Photo: Antonin Halas
The electric solar wind sail was invented in Finland in 2006 and with
its revolutionary efficiency it promises faster and cheaper access to
the solar system for small and medium-sized spacecraft, potentially
enabling a host of new scientific and commercial space applications.
Now the University of Tarto together with Finnish Meteorological
Institute and other European partners particularly from Estonia and
Finland are joining forces to develop the first-ever orbital test of
the electric sail physical principle and technology. The ESTCube-1 is
a 1 kg nanosatellite and Estonia's first satellite, with planned
launch in 2012. It will open a 10 meter tether made of very thin metal
wire and charge it to 200 V with a miniature onboard electron gun. As
the satellite flies in its orbital path through the ionospheric plasma, the speed difference between the satellite and the plasma induces a small force on the tether which can be measured. The measurement is used to validate and calibrate existing plasma physical theory of the electric sail effect.
Later, production-scale electric sails will use much longer tethers
and will fly in the solar wind, utilising the much larger speed
difference between the satellite and the fast-moving solar wind. The
solar wind exists everywhere in the interplanetary space with the
exception of Earth's surroundings which are protected from the solar
wind by Earth's magnetic field.
According to estimates, electric sails can be orders of magnitude more
efficient than existing methods (chemical rockets and ion engines) for
many transport tasks in the solar system. Scientifically, they could
revolutionize solar system science by enabling fast missions out of
the heliosphere and affordable sample return missions from planetary,
moon and asteroid targets. Commercially, electric sail could enable
the economic utilization of asteroid resources for e.g. orbital rocket
propellant production or orbital manufacturing of structural
parts. These capabilities could be used for making solar power
satellites an economically attractive global energy solution. Solar
power satellites have large solar panels and send electric power to
Earth using microwaves. Relative to ordinary ground-based solar panels they have the key benefit of producing continuous power which is independent of surface illumination and weather conditions.
Researcher Pekka Janhunen, tel. +358 9 1929 4635, email@example.com