On the 13th of December 2019, Samuele Boschi successfully defended his doctoral thesis: The flux of extraterrestrial spinels to Earth associated with He-3 anomalies in Cenozoic and Ordovician sediments. The Faculty opponent was Professor Luigi Folco, University of Pisa, Italy. The examination committee comprised three persons: Professor Jan Smit, Vrije Universiteit Amsterdam; Associate Professor Davide Lenaz, University of Trieste; and Professor Per Ahlberg, Lund University.
Samuele’s hard and meticulous work for 4 years resulted in a thesis with many peer-reviewed articles in high ranked journals. He is also the first to become a PhD within the field of Astrogeobiology.
Two members of the examination committee and the Faculty opponent at the AGB office. From left to right: Jan Smit (holding a fossil meteorite), Luigi Folco and Davide Lenaz.
Luigi Folco, Jan Smit and Davide Lenaz in the hydrochloric acid laboratory.
An extraterrestrial trigger for the mid-Ordovician ice age: Dust from the breakup of the L-chondrite parent body
Birger Schmitz1*, Kenneth A. Farley2, Steven Goderis3, Philipp R. Heck4,5, Stig M. Bergström6, Samuele Boschi1, Philippe Claeys7, Vinciane Debaille8, Andrei Dronov9,10, Matthias van Ginneken11, David A.T. Harper12, Faisal Iqbal1, Johan Friberg1, Shiyong Liao13,14, Ellinor Martin1, Matthias M. M. Meier15,16, Bernhard Peucker-Ehrenbrink17, Bastien Soens7, Rainer Wieler15, Fredrik Terfelt1
1Astrogeobiology Laboratory, Department of Physics, Lund University, Lund, Sweden.2Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA. 3Department of Chemistry, Vrije Universiteit Brussel, Brussels, Belgium. 4Robert A. Pritzker Center for Meteoritics and Polar Studies, The Field Museum of Natural History, Chicago, IL, USA. 5Department of the Geophysical Sciences, The University of Chicago, Chicago, IL, USA. 6School of Earth Sciences, The Ohio State University, Columbus, OH, USA. 7Analytical, Environmental, and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium. 8Laboratoire G-Time, Université Libre de Bruxelles, Brussels, Belgium. 9Geological Institute, Russian Academy of Sciences, Moscow, Russia. 10Institute of Geology and Oil and Gas Technologies, Kazan (Volga Region) Federal University, Kazan, Russia. 11Royal Belgian Institute of Natural Sciences, Brussels, Belgium. 12Department of Earth Sciences, Durham University, Durham, UK. 13Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, China. 14CAS Center for Excellence in Comparative Planetology, Hefei, China. 15Department of Earth Sciences, ETH Zürich, Zürich, Switzerland. 16Naturmuseum St. Gallen, St. Gallen, Switzerland. 17Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
The breakup of the L-chondrite parent body in the asteroid belt 466 million years (Ma) ago still delivers almost a third of all meteorites falling on Earth. Our new extraterrestrial chromite and 3He data for Ordovician sediments show that the breakup took place just at the onset of a major, eustatic sea level fall previously attributed to an Ordovician ice age. Shortly after the breakup, the flux to Earth of the most fine-grained, extraterrestrial material increased by three to four orders of magnitude. In the present stratosphere, extraterrestrial dust represents 1% of all the dust and has no climatic significance. Extraordinary amounts of dust in the entire inner solar system during >2 Ma following the L-chondrite breakup cooled Earth and triggered Ordovician icehouse conditions, sea level fall, and major faunal turnovers related to the Great Ordovician Biodiversification Event.
NASA’s New Horizons spacecraft passed within 2200 miles of object 2014 MU69, also called “Ultima Thule”, in the Kuiper Belt 6.6 billion kilometres from Earth and 1.6 billion kilometres beyond Pluto. Ultima Thule is the most distant object ever studied up-close by humans.
At the NOVA-NASA event in connection with the flyby at New Years Eve Walter Alvarez gave a talk entitled “Studying the Solar System by looking down”.