2018.B.1.3. Electric Solar Wind Sail tether payloads onboard CubeSats

Author(s)

Jouni Envall (1)
Petri Toivanen (1)
Pekka Janhunen (1)

Finnish Meteorological Institute, Finland

Session

B.1

Keywords

E-sail, tether, asteroid mining, ESTCube

Abstract

Electric Solar Wind Sail (E-sail) is a novel propulsion method, which uses long, conducting, electrically charged tethers to harness the momentum of solar wind protons in order to generate thrust. When fully functional, E-sail has potential to revolutionize space travel within our solar system. Operating without consumable propellant, E-sail enables exiting new mission concepts for e.g. planetary exploration and asteroid mining. First samples of E-sail tether have flown onboard the ESTCube-1 and Aalto-1 CubeSats. Here we introduce the instrumentation to be used in the next steps of E-sail CubeSat tests.

ESTCube-2 and ESTCube-3 are two 3-unit CubeSats with quasi identical E-sail payloads, whose missions are to unreel and test E-sail tethers in low Earth orbit (LEO) and in solar wind, respectively. For ESTCube-3 to be successful novel instruments are needed, e.g. CubeSat compatible cold gas thrusters and star tracker based attitude determination system. These custom built systems are first tested onboard ESTCube-2 in LEO. Each satellite encases a single, in-house built, 300 meter long multifilament tether, packed on a purpose-built reel. The payload also includes a stepper motor driven reel-out system and a high voltage source, used to charge the tether up to 6-10 kV potential with respect to ambient plasma environment. Electron guns are used to remove excess electrons, gathered by the tether when charged positively, in order to maintain the voltage. The entire payload has been miniaturized to fit into 0,5-1 CubeSat units.

Successful mission for each satellite would include a verified reel-out of the tether, coupled with quantitative measurement of the E-sail force, i.e. Coulomb drag, interacting between the tether and the surrounding plasma. Success of ESTCube-3 would mark the first demonstration of using solar wind for spacecraft propulsion.