Lucas Lange defended his doctoral thesis on Thursday, November 21, 2024, at LMD. As part of the ERC project “Mars Through Time,” Lucas studied and modeled the dynamics of water and CO2 ice on the surface and in the subsurface of planet Mars. Although the planet today resembles a vast cold desert, numerous clues on the Martian surface and in its subsurface indicate that Mars had a very different appearance in its recent past. Indeed, many traces of glaciers are present on the surface, and a significant amount of water ice exists in the subsurface, even though water ice is now unstable almost everywhere on the planet.

To solve this Martian “puzzle” and better understand the paleoclimates of Mars, thereby deciphering the remnants of the ice ages we observe today, Lucas focused on the stability and dynamics of these ices. By contributing to the improvement of the Martian climate model and the development of a planetary evolution model at LMD, Lucas was able to demonstrate that the water ice found in the subsurface today is likely a remnant of the last ice age, which occurred about 630,000 years ago.

Lucas also demonstrated that pure water ice could not have melted in the recent past. Finally, he showed that the carbon dioxide glacier at the South Pole is in equilibrium with the current atmosphere, thus disproving theories of a recent secular climate change on Mars.
Lucas is now continuing his Martian adventure as a postdoc at LMD, while also focusing on frosts on Pluto, before starting a postdoc at the Jet Propulsion Laboratory in April.