We propose a paradigm shift to investigate the extremely ancient terrains (>3.9 Ga) for clues on the early formation of Mars.
The extremely ancient (>3.9 Ga) terrains could provide clues to the early formation of Mars, the solar system, and Earth.
NASA's main scientific reason for exploring Mars is to determine the early evolution and the possibility of life on the red planet. Scientists have adopted an approach for identifying habitable environments on Mars that could be conducive to the early development and preservation of life (e.g., robotically exploring hydrothermal and lake deposits in impact basins). We believe the best approach in the search for life on Mars is to investigate the ancient terrains that exhibit sedimentological records comprising rock materials deposited during a time when Mars was more geologically and hydrologically active. A paradigm shift from investigating middle age (<3.7 Ga) resurfaced Martian environments to exploring the extremely ancient (>3.9 Ga) terrains is proposed here. Terra Cimmeria, Terra Sirenum, and Arabia Terra are all distinctly older terrains that have not been modified by the formation of the giant four impact basins (i.e., Hellas, Isidis, Argyre, and Chryse) and formed during a time when Mars contained a thicker atmosphere and operating dynamo/magnetic field. Exploring these ancient terrains will not only provide the best opportunity to inform on the earliest stage of Mars' evolution but also the early Earth and solar system.