Lou Friedman is "our man in Japan" to watch IKAROS sail deployment
Planetary Society Executive Director Lou Friedman is now in Japan, joining the rest of the IKAROS team to watch the eagerly anticipated deployment of its solar sails. According to Lou, the sail deployment is scheduled for tomorrow and Saturday at around 13:00-17:00 UTC (between 6 and 10 a.m. Pacific time). I'll be staying close to my computer over the next couple of days to watch and wait for updates.
The latest news from the IKAROS blog is exciting. Yesterday, the deployment motors were checked out, and appeared to be working well. Here's a diagram that will help you understand what I'm talking about. The deployment motors are connected to the black bars that cross the silver folded sail material. To deploy the sails, the spacecraft spins, sending the tip masses (deployed on May 28) outward. Then the black bars, referred to as "stopper (rotation guide)" in the diagram below, driven by the deployment motors, are slowly rolled around the cylindrical spacecraft, allowing the sail material to be pulled outward by the tip masses, unrolling in a slow, controlled way. When this stage of deployment is complete, the sails will still be accordion-pleated.
IKAROS sail deployment diagram
You can see a very small outward motion of one of the four folded sails in response to yesterday's test of a deployment motor. The IKAROS blog doesn't state whether all four motors were tested in this fashion; it just shows the photo documentation from one camera.
ISAS / JAXA
IKAROS sail deployment motor test successful
These images, from one of IKAROS' four sail deployment monitoring cameras, show a small outward extension of folded sail under centrifugal pull from the tip mass connected to it, in response to a small motion of the deployment motor. The test was conducted on June 2, 2010, in preparation for the beginning of deployment of all four sails on June 3.
In more recent IKAROS blog entries, dated June 3, there are such tantalizing lines as "Started the development of primary IKAROS. The four arms of the cross shape, 2.7m stretched so." (This is the Google translation from the original Japanese.) And: "Finally began to expand primary....So the first step to sail deployment, operation room and there was always a different tension. More expansion is expected to be continued tomorrow first." It is hard to be certain what these statements mean, but it sounds an awful lot like they have already begun the "first stage deployment" explained in the second row of pictures in the diagram above. I'll post more when I know more!