[FPSPACE] Fw: [JAXA:0255] Small Solar Power Sail Demonstrator 'IKAROS'Confirmation of Photon Acceleration

LARRY KLAES ljk4 at msn.com
Tue Jul 13 03:42:43 EDT 2010

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-----Original Message-----
From: JAXA Press Release Mail Service <jaxapr at jaxa.jp>
Date: Tue, 13 Jul 2010 06:30:42 
To: <ljk4 at msn.com>
Subject: [JAXA:0255] Small Solar Power Sail Demonstrator 'IKAROS'
 Confirmation of  Photon Acceleration

                       ***  JAXA MAIL SERVICE  ***
                   Japan Aerospace Exploration Agency
             Small Solar Power Sail Demonstrator 'IKAROS'
                 Confirmation of Photon Acceleration

                                                    July 9, 2010 (JST)
                             Japan Aerospace Exploration Agency (JAXA)

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 (*1) in the course of 
determining its precise orbit after its sail deployment. The IKAROS 
was launched by JAXA on May 21, 2010 (Japan Standard time, and all the
following time and dates are JST unless noted otherwise,) and has been
under operation since then.
The thrust by solar light pressure is 1.12 mili-Newton (*2,) which is
the expected value.
With this confirmation, the IKAROS was proved to generate the biggest
acceleration through photon during interplanetary flight in history.

(*1) Photon acceleration is to accelerate an object by pressure of 
     solar photon (solar light pressure.)
(*2) Newton (N) is a unit that shows the amount of net force required
     to accelerate a mass of one kilogram at a rate of one meter per
     second per second. In other words, it indicates the thrust power
     of the demonstrator. 1.12 mN is equivalent to about 0.114 g of 
     gravity loaded onto an object on the Earth.

Figure 1 
Doppler Measurement at the Second-stage Sail Deployment

The above Figure 1 shows the difference between calculated value 
(without photon acceleration) and observed value (result of Doppler 
measurement) of IKAROS's line-of-sight velocity (*3) 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 9:36 (Universal Time,) 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.

(*3) Line-of-sight velocity is a velocity with direction components 
     connecting a ground station and the IKAROS among flight 
     velocities relative to the ground.

Figure 2 
Estimated Parameters Based on IKAROS Orbit Determination Result

Sail's effective cross section area ratio = the estimated sail area 
divided by the area at the time of manufacturing
Sail specular coefficient = amount of secularly reflected photons 
divided by total incident photons

Figure 2 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 in Figure 2 shows the combination of the sail's optical 
parameters to realize the estimated thrust.
The area in the square in Figure 2 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 you can see in 
Figure 2.) 
As Figure 2 shows, the IKAROS exhibits its photon acceleration 
capability as designed.

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Publisher : Public Affairs Department
            Japan Aerospace Exploration Agency (JAXA)
            Marunouchi Kitaguchi Building,
            1-6-5, Marunouchi, Chiyoda-ku, Tokyo 100-8260


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