On Earth, scientists can build a spacecraft out of special sterile facilities. Scientists can decontaminate each component as it is assembled to the spacecraft, and they can test for any remaining contamination.
NASA spends a humongous amount of money, annually, making sure spacecrafts are properly sterilized so that our Mars landers wouldn’t bring any bacterial life from Earth to mix it up with whatever may be living there.
Since Earth’s microbes are tough, they can survive in extreme environments and temperatures. Some have even remained alive despite being exposed to ultraviolet and ionizing radiation and the vacuum of space. This is why the planetary protection advocates are so concerned about our exploration of other planets in the solar system.
The so-called Planetary protection is a guiding principle in the design of an interplanetary mission, aiming to prevent biological contamination of both the target celestial body and the Earth.
Concerns about the contamination of the icy moon Europa, for instance, prompted controllers of NASA’s Galileo mission to crash the spacecraft into Jupiter in 2003 so that microbes wouldn’t accidentally take seed on what could be a habitable moon.
However, despite the best efforts of spacecraft cleaners, some microbes seem to survive conventional cleaning processes. This is why a new method is emerging that uses ionized gas to kill the microbes.
The method was presented at the European Astrobiology Meeting in October 2014, in an effort led by Ralf Moeller, a space microbiologist at the German Aerospace Center (DLR) and Katharina Stapelmann, a plasma researcher at Ruhr-University Bochum in Germany.
Plasma sterilization is a process not only compatible with modern spacecraft, but it also enables successful removal and inactivation of most resistant microbial species isolated in spacecraft assembly facilities,” Moeller wrote in an email to Astrobiology Magazine.
He added that, to characterize spacecraft-assembly inhibiting microorganisms thoroughly in order to assess their potential for forward contamination, and development of more effective reduction, cleaning and sterilization technologies, is in the best interest of all spacefaring nations and research agencies, such as NASA and the European Space Agency (ESA).
When a NASA mission leaves Earth, it is designed to meet internationally accepted standards for planetary protection.
For most Mars missions — including fairly recent ones, such as Europe’s Mars Express and NASA’s Mars Exploration Rovers (Spirit and Opportunity) — scientists examined the microbial diversity of organisms that were left over after these steps.
In most cases, spore-forming bacteria constituted a dominant fraction of those microorganisms cultivated after heat-shock treatment. Microbes residing in the clean rooms during the spacecraft assembly process could gain access to a spacecraft, and possibly survive en route to extraterrestrial systems,” Moeller said.
Last year, the researchers presented a newer form of sterilization at the European Astrobiology Meeting. The method involves using plasma — ionized gas — at low pressure on the spacecraft.
The method is very fast. Full spore inactivation of 100 million of bacterial spores was achieved in five minutes, even with spores of Bacillus pumilusSAFR-032, a space craft assembly facility isolate, which encounters the highest resistance to UV radiation and further sterilization methods. So far, the method is not used for spacecraft in development yet. Another method based on plasma but operated under atmospheric pressure is planned to be used on the International Space Station, if a recent proposal is accepted,” Stapelmann said.
Stapelmann’s and Moeller’s method may take some time to gain acceptance, given that there are already established procedures in place. The current methods of sterilizing surfaces in general (not spacecraft) involve high pressure, high temperature, and radiation through ultraviolet or gamma rays, Moeller pointed out. There are drawbacks to these methods — namely, they can damage the underlying material, leave residues and create microbial resistance.
Plasma sterilization is emerging as an alternative to commonly used sterilization techniques, due to many advantages. It’s cost-effective, fast, efficient, and safe in terms of thermal, chemical, or irradiation damage.
via Astro Bio