Znamya_2.5 failed http://news.bbc.co.uk/2/hi/science/nature/273220.stm
"The total force exerted on an 800 by 800 meter solar sail, for example, is about 5 Newtons (1.1 lbf) at Earth's distance from the Sun,[2] making it a low-thrust propulsion system, similar to spacecraft propelled by...