Speaker: Roberto Orosei

Affiliation: National Institute for Astrophysics / University of Bologna

Academic title: Senior Researcher / Professor

Honorary title: PI of ESA's MARSIS radar

Abstract:

Radar sounders with the capability of probing the subsurface of a planetary body from orbit first reached Mars in 2003. Since then, thousands of observations have been recorded by the MARSIS experiment aboard ESA's Mars Express spacecraft, capable of deep penetration, and the SHARAD radar on NASA's Mars Reconnaissance Orbiter, with a tenfold-better vertical resolution. Polar caps are prime targets for radar sounding, as low-temperature ices are very transparent to electromagnetic waves at frequencies from MHz to 100's of MHz. In both caps, dust is mixed with ices in proportions ranging from a few to several percent, unlike terrestrial ice sheets. Dust layers observed in images of scarps and throughs in the Polar Layered Deposits, the main geologic unit constituting the Martian polar caps, can be traced in radar sections for hundreds of kilometers, documenting the history of alternate ice and dust accumulation tied to the climatic history of Mars. Marked differences can be observed in the radar properties of the Northern and Southern caps. It has been proposed that such differences are due to different timing and deposition mechanisms, which has important implications for the understanding of the Martian climate in the last tens of million years and could explain why radar evidence of the presence of liquid water has been found at the base of the Southern polar cap, but not in the North.

Biography:

Roberto Orosei was born in Reggio Emilia, Italy. He studied at the University of Bologna and received a Ph.D. degree from the University of Rome "La Sapienza". He is a science team member of space experiments for the Rosetta and Jupiter Icy Moons Explorer missions of the European Space Agency, and for NASA's Cassini, Mars Reconnaissance Orbiter, Dawn and Juno probes. He is the principal investigator of the MARSIS radar on board ESA's Mars Express spacecraft, which provided evidence of the presence of liquid water beneath the South polar cap of Mars. He currently works at the Institute for Radioastronomy in Bologna and teaches a course of astrobiology at the University of Bologna.