Trace-Metal Concentrations in Coastal Marshes of the Lower Parana River and the Rio-de-La-Plata Estuary

Fil: Villar, Carlos Alberto. Instituto de Limnología Dr. Raúl A. Ringuelet (ILPLA). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Stripeikis, J.. INQUlMAE. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires; ArgentinaFil: Tudino, M.. INQUlMAE. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires; ArgentinaFil: Dhuicque, L.. INQUlMAE. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires; ArgentinaFil: Troccoli, O.. INQUlMAE. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires; ArgentinaFil: Bonetto, Carlos Alberto. Instituto de Limnología Dr. Raúl A. Ringuelet (ILPLA). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin

GRAVL: a new satellite mission concept aiming to detect earthquakes with a magnitude of 6.5 Mw and higher

Data from the US and German Gravity Recovery And Climate Experiment (GRACE) showed indications of pre-, co-, and post-seismic mass redistributions associated with earthquakes down to a magnitude of 8.3 Mw. These demonstrated state-of-the-art capabilities in obtaining high spatial resolution space-based gravimetry, and helped to improve understanding of mantle rheology, potentially even providing a route to developing early warning capabilities for future seismic events. We describe a new mission concept, GRAvity observations by Vertical Laser ranging (GRAVL), which aims to extend the earthquake detection limit down to magnitude 6.5 Mw, significantly increasing the number of observable events. GRAVL directly measures the radial component of the acceleration vector via “high-low” inter-satellite laser ranging, increasing gravity field sensitivity. A constellation of Low-Earth Orbit (LEO) satellites act as test masses, equipped with reflectors and high precision accelerometers to account for non-gravitational forces. Two or more larger satellites are placed above these, in Geostationary or Medium Earth Orbit (GEO / MEO), and measure the distance to the LEO satellites via time-of-flight measurement of a laser pulse. To do this, the GEO/MEO spacecraft are each equipped with a laser, telescope and detector, and additionally require highly accurate timing systems to enable ranging accuracy down to sub-micron precision. To detect co-seismic mass redistribution events of the desired magnitude, we determine a gravity field measurement requirement of order 0.1 µGal at a spatial resolution of approximately 100 km over a 3-day revisit interval. These are challenging requirements, and we will discuss possible approaches to achieving them. The GRAVL mission concept was developed during the FFG/ESA Alpbach Summer School 2019 by a team of science and engineering students, and further refined using the Concurrent Engineering approach during the Post-Alpbach Summer School Event at ESA Academy's Training and Learning Facility at ESEC-Galaxia in Belgium

MICROSCOPE Mission: Final Results of the Test of the Equivalence Principle

International audienceThe MICROSCOPE mission was designed to test the weak equivalence principle (WEP), stating the equality between the inertial and the gravitational masses, with a precision of 10-15 in terms of the Eötvös ratio η. Its experimental test consisted of comparing the accelerations undergone by two collocated test masses of different compositions as they orbited the Earth, by measuring the electrostatic forces required to keep them in equilibrium. This was done with ultrasensitive differential electrostatic accelerometers onboard a drag-free satellite. The mission lasted two and a half years, cumulating five months worth of science free-fall data, two-thirds with a pair of test masses of different compositions—titanium and platinum alloys—and the last third with a reference pair of test masses of the same composition—platinum. We summarize the data analysis, with an emphasis on the characterization of the systematic uncertainties due to thermal instabilities and on the correction of short-lived events which could mimic a WEP violation signal. We found no violation of the WEP, with the Eötvös parameter of the titanium and platinum pair constrained to η(Ti,Pt)=[-1.5±2.3(stat)±1.5(syst)]×10-15 at 1σ in statistical errors