Over the next three years, the Planetary Society will build and fly a series of three solar-sail spacecraft dubbed LightSails powered only by sunlight, first in orbit around the Earth and eventually into deeper space.

The third, with help from a small rocket, will sail out of Earth orbit to the L1 Lagrange point (between the Earth and the Moon) with a package of scientific instruments to monitor the output of the Sun and provide early warning of magnetic storms that can disrupt power grids and damage spacecraft.

[ New York Times ]