Sasha and I had another full day of ATV training today, starting with a lesson on docking system malfunctions.
ATV uses a slightly modified version of the Russian docking system, the one of the Soyuz and of the Progress. It’s a very robust system that has proven itself time and again. However, we do have a few contingency plans in case something goes wrong.
The main thing that needs to work is the retraction of the docking probe. As you can see in the picture, once ATV is on orbit the docking probe is extended. It’s the head of the docking probe that makes the first mechanical connection to Station. Then the probe is slowly retracted, pulling in ATV until the full docking interfaces can be mated and the hooks can be closed.
If the probe can not be retracted for whatever reason, we have a problem. The probe head is captured, but we have no rigid mechanical connection between ATV and Station. With ATV attached only via the probe, we can not apply control torques to the Station to keep it in a desired attitude. Until we solve the problem, we have to stay in free drift.
That’s why, if we really could not retract the probe, neither automatically nor via manual commands, pretty soon we would have to send ATV away. For a really bad day, we even have to option to pyrotechnically separate the docking mechanism. That would be really the last resort option, though, because if would end ATV’s mission for good and make the docking port unavailable.
Photo 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:
https://anne.cpamoa.free.fr/blog/index.php/category/logbook-samantha
26/11/2013