We built a unique experimental setup, combining femtosecond laser pump-probe techniques with resistively heated and laser heated diamond anvil cell, which has proved capable of probing the acoustic properties of materials over a very wide pressure range, exceeding one million times atmospheric pressure, and at temperatures up to 4000 degrees. Upon further optimization of the experimental protocol we will be able to probe the acoustic properties of a variety of planet-forming materials at the pressure and temperature conditions existing in planetary deep interiors.
Setup for experimentation in multi-anvil press was optimized by the use of newly developed materials and innovative technical solutions enabling to retain liquids at high pressure and high temperature conditions, minimizing the risk of chemical reaction, but as well the contribution of the sample’s environment to the collected signal. These technological advances, together with an improved data collection protocol, which combines angular and energy dispersive X-ray diffraction, absorption and X-ray imaging, allowed to obtain data of unprecedented quality on liquid metals at the conditions of the core of the Moon and Ganymede, and on solid and partially molten rocks at the conditions of the Martian mantle.
Multiple synchrotron campaigns for x-ray diffraction and absorption measurements at simultaneous high pressure and high temperature conditions, complemented with electron microscopy analysis of the recovered samples, have allowed studying the phase diagram of the binary Fe-S, Fe-Si, Fe-O and Fe-C systems. Equation of states have been determined for several Fe-Si and selected Fe-Si-C solid alloys. Local structure, density and thermo-elastic parameters, including thermal expansion, have been determined for liquid Fe-S, Fe-Si and Fe-S-C alloys at record pressure and temperature conditions.
The ensemble of the results obtained on the iron alloys expected to form the core of the telluric planets allowed us to propose compositional and crystallization models for the core of several bodies of the Solar system, including the Moon and other satellites such as Ganymede, small planets such as Mercury and Mars, and larger objects, from Earth to exoplanets. In particular, collected data have been used to provide the thermodynamic model of liquid iron alloys currently used as the reference for the thermo-elastic properties of the Mars’ core.
Phase equilibria experiments allowed relating bulk chemical composition to mantle mineralogy, addressing the effects of pressure, temperature and redox conditions. Experiments by x-ray diffraction, radiography and ultrasonic interferometry, have been carried out to determine solidus and liquidus of rocks representative of the Martian mantle, as well as the pressure- and temperature-dependent melt fraction. Velocity measurements on analogues of the Martian mantle have been performed at pertinent pressure and temperature conditions providing guidance for the interpretation of the seismic data collected by the InSight mission.
Obtained results have been disseminated to the scientific community via technical and scientific papers (29 papers published so-far, including 1 Nature, 2 Science, 1 Nature Communications and 2 PNAS) and by presentation to international conferences. Dissemination towards general public has been systematically pursued, via presentation in science festivals and interventions at schools (pre-schools, elementary schools, observation courses and short internships proposed to middle and high school students).
