Periodic Reporting for period 1 - NoSHADE (Novel perspectives on our Solar System History recorded in the Atacama DEsert)
Okres sprawozdawczy: 2023-04-01 do 2025-09-30
In the past, our planet has witnessed cosmic events that may even have had an impact on climate and life. The aim of this project is to detect relatively recent (up to 10-15 million years old) cosmic events that occurred in and around our Solar System.
Cosmic events that have occurred in our Solar System are, for example, collisions between asteroids or the sublimation of comets, which form interplanetary dust. The relics land on Earth as micrometeorites, e.g. cosmic spherules with sizes of around 10 µm to 2 mm. Interplanetary cosmic events could become visible in the Earth’s record, e.g. through variations in the flux and types of micrometeorites. So far, however, there is no continuous record of micrometeorite input over millions of years available.
Star explosions (Supernovae) occur outside our Solar System, which, if they happen close enough (a few 100 light years), leave traces on Earth in the form of radionuclides. Particularly exciting are those that do not occur on Earth itself, such as 60Fe. This radionuclide with a half-life of 2.6 million years is formed and ejected by exploding stars. So far, it has been detected in deep-sea sediments, 2-3 and 7 Myr ago. The younger signal is closely linked to the formation of our Local Superbubble. This is a cavity in the interstellar medium, which was created by sequential Supernova explosions and in which our solar system is embedded today. The older signal is still poorly understood and could originate from the passage of our Solar System through an older superbubble. A higher temporal resolution of these signals would advance our understanding of their origin.
The Atacama Desert in Chile is particularly suitable for this study because it has been extremely dry for 10-15 Myr. This leads to an accumulation and preservation of cosmic traces because of the extremely slow deposition rates of the sediments and the low weathering rates. We carry out analyses in time-resolved sediment profiles from the Atacama Desert to investigate the quantities, timing, location and type of cosmic event that took place during the past 10-15 million years. This study will also shed light on whether cosmic events over the last 10-15 million year have had an impact on Earth's history, possibly changing the climate or the course of biological evolution.
Cosmic events that have occurred in our Solar System are, for example, collisions between asteroids or the sublimation of comets, which form interplanetary dust. The relics land on Earth as micrometeorites, e.g. cosmic spherules with sizes of around 10 µm to 2 mm. Interplanetary cosmic events could become visible in the Earth’s record, e.g. through variations in the flux and types of micrometeorites. So far, however, there is no continuous record of micrometeorite input over millions of years available.
Star explosions (Supernovae) occur outside our Solar System, which, if they happen close enough (a few 100 light years), leave traces on Earth in the form of radionuclides. Particularly exciting are those that do not occur on Earth itself, such as 60Fe. This radionuclide with a half-life of 2.6 million years is formed and ejected by exploding stars. So far, it has been detected in deep-sea sediments, 2-3 and 7 Myr ago. The younger signal is closely linked to the formation of our Local Superbubble. This is a cavity in the interstellar medium, which was created by sequential Supernova explosions and in which our solar system is embedded today. The older signal is still poorly understood and could originate from the passage of our Solar System through an older superbubble. A higher temporal resolution of these signals would advance our understanding of their origin.
The Atacama Desert in Chile is particularly suitable for this study because it has been extremely dry for 10-15 Myr. This leads to an accumulation and preservation of cosmic traces because of the extremely slow deposition rates of the sediments and the low weathering rates. We carry out analyses in time-resolved sediment profiles from the Atacama Desert to investigate the quantities, timing, location and type of cosmic event that took place during the past 10-15 million years. This study will also shed light on whether cosmic events over the last 10-15 million year have had an impact on Earth's history, possibly changing the climate or the course of biological evolution.
Our main study area is in the north of Chile in the hyperarid core of the Atacama Desert. Two field campaigns were conducted, during February/March 2024 and during March/April 2025. In the field, we acquire data for pre-characterizing the soils and their environmental settings, e.g. through portable hand-held X-Ray Fluorescence (XRF) for elemental composition analyses; drone imaging for photogrammetry, geomorphology, and optical and infrared spectroscopy; Ground-Penetrating Radar (GPR) and Transient Electromagnetic (TEM) for shallow and deep subsurface mapping. We use several excavation methods to obtain million-year-old soil profiles including shovel & pickaxe, motorized dredger, excavator, and core drilling probe.
