Small Solar Power Sail Demonstrator 'IKAROS'

Successful Attitude Control by Liquid Crystal Device

The Japan Aerospace Exploration Agency (JAXA) performed an attitude control experiment (*1) of the solar sail of the Small Solar Power Sail Demonstrator "IKAROS," after its deployment, using an attitude control device, or the liquid crystal device, on July 13, 2010 (Japan Standard Time, the following dates and time are JST, unless otherwise noted. ) We have since confirmed that the attitude control performance was successfully accomplished as planned through post-experiment data verification and analysis. The IKAROS was launched from the Tanegahima Space Center on May 21, 2010.

The liquid crystal device is a thin-film instrument to change the surface reflection characteristics of sunlight by turning on and off the power of the device. It is an engineering test device to control attitude using only sunlight pressure without any additional propellant.

Two kinds of technologies are extremely important for a spin solar sail, like the IKAROS's sail: one is technology to generate small attitude control torque (*2) constantly without causing oscillation on the large flexible sail, and the other is technology to control the direction (attitude) of large angular momentum generated by the spinning membrane without consuming propellant. The attitude control method using sunlight pressure is one of the most feasible methods for satisfying the above two technological requirements, and JAXA has been a global leader in developing this original method.

JAXA will continue the attitude control experiment by the IKAROS to evaluate the details of the attitude control performance while continuing to conduct research on attitude control technology using sunlight pressure as a technology that enables navigation for longer in time and further in distance by a solar sail.



*1 The IKAROS usually uses its onboard thrusters attached to its main body, not the liquid crystal device, for attitude control during normal operations.



*2 Torque is a moment of force to rotate an object about an axis or pivot. For the attitude control experiment using the liquid crystal device this time, the attitude control torque was minimal as sunlight pressure was used for attitude control, thus, by generating torque constantly, it was possible to control attitude without causing vibration on the membrane.





