Kornienko was selected as a test cosmonaut candidate and, in 1999, following basic training at the Yuri Gagarin Cosmonaut Training Center, he was qualified as a test cosmonaut. Since 1999, he has trained in the International Space Station group. He served on the ISS Expedition 8 backup crew as a flight engineer. In 2005, he was assigned to the Soyuz TMA-10 and Expedition 15 back-up crew as Flight Engineer 1. Expedition 23/24 Kornienko was aboard the space station as a Flight Engineer, being part of the Expedition 23/24 crew. He lifted off on 2 April 2010, along with fellow Russian cosmonaut Aleksandr Skvortsov and NASA astronaut Tracy Caldwell-Dyson aboard Soyuz TMA-18 from the Baikonur Cosmodrome. Ending Expedition 24, the Soyuz TMA-18 spacecraft carrying Mikhail Kornienko, Alexander Skvortsov and NASA astronaut Tracy Caldwell-Dyson undocked from the space station at 10:02 pm EDT on 24 September 2010. Following a normal descent, the Soyuz crew landed at 5:23 am GMT ear Arkalyk, Kazakhstan on 25 September. After returning to Earth and sharing his experiences to an audience, Kornienko said "The thing you miss there most of all is the Earth itself, I missed smells. I missed trees, I even dreamt of them. I even hallucinated. I thought I smelled a real fire and something being barbecued on it! I ended up putting pictures of trees on the walls to cheer up. You do miss the Earth there". Spacewalks On 27 July 2010, Kornienko and fellow Russian cosmonaut Fyodor Yurchikhin participated in a spacewalk outside the ISS. The two cosmonauts on 23 July put on their Orlan spacesuits and performed a dry run of the spacewalk activities. From inside the Pirs docking compartment they checked out the Orlan systems, practiced translation movements and tested their mobility. During the spacewalk, Kornienko and Yurchikhin outfitted the Rassvet module's (MRM1) Kurs automated rendezvous system, installed cables and remove and replaced a video camera. The spacewalk began at 04:11 UTC as Kornienko and Yurchikhin donned in Orlan spacesuits, depressurized the internal volume of the Pirs docking compartment airlock and ventured outside into space. It was the 25th Russian spacewalk performed from the station. At one point around 06:45 UTC the two spacewalkers accidentally lost an unidentified object that floated away from their perch on the side of the ISS. The cosmonauts speculated that the lost item was an attachment fixture to secure the cables in place once they