In the next ten years, one of the world's leading space powers plans to launch a mission to Mars. The main objective of this expedition is to search for signs of life on the Red Planet. However, researchers face a significant challenge: how to distinguish potential Martian life from terrestrial microorganisms that may have been accidentally brought by space probes.

Recent research has shown that it is extremely difficult to fully protect Mars from terrestrial biological contamination. Space agencies employ strict sterilization protocols for equipment sent to other planets. Devices are heated to temperatures between 120 and 200 degrees Celsius, assembly facilities are regularly treated with hydrogen peroxide, alcohol solutions, and ultraviolet light, and the air is filtered through HEPA filters.

The need for such measures is explained by Earth's history, where invasive species have repeatedly and radically altered local ecosystems. On Mars, the presence of primitive life forms is suspected—this is suggested by recorded fluctuations in methane and oxygen concentrations in the atmosphere. For scientific conclusions to be reliable, it is crucial to confirm that any discovered organisms are of Martian origin.

American researchers have found that the bacterium Tersicoccus phoenicis is almost impossible to completely eliminate from the sterile rooms where spacecraft are assembled, and therefore from the spacecraft themselves. The results of their work are published in the journal Microbiology Spectrum.

Tersicoccus phoenicis was first identified in NASA's clean rooms and on the surface of the Phoenix Mars lander. Later, this microorganism was also found in South America, confirming its global presence in aerospace industry facilities. The bacterium demonstrates remarkable survival in conditions of intense sterilization and minimal moisture.

The study's authors determined that this species has adapted not only to extreme environmental conditions but also to the methods used to detect it. Standard sterility checks involve culturing samples from surfaces on nutrient media. However, Tersicoccus phoenicis proved resistant to this method: after exposure to adverse factors, only 1–4 cells out of a million began to multiply under laboratory conditions. At the same time, the rest did not die—even after 83 hours of sterilization, growth remained minimal.

Previous tests did not last as long, so the survival of this species went unnoticed. Researchers found a way to speed up the process by adding a protein from the related bacterium Micrococcus luteus to the nutrient medium. This reduced the time to the onset of growth to 31 hours.

Scientists emphasized that the entire group of actinobacteria possesses similar survival mechanisms, which means other species may also have comparable resistance. Existing methods do not guarantee accurate determination of the complete cleanliness of rooms or equipment. The use of Micrococcus luteus protein may improve the situation, but its effectiveness against all potential bacterial species has yet to be established.

In the 2030s, SpaceX is planning large-scale Mars missions, which will significantly complicate efforts to prevent biological contamination of the planet with terrestrial organisms. Therefore, it is already necessary to identify which bacterial species could be delivered to Mars by automated stations. Otherwise, there is a risk of discovering new types of microorganisms on the Red Planet, similar to Tersicoccus phoenicis, capable of surviving sterilization and thriving in Mars-like conditions.