Back in the Soyuz sim today with Terry and Anton, this time wearing the Sokol and set to practice an emergency descent after undocking.
These scenarios are always very intense but, on the other hand, somewhat shorter than a normal descent, because we rush to make an early opportunity to turn on the engine for a braking burn, about 40 min after opening the hooks to undock from ISS.
Today we started out with a leak in the Soyuz, to which we added a second failure that, in itself, would lead to an emergency descent: a depressurization of the high-pressure helium lines. There are no pumps in the Soyuz propulsion system: it’s a simple and robust design that uses high-pressure helium to pressurize the propellant tanks. If the helium starts leaking, we need to turn on the engine before the pressure becomes to low for the deorbit burn.
So, with a leaking descent module and leaking helium tanks, we were all set for a ballistic reentry using Program 5, which I have explained in this previous logbook.
Except that Dima, our evil instructor, also threw a main computer failure at us, so we had to revert to flying our ballistic reentry in the so-called “analog loop” – it’s the older computer from the previous Soyuz series, which leaves a lot of work up to the crew and has a lot less built-in automatic checks. Main thing: you need to build the attitude and turn on the engine manually and, if the engine fails, you need to manually shut it down and turn on the backup thrusters.
We had an engine failure so early on in the burn today that we burned on the backup thruster for over half an hour (instead of the nominal 3 min and 41 seconds) and we ended separating from the service module by thermal sensors, instead of by command… how that works, is a story for another logbook!
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/
14/08/2014