I mentioned in yesterday’s Logbook that the Soyuz commander has a periscope view available. You can see the actual periscope in the attached picture.
As you might have noticed, it has two circular openings offering two views that are offset by 90 degrees. To change between views a mirror inside the periscope is rotated.
Most of the time the view of interest is the one “straight out” along the axis of the periscope. Whenever there is a need to fire the engines, the reference orientation in which the Soyuz puts itself is along the local vertical: in this orientation the periscope faces towards Earth. The optical setup is such that the commander sitting in the center seat will see the entire globe symmetrically in the field of view if the Soyuz is properly oriented. Also, any feature on the surface of the Earth will be running from top to bottom (or from bottom to top if it’s a braking attitude).
When we approach the Station for rendez-vous the mirror is turned so that the commander can now have a forward view. This is the view we would use to align the Soyuz manually if we had to fly a manual docking.
Should the mirror remain stuck on the initial position – you guessed it – we have backup option. We can use a camera view and a second target which is aligned with the camera: that’s the circular target on yesterday’s picture!
Picture credit: NASA
(Trad IT) Traduzione in italiano a cura di +AstronautiNEWS qui:
https://www.astronautinews.it/tag/logbook/
(Trad ES) Tradducción en español aquí:
https://www.intervidia.com/category/bitacora/
(Trad FR) Traduction en français par +Anne Cpamoa ici:
08/12/2013