I noticed this in the launch of Nauka MLM to the ISS.
(Previously I had assumed it would dock in a similar manner to Progress or Soyuz, that is coming from behind and underneath - this says the station will change its whole attitude, something not seen since the early years of construction)
Image is from me screen capping my monitor!
NASA video feed.
https://civiliancomms.tripod.com/spacecomms/iss/iss_appendix_c.html
XPOP means that the ISS X axis is perpendicular to the orbital plane.
The X-Axis Perpendicular to Orbit Plane (XPOP) reference frame is shown. XPOP is a quasi-inertial reference frame that can be visualized by a 90° yaw of the LVLH frame at orbital noon. The X-axis points out of plane, while both the Y- and Z-axes lie in the orbital plane. Note that unlike LVLH, which is rotating with the Station as the Station rotates about the Earth, XPOP remains fixed with the Station X-axis pointing out of plane and the Z-axis is aligned with the orbit noon vector. XPOP is a “quasi-inertial” reference frame, because as the orbital plane slowly regresses, the XPOP reference frame also regresses to keep the X-axis pointing out of the orbital plane.
Is the new ISS attitude for Nauka's docking going to be thus:
-XLV ZVV ? (assuming ISS negative X axis is pointed to the local vertical and the positive Z axis is pointed into the velocity vector)
Previously, during stages of construction I recall the station held -XLV -ZVV X-POP attitude.
And then I am assuming again that the ISS will reverse its movement to regain TEA position.
Or will it 'follow through' with the yaw direction instead (completing a circle, if you will)?
So I guess my questions are:
- Will the ISS adopt a -XLV ZVV X-POP attitude for the Nauka docking?
- How will it achieve this?
- Will it yaw to starboard or port?
- Will it yaw and pitch separately or all at the same time (unlikely)?
- Will the Solar Array spend a little time during this manoeuvre not in its optimum sun-facing attitude.
- How long will it take?
- Are they only using the CMG's for this?
- When it goes back to TEA, does it simply reverse its motions or will it carry them on through?
- Who is in charge during this - Russian module so the Russians or Houston for overall ISS control?