So, now I am back, working at full speed to a launch date that is now, wow, only 79 days away!
Since my last logbook I have had brief trips to Japan and to Europe that included some refreshers on the JEM and Columbus systems respectively, but mostly training on the JAXA and ESA experiments that I will perform during my stay on ISS. I’ll try to catch up on that in some upcoming logbook.
Now ‘m back in Houston for my final few weeks of training at the Johnson Space Center. As usual, training here is extremely varied: yesterday was my first day and I had a phlebotomy class, a few brief classes on the experiments Body Measures and Salivary Markers, a consultation class on the Environmental Control System, a proficiency class on the onboard application we use to locate a hidden fire and a couple of IMAX classes, including a trip to the Galveston IMAX theatre to watch footage that I recorded with Terry back in July.
Today, Terry and I said our final goodbye to procedure 2.600, at least in terms of training. And I certainly hope we will not use it on orbit, though you never know! The infamous 2.600 is the “Unknown EPS bus failure” procedure, with EPS being the Electrical Power System. It’s meant to cover a major power loss, which could potentially affect communication with the ground: that could happen because the communication systems loose power or because we loose ISS attitude control or simply pointing data (so the antennas don’t know where to find the communication satellites). Or a combination of all those things. Moreover, with a major power bus loss we could partially loose internal and/or external cooling, which would put us on a so-called thermal clock: within a few hours, some components would start to overheat.
As you might imagine, the ISS has a lot of self-protection features: they are called FDIR (Fault Detection Isolation and Recovery). The problem when you have a major power bus loss, like we had today in our scenario, is that you might loose power to the computers that are responsible for the FDIR response: for example the computer that would normally recover communication to a backup string.
Slowly but certainly, the ISS main computers, the ones at the top of the hierarchy, will bring online backup units for all the lower level computers, according to a predetermined priority sequence. But full recovery might actually take a full hour and crew intervention is still required to make sure that the Station is brought to a safe configuration, especially in terms of cooling.
In our scenario today the very first priority was to recover attitude control by putting the Russian GNC computers in charge (GNC = Guidance, Navigation and Control, which includes keeping the ISS in the proper orientation). As soon as the Russian computers gain attitude control, they immediately fire the thrusters to bring the ISS back to its nominal attitude along the local vertical and the velocity vector. You may wonder why that transition to Russian control doesn’t happen automatically in case of loss of attitude. Well, the problem lies with the solar arrays: they track the Sun and they could be oriented in such a way that thruster firing might damage them. So we first need to bring the solar arrays to a fixed, safe position: one of the things that 2.600 will guide you to do!
Futura mission website (Italian): Avamposto42
avamposto42.esa.int
(Trad IT) Traduzione in italiano a cura di +AstronautiNEWS qui:
https://www.astronautinews.it/tag/logbook/
(Trad FR) Traduction en français par +Anne Cpamoa ici:
https://spacetux.org/cpamoa/category/traductions/logbook-samantha/
(Trad ES – Currently not updated) Tradducción en español aquí:
https://www.intervidia.com/category/bitacora/
05/09/2014