In Situ Measurements of Meteoric Ions

摘要: Extraterrestrial material is the source of metal ions in Earth's atmosphere, Each year approx. 10(exp 8) kg intercepted by Earth. The origin this predominantly solar orbiting interplanetary debris from comets or asteroids that crosses orbit. It contains a very small amount interstellar material. On occasion Earth passes through enhanced amounts associated with orbit decaying comet. This leads to meteor shower displays for up several days. number flux typically times average sporadic background influx Meteoric some earliest formed system. By studying relative elemental abundances atmospheric ions, information can be gained on chemical composition cometary and makeup early Using situ sampling rocket-borne ion mass spectrometers; there have been approximately 50 flights made measurements at attitudes between 80 130 km. altitude range where incoming meteoric particles am ablated, larger ones giving rise visible meteor. displays. In rocket isotopic ratios different atomic components molecular concentrations determined used identify unambiguously measured species investigate processes controlling distributions ionosphere was first sampled an spectrometer flown 1956. 1958 identified, fbr time, layer near 95 These data were interpreted as evidence extraterrestrial rather than terrestrial source. Istomin predicted: "It seems probable improvement method analysis E-region may determining those meteors which do not reach ground. Particularly, we hope get about difference showers also meteoroids". visions categorized aims many subsequent experiments lower ionosphere, Although use such deduce classes meteoroids has successful, past four decades observations provided po%erful sets advancing our understanding ablation, composition, neutral chemistry well ionospheric dynamics.