International Space Station Expedition 16 have experienced high deceleration forces during the re-entry of their Soyuz TMA-11 flight.
The Soyuz spacecraft was either commanded or automatically entered into a ballistic re-entry due to anomalous data from it’s guidance systems. A ballistic trajectory is considerably steeper than a normal trajectory and causes the aerodynamic braking to increase much faster than during a shallow re-entry. It’s probably testament to the design of the Soyuz that it can withstand such a manouver.
CDR Peggy Whitson, FE1 Yuri Malenchenko and Spaceflight Participant Yi So-yeon experienced up to 10Gs of sustained deceleration to ultimately land about 295 miles off their original target in the Khazakh Steppes . Due to the distance involved, recovery forces took 45 minutes to reach the capsule. The crew were given medical examinations on site.
My understanding is that the ballistic re-entry profile is a fail-safe mode where the full guidance system cannot be relied on to execute the shallow re-entry profile correctly. I would guess that the ballistic profile is initiated by a relatively straight forward extended burn by the motor on the PAO to reduce orbital velocity and create a ballistic descent.
Tags: ballistic reentry, burn, expedition 16, khazakhstan, off course, pao, Peggy Whitson, soyuz, tma-11, Yi So-yeon, Yuri Malenchenko
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