Microbial lifeforms that can survive and even thrive in extreme environments — known as extremophiles — have become the focus of much research in recent years.
Such extreme-adapted lifeforms are found living in some of the planet’s most challenging environments: in the frigid and high saline reservoirs a mile beneath Antarctic glaciers or living in the deep ocean alongside smoking, sulfur-spewing thermal vents. A few, such as the polyextremophile Deinococcus radiodurans, can withstand hundreds or even thousands of times the radiation dose that would kill any larger animal.
But when we think of an extreme environment we tend not to view being completely “clean” or sterile as one such environment. But that’s exactly the kind of environment astronautical engineers must maintain to protect their space crafts from accidentally contaminating other worlds by allowing microbes to hitch-hike into space.
Space programs must maintain extremely clean (i.e., microbe free) environments in the form of clean rooms which are kept “totally” sterile through a strict protocol. Clean room air is constantly filtered. All surfaces in a clean room are repeatedly scrubbed with alcohol and hydrogen peroxide and then heated to high temperatures than microbes can not tolerate. Persons entering a clean room must wear full coverage (except for the eyes) prophylactic clothing and are even subject to a high-pressure ‘air-blasting” before entering to remove any residual bugs or potential bug-harboring substances that might be present on the body.
For this reason as well as the critical importance of preventing accidental contamination of any probed world, the discovery of any microbial life in a clean room is a matter of great concern. And, if such a microorganism were to be both highly adapted to sterile conditions and a previously unknown life form, the concern is magnified.
A Brief History of a New Bug
Our story begins in 2007 in a clean room at NASA’s Kennedy Space Center (Florida). There, NASA engineers were busy making final adjustments to the Mars lander Pheonix prior to its launch. And it was there that the first evidence of this unusual microbe surfaced.
Two years later, in May of 2009, European Space Agency (ESA) engineers working at the agency’s South American site were preparing the Herschel Space Telescope prior to launch on-board an Ariane 5 rocket. They began a concerted search for any contamination in or around the site and found traces of what appeared to be a similar microorganism.
The existence of an organism that could survive such sterilization procedures (in an environment devoid of nutrients) naturally becomes a subject of great scientific curiosity. Following the 2009 discovery, Scientists from NASA and ESA teamed up to investigate the highly unusual bacterial life form.
A Brand New ‘Phoenix’ of a Microbe – Found Nowhere Else (So Far)
Designated Tersicoccus phoenicis (‘tersi’ means ‘clean, ‘coccus’ refers to its spherical shape, and ‘phoencis’ refers to both the Mars lander and the indestructible bird of Greek myth), scientists determined that the bacterium was more unusual than they had thought; it was a new genus (a higher category of taxonomic classification) as well as a new species. The new “extreme” microorganism was described in a paper published in the International Journal of Systematic and Evolutionary Microbiology this past July.
Parag Vaishampayan, a microbiologist at the NASA Jet Propulsion Laboratory (who led the team behind the Kennedy Space Center detection) commented:
“This is the first report of bugs isolated in two different clean rooms, and nowhere else.” [quote source]
Microbiologist analyzing the bug found that it shares less than 95% of it genome with its next closest related bacterium. They also characterized the bacterium’s cell wall as having a “unique molecular composition”. This and other unique properties helped classify the bug as a genuinely new type of bacterium.
Big Questions for a Small Life Form
Other questions remain: scientists do not yet know if T. phoenicis lives only in clean rooms or if it is found elsewhere on Earth but has avoided detection up to this point. Its “extreme” adaptation may be the result of a lack of competition. The new bug may not be able to thrive under normal (high microbe diversity) conditions or environments; it dominates only when all other competing microbial life forms are eliminated. So, it may indeed be present in other nutrient and microbe-rich locales but in such small numbers that it goes undetected.
But there is another question of deep concern here that revolves around the issue of “planetary protection”: Has such a life form survived previous clean missions, such as Mars rover missions, or the Pheonix lander mission, and made its way secretively to another world already?
According to Peter Smith, Phoenix’s principal investigator:
“This is a minimal risk considering that the portions of the spacecraft that are actually part of the experimental or sample collecting apparatus are kept exceptionally clean, if not sterile. The surface environment on Mars is superlow pressure, no water, high [in] ultraviolet flux and high [in] cosmic radiation. In other words, a terrible place for life, even microbes that like clean rooms.” [quote source]
However, there is evidence that at least some microbial life forms can indeed survive the harsh conditions of space. In 2008, and experiment called PROTECT was conducted on-board the International Space Station. In the experiment, spores from two species of bacteria (Bacillus subtilis and B. pumilus) were mounted outside the space station for a year and a half, where they were subjected to the vacuum of space with its extremely cold temperatures and a nearly constant assault of radiation. Although most of the bacterial spore died, some did survive. This proved, at least indirectly or in principle, that some microbes could survive the trip to Mars and perhaps even survive on the Martian surface. To do so, the microbes would need to find a protective niche, of some kind, and/or develop an efficient DNA repair mechanism (like the D. radiodurans bacterium noted earlier; see photo, at lower right).
Of course, the other critical reason for all this cleanliness is to insure that this or any other Earth-derived microbial life form would be mistaken for an alien life form. And, as of yet, there is no proof that T. phoenicis or any other microbe has actually made it to Mars. That said, at least a few thinkers suspect that such microbes may already exist on Mars and other worlds.
According to Cornell University astrobiologist Alberto Fairén (as quoted in a recent SciAm article):
“This genus has surely traveled to Mars already, recently in one or more of our spacecraft—they live comfortably in the clean rooms where we build the craft, right?—and maybe even onboard meteorites millions or billions of years ago. Therefore, if these bugs can actually survive on Mars, they must be there already.”
While one might disagree with this reasoning, it reflects one basic fact: Life (at least some microbial life) is stubborn — it holds on even in the most extreme of environments. But are the conditions that promote the biogenesis of even simple life forms more varied, more flexible, than we suppose?
More things in Heaven and Earth, Horatio…
Some source material for this post (including top image and quotes) came from the SciAm article: ‘New Bacterial Life-Form Discovered in NASA and ESA Spacecraft Clean Rooms’ By Clara Moskowitz
Top photo: This species of bacteria, named Tersicoccus phoenicis, was discovered in two spacecraft clean rooms, where it endured harsh sterilization procedures and coped with a lack of nutrients to survive. Image: NASA/JPL-Caltech.
Bottom Photo: A tetrad of D. radiodurans; credit: Oak Ridge National Laboratory