4.19.2006

How to Make a Life-Detector

“To some people it may seem that the very strangeness of Martian life precludes for it an appeal to human interest. To me this is but a near-sighted view. The less the life there proves a counterpart of our earthly state of things, the more it fires fancy and piques inquiry as to what it be.” Percival Lowell, Mars and Its Canals

On a Thursday afternoon in early February, in a residential neighborhood of Chevy Chase Heights, the dingy-brown building of Carnegie Institution’s Geophysical Laboratory looms from the top of a steep and grassy hill. At the bottom of the hill is a wooden entrance sign, just 20 feet from a pile of logs and tree stumps. On one branch of one naked magnolia a gray hooded sweatshirt hangs forgotten. The grass of the grassy hill is dead, and crunches when you trudge through it. The lab houses one hundred and fifty of the nation’s best scientists, but only a handful of cars are parked along the edge of the driveway that winds up sharply to the front door. When the elderly secretary enters the door’s security code, you can hear the slow punch of the buttons, and the soft shuffle of her shoes on polished linoleum as she escorts you down the empty corridor.  In short, it’s everything you might expect from a Martian-life-detection lab.

In 1996, NASA triumphantly announced the find of ALH84001, the meteorite that supposedly harbored fossils of ancient Martian life. Andrew Steele was the young Brit who showed, just months after the announcement, that meteorite ALH84001 was contaminated with Antarctic bugs. But even after undercutting NASA’s triumphant find, Steele still believed we might one day find life on the Red Planet. In the last decade, with the help of groups who study the biological workings of extremophiles on Earth, many astrobiologists and astronomers have tried various approaches to the hunting of life beyond Earth’s orbit. Steele’s group, focused on making life-detection instruments for both rover and manned missions to Mars, finds a home in a few of the microbiology labs in the creepy building on the hill.

Though a decade has passed since he trumped NASA’s claim, Steele still looks like a grungy twenty-something. He’s tall, lean, and slightly apish. His wavy blonde hair covers the letters printed on the back of his t-shirt, so you can’t quite read the name of the garage band that’s printed on it; his blue jeans are so faded they’re white. He’s dirty, but wears jewelry—rainbow bracelets on his wrist and a heavy Celtic cross around his neck. He walks lightly on old green sneakers, the same ones he had in August, when he traveled to the other side of the world to test his gadgets.  

In August of 2003, 2004, and 2005, Steele and his colleagues went to the Arctic Circle island of Svalbard. Svalbard is not only cold—dropping down to -12 degrees Celsius (10 degrees Fahrenheit), even in August’s 24 hours of daylight—but dusty, and dangerous. (Steele’s crew, armed with shotguns, had to switch between crushing up rock and watching for polar bears.) The island is the only place on Earth with a volcano that has the kind of rock that was sampled on the Viking missions. And most important, the rock harbors microorganisms that Steele’s gadgets can try to detect.

The gadgets are called microarrays, matchbook-sized