ESTCube-2 plasma brake payload for effective deorbiting

In this paper, a novel, efficient, lightweight and cost-effective method for satellite deorbiting is presented. The plasma brake deorbiting technology is based on the electrostatic Coulomb drag effect utilising the momentum exchange between the atmospheric ion flow and a negatively charged body. ESTCube-2 is a three-unit CubeSat that will deploy an electrostatically charged tether to test deorbiting with the help of a plasma brake. The satellite will be equipped with a 300 m long tether, a tether deployment system and a high voltage supply to charge it up to 1 kV. Eventually, the system will occupy up to half a CubeSat unit with a tether mass around 22 g or less. It is estimated that such a system can reduce the orbital altitude of an average-size (4 kg) nanosatellite from 700 km to 500 km in half a year. While simpler deployment strategies can be utilised for operational missions, centrifugal deployment will be used on ESTCube-2 to provide precise measurements of the Coulomb drag effect with the tether spinning up and down the plasma stream. All of the satellite bus subsystems will be integrated into one miniaturised system occupying 0.6 units. During the development of the integrated satellite bus, the main requirements were to provide 45 Nms of total angular momentum in order to deploy the whole tether, to provide a means of deployment verification, and to provide up to 3 W of electrical power for the payload. The satellite is planned to be ready by the end of 2018 and launched in the first half 2019. Moreover, the plasma brake is scalable for larger satellites by increasing the length of the tether. The thin wire (<50 μm), that the tether is made of, creates minimal risk to other satellites in the event of accidental collision and is comparable with the impact from micrometeoroids and already existing debris impacting satellites continuously. Deorbiting time of theoretically damaged tether is analysed in the paper. This paper also presents alternative implementation of the payload – propellantless propulsion (E-sail). The ESTCube-2 satellite will evaluate an E-sail effect and will perform actual end-of-life deorbiting.