The search for extraterrestrial life begins, and perhaps ends, in a white gymnasium-size room in the smoggy foothills of Pasadena, California, on the sprawling campus of NASA’s Jet Propulsion Laboratory. This is the Spacecraft Assembly Facility (SAF), where interplanetary probes are assembled and tested before being launched toward their various cosmic destinations. The Mars Pathfinder rover, which in 1997 captured
stunning photographic vistas of the Martian surface, was built here. Spirit and Opportunity, the two rovers that continue to roam and prod Mars for evidence of water, were built here. Cassini, now orbiting Saturn, and Huygens, a small probe that in December will drop into the atmosphere of Saturn’s moon Titan, were built here too. The Spacecraft Assembly Facility is a gateway, truly a portal to the rest of the universe. What passes through it promises to reveal a great deal about the origins, and possible fate, of life in the cosmos.
Come on in. First, however, you must be decontaminated. A visitor places one foot, then the other, into an automatic shoe scrubber, a box on the floor with spinning bristles that flagellate the soles for a minute or so. A guide provides blue paper booties to slip over shoes, a blue shower cap to cover hair, and a white gown, made of paper with a shiny cling-free coating, to wear over your clothing. Finally, an air shower—a glass booth with several nozzles blowing furiously. Then and only then, ruffled but purified, may you enter. Inside the facility, a company of blue-bootied, shower-capped, paper-gowned technicians fuss over the skeletons of spacecraft-to-be. The room is arid as a desert, the humidity a drastically low 42 percent. The floors are regularly scrubbed to remove dander and bacteria. NASA’s intent is to create an environment hostile to any microbes that might hitch a ride aboard the outbound spacecraft yet benign to the human engineers who must assemble these delicate vehicles. If that sounds like an impossibility, it is. Welcome to the paradox of planetary protection.
In 1967, inspired by a new international outer-space treaty, the space-racing nations of the world agreed to spare no effort in preventing the potential spread of organisms from one moon or planet to another. At NASA, this mandate evolved into an official planetary protection policy, a Sisyphean effort to shield the universe from the people exploring it.
Traditionally, the assumed beneficiary of planetary protection has been the planet Earth. We’ve all seen the movies, we know the disaster scenarios: Extraterrestrial spores return from outer space, and in no time the citizens of Earth are heaps of dust or brain-dead zombies. Accordingly, NASA has developed an elaborate quarantine protocol to handle soil samples retrieved from other planets—comforting, perhaps, but statistically of marginal value. Contagion spreads from the haves to the have-nots, and so far as scientists have yet determined, Earth is the only planet with life to give. Besides, virtually all the spacecraft that leave Earth depart on one-way missions: They drift eternally through interstellar space, or they burn up in foreign atmospheres, or they sit on Mars, never rusting, transmitting data until their batteries fade away. Among all the lawns in the cosmos, ours is the one with dandelions, and the wind is blowing outward.
No, if anybody should be worried about biocontamination, it’s our planetary neighbors. In the coming decade, NASA has scheduled no less than four major missions to Mars to grope for hints of water or life. Down the road is a robot that will drill below the icy surface of the Jovian moon Europa to probe a briny ocean believed to exist there, and the Titan Biological Explorer, which will plumb the atmosphere of the Saturnian moon Titan for the chemical precursors of life. Interplanetary traffic is picking up, and NASA would like to avoid going down in history as the agency that accidentally turned the Red Planet green with life.
But the true worry isn’t ecological; it’s epistemological. Any earthly contamination—of the Martian soil or of the instruments sent to study it—would seriously muddy the multibillion-dollar hunt for extraterrestrial life. As Kenneth Nealson, a University of Southern California geobiologist and Jet Propulsion Laboratory visiting scientist, recently told the journal Nature: “The field is haunted by thinking you’ve detected life on Mars and finding that it’s Escherichia coli from Pasadena.” As it turns out, that fear is well founded. Not only does microbial life survive in the Spacecraft Assembly Facility; in some cases it thrives there. There is no question whether we’re exporting life into the cosmos—we absolutely are. What’s left to determine is exactly what kind of life is emigrating and how far it is spreading.
“Bugs are very clever,” Kasthuri Venkateswaran says with affection. “They started out on Earth 3.8 billion years ago, when nothing else was here!”
Venkateswaran—bow tie, oxford shirt, smart round glasses—occupies a bunker-like office a couple hundred yards up the hill from the Spacecraft Assembly Facility. Unofficially, he is an astrobiologist, a job description recently coined at NASA to describe the cadre of scientists involved in the agency’s accelerating search for life beyond Earth. Officially, he is the senior staff scientist of the biotechnology and planetary protection group. While his celebrated colleagues design ever more inventive spaceships and robots to scour the surface of Mars for some signature of life, Venkateswaran quietly examines the machinery itself, searching for any clever microbes—“bugs,” he calls them—that might try to tag along. Neat and kindly as country doctor, he is in fact the biological protector of the universe. To colleagues and, at his insistence, visitors, he is simply “Venkat.”