New Experiments to Model Mars’s Thermal Evolution

Wednesday, October 18, 2017

The Geophysical Laboratory’s Alex Goncharov and DTM's Peter van Keken were awarded a Venture Grant to apply a novel flash-heating method for high- pressure/high-temperature experiments to measure the thermal conductivity of Mars. They will then develop new models to understand why that planet cooled so fast and early.

Peter van Keken (left) and Alex Goncharov (right).  Peter van Keken (left) and Alex Goncharov (right). 

Modelling planetary dynamics requires the knowledge of surface heat flux, which is highly uncertain at high pressure and temperature conditions of the mantle and core. Goncharov and van Keken will use their Carnegie Science Venture grant to measure olivine, the dominant Martian mantle mineral at high pressure and temperature using a novel technique. They will use the results to develop thermal evolution models for Mars.

The new technique is a flash-heating method. A sample is compressed in a diamond anvil cell then continuously heated from both sides by an infrared laser to a stable temperature. Then, a second infrared laser delivers a pulse to one side of the sample generating a thermal disturbance. This innovation will enable the most accurate experimental measurements of thermal conductivity to date. They will then create 3-D thermal evolution models of the Moon and Mars.

The schematic above shows the flash-heating diamond anvil cell method.

The rate at which a planet loses heat determines its internal structure and its geologic activity. Compared to Earth, the geologic activity on the Moon and Mars stopped long ago as did Mars’s magnetic field, probably from an abrupt decrease of heat flow. To understand what happened to Mars requires information on its interior structure and the mechanism and rate of the cooling. Thus far, such information is insufficient.

NASA will launch the InSight mission to Mars in May of 2018, providing the first seismic and surface heat flux data. The subsequent Carnegie model will incorporate InSight seismic results and surface heat flow measurements. This award will support a new GL-DTM postdoc and will contribute to regular diamond replacements, and to the team’s travel budget.

Carnegie Science Venture Grants ignore conventional boundaries and bring together researchers from different backgrounds with fresh eyes to explore pressing questions. Each grant provides $100,000 support for two years. These projects are likely to grow in unexpected ways. The grants are generously supported, in part, by trustee Michael Wilson and his wife Jane and by the Monell Foundation.

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