Survival of microorganisms in outer space
Entirely apropos of the upcoming class discussion on microbial control, I present this link to an excellent essay on Gizmodo, the Gadget Guide on how NASA worked to prevent a potential Earth-bound plague from pathogens that might have been introduced via returning astronauts. In the early days of the space program, the potential risk that returning astronauts might also bring back an infectious agent with them was not known. Consequently, NASA introduced pretty significant decontamination measures upon recovery of the astronauts.
With the Apollo missions, astronauts were put into a 3 week quarantine, which was expected to be a sufficiently long time period for any novel pathogens to incubate. The recovered equipment (spacecraft, cameras and film, moon rocks) were decontaminated with strong bleach and kept in quarantine as well. During quarantine, all generated waste as well as expunged air was incinerated before disposal.
Methods today are somewhat less stringent. NASA has created categories with specific associated risks, with Category I being for missions to the Sun, Moon, or other celestial body, with no interest in any potential biological system. Category V is for any mission that sets down on a foreign body and returns with materials to Earth. The risk factors (with the exception of Category V) are now not put in place to prevent the introduction of a pathogen into a terrestrial environment, but instead are designed to prevent introducing microorganisms from Earth into an extraterrestrial environment.
This is not as far fetched as it might initially seem. Tardigrades are microscopic animals that are able to survive the vacuum and cold of space just fine, however these organisms were put on board the International Space Station on purpose. Another story illustrates the potential dangers more clearly. Surveyor 3 landed on the Moon in 1967, and transmitted a number of pictures back to Earth prior to the manned Moon landings. Apollo 12 (the second manned Moon landing) was able to visit the Surveyor 3 landing site, and returned to Earth with the mounted camera, which now can be seen in the National Air and Space Museum.
Even though Surveyor 3 was constructed in a state of the art clean room prior to launch, biologists were able to recover viable Streptococcus cells that had been carried to the moon and back, and remained in a viable state for 3 years on the lunar surface, while being exposed to extremes of temperature, constant vacuum, and high levels of radiation. Because of this finding, current precautions include exposing the space craft to hydrogen peroxide vapors with multiple cycles of vacuum. Hopefully these precautions will prevent us from inadvertently destroying all life on another planet!