报告人：Jürgen Oberst（德国柏林工业大学 教授）

时间：2024年10月12日（周六）15:30-16:30

地点：测绘馆401会议室

报告简介：

Mars is the most Earth-like planet. Owing to the tilt of its rotational axis, it exhibits summer-and winter seasons just like on our planet. Mars boasts prominent polar caps, varying in size and shape during these seasons. We have analyzed MOLA (Mars Orbiting Laser Altimeter) data obtained by the Mars Global Surveyor to map the changing levels of (CO2) snow and ice on the polar caps. Using techniques of co-and self-registration of the altimeter tracks with respect to reference DTMs, we achieve a high measurementaccuracy, which allowed us to derive maps at high spatial and temporal resolution. We find layers of snow and ice piling up to levels of 2-3 meter in winter seasons. In addition, we see unusual off-season accumulations of these deposits in some regions. Also, we employed multitemporal images obtained by the HiRISE camera on Mars Reconnaissance Orbiter to monitor the steep margins of the polar caps, where avalanches and ice block falls are known to occur frequently. We use machine learning techniques to identify, map the extent, and measure the overall volume of mass wasting. We find Mars’ polar scarps retreating on rates of up to 3 meter/1000 years, however, in unusual non-uniform patterns, implying a highly asymmetric retraction of the circumpolar caps. All data attest to the intense and highly complex dynamics of the polar areas of Mars.  Given the challenges of climate change on Earth and current melting of Arctic and Antarctic ice sheets, it is advisable to study and understand climate processes on our neighbor planet Mars.

报告人简介：

Prof. Jürgen Oberst received his Ph.D. from the University of Texas at Austin in 1989. He is Chair of Planetary Geodesy at the Technical University Berlin, involved in various camera - or Laser altimeter experiments on space missions, such as Lunar Reconnaissance Orbiter, Mars Express, BepiColombo, and JUICE. His interests include the modeling of the orbits, shape, rotation, and interior structures of planets and their satellites, asteroids and comets.