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 (N/sub 2/). The micro convergent-divergent nozzles, obtained by a 500 /spl mu/m thickness silicon wafer, have a throat area of about 300 /spl mu/m/sup 2/ 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 /spl mu/N. 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.