COMPARISON GAS-TO-DUST RATIO ISON vs 18 COMETS

I have measured and compared the gas-to-dust ratio ( GDR ) , the GDR of the comet C/2012 S1 ISON with 18 comets of half , the dust outflow velocity is assumed to be proportional to the heliocentric distance to the -0.5 power , the GDR for the 18 comets is not constant , the ISON's comet show the water outgassing rate of 1 kgs/sec based in SWIFT ( NASA ) and the 850 kgrs/sec of dust rate in r=4.9 au. , the next equation ( Weiller et al. 2003 ) log M gas / log Mdust = log Q ( OH ) / Afp , his solution to the ISON's comet is 0.0011 , for the 18 comets increasing gas production may be quantified by setting the dust production proportional to the gas production raised to the 0.55 (+-0.17) power interpret this increase as showing that outgassing is primarily throught a porous mantle , trough which gas can flow relatively easily but in which most of the dust grains are trapped for 18 comets , ISON's comet sublimate large amount of dust and the gas are trapped .