Assessment of the Large Meteoroid Characteristics from the Light Curves Obtained by Satellite and Groundbased Networks

Details Assessment of the Large Meteoroid Characteristics from the Light Curves Obtained by Satellite and Groundbased Networks Assessment of the Large Meteoroid Characteristics from the Light Curves Obtained by Satellite and Groundbased Networks

Sep 1995

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995metic..30q.556n&link_type=abstract

Meteoritics, vol. 30, no. 5, page 556

Computer Science

2

Ablation, Atmosphere, Bolide, Fragmentation, Impacts, Meteoroids, Radiation

Scientific paper

A relatively small number of satellites at high altitude orbits (20,000 km or higher) provide coverage of most of the Earth's surface. It is possible to have essentially continuous, day and night, all weather coverage over the entire surface of the Earth [1]. Space based infrared sensors have detected over 200 bright flashes in the atmosphere since 1972. Average number of flashes per year is 30. In addition optical sensors have detected 16 light curves in the visible (mainly during the last year). These bright flashes have been caused by explosive disintegration of large meteoroids in the atmosphere. Information from IR sensors and light curves have been analyzed. This analysis give important information on the energy - frequency distribution of the impacting meteoroids, their sizes, strengths and even composition. For an example, preatmospheric kinetic energies of meteoroids which caused 15 April 1988, 1 October 1990, 4 October 1991 and 1 February 1994 events are 8-9, 5-8, 1-2, and 40 kt TNT respectively. Three of them were stones or chondrites and deposited their energy at the altitudes of 30 to 45 km. Last one was probably an iron (initial velocity 24 km/sec, angle of trajectory inclination 45 degrees [2]) and penetrated to the altitude of about 20 km (strength of about 100 Mdyn/cm^2). Radiation-hydrodynamic 1D, 2D and even 3D numerical simulations [3,4] of the meteoroid flight in the atmosphere for various sizes, velocities, heights of flights have been conducted and used in the analysis. They were based on the detailed tables of spectral opacities for hot air and ablated material for various wavelengths, temperatures, densities, and composition (iron, stone, chondrite and cometary material). Radiation heat transfer, ablation, fragmentation, and dispersion of fragments have been taken into account. Detailed spectra of the emitted radiation has been obtained. Data from satellite network has been compared with the data from ground based photographic networks and eyewitnesses reports. 15 June 1994 event is of special interest, as in this case a meteoroid which crossed USA and caused meteorite fall near Montreal, Canada [5] has also been detected by satellites. References: [1] Tagliaferri E. et al. (1994) in Hazards Due to Comets and Asteroids (T. Gehrels, ed.), 199-200, Univ. of Arizona, Tucson. [2] McCord T. B. et al. (1995) JGR Planets, E2, 3245-3249. [3] Nemtchinov et al. (1994) Planet. Space Sci., 42, 491-506. [4] Nemtchinov et al. (1995) Solar System Res., 29, 155-173. [5] Brown P. et al. (1995) The Fall of the St. Robert Meteorite, Univ. of Western Ontario, Canada (preprint).

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