On the Bottom Half

Space Update.

I've been remiss in my duties to keep my genteel readership informed on the great happenings of STS-115. Big events around here have prevented me from my blog.

The first EVA was a huge success with Joe Tanner and Heidemarie Stefanyshyn-Piper (say that five times fast!) working through their 'to-do lists' so quickly that everyone was running to keep up with them. Several get ahead tasks were added to each spacewalkers' activity column, helping the mission continue to go off without incident. The major tasks were to attach cabling and wiring, remove launch straps and restraints, and position the array booms for the subsequent unfurling. The cables and wiring will allow power and data transmission to and from the new array when fully activated.

The second EVA is the most important from any Canadian spacenut's point of view with venerable Canadian astronaut Steve Maclean and fellow astronaut Don Burbank taking their long awaited walk among the stars. The primary tasks on this EVA were removal of all launch locks that secured the Solar Alpha Rotary Joint (SARJ) assembly and then several get ahead tasks added to each astronaut's activity column in light of the speed set during the first EVA. The SARJ is the primary pointing mechanism to keep the P4 arrays pointed into the sun. There is also a beta gimble assembly on each of the two arrays allowing further pointing precision.

Yesterday was the very successful unfurling of the solar arrays on the P4 truss segment. After a software glitch prevented the ground checkout of the SARJ from occuring on timeline, NASA engineers again rode to the rescue and executed a work around for the glitch alllowing the completion of the SARJ checkout. It was spectacular to watch such a massive structure spin like that. Cool, very cool. The unfurling was performed in two steps for each array to accomodate what NASA affectionately calls 'stiction'. The atomic oxygen coating on the solar cells tends to make adjacent panels, which are folded together zig-zag style like in the paper fans we all made in grade school, stick together. This requires above-nominal tension to pull them apart.

This phenomenon was first discovered during the unfurling of the first major solar array truss segment a few years ago - P6 - when surprising major movement was experienced during the then single-stage unfurling. NASA engineers spent the last several years working on the problem and the solution was to unfurl the array in multiple steps. The first step unfurls to about 49% of total length. 30 minutes of solar conditioning follows, during which time, I assume, the atomic oxygen coating flashes off. After that, the rest of the unfurl occurs. What a sight! This beautiful golden filigree of the arrays slowly reveals itself, shaken only by gentle waves as the last few stiction-stuck panels pull apart. Truly a sight. Check out the mission website and replay the video of the array unfurl. Spectacular!

The rest of the day was a bit of a low exertion day as cargo was transferred from the Orbiter to the ISS.

Today, the third and final spacewalk is underway with Joe Tanner and Heidemarie Stefanyshyn-Piper having completed prep work allowing the P4 radiator to be extended, and now working on some maintenance activities to equipment onboard the ISS. Currently, they are engaged with changing out a faulty S-band telemetry antenna from the ISS. There was some complex gimbling activity that was very difficult to coordinate between the spacewalkers and mission control, but all is well - ground commands weren't working so mission control told Joe Tanner to 'manually position' the old antenna for removal and continue with the replacement/repair acitivity. I believe that's a NASA euphemism...

Some fairly big developments on this other fronts in life right now: the bid with the RAAF didn't pan out. However, if I could somehow get permanent residency, then I could try my hand at application. They maintain three different flying corps - Air Force, Army, and Navy. Each has their own and different entry requirements, but, frustratingly, they all require bona fide Australian citizenship or Permanent Residency to get any foot in the door. Hmmmm...

posted by Kyle @ 07:36