EPFL Spacecraft Team is an association running student-led space mission, which performs real science with Swiss academia and industry while educating the next generation of space enthusiasts engineers. We organize In-Orbit-Demonstration of scientific instrument and benefit from strong support from Swiss space institutes and industries. Our first mission is called CHESS. It is a CubeSat constellation for high-Performance Time-Of-Flight Mass Spectrometry for Earth Atmosphere. This project, led by EPFL, federates multiple universities in Switzerland. Among which UniBe, Hochschule Luzern, Hes.so, ETHZ, He-arc.