The Japanese space agency reported on their web site today that acceleration of the IKAROS spacecraft by solar pressure has been confirmed.
This is a significant milestone on their flight -- probably the next-to-last step before complete controlled solar sail flight is achieved (turning the spacecraft to add or subtract velocity in a controlled manner). As we have noted many times before, just sensing of acceleration from photon pressure is not new; the acceleration by sunlight pressure on spacecraft has been known about ever since the beginning of the space age. It is, however, a new proof of engineering -- harnessing the force of light pressure force to modify a sailcraft's path in a controlled way.
The IKAROS spacecraft continues to perform well, and the world-wide kudos which the Japanese Space Exploration Center (JSpEC) is receiving -- for this mission, and for the successful return of the Hayabusa sample capsule -- are well deserved. For those of our members living near New York, the JSpEC team will give a special report at a free public event organized by The Planetary Society on Wednesday, July 21.