A set of data collected recent years for the natural thermoluminescence（NTL） and cosmogenic nuclide of a group of ordinary chondrites with terrestrial ages<30 years has been examined in order to see if there is evidence for changes in radiation and thermal history which correlate with cosmic ray exposure age. It was found that the meteorites with long cosmic ray exposure ages had smaller perihelia

probably because of a similar evolution of their orbits. The results suggest that the meteoroid orbits of ordinary chondrites evolved from perihelion of 1.0 AU to 0.9 AU over the last 50 million years. The meteoroid bodies experiencing solar reheating during exposure have slightly lower natural TL levels than the normal ones

while the reheating events before exposure affect natural TL levels more obviously.