From Space Daily:

The electric sail is a Finnish invention which uses the solar wind as its thrust source and therefore needs no fuel or propellant. The solar wind is a continuous plasma stream emanating from the Sun. Changes in the properties of the solar wind cause auroral brightening and magnetic storms, among other things.

Progress without problems
Over its two-year history, the electric sail has developed rapidly from invention towards implementation and has aroused much international interest. The main parts of the device are long metallic tethers and a solar-powered electron gun which keeps the tethers positively charged.

The solar wind exerts a small but continuous thrust on the tethers and the spacecraft. The electric sail and its applications have been developed mainly at the Finnish Meteorological Institute, but component work is carried out at the University of Helsinki and in Germany, Sweden, Russia and Italy.

“We haven’t encountered major problems in any of the technical fields thus far. This has already enabled us to already start planning the first test mission”, says Dr. Pekka Janhunen. An important subgoal was reached when the Electronics Research Laboratory of the University of Helsinki managed to develop a method for constructing a multiline micrometeoroid-resistant tether out of very thin metal wires using ultrasonic welding.

Electric solar sails were first proposed by Zubrin and Andrews in 1990 (magnetic actually) for use in the Mars Express Program. Mass is the issue here though. The smaller the payload, the faster the system can get a probe through the solar system, Mars in 30 days, Jupiter in 4 months and Saturn in 10 months. A probe to Pluto and the inner Kuiper Belt would still take years, but in four and a half instead of ten.

It’s nice to see an advanced propulsion technique finally coming out to the mainstream and will actually be physically tested and hopefully put to use.

As long as government bureacracies keep their mitts off from it!

Original article

Abstract from Finnish Meteorological Institute

Centauri Dreams post from April 2007