LIVE: STS-115 Flight Day 5 (EVA-2)

• #120 by dutch courage on 13 Sep, 2006 20:39
• Quote

  RedSky - 13/9/2006  10:11 PM
  
  I don't know if this has been discussed,  but what is the normal sun tracking mode once they are operational (i.e.,  after assembly complete).  They will move roughly 180 degrees tracking during a 45 minute daylight pass... but then what?  Do they just continue rotating in the same direction and speed (i.e., tracking the sun through the earth) until they are back in position for sunrise? ... or do they slew back to the sunrise starting position the way they came?  If they reverse back to the starting position for sunrise, does that take 45 minutes or is it done faster?

  
  The solar arrays will continue turning even on the night-side. This also generates less vibration which is imortant for all kinds of expiriments.
  
• #121 by henrycheck on 13 Sep, 2006 20:44
• The alpha joint will rotate continuously at four degrees per minute and "track the sun through the earth." Picture a Mississippi River paddlewheel steamer. The beta gimbal rotates to present the maximum surface area to the sun.
  
• #122 by MKremer on 13 Sep, 2006 20:45
• That's right, it's much easier on the station and array hardware to keep continuously tracking through darkness than to stop and restart every hour or so for each orbit.
  
• #123 by RedSky on 13 Sep, 2006 21:01
• Thanks, guys.  That's what I wanted to know.  Reminds me of my old 6" reflector telescope with clock drive.  Except that was a 24hr day... not 90 minutes.   As a kid, I remember one night I was out with the scope and came indoors, got distracted by something, forgot about it and went to bed.  The next morning, leaving for school and seeing the scope outside pointed down into the ground and thinking... Oh, I guess thats where M13 is now.
  
  
• #124 by MKremer on 13 Sep, 2006 21:21
• Quote

  RedSky - 13/9/2006  3:48 PM
  The next morning, leaving for school and seeing the scope outside pointed down into the ground and thinking... Oh, I guess thats where M13 is now.

  
  Funny!
  
• #125 by eeergo on 13 Sep, 2006 21:54
• Another SARJ-related question: I read somewhere that it didn't need to 'unwind', so how are the cables and pipes installed to allow that and not twist?
• #126 by nacnud on 13 Sep, 2006 22:00
• I guess they use slip rings
• #127 by nathan.moeller on 13 Sep, 2006 22:03
• Any word on the debris sighting from P/4 I read about earlier?
• #128 by MKremer on 13 Sep, 2006 22:13
• Quote

  nacnud - 13/9/2006  4:47 PM
  
  I guess they use slip rings

  
  Yes, they do. Also, no pipes needed - cooling is internal to P4 (like S4, P6, and S6) and only needs power/data lines.
  
• #129 by eeergo on 13 Sep, 2006 22:15
• Thanks for the info guys, I was really curious about it
• #130 by henrycheck on 13 Sep, 2006 22:17
• Quote

  nacnud - 13/9/2006  5:47 PM
  
  I guess they use slip rings

  
  
  NASA is calling them "roll ring assemblies." The first I ever heard of this technology being applied to spaceflight was for the Galileo mission to Jupiter. Part of Galileo was three-axis stabilized and part rotated.
  
  
• #131 by lcs on 13 Sep, 2006 23:22
• 4A mast deploy coming up at 7 pm ET ?  I guess that's why they aborted the FD highlights newsreel.
  
  7:10 - Very weird.  The deploy is occuring but they are not showing it. You can see the shadows moving.
• #132 by DaveS on 13 Sep, 2006 23:28
• Quote

  lcs - 14/9/2006  1:09 AM
  7:10 - Very weird.  The deploy is occuring but they are not showing it. You can see the shadows moving.

  Eh, that could be because the station itself is moving relative to the sun, kinda like shadows here on Earth.
• #133 by nathan.moeller on 13 Sep, 2006 23:29
• I wonder why they wouldn't show it Man I think I'm gonna be up late tonight watchin' these things deploy.  Can you say Dr. Pepper?!
• #134 by DaveS on 13 Sep, 2006 23:31
• A problem has been noted with SARJ drive lock assembly. It is being evaluated by ground teams.
• #135 by psloss on 13 Sep, 2006 23:32
• PAO says there's an issue with (I think) one of the drive lock assemblies; they are troubleshooting.
  
• #136 by Rapoc on 13 Sep, 2006 23:32
• I think the truss is still in the wrong oreantation ...
  Yes, on NASA TV: The SARJ has a problem and is in hold. So the deploy of the arrays is in hold too.
• #137 by Joffan on 13 Sep, 2006 23:37
• Maybe they have a screw loose...
  
  It's strange that the first word of this is when the deploy is scheduled, the SARJ must have been out of alignment since the test rotations.
  
  I guess they have some EVA time to fix it if necessary, although it might mean there's no time for EVA support after full deployment.
• #138 by nathan.moeller on 13 Sep, 2006 23:39
• Did they send a bad command or what?  Must be an Aggie at the controls
• #139 by DaveS on 13 Sep, 2006 23:42
• Is anyone else but me thinking on the bolt that Joe Tanner lost and was last seen heading towards P3 could be a cause for the problems?