boulder colorado researchers attempting to catalog asteroids and other objects in orbits that come close to earth announced a startling discovery on thursday most comets from the outermost reaches of the solar system that begin approaching the sun never make itwe had this huge mismatch between what we expected to see and what we saw harold levison with the southwest research institute said in an interview levison who crafts computer models and simulations of solar system physics and his colleagues found only one in 100 comets expected from the oort cloud seems to survive the journey the finding applies only to comets from the oort cloud levison said it is a region of space between 50000 and 100000 times as far from the sun as earth it serves as home base for perhaps a trillionplus comets scientists suspect oort cloud comets originally were formed between jupiter and neptune and were flung to their outlying abode by jupiters massive gravity because the oort cloud surrounds the solar system like a sphere comets from this region approach the sun from all different directions making them easier to spot than their celestial cousins in the relatively flat kuiper belt region beyond pluto kuiper belt comets in comparison are smaller slower and generally located within a few degrees of the angle at which the planets circle the sun making them more difficult to spot the pool of kuiper belt comets is thought to be substantially smaller than oort cloud comets the belt astronomers theorize is a collection of material left over from the formation of the solar system beyond neptunes orbitlevison speculated that volatile gases in the comets may be warming too quickly to keep their icy bodies intact as they make their highspeed approach toward the sun the kuiper belt comets which move slower perhaps are heated more gradually thereby avoiding thermal shock he saidalthough scientists understanding of comet chemistry is in its infancy it has been less than a decade since technologies have become available for astronomers to probe comets composition highly volatile compounds such as carbon monoxide methane and ethane have been found in the small number of comets studied so far said michael disanti with nasas goddard space flight center in greenbelt md and the catholic university of america in washingtonlevisons findings are surprising however added neil dellorusso also with goddard who studies comet chemistry this wouldnt affect our science unless someone came up with a reason of why certain types of comets would be disrupted rather than others he saidother researchers point out the apparently missing comets may in fact be present but are not easily visible because they have lost their ability to outgas as the venting of gases that produces those famous cometary tails is called instead the comets may evolve into lowlightreflecting objects resembling asteroids and become virtually undetectable against the blackness of space said mark bailey with the armagh observatory at