Re: [meteorite-list] Annual Influx Rate and Average Velocity
Simple mathematics requires that any particular meteoroid class will have "one average velocity". But the standard deviation is huge! It doesn't matter whether you are talking about dust, pebbles, boulders, or asteroids: the body will have an orbital velocity where it crosses Earth's orbit that depends on the eccentricity of the orbit (and there is a very wide range, from circular to slightly hyperbolic). The actual impact velocity is further determined by the inclination, whether the orbit is prograde or retrograde, and by Earth's axial rotation. So I don't think that there is much value to the idea of an "average" meteoroid velocity unless you break down your categories much finer. Chris *** Chris L Peterson Cloudbait Observatory http://www.cloudbait.com On 8/23/2011 2:22 PM, Robert Beauford wrote: I need a decent estimate of average annual meteorite influx rate (total mass at all scales per year) and I'm not sure who has done the best and most recent job. Can anyone suggest a source? Also, does anyone have any idea whether anyone has worked out a meaningful average speed (from real data) for inbound objects? I suspect that everything from pebble size to large masses have one average velocity and that dust has a different average velocity. Any insights would be greatly appreciated. Thanks, Robert Beauford __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
[meteorite-list] Annual Influx Rate and Average Velocity
Hi Robert, AL, and List, Some references, which may be helpful: MILLARD H.T. (1963) The rate of arrival of meteorites at the surface of the earth (J. Geophys. Res. 68, 4297-4303). PARKIN D.W. et al. (1968) Influx measurements of extraterrestrial material (Science 159, 936-946). HARVEY R.P. (1987) Statistical comparisons of Antarctic and modern meteorite falls (abs. Meteoritics 22-4, 1987, 403). HARVEY R.P. et al. (1989) Statistical comparisons of Antarctic and modern meteorite falls: Mass frequency distributions and relative abundance by type (Meteoritics 24-1, 1989, 9-14). SAMUELS S.M. (1989) Applications of statistics to Antarctic, non-Antarctic differences (abs. Meteoritics 24-4, 1989, 323). HUSS G.R. (1990) Meteorite infall as a function of mass: Implications for the accumulation of meteorites on Antarctic ice (Meteoritics 25, 1990, 41-56). HUSS G.R. (1991) Meteorite mass distributions and differences between Antarctic and Non-Antarctic meteorites (GCA 55, 105-111). HUGHES D.W. (1980) On the mass distribution of meteorites and their influx rate (in Solid Particles in the Solar System, eds. I. Halliday and B.A. Mclntosh, pp. 207-210. I.A.U.). HUGHES D.W. (1981) Meteorite falls and finds: Some statistics (Meteoritics 16, 269-281). HUGHES D.W. (1982) Meteorite falls and finds: Some statistics (Meteoritics 16, 269-281). HALLIDAY I. et al. (1982) A study of the relative rates of meteorite falls on the earth's surface (Meteoritics 17, 31-46). HALLIDAY I. et al. (1984) The frequency of meteorite falls on the earth (Science 223, 1405-1407). HALLIDAY I. et al. (1989) The influx of meteorites on the earth's surface (Meteoritics 24, 173-178). HALLIDAY I. et al. (1991) The frequency of meteorite falls: Comments on two conflicting solutions to the problem (Meteoritics 26-3, 1991, 243-249). HALLIDAY I. et al. (1996) Detailed data for 259 fireballs from the Canadian camera network and inferences concerning the influx of large meteoroids (Meteoritics 31-2, 1996, 185-217). CEPLECHA Z. (1996) Luminous efficiency based on photographic observations of the Lost City fireball and implications for the influx of interplanetary bodies onto Earth (Astron. Astrophys. 311, 329-332). Regards, Bernd __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Annual Influx Rate and Average Velocity
Hi Robert and all, I think it is John G. Burke in his book Cosmic Debris that has a chart that shows influx and a pretty broad scale. The scale shows Impacts that occur. A 1 micron diameter object collides every microseconds, a 1 mm diameter every 30 seconds, a 1 meter diameter every year, a 100 meter diameter every 10,000 years and a 10 km diameter every 100,000,000 years. I know that is pretty broad for what you want. There was also a Canadian Study done a few years back. Think they figured 10,000 objects over 100 grams influx. Over 3/4 of those hit water. About 3,000 hit land in a years time in the 100 gram range. As for speeds, depending if the Earth is traveling into a stream or if the stream is catching up would give a drastic variation in collisions speeds. The ones that tend to catch up survive most often. Perhaps others can chime in on this and help out further. --AL Mitterling - Original Message - From: "Robert Beauford" To: Sent: Tuesday, August 23, 2011 4:22 PM Subject: [meteorite-list] Annual Influx Rate and Average Velocity I need a decent estimate of average annual meteorite influx rate (total mass at all scales per year) and I'm not sure who has done the best and most recent job. Can anyone suggest a source? Also, does anyone have any idea whether anyone has worked out a meaningful average speed (from real data) for inbound objects? I suspect that everything from pebble size to large masses have one average velocity and that dust has a different average velocity. Any insights would be greatly appreciated. Thanks, Robert Beauford __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
[meteorite-list] Annual Influx Rate and Average Velocity
I need a decent estimate of average annual meteorite influx rate (total mass at all scales per year) and I'm not sure who has done the best and most recent job. Can anyone suggest a source? Also, does anyone have any idea whether anyone has worked out a meaningful average speed (from real data) for inbound objects? I suspect that everything from pebble size to large masses have one average velocity and that dust has a different average velocity. Any insights would be greatly appreciated. Thanks, Robert Beauford __ Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
