Doris Breuer
Biography & lecturer abstracts
 |
Lecture Interior-1: Interior structure and composition
The interior structure of Mars consists – like the Earth – of an iron-rich core, a silicate mantle, and a basaltic crust. The extent of these major reservoirs, however, is unknown and has been constrained so far with gravity data (e.g., the moment of inertia factor). Estimates of the size of the iron-rich core range between 1500 and 1800 km depending mainly on the content of light elements in the core while the average crustal thickness is estimated to be between 30 and 80 km. With the help of the martian meteorites that provide information on the composition of the interior, models can be further constrained. One fundamental open question is for instance related to the presence of the endothermic mantle phase transition (spinel/perovskite transition) - if present, it is located close to the core-mantle boundary and strongly influences the mantle flow.
Lecture Interior-2: Mantle dynamics and thermo-chemical evolution
The thermo-chemical evolution of Mars is strongly linked to its crustal evolution. Observations suggest that the bulk of the crust formed during the first few hundred million years, but crater counting support also recent volcanic activity and thus crust production. To fit these observational constraints, including those of the elastic lithosphere thickness, recent thermal evolution models favour the presence of volatiles in the martian interior – an assumption that influences also the atmosphere evolution of the planet via mantle degassing due to melt generation. Two striking features of the martian surface, i.e., the crustal dichotomy between the northern and southern hemispheres and the large volcanic provinces, are possibly linked to the interior dynamics – although the origin of these features are controversially discussed.
Lecture Interior-3: Magnetism and magnetic field generation
The detection of the strong remnant magnetization of the martian crust was one of the surprising discoveries by the Mars Global Survey (MGS) mission, suggesting a self generated dynamo in the iron-rich core early in the evolution. It has been suggested that a thermally-driven dynamo is responsible for the early dynamo action, which implies that the magnetic field is generated in an entirely liquid core – in contrast to the Earth where the present dynamo is caused by chemical convection due to the formation of an inner solid core. A thermally-driven dynamo places constraints on the thermal evolution of the planet and possible scenarios are either a super-heated core, as a consequence of the planet's accretion and core formation, or early plate tectonics on Mars.
Lecture Interior-4: Measurements & modelling
To calculate the thermal evolution of terrestrial planets, either parameterized convection or full dynamic models are used. The advantages and disadvantages of the two methods will be presented. In the second part of this lecture, we discuss existing and future data from space missions that are needed to better constrain the interior structure and the thermal evolution.