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March 19, 2009

Solar Space Walks

Astronauts Steve "Swanny" Swanson and Richard Arnold will begin the first of the three planned STS-119 space walks Thursday afternoon starting at 1:13 p.m. Central time. Their primary task is to install the Starboard outboard solar array wing called S6.

Because of clearance issues, the S6 was pulled from the shuttle cargo bay by the space station's robotic arm (operated by Sandy Magnus and John Phillips). Then it was handed to the shuttle arm (operated by Tony Antonelli and Joseph Acaba)which moved it out to the right (starboard) side of the shuttle. Then the station arm rolled down its rails on the front of the truss, and (Phillips and Koichi Wakata) grabbed the S6 from the shuttle arm. The shuttle arm let go, and the station arm then provided "valet parking" overnight.

The two spacewalkers will connect the plumbing and electrical and data cables needed for the solar panels to deploy and begin operations. The spacewalk is planned to last six and a half hours, ending around a quarter to 8.

The IV crewman--who will be coordinating the spacewalk from inside, is Joseph Acaba. Phillips and Wakata will be operating the station arm.

Mission Control said today that no focused inspection of the shuttle tiles is required. This cleared the timeline so that if the first spacewalk goes well, the deployment of the golden arrays (definitely worth watching!) will be on Friday, putting the crew ahead of schedule.

I can't help but wonder if they will somehow manage to squeeze in that fourth EVA after all (it was scrubbed when the launch was delayed).

The timeline keeps shifting, giving the flight planners (which is what I used to be) a good workout. Updates to the timeline are included in what are called "Execute Packages." These are uplinked to the crew and posted online as pdf files for those who want details: However, you should be warned, these messages are full of acronyms (DAP to LVLH is Digital Auto Pilot to Local-Vertical Local-Horizontal) and are not likely to make a lot of sense even when decoded (DAP to LVLH is setting prior to an attitude maneuver) unless you have some detailed knowledge of shuttle and station systems.

I am no longer familiar with all the terms, but I did glean some information from reading the Flight Day 4 package. One thing I learned is that the station arm snare cables, the two wires that rotate and wrap around the "doorknob" grapple fixtures, were not in the proper configuration. The solution, open and close them! I don't know if that worked or not, but it always helps with my models! (See my Space Station Science book to make a robotic hand of your own.)

They are also having some trouble with the bicycle ergometer on the middeck of the shuttle. This is their exercise bike. The plan was "to reseat the braking band and/or untwist calibration strap on flywheel, check for floating debris." The creative procedure had them cut a 6x6 square from a T-shirt to use as a filter over the vacuum cleaner hose. The directions called for wetting the shirt to help it hold on to debris. This is classic Mission Control problem solving--use what they have on board to troubleshoot and fix things. There is no option to run to the hardware store!

These kind of activities are the nitty-gritty of spaceflight. In order for astronauts to do big things such as move 31,000-pound truss segments and perform breathtaking spacewalks, all, or at least most, of the little stuff has to work.

I salute the team of people working 24/7 on all these activities, big and small. They make human spaceflight seem easy--and also put on a great show for all of us to watch online. Thanks!

To the stars,

Marianne Dyson
NSS Advisor (Though the views expressed here are my own and not those of NSS!)

Posted by m_dyson at March 19, 2009 12:47 AM



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