Lightsail 2 is supposed to be a demonstration flight for solar sail technology. They plan to demonstrate that they can raise the apogee of their satellite using only light pressure on their sail.
But if you are in a circular orbit around the earth, how would that work? Half the time the sun is at your back, thus the 'wind' is at your back and you are gaining speed. The other half of the time though you are facing the 'wind' and thus losing speed. Wouldn't the net effect of the sail be 0?