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NASA discovers bacteria that “fakes being dead” and challenges sterilization in space cleanrooms. Learn more about Tersicoccus phoenicis.
In 2013, NASA identified a bacterium capable of surviving rigorous sterilization processes in cleanrooms used for spacecraft assembly, but only recently — in 2025 — have scientists been able to explain how this microorganism manages to escape detection. It is Tersicoccus phoenicis, initially found after samples collected in 2007 during the preparation of a space mission. The discovery, made in environments separated by about 4,000 kilometers, revealed an unusual survival capability based on a state of deep dormancy, raising concerns about contamination in space missions and highly controlled environments on Earth.
From collection in 2007 to discovery in 2013
The story began in 2007, when engineers collected samples from the floor of an assembly room at the Kennedy Space Center during the preparation of the Phoenix Mars module. Years later, in 2013, scientists analyzed this material and identified a previously unknown bacterium.
The same organism was also detected in a cleanroom in French Guiana, approximately 4,000 kilometers away. This fact drew attention for a specific reason: it was the first time a new microorganism appeared in two extremely controlled and geographically separated environments.
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NASA revealed how the bacteria managed to escape
The answer to this behavior only came more than a decade later. In 2025, a study published in the scientific journal Microbiology Spectrum explained the survival mechanism of Tersicoccus phoenicis. According to researchers, the bacterium enters a state of deep dormancy, reducing its activity to almost imperceptible levels. This prevents traditional methods from identifying it.
Microbiologist Madhan Tirumalai described the phenomenon directly: “It’s not dead. It was faking being dead.” The statement summarizes the main challenge faced by scientists: differentiating truly dead organisms from those that are merely inactive.
The cleanrooms used by NASA are designed to be some of the most controlled environments on the planet. In these locations, several strategies are applied simultaneously:
- Continuous air filtration
- Pressure control to prevent particle entry
- Use of radiation, heat, and chemical substances
- Elimination of any moisture source
Even with this set of measures, the presence of the bacteria showed that not all microorganisms are completely eliminated. This scenario indicates that extremely sterilized environments may not be infallible.
The bacteria’s resistance and adaptation to the extreme environment
Tersicoccus phoenicis not only survives but also adapts to conditions considered hostile to life. Without nutrients, exposed to chemicals, and subjected to adverse conditions, it finds a way to persist.
One of the strategies involves dormancy, which allows the microorganism to temporarily “shut down” its vital functions. In some cases, bacteria can also form resistant structures or even utilize compounds present in cleaning products. This behavior suggests that the very attempt to eliminate microorganisms may favor the survival of the most resistant ones.
Concerns have increased with more recent discoveries. In 2025, scientists identified 26 new bacteria in samples collected from cleanrooms. Furthermore, over the years, hundreds of microorganisms have already been found in these environments, both at NASA and the European Space Agency.
Biologist Nils Averesch highlighted that microbial diversity still exists in these highly controlled locations, indicating that the problem is far from being fully resolved.
The presence of resistant bacteria represents a significant risk for space exploration. Missions seeking signs of life on other planets depend on environments completely free of terrestrial contamination.
If microorganisms from Earth are accidentally transported, they could compromise the results of scientific analyses. Furthermore, there is concern for the health of astronauts, especially on long journeys.
NASA and the invisible risk in crewed missions
Even with rigorous protocols, such as quarantine periods before launches, the possibility of microorganisms remaining on spacecraft cannot be ruled out. Another relevant factor is that the human immune system can undergo changes in the space environment, which could hinder the response to possible infections.
To date, there are no records of serious illnesses caused by this type of bacteria on missions, but the topic continues to be closely monitored. Researchers identified that *Tersicoccus phoenicis* possesses a gene linked to a protein called resuscitation promoting factor (RPF).
This element allows the bacterium to return to activity after long periods of dormancy. In laboratory tests, when this factor was introduced, the cells began to grow again — in some cases after several days.
Tirumalai emphatically described the effect: “But the moment you add RPF to it: boom!” This reaction demonstrates how the microorganism can remain hidden and then suddenly return to activity.
Consequences go beyond NASA and space
Although the discovery is linked to space exploration, its implications extend to various sectors on Earth. Environments such as hospitals, food industries, and pharmaceutical laboratories also depend on high levels of sterilization. The existence of bacteria capable of escaping detection can pose risks in these locations.
Biochemist William Widger highlighted the concern by stating that some of these organisms can be problematic, especially if not identified correctly. Based on the latest discoveries, scientists advocate for changes in detection methods. One strategy involves stimulating the “activation” of dormant bacteria to facilitate their identification.
Another approach is to analyze genetic material, even when there is no visible growth in the laboratory. These measures can help reduce risks both in space missions and in critical environments on Earth.
The trajectory of *Tersicoccus phoenicis* — from its collection in 2007, through its identification in 2013, to its scientific explanation in 2025 — shows how science can take years to fully understand a phenomenon. Throughout this period, NASA advanced its understanding of the limits of sterilization and revealed that microorganisms can develop surprising survival strategies.
With information from National Geographic
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