ESA astronaut André Kuipers (middle) and cosmonaut Gennady Padalka (right) practising using ESA’s Kubik incubator before their first mission together in 2004.

The incubator contains microscopic Caenorhabditis elegans worms to investigate how they adapt to space conditions.

Eight years later André and Gennady were reunited on the International Space Station with a follow-up study on the same species of worms.