Implications for meteoroid chemistry from the height distribution of radar meteors

• Published in: Advances in space research 1997-01, Vol.20 (8), p.1501-1504
• Main Authors: Elford, W.G, Steel, D.I, Taylor, A.D
• Format: Article
• Language: English
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/S0273-1177(97)00425-0

We have gathered substantial evidence from novel radar meteor observations that most meteoroids start to ablate at altitudes considerably in excess of 100 km (at heights up to ∼140 km). This beginning height h b is a strong function of the melting point of the meteoroid. Theoretical modelling indicates that for stony meteoroids observed as faint radio meteors these heights range from h b = 116 km (for entry speeds v ∞ = 70 km s −1) to 90 km (for v ∞ = 15 km s −1). Meteoroids that begin ablating above these heights must have lower temperature melting points. We interpret the observations in terms of a population of the meteoroids largely constituted of heavy organic compounds that are susceptible to gross-fragmentation as they heat and encounter the Earth at speeds greater than ∼30 km s −1.