NASA division's goal: No stowaway microbes

When NASA's Phoenix Mars Lander rocketed into space Saturday, it went, like all missions, with the assurance that as few Earth microbes as possible tagged along.

Hitchhiking microbes could contaminate the experiments, making it impossible for scientists to distinguish between organism that came from Earth or Mars.

Or worse — an errant microbe could infect the planet.

Keeping the spacecraft sterile was the job of an obscure but crucial part of NASA known as the Planetary Protection unit at the Jet Propulsion Laboratory (JPL) in La Cañada Flintridge, Calif., where Jason Kastner supervises a small team of scientists working in labs that smell of bacterial cultures.

Phoenix had to be even cleaner than most missions, going a step beyond Planetary Protection's sterilizing procedures. Merely killing all the bacteria wasn't good enough for this trip to Mars' north pole in search for signs of water and organic material.

Phoenix scientists had to scrape every bit of organic material from the craft.

Since a 1967 United Nations treaty, Planetary Protection has sterilized every NASA mission.

NASA's official worrywarts are anxious not only about microorganisms contaminating other celestial bodies but also about organisms reaching Earth.

"If we're bringing samples back to Earth, we don't want to bring back something like the Andromeda Strain," said Kastner's boss, Cassie Conley, NASA's planetary protection officer in Washington, referring to the Michael Crichton novel in which a space pathogen kills humans.

So far, NASA has obtained only low-risk samples from space. The Stardust mission collected comet dust in 2004, and the Genesis probe launched in 2001 gathered solar wind particles. Scientists said there was little likelihood for life in such environments.

The past and possible current presence of liquid water on Mars, however, indicates that life might exist. NASA has plans to bring back a piece of the Red Planet about 2020.

Although Conley doubts that anything dangerous lurks in our solar system, she expects to treat Martian soil as if it were more dangerous than the Ebola virus.

Things likely will be even more uncertain if humans travel to the Red Planet. From a Planetary Protection standpoint, humans are dirty creatures. And unlike spacecraft, they can't be baked in an oven until they are free of bacteria.

Because scientists must be so careful to keep Earth organisms in their proper place, NASA puts its missions together in a "clean room." Air filters protect the spacecraft from contamination, and workers must wear head-to-toe suits to go inside.

The partially assembled Mars Science Laboratory — the next-generation rover scheduled for launch in 2009 — is the lone occupant of the largest clean room at JPL.

Planetary Protection scientists are continually suiting up to swab the room and equipment, looking for microscopic intruders.

Among the toughest potential passengers are bacteria called Bacillus.

"Bacillus is able to have a protective coat and kind of hunker down," Kastner said.

That coat makes Bacillus the organism to kill for Planetary Protection. If all the Bacillus is gone, Kastner and his colleagues can assume that less-hardy microbes died with it.

Sometimes, the tests turn up more than the usual suspects. Planetary Protection scientist Kasthuri Venkateswaran has discovered new organisms lurking on the spacecraft. He named one after the mission on which he found it: Bacillus odysseyi, a bacterium that evolved to live in the spare environment of a clean room.

Venkateswaran discovered another kind of Bacillus apparently living off energy from the aluminum surface of a spacecraft, with no apparent source of nutrients or water.

Until recently, scientists had no idea just how hardy some Earth organisms could be. In the past few decades, researchers have found microorganisms inhabiting deep-sea hydrothermal vents, toxic mine runoff and highly acidic caves.

To stay ahead of the bacteria, Kastner's team is developing new ways to seek and destroy microorganisms.

They are investigating alternative methods, such as using vaporized hydrogen peroxide, to clean surfaces. The technique is used to clean medical instruments.

NASA's gold standard is to use dry heat to sterilize spacecraft — the entire Viking lander was cooked at 233 degrees Fahrenheit for 30 hours. This method, however, could be dangerous for some electronics, such as those on the Mars Science Laboratory.

"If I told the engineers that they had to put the entire MSL in the oven for two days," Kastner said, "they would have a fit."