Sunday, January 29, 2012

Expedition 26 Soyuz Landing: Soyuz TMA-01M spacecraft

Russian support personnel work to help get crew members out of the Soyuz TMA-01M spacecraft shortly after the capsule landed with Expedition 26 Commander Scott Kelly and Flight Engineers Oleg Skripochka and Alexander Kaleri near the town of Arkalyk, Kazakhstan on Wednesday, March 16, 2011.

You might have noticed in post-landing pictures that nobody approaches the “bottom” part of the Soyuz descent module. Ever wondered why?

Many people have suggested that it might be very hot. In fact, that is not the case. 

The real heat shield is ejected at an altitude of ca. 5,5 km when the capsule is already hanging under the parachute.

Others have suggested that there might be a danger of accidental firing of the retrorockets. 

Although this sounds like a reasonable suggestion, we are not aware that this presents a risk.

These are two sources of danger that we know of:

1) The gamma-ray altimeter
This device is responsible for generating a signal before ground impact (ca 0,74m) that causes retrorockets to fire

2) Antenna deployment
There are three UHF antennas on the bottom of the descent module. When the descent modules comes to a stop laying on its side, the highest one of the three is automatically deployed eight minutes after ground contact, or earlier by the crew. 

For deployment, the panels covering the antennas are shot away by explosive charges. In case of positive contact with the rescue squad, the crew is typically told to inhibit further antenna deployment; however, a residual danger remains, hence the Keep-Out-Zone.

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