Cleanliness is key for robotic space explorers WATERTON CANYON, Colo. - The concrete-floored room looks, at first glance, like little more than a garage. There is a red tool chest, its drawers labeled: "Hacksaws." Allen wrenches. There are stepladders and vise grips. There is also, at one end of the room, a half-built spaceship, and everyone is wearing toe-to-fingertip protective suits. Touch. Anything. Bruce Jakosky says the words politely but tautly, like a protective father - which, effectively, he is. Jakosky is the principal investigator behind NASA's next mission to Mars, putting him in the vanguard of an arcane niche of science: planetary protection - the science of exploring space without messing it up. PHOTOS: Stunning images of Earth at night As NASA pursues the search for life in the solar system, the cleanliness of robotic explorers is crucial to avoid contaminating other worlds. Contaminants from Earth could inadvertently kill life forms on other planets just as we discover that they exist. The decontamination of spacecraft, an obscure arm of space science, has grown in importance as NASA turned its attention to places such as Mars, Titan and Europa that have environments that are potentially conducive to life. Jakosky's immediate concern is a $671-million probe named the Mars Atmosphere and Volatile EvolutioN orbiter, or MAVEN, which Lockheed Martin Space Systems is building south of Denver. The craft is scheduled to launch in late 2013. Its mission is to delve into Mars' transition from a wet and warm planet to one that is dry and cold - vital research for determining whether Mars ever harbored life. The spacecraft needs to be scrubbed so that when it impacts Mars, it is carrying no more than 500,000 spores of microbial life, so few they could fit on the head of a pin. The goal is simple, said Jakosky, a University of Colorado at Boulder professor: "Don't contaminate Mars or jeopardize your science." The trick is in the execution. Many of the achievements that marked the onset of the Space Age meant sending astronauts into space. Today, scientists have entered a gilded age of robotic space exploration. The rover Curiosity that landed on Mars this summer is just one in a suite of machines that have been sent to study new corners of space. Other missions will send probes to intercept an asteroid and visit a distant moon that could contain three times as much water as Earth. It is an era fraught with anxiety for those who have the curious task of keeping space free of contamination. "This business is not for the faint of heart," Jakosky says. Planetary protection must operate on three levels at once. First, spacecraft must not bring a potentially harmful level of microbes from Earth to another planet or celestial body. Scientists also must be careful not to mess up their own work - signs of extraterrestrial life could be "discovered" but could actually be false-positives born on a launch pad at Cape Canaveral. "Taking life from Florida to Mars might give you the wrong impression about Mars," said John D. Rummel, NASA's former planetary protection officer, now a professor of biology at East Carolina University. Most pressingly, when robots or astronauts return with samples from space, scientists must take care not to expose the Earth to alien contaminants. No one knows what would happen - probably nothing, but considering how the Earth struggles with its own invasive species, such as zebra mussels in the Great Lakes, no one wants to find out. "We have seen on Earth the problems of transporting things from one place to another," said NASA's planetary protection officer, Catharine Conley. The most nightmarish specter was raised in the novel "The Andromeda Strain," in which a satellite returns from space and wipes out every soul in Piedmont, Ariz. Rummel half-jokes that avoiding this scenario has its own commandment: "Though shalt not kill taxpayers." Outside the bay where MAVEN is being built, a bright yellow line is painted on the floor. No sole of a shoe harboring gunk from the outside world has ever stepped on the wrong side of the line. Even getting to the door of the bay requires a serious rigamarole; you are required to stomp your real-world shoes on top of a sticky floor pad to get rid of as many germs as you can before you are permitted to even enter the dressing room.