Complex sentence: Soyuz TMA-11 suffered a reentry mishap similar to that suffered by Soyuz 5 in 1969; the service module failed to completely separate from the reentry vehicle and caused it to face the wrong way during the early portion of aerobraking.
Split into simpler sentences: Soyuz TMA-11 suffered a reentry mishap similar to that suffered by Soyuz 5 in 1969. The service module failed to completely separate from the reentry vehicle and caused it to face the wrong way during the early portion of aerobraking.