Science With GALILEO

In these last decades scientific activities by Global Navigation Satellite Systems (GNSS) were developed covering a wide spectrum of topics. We will focus on two scientific areas: Fundamental Physics Experiments (FP), and atmosphere remote sensing by GALILEO. On August 22
^nd
2014, two Galileo satellites (GSAT5-6) were launched on wrong very high eccentric orbits (e=.156). The two satellites have provided the unique opportunity to perform investigations in the field of General Relativity and Gravitation (GR). Dark matter (DM) makes up about 85% of all matter in the Universe and nothing is known about its nature. There is a growing interest in finding candidates alternative to Weakly Interacting Mass Particles (WIMP). Some models provide DM in the form of spatially large objects, such as Topological Defects (TD), of the same order of Earth that can cause anomalies in atomic clocks.The transit of TD induce changes in Fundamental Constants such as: the fine structure constant, the ratio of the light quark mass to the quantum chromodynamics energy-scale, and the electron and proton masses. GALILEO clocks can be suitable to detect the DM. Gamma ray bursts (GRB) are caused by extremely energetic events in the very distant universe. They have durations from seconds to minutes and cover the entire electromagnetic spectrum. The challenge is their detection and location in the sky in real-time allowing detailed follow-up observations of these exotic events within minutes by dedicated satellites and earthbound telescopes. A GNSS constellation like Galileo is the ideal detector for GRB. We have a radio occultation event when a Low Earth Orbit satellite (LEO) equipped with a spaceborne receiver, catches signals when a GNSS satellite is eclipsing/rising behind Earth. In this geometry configuration GNSS signals propagate tangentially through Earth's atmosphere. From the received signal is possible to retrieve very accurate Temperarture, Pressure and Humidity profiles of the atmosphere as well as its ionosphere structure.