The Japan Aerospace Exploration Agency (JAXA) would like to announce that we have confirmed the successful acceleration of the Small Solar Power Sail Demonstrator "IKAROS" by photon in the course of determining its precise orbit after its sail deployment.
The IKAROS was launched by JAXA on May 21, 2010 and has been under operation since then.
The thrust by solar light pressure is 1.12 mili-Newton which is the expected value. With this confirmation, the IKAROS was proved to generate the biggest acceleration through photon during interplanetary flight in history.
This figure shows the difference between calculated value (without photon acceleration) and observed value (result of Doppler measurement) of IKAROS's line-of-sight velocity on June 9, when the second-stage sail deployment was carried out. The calculated value does not incorporate photon acceleration, thus, the graph shows a flat line if there is no photon acceleration. With photon acceleration, the line inclines. For about one hour around 09:36 UTC, when the second-stage deployment was in operation, data was lost; however, you can clearly see that the graph line starts inclining after the second-stage deployment compared to the flat line prior to the event.
Credit: JAXA
This figure compares the IKAROS's orbit determination result and sail's optical parameters at the time of it's manufacture (namely sail's effective cross section area ratio and sail's specular coefficient) since June 9. The estimated thrust by solar light pressure due to the orbit determination this time is 1.12 mN (mili-Newton,) and the sky blue curve line shows the combination of the sail's optical parameters to realize the estimated thrust. The area in the square shows the estimated parameter range based on the design values at the time of sail manufacturing. (The sail's shape is deformed by light pressure in orbit, thus the estimated value is dispersed from the design value.) As the figure shows, the IKAROS exhibits its photon acceleration capability as designed.
Credit: JAXA
