Question about Soyuz reentry

[PeterRoss]

In fact, it's more about pre-reentry stage of flight. I've read in wiki that Soyuz detaches the orbital module before performing deorbit burn. Which means, to my inderstanding, that orbital module remains on near-ISS orbit as a piece of junk? Isn't it dangerous for the ISS and arriving/departing ships?

I've noticed already that the orbit is a big thing and so on, but this orbit looks so close to ISS orbit and in the same plane too. Since they're detaching the orbital module for saving propellant purposes I doubt they can move orbit far enough from ISS without making the whole thing about first-detaching-and-then-burning fuel-inefficient.

Or am I wrong?

 

[Urwumpe]

In fact, it's more about pre-reentry stage of flight. I've read in wiki that Soyuz detaches the orbital module before performing deorbit burn. Which means, to my inderstanding, that orbital module remains on near-ISS orbit as a piece of junk? Isn't it dangerous for the ISS and arriving/departing ships?

They don't do it anymore, they did it with the introduction of the Soyuz T model. After a few critical situations (failed deorbit burn because of software problems, crew had only the tiny reentry module as hab, little food, no toilet.), it was decided that it is better to keep the OM until after de-orbit.

The OM deorbited uncontrolled because of exospheric drag rather quickly.

I've noticed already that the orbit is a big thing and so on, but this orbit looks so close to ISS orbit and in the same plane too. Since they're detaching the orbital module for saving propellant purposes I doubt they can move orbit far enough from ISS without making the whole thing about first-detaching-and-then-burning fuel-inefficient.

You don't make plane changes and the separation is done by simply getting a small difference to the ISS with small maneuvers undocking (TORVA) in the plane. The early OM separation just permitted to transport more cargo back from Mir or to Mir. If you have just a few meters difference to the ISS orbit, you can quickly get ahead of the ISS and have a few hundred kilometers separation after a few hours of flight.

Or am I wrong?

Yes.

 

[PeterRoss]

Thanks for your answer:tiphat: