Soyuz TMA-8 was a transport mission for portions of the International Space Station (ISS) Expedition 13 crew.

Flight Engineer Marcos Pontes joined the TMA-8 crew for the ascent and docking with ISS, spent approximately seven days aboard the ISS conducting experiments as part of the Missão Centenário, then returned to Earth with the outgoing members of Expedition 12 aboard Soyuz TMA-7.

Vinogradov and Williams were joined on their return trip to Earth by Spaceflight Participant Anousheh Ansari who launched aboard Soyuz TMA-9 and spent approximately eight days aboard ISS conducting experiments for the European Space Agency.

Near the end of second stage burn, a communications blackout occurred at Moscow Mission Control.

[4] They replaced the Expedition 12 crew, Commander William McArthur and Valery Ivanovich Tokarev.