Zhangheng-1, also known as CSES (China Seismo-Electromagnetic Satellite) is a scientific mission dedicated to studying the ionospheric precursors of earthquakes. Data collected by the mission will also allow studying solar-terrestrial interactions and phenomena of solar physics. This mission is a collaboration between China National Space Administration and the Italian Space Agency. CSES satellite weighs about 730 kg and it is to reside in a 98° sun-synchronous circular orbit at an altitude about 500 km, where it is expected to operate for 5 years.