Specialists of the research laboratory of electronics of the University of Helsinki has developed design and technology deployment electric space sails (ESAIL)with a radius of 1 kilometre, which, interacting with the charged particles of the solar wind, would ensure constant acceleration of the spacecraft traveling to a long and distant journey into the depths of space.

Note that electric sail ESAIL has nothing to do and works on entirely different principles than traditional solar sail, generating a thrust at the expense of energy of incident photons of light. In comparison with other methods, such as using ion engines, electric sail can produce great craving for its own weight and energy consumption. And as the spacecraft with a sail ESAIL practically does not consume fuel, he can move in space indefinitely.

Design of electric solar sails ESAIL was developed by Dr. Pekka Janhunen (Dr. Pekka Janhunen) of the Finnish Space center Kumpula in 2006. Sail consists of long and thin, 25 to 50 microns, aluminium conductors, forming the "rays" sails. Maximum configuration sail ESAIL can consist of 100 rays, and the length of each of them is 20 kilometers. During previous attempts to create such a sail appeared that current technology does not allow reliable weld between themselves so long and thin wires, but new technology developed by Finnish scientists, allows without big problems welding of thin aluminum wire with the help of ultrasound. And this, in turn, allows to think about deploying a full-scale tests such sails.

The electric field is sufficient tension will extend from the rays of the sails in space at a distance of 100 meters. Charged particles of the solar wind plasma, flying with great speed, will face an electric field sails, starting from him, like two magnets that are deployed to each other the same poles. This interaction creates the impulse of power, that will accelerate the spacecraft. On the spaceship will be installed electric power source with high output voltage and electron gun, with which the rays of the sails will be established and maintained a positive electric potential. Deployed rays sails will be held straightened in space at the expense of centrifugal forces generated by the rotation of the whole structure around its axis.

According to Finnish researchers, spacecraft, weighing 1 tonne and sails out of 100 rays length of 20 kilometers, at the expense of the solar wind will receive acceleration in 1 millimeter per second squared. This acceleration during the year to accelerate the spacecraft to a speed of 30 km/s, which will continue to grow.

The only metallic conduit may not serve as a beacon of sails ESAIL due to the fact that any "gift from space" in the form of micrometeorite can shorten it. Therefore, the best option are several parallel microwires at a distance of a few centimeters one from another, and welded together perpendicular jumpers. This approach will allow to preserve the integrity of the design of the beam sails when hit micrometeorites that can damage one or two conductors of a ligament.

A thin wire for manufacturing rays sails ESAIL is made and welded in place as the unfolding of the sail using a computerized high-precision mechanical devices. This device, combined with modified industrial device of ultrasonic precision welding, is the technology, developed by researchers of the laboratory of the University of Helsinki, which will allow to expand solar power sails ESAIL in space in the near future.

Traction force, which will be able to provide sail ESAIL, was calculated only in theory, it is still so far has not been tested in practice. The first practical implementation of the idea sails ESAIL will be Estonian microsatellite ESTCube-1, which will be launched into space in March 2013. Satellite ESTCube-1 will spread in space rays sails ESAIL length of 1.5 meters, which will allow first of real measurement of the forces acting on the sail and spacecraft. The next stage of the program implementation ESAIL will be nanophotonic Aalto-1 University Aalto University), which will be launched in 2014 and will spread the sheet with radius already 100 meters.

The European Union is an organization providing most of the financial support of the project ESAIL. The European Union's contribution to the project amounts to 1.7 million euros.