[4] The Soyuz TMA-21 spacecraft launched from Baikonur Cosmodrome on 4 April 2011, carrying Expedition 27 crew members Aleksandr Samokutyayev, Andrei Borisenko and Ronald Garan.

[7] After departing the space station, the spacecraft was used for the Radar-Progress scientific experiment to investigate a reflection feature of the plasma generated by operations of the Progress propulsion system.

The following day, on 23 May, the Soyuz TMA-20 spacecraft departed from the ISS, returning Expedition 27 crew members Paolo Nespoli, Catherine Coleman and Dmitri Kondratyev to Earth.

Soyuz TMA-20 landed safely in central Kazakhstan at 02:27 UTC on 24 May 2011,[10] having taken photographs of the shuttle docked at the ISS prior to re-entry.

[11] This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.