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Michele Zanin
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si riparte, sempre a piedi...

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good read

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going ballistic!
L-495: Logbook

Today I go ballistic!

The Cosmonaut Training Center here in Star City is the home of the world’s biggest centrifuge with its 18-meters arm. It’s a pretty impressive beast. I had a first ride in it last week and I’ve written about it here:

http://blogs.esa.int/astronauts/2013/07/22/a-ride-in-the-worlds-biggest-centrifuge/

But while last week I only went to 4.3 G, this time I will experience up to 8G. The purpose of this is not to inflict unnecessary pain on poor crewmembers, but rather to prepare us for the case of a ballistic reentry, when G loads can easily go up to 8G and more!

So, what’s a ballistic re-entry? That’s a mode in which nobody, neither the crew nor the computer, is trying to control the re-entry trajectory of the vehicle. It pretty much comes down like an inert body with a trajectory dictated purely by its geometric characteristics and mass distribution. With one trick: the capsule is put into a continuous rotation around it’s longitudinal axis of about 13°/sec.

So, why would we choose to go ballistic? Not that the nominal re-entry is a smooth ride, but this one is definitely rougher. Well, it could happen because of a number of failures during the nominal reentry. That’s why whenever a crew is returning from orbit there are always two rescue teams waiting: one at the nominal landing site and the other at the ballistic site.

But it could also happen that you have to leave the orbit quickly because of an emergency, for example a fire or a depressurization. In that case the control teams at Mission Control Moscow don’t have the time to calculate and upload into the onboad computer the data for a controlled re-entry. So ballistic it is! And no, there won’t be a rescue team waiting in this case.

Picture credit: GCTC

#SamLogbook
Traduzione italiana a cura di +AstronautiNEWS qui:
http://www.astronautinews.it/tag/logbook/
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a casa, dopo quasi 5 mesi di viaggio...
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