Thus far, Venkat has identified 22 species of microbes in the Spacecraft Assembly Facility, in other, similar NASA environments, even on actual spacecraft. Many are microorganisms common to arid environments, such as B. mojavensis
, a bacterium that probably drifted in from the Mojave Desert. A handful are entirely new species. One, which Venkat has named B. nealsonii
(in honor of Kenneth Nealson, who was his supervisor at the Jet Propulsion Laboratory), possesses two protective coats, making it a tough spore capable of surviving in the ultradry environment of the assembly facility. As Venkat discovered, the second spore coating also offers a secondary benefit: It makes the organism unusually resistant to gamma rays, a form of cosmic radiation that, in large doses, is fatal to men and microbes alike. (Earth’s atmosphere screens out most gamma radiation; Mars, in contrast, is a gamma-ray frying pan.) Tough as it is, the bacterium is probably not unique to NASA. The world of undiscovered microbes is vast, and Venkat suspects that B. nealsonii
also resides outside the assembly facility.
Venkat has found bugs in the spacecraft-assembly facility at the Kennedy Space Center in Florida; on hardware and in drinking water from the International Space Station; in circuit boards destined for an upcoming mission to Europa; and on the metal surface of the Mars Odyssey spacecraft, which has been orbiting Mars since October 2001. While Odyssey was being assembled at the Kennedy Space Center, Venkat isolated a new species of bacterium—Bacillus odysseyi, officially—that carries an extra spore layer, or exosporium, that makes it several times more resistant to radiation than other spore-forming microbes found in the facility. “It carries novel proteins as a sunscreen,” Venkat says. Like B. nealsonii, B. odysseyi may turn out to live elsewhere besides its assembly facility. But what’s notable, Venkat says, is that the very traits that render these bugs impervious to decontamination also grant them a decent chance of surviving the radiation shower they would encounter en route to and on the surface of a place like Mars.
One discovery, a bacterium named Bacillus pumilis, has given Venkat particular cause to marvel. He found the microbe thriving directly on spacecraft surfaces, presumably drawing its energy from ions of trace metals like aluminum and titanium. “Aluminum is toxic,” Venkat exclaims, baffled. “There are no nutrients. There is no water.” In addition, the species exhibits a remarkable defense against desiccation. The individual cells form protective spores, which then band together to create what Venkat calls an igloo. In microphotographs, this spore house looks rather like a macaroon. Moreover, when Venkat cuts open the igloo, he finds no visible trace of the individual spores; they’ve all dissolved into the collective matrix. High-tech methods of life-detection reveal no evidence of life. Yet when Venkat warms up the igloo and adds a little moisture, B. pumilis again springs into being. If the microbe is any indication of the sort of life that awaits discovery on Mars or elsewhere, he says, good luck to the robot sent to detect it.
B. pumilis itself isn’t a new species. It has been studied throughout the world for years, but its igloo-forming habits were not well known. For instance, its attachment to aluminum is novel. Last month, Venkat published a paper claiming that the SAF version of B. pumilis is in fact a new species after all—a substrain that has adapted and evolved to the conditions imposed on it by NASA, like an herbicide-resistant dandelion or the supertough microbes that sometimes spring up in hospitals. He has named it Bacillus safensis, and it represents precisely the kind of organism that his fellow astrobiologists are looking for in outer space. It’s not a Martian, but in form and function it may turn out to closely resemble one.
It is, in any event, one step closer than any other earthly creature to becoming the first organism to survive on another planet. Venkat has found the bacterium in every other NASA assembly facility he’s studied. Three years ago he found it on the Mars rovers Spirit and Opportunity, then under assembly at the Jet Propulsion Laboratory. At this very moment, the rovers are actively poking around in the Martian dirt, as they have been for the past nine months. B. safensis is almost certainly aboard them, alive and well, Venkat says. “They could be there for millions of years because they are spores. Whether they will become active and begin terraforming—that research is still ongoing.”
The Space Assembly Facility is a standing paradox. Through its assiduous effort to avoid spreading life throughout the cosmos, NASA has created an environment that inadvertently fosters the very kind of life it is traveling so far beyond Earth to find. As Venkat says, “We have a kind of survival of fitness.” What began as a means to an end is now an end in itself; the doorstep has become a laboratory, a nursery even, a small-town study in life’s cosmic persistence. It is a study, too, in the impossibly high cost of perfect hygiene. Venkat found that, in at least one instance, some of the microbes appeared to have been introduced during the cleaning process devised to eliminate them. Wherever humans go, it seems, we go with company. Looking around the assembly facility with Mora and Gomez, I saw a man-made cosmos, every surface a habitable planet, its ethers traversed by micronauts riding spacecraft named Human Hair and Eyeball Cell.
“People are the dirtiest things around,” Gomez said.
“Yeah,” said Mora. “We’re the contaminants.”
ANYBODY OUT THERE?
As NASA’s search for extraterrestrial life advances, it more and more resembles a trip through a hall of mirrors. The farther from Earth our gaze wanders, the more our very presence seems to nag us. Can we search for foreign life without contaminating it with our own? Can we discern the contamination from the real thing? If ultimately we’re related, if we’re all evolutionarily relatives from way back, is there even a difference? Some scientists wonder whether logic will permit us to find anything but ourselves out there: Our understanding of what constitutes life is shaded by what we know on Earth, so that’s all we know how to look for. It’s like that old joke about the guy who hunts for his keys under the lamppost because that’s where the light is. In his office, NASA microbiologist Kasthuri Venkateswaran—known as Venkat—nods vigorously in affirmation.
“Maybe it’s something you’re not able to detect with the naked eye. Maybe it exists on a different wavelength,” he says. A public-relations minder from NASA looks less than thrilled by Venkat’s speculations. He goes on: “You might think I’m crazy. Maybe there’s somebody walking around right now that we can’t see.”
The hunt for extraterrestrial life marks the ultimate test of humankind’s self-knowledge. We cannot find and recognize “other” until we can first, at the most basic cellular level, recognize “us.” Therein lies the true value of Venkat’s microbes. Having found B. nealsonii, B. safensis, and their kin—having in some sense fostered their creation and survival—NASA has no plans to destroy them all. On the contrary, Venkat intends to keep them alive as a sort of microbial archive for future reference. Someday, maybe soon, scientists will flip over a rock on Mars or Europa or somewhere out there and claim the profound, the first-ever discovery of “them.” How to tell for certain? We will hold up a mirror and compare appearances; that mirror awaits in Venkat’s office. His microbes are us: our emissaries, our representatives, the reflection of our wily selves. Deciphering and confirming the distinction—them or us—will most likely take years. But as Venkat sees it, those are precisely the hard facts that humans evolved to tease apart.
“It’s tough,” he says. “But that’s where our intelligence comes in.”
— A. B.
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