During the two campaigns, several 100 kg of sample material was collected. For deciphering the formation processes and age distribution of the exotic sediment profiles, we analyse the samples for 1) sedimentology, e.g. through sieving and leaching for grain-size analyses, 2) geochemistry, e.g. through X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD) for elemental and mineralogical composition, and 3) isotopes, e.g. through mass spectrometry (MS) for C, N, O stable isotope ratios of organic matter, carbonates, and nitrates as well as accelerator mass spectrometry (AMS) for depositional age dating with meteoric 10Be.
Micrometeorites are hand-picked from the previously leached and sieved sediment samples. Their identification is based the analysis of surface textures and composition using Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray spectroscopy (EDX). Their mineralogy is obtained with Electron MicroProbe Analysis (EMPA) from polished cross-sections. For estimating their heliocentric distance of origin in our Solar System, we analyse their content of cosmogenic radionuclides, which are produced in dust grains in space by irradiation from cosmic rays. Generally, longer travel times of the dust grains, lead to higher concentration of radionuclides. The measured concentrations are compared to a numerical model (MiMiTracer – Micrometeorites: Modelling irradiation and Transport of cosmic dust to earth) calculating the production of radionuclides in cosmic dust grains as they travel through space.
For the detection of past Supernova signatures, 60Fe is chemically extracted from the sediment samples and measured with AMS at the Heavy Ion Accelerator Facility (HIAF) at the Australian National University in Australia.
During the two campaigns, several 100 kg of sample material was collected. For deciphering the formation processes and age distribution of the exotic sediment profiles, we analyse the samples for 1) sedimentology, e.g. through sieving and leaching for grain-size analyses, 2) geochemistry, e.g. through X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD) for elemental and mineralogical composition, and 3) isotopes, e.g. through mass spectrometry (MS) for C, N, O stable isotope ratios of organic matter, carbonates, and nitrates as well as accelerator mass spectrometry (AMS) for depositional age dating with meteoric 10Be.
Micrometeorites are hand-picked from the previously leached and sieved sediment samples. Their identification is based the analysis of surface textures and composition using Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray spectroscopy (EDX). Their mineralogy is obtained with Electron MicroProbe Analysis (EMPA) from polished cross-sections. For estimating their heliocentric distance of origin in our Solar System, we analyse their content of cosmogenic radionuclides, which are produced in dust grains in space by irradiation from cosmic rays. Generally, longer travel times of the dust grains, lead to higher concentration of radionuclides. The measured concentrations are compared to a numerical model (MiMiTracer – Micrometeorites: Modelling irradiation and Transport of cosmic dust to earth) calculating the production of radionuclides in cosmic dust grains as they travel through space.
For the detection of past Supernova signatures, 60Fe is chemically extracted from the sediment samples and measured with AMS at the Heavy Ion Accelerator Facility (HIAF) at the Australian National University in Australia.
The outcome of this project will advance our understanding in a multi-disciplinary manner: From deciphering the interaction of our Solar System with its environment to providing the most precise cosmic dust input data for climatologists and palaeontologists.
First, the measurement of SN radionuclides, which reflect the nucleosynthesis within our galactic neighbourhood, will expand our understanding of nucleosynthesis processes in massive stars and their subsequent distribution in our Galaxy. The number and timing of nearby SNe will contribute to the understanding of the evolution of our interstellar environment, e.g. the formation of the Local Superbubble.
Second, the measurement of cosmogenic radionuclides in individual micrometeorites from time-resolved sedimentary records will expand our understanding of the origin and transport of dust particles in our Solar System and their evolution over millions of years.
Finally, the sedimentological and geochemical data in combination with the chronostratigraphy will provide an unprecedented opportunity to resolve many unknown aspects of Atacama Desert soil formation and evolution. Such insights into these extraordinary sedimentary records will be of paramount value for the wider scientific community for studying e.g. the climate history and biological evolution in the region.
First, the measurement of SN radionuclides, which reflect the nucleosynthesis within our galactic neighbourhood, will expand our understanding of nucleosynthesis processes in massive stars and their subsequent distribution in our Galaxy. The number and timing of nearby SNe will contribute to the understanding of the evolution of our interstellar environment, e.g. the formation of the Local Superbubble.
Second, the measurement of cosmogenic radionuclides in individual micrometeorites from time-resolved sedimentary records will expand our understanding of the origin and transport of dust particles in our Solar System and their evolution over millions of years.
Finally, the sedimentological and geochemical data in combination with the chronostratigraphy will provide an unprecedented opportunity to resolve many unknown aspects of Atacama Desert soil formation and evolution. Such insights into these extraordinary sedimentary records will be of paramount value for the wider scientific community for studying e.g. the climate history and biological evolution in the region.