The JUpiter ICy moons Explorer (JUICE) of the European Space Agency (ESA) has the purpose to investigate Jupiter and its icy moons Europa, Ganymede and Callisto in great detail. Among other scientific goals, JUICE will investigate the Jupiter system as a potential habitable system because the three icy moons have subsurface oceans where life might be possible. On board of JUICE is the Particle Environment Package (PEP), which consists of six individual instruments measuring electrons, ions and neutral particles in an energy range from meV up to MeV. One of these six instruments is the Neutral gas and Ion Mass spectrometer (NIM) from the University of Bern. The NIM instrument is designed to measure the chemical and isotope composition of the icy moons’ exospheres during the flybys of JUICE of the icy moons and also during JUICE final destination in Ganymede’s orbit. Knowing the chemical and isotope composition allows to investigate the origin and evolution processes involved in the formation processes of the icy moons, Jupiter and our solar system.

NIM is a time-of-flight mass spectrometer able to measure thermal neutral molecules and ionospheric ions. This thesis shows the journey from finalising the flight design of the NIM instrument to the actual testing, qualification, and calibration until delivery of the NIM Proto-Flight (PFM) instrument in December 2020 to the JUICE spacecraft. On this journey, different flight components were tested and analysed as they became available during the development and finalisation of the PFM and Flight-Spare (FS) instrument. From the foreseen scientific scope for the NIM instrument, a list of measurement requirements was delivered. This work shows that NIM PFM and NIM FS meet all these requirements.