral gas released on impact. A scenario of impact induced hazard following days of passage of a high-energy plasma cloud, such as a coronal mass ejection cloud, is discussed. Some mitigation methods are discussed. Finally, we discuss whether electrons can be accelerated to high energies in a meteor trail.