Micropropulsion experiment on UNISAT-2

The design and implementation of an experimental micropropulsion system, under development jointly by Mechatronic and INFM, is described. The flight experiment will be performed on-board the microsatellite UNISAT-2, in the framework of a cooperation between University di Roma "La Sapienza", Mechatronic and INFM. The main goal of the experiment is to have a preliminary assessment of the microthruster performance in orbit. The thruster configuration for the UNISAT-2 experiment is cold-gas, using pressurized nitrogen (N₂). The micro convergent-divergent nozzles, obtained by a 500 μm thickness silicon wafer, have a throat area of about 300 μm² through which the pressurized gas flow is accelerated. Ground tests performed to evaluate the microthruster performance are described, showing that the maximum thrust is of the order of 500 μN. Two pairs of microthrusters are mounted with their thrust direction orthogonal to the spin-axis of the UNISAT-2 spacecraft, and are used to perform spin-up/spin-down maneuvers. Measuring the satellite spin rate variation, after thruster activation, the average thrust is evaluated.