The problem is that we need two sets of coordinates: One for STS-114 and one for STS-121 and subsequent flights. I'll explain why:
Prior to the launch of STS-114, the Orbiter Structures team at JSC re-ran some thermal analysis simulations and found that the clearances between the RMS End Effector electrical connector housing on the forward end on the OBSS and the very edge of the graphite/epoxy composite dish of the Ku band DA was around 1" nominally but when taking in the thermal expansion that both structures would experience on-orbit, those clearances would shrink to nothing and zero, preventing the Ku band DA from being deployed and activated as planned on FD1. So they had re-plan FD1 and FD2 to take in account the delayed Ku band DA deploy and activation activities which also delayed the downlink of critical post-launch data that had been recorded onboard (mainly high resolution Wing Leading Edge Impact Detection Subsystem sensor data and the photos from the new digital camera in the LOX ET umbilical well). Ku band deploy and activation was moved until after the crew had unberthed the OBSS for the first time, on FD2.
To avoid this on subsequent missions, they moved the OBSS and the MPMs a few inches further aft, to provide more clearance so that the Ku band DA could be deployed without having to power up the RMS, move it over and unberth of the OBSS.
All of this came to light very late, after the mission had been delayed from the May/June daylight launch period to the July/August daylight launch period when the orbiter was already on the pad having gone through the first tanking test.
As far as SSU is concerned, right now we have the MPMs in the original STS-114 positions which actually was based on the original plans to have a second RMS on the starboard side. The starboard RMS would have been a mirror version of the standard port RMS, so all the positions in the X/Z axes was identical. Since all orbiters were "scarred" for that RMS, they just decided to reuse the original mounting locations. Our MPM positions are accurate, it's just that the OBSS is just a tad bit too short.
Somehow I remember reading something about that. :blink:
Anyway, if the MPMs are in the correct "original" position, then it's fine with me (we don't have a thermal simulation so...), and we should correct the OBSS.