Aalto-1 is a university CubeSat mission carried out by a consortium of Finnish universities and RD institutions.The project is lead by Aalto University's School of Electrical Engineering. The satellite is designed to have atwo-phased science mission. The first six months of the mission are dedicated to remote sensing experiments,executed with an on-board spectral imager and a radiation monitor. The second mission phase is de-orbitingdevice test, conducted with Electrostatic Plasma Brake (EPB) instrument. This payload and de-orbitingconcept is developed by the Finnish Meteorological Institute (FMI) and it is based on the principle of theelectrostatic interaction with moving plasma. It uses a charged tether which will experience a drag dueto Coulomb force whenever there is a relative motion between plasma and tether. The de-orbiting deviceexperiment is divided into four sub-phases, to obtain all the needed measurements, to prove this concept. TheEPB experiment phase begins with spinning up of the satellite using magnetorquers to an angular velocity of200 °/s while maintaining the satellite's rotation axis parallel to inertial Z-axis. This is needed to keep thetether stretched by centrifugal force during the deployment. The EPB tether will then be deployed to a lengthof 10 m, using a motor in the EPB system. An analysis has been made to determine that the tether-plasmainteraction can be observed from the change in the spin rate of the satellite. The tether will be activated closeto the poles, with positive and negative voltages, in order to take advantage of the orientation of Earth's localmagnetic field. The third sub-phase includes further reel-out of the tether up to a 100 m length. In this lastphase of the EPB experiment, the satellite's spin rate is brought down, by tether extension, to around 27 °/s.The charged tether will then exert a force against the direction of orbital velocity and will tend to brake thesatellite into Earth's atmosphere. The collected satellite position, attitude, spin rate, EPB tether charge andsatellite deceleration rate measurement data will be sent to the ground station during each pass. The dynamics,ADCS's operation and effects of the force exerted by the deployed tether have been analysed in different phases.Also, the preliminary simulations of its behaviour coupled with the satellite's ADCS have been performed.
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