New research being presented at the Astrobiology Science Conference shows the International Space Station has an irritating mould problem — not only on the inside, but the outside, too.

The spores — which astronauts spend hours cleaning every week — can survive X-ray exposure at 200 times the dosage that would kill a human being, according to Marta Cortesao, a microbiologist at the German Aerospace Centre in Cologne, who is presenting the research.

And that's not all. The common mould spores found on the ISS — aspergillus and penicillium — can also survive extreme temperatures, ultraviolet light, chemicals and dry conditions. Their resilience not only makes it harder to clean, but more likely to survive long-term.

"We now know that [fungal spores] resist radiation much more than we thought they would, to the point where we need to take them into consideration when we are cleaning spacecraft, inside and outside," Cortesao said in a statement.

"If we're planning a long-duration mission, we can plan on having these mould spores with us because probably they will survive the space travel."

The research touches on this, and it warns astronauts to follow recommended planetary protection protocols designed to prevent visiting spacecraft from contaminating other planets and moons in our solar system with microorganisms from Earth. The study suggests that, because of the risk of contamination, these fungal spores may need to be considered a more serious threat.

But the spores may not be all bad though. Cortesao's research is looking for ways the space-growing fungi may help us long-term, investigating their capacity to grow in less than ideal conditions. The study's aim is to harness the hardy microbes as biological factories to create materials astronauts may use on longer missions, such as antibiotics and vitamins.

Although the research is vast, it did not address the spores' ability to withstand the combination of radiation, the vacuum of space, the cold and low gravity.

Experiments designed to further test fungal growth in micro-gravity are set to launch in late 2019.