Abstract:

The study of noble gas isotopes of Martian meteorites indicates at least five different impact events of 12 Martian meteorites within and up to 15 million years were occurred on the Martian surface and were ejected from the Martian crust material. Their ejection times were 0.8Ma,2.76Ma,3.84Ma,11.0Ma and 14.4Ma respectively. Among 12 Martian meteorites Chassigny Martian meteorite is chemically distinct from the nakhlites its ejection age is 11.6Ma. If the Chassigy event is not related to the nakhlite, the number of the impact events should be six. McKay et al. (1996) give evidence that Martian bacteria have lived in the Martian meteorite Allan Hills 84001.But many scientists presented some counter-evidence about the traces of ancient Martian life. Based on the comprehensive study of Martian meteorite Allan Hills 84001,up to now the question that whether or not it contains evidence of traces of ancient Martian life is uncertain or it leaves many unanswered questions, or the possibility of existence of ancient Martian life is very small.