ISS Prepares to Grow
NASA Space Station On-Orbit Status 24 August 2006
“Good-bye XPOP: On Saturday (8/26), ISS attitude, currently still in sun-oriented XPOP (x-axis perpendicular to orbit plane), will be changed to earth-fixed LVLH XVV (local vertical local horizontal/x-axis in velocity vector). With solar Beta angle decreasing below 40 degrees and P3/P4 with new solar arrays arriving on 12A, XPOP attitude will no longer be required for the ISS in the future.”
