UltraSail

UltraSail was conceived in 2003 by the CU Aerospace/University of Illinois team and is an ultra-large, ultra-lightweight, high aspect ratio, square kilometer-class solar sail concept with spinning blades capable of performing a variety of interplanetary and Lagrange point missions on timescales comparable to other existing low-thrust technologies, and in some cases, faster than chemical propulsion. A primary advantage of UltraSail is the ability to deliver payload mass fractions as high as 60%, thereby enabling smaller launch vehicles to be used with correspondingly lower launch costs.

In this video, a hub satellite is shown with four solar sail blades deploying simultaneously. After deployment, the blades are shown spinning up and then angling slightly with the shape of the UltraSail analogous to a four-blade Dutch windmill.