Anton and I spent the afternoon in the Soyuz simulator today, warming up as we wait for our third crewmember Terry to join us in the sim next week.
First we practiced the nominal undocking sequence and a nominal reentry burn, of course with a number of malfunctions. Then we moved on to practicing a ballistic reentry. I have explained in this earlier logbook that it’s not a very comfortable way of returning to the planet.
To add a little bit of detail, let’s take a look at today’s second scenario: we had just left ISS and discovered that we were loosing our atmosphere into space. Pressure in our descent module was decreasing with a rate of 1 mm Hg every 10 seconds. (Yes, the Russian space community loves mm of mercury!)
Our computer was programmed with all the data for a comfortable nominal reentry, but that would have meant turning on the engine to give the braking impulse and reenter the atmosphere only about two hours later! Not a good idea in our scenario to wait that long.
That’s where the so-called Program 5 comes in: a predetermined sequence of commands stored in the computer with very generic parameters for the reentry burn. Certainly not enough for a controlled reentry, but enough for a ballistic ride through the atmosphere. The key of course is to start Program 5 at the right time. We have a printed table called Form 23-14 which contains the “magic time” for each and every orbit: Russian cosmonauts print it out every single day on Station and make sure a copy is in every Soyuz, to be prepared in the case of an emergency evacuation!
Of course, in our case things were not so easy. We got a computer failure before the engine burn and we ended up having to do everything manually. But even in that case, Form 23-14 is your best friend: it tells you at what time you need to press the button and manually turn on the engine.
Why is that so important? Well, it’s you only guarantee that you will land in a relatively safe area, rather than, for example, in the middle of the ocean or on a Himalayan mountain peak!
(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://spacetux.org/cpamoa/category/traductions/logbook-samantha/
31/01/2014