2012.C.1.4 E-Sail Test Mission: Reaching the Solar Wind With a CubeSat

Author(s)

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

Finnish Meteorological Institute

Session

C.1 – Propulsion Issues for Interplanetary Cubesat Missions

Keywords

electric solar wind sail e-sail GTO

Abstract

The electric solar wind sail, or E-sail, is a novel propellantless propulsion method, invented at the Finnish Meteorological Institute in 2006 [1,2]. It harnesses the momentum of solar wind plasma to produce thrust for a spacecraft. The sail consists of long, centrifugally stretched conducting tethers, kept at high positive voltage with respect to the solar wind plasma. The estimated effectiveness in terms of produced impulse per unit mass is 100 to 1000 times higher than that of ion engines and chemical rockets, respectively. Once operational, the E-sail could revolutionize the space travel within the solar system and its surroundings.

E-sail is currently being developed to TRL 4-5 under the European Union funded project ESAIL. Two CubeSat missions are being prepared, both of which will test certain E-sailing concepts at LEO. The Estonian ESTCube-1 is to be launched during the first half of 2013 and the Finnish Aalto-1 in 2014.

The next logical step in space testing would be to take the satellite into solar wind. In our paper we discuss ideas of how to achieve this goal with a 3U CubeSat. Our platform would include four tethers, each 200-400 m long. The satellite would be placed in an Earth orbit with an apogee high enough to reach the solar wind. Once in orbit, the tethers shall be deployed from their storage reels by spinning the satellite and using centrifugal force to stretch the tethers. When voltage is applied to the tethers, the resulting E-sail force can be observed as a change in the orbital parameters.

Comparing such mission to the conventional CubeSat missions at LEO, the most demanding challenges arise from the relatively high delta-v requirement of both reaching a proper orbit and producing the required spin to open the tethers, together with issues related to communications and radiation tolerance.

In our paper we introduce a concept of utilizing a piggyback launch to GTO and elevating the orbit apogee to 160000 km with an on-board thruster. If an electrolysis propulsion system, such as suggested by Zeledon and Peck [3], was utilized, we estimate that 1 kg of water as propellant would enable both the orbit elevation and the satellite spin-up.

[1] Janhunen and Sandroos, Ann. Geophys. 25 (2007) 755.

[2] Janhunen et al., Rev. Sci. Instrum. 81 (2010) 111301.

[3] Zeledon and Peck, “”Electrolysis Propulsion for CubeSat-Scale Spacecraft,”” AIAA SPACE 2011 Conference & Exposition, Long Beach, CA, Sep 27-29, 2011.