Vision and Voyages for Planetary Science in the - Solar System ...

dynamo formed (giant impact, degree-one convection, magma ocean cumulate overturn) have striking
similarity to those proposed for the formation of the martian crustal dichotomy. 61 Massive volcanic
domes and escarpments (e.g., Tharsis and Elysium) indicate that large hotspots likely played a significant
role in the geologic, tectonic, and thermal evolution of the planet, as well as the surface history through
release of acidic volatiles to the martian atmosphere, 62 the transport of aqueous fluids over immense
distances, and the formation of hydrothermal deposits. 63 It is likely that the cessation of the magnetic
field had a major effect on the evolution of the early martian atmosphere. 64 Thus, the history of the
interior is closely connected to the atmosphere, surface mineralogy, and potential habitability, and the
measurement of interior properties, identification of possible mantle phase transformations, and
petrologic/geochemical studies of martian meteorites would provide crucial constraints on magmatic
processes on early Mars.
Recent Mars (post ~3.0 Ga) appears to have been less active than its earlier history, with
substantially reduced global aqueous modification and lowered erosion rates. 65 Radiogenic isotopes in
martian basaltic meteorites show that the products of early differentiation may have remained isolated for
most of the history of Mars. The young ages of martian meteorites have placed constraints on both the
igneous history of the planet and also dynamic models for material transport from Mars to Earth. Orbital
observations show clues for volcanic activity in the last hundred million years.
Secondary minerals in martian meteorites show a range of ages from 3.9-billion to 100-million
years oldMa, suggesting that fluids were present in the martian crust for most of Mars’s history. 66
Secondary minerals in martian meteorites also record isotopic signatures indicating interaction with the
martian atmosphere, and impact glasses have trapped martian atmosphere and possibly regolith material.
We now have global maps of topography, 67 mineral distribution, 68 and morphology at scales of 6-
18 m, 69 with local topography and texture at scales of