2015: Mission is possible: Nanocarbon material for electric sail
Nanographite field emission cold cathodes fabricated at the Faculty of Physics were successfully tested in a prototype of the electric sail during a space mission.
The electric sail (E-sail) is a new method of propelling a spacecraft by using solar wind as a thrust source. The concept was recently proposed by Dr. Pekka Janhunen from Finland. The E-sail spacecraft consists of long conductive tethers which are centrifugally stretched by spacecraft spin. In order to generate an electrostatic field, that deflects solar wind heavy ions, the tethers must be positively charged at high voltage. The scattered solar wind ions lose part of the flow-aligned component of their momentum which gets transmitted to the tethers and to the spacecraft that experiences corresponding propulsive acceleration. The positive voltage of the tethers can be obtained by using an electron gun (E-gun) that removes negatively charged electrons from the system by smoothing them away into the surrounding solar wind plasma. Field emission (FE) cold cathodes are especially attractive for this application, taking into account necessity to provide efficient electron emission with minimal energy consumption.
Applicability of nanographite cold cathodes has been evaluated for this purpose in a recent collaborative work of the group of researchers from Finland and the Faculty of Physics of M.V. Lomonosov Moscow State University. The tests performed in laboratory conditions have shown that nanographite cathodes produced at the Faculty of Physics have characteristics suitable for the E-guns of the electric sail. The results were confirmed during space mission of ESTCube-1 nano-satellite launched at May 7, 2013 from European spaceport near Kourou in French Guiana.
The results of this work have been published in the paper: V.I. Kleshch, E.A. Smolnikova, A.S. Orekhov, T. Kalvas, O. Tarvainen, J. Kauppinen, A. Nuottajärvi, H. Koivisto, P. Janhunen, A.N. Obraztsov, “Nano-graphite cold cathodes for electric solar wind sail”, Carbon 81, 132-136 (2015).