At an extravehicular activity Russian cosmonauts took samples from the outside of the Russian module. Those samples were then analyzed in a laboratory on Earth. Within this sample bacterial DNA was discovered.

However, the method by which the samples were analyzed in this case is disputed, as it cannot detect all kinds of bacteria and it also can not test whether the discovered bacteria are living and thriving or not.

Also the biomass that can be extracted from such samples is strongly limited so that at the moment no further tests could have been conducted on it. To do this, more samples would be needed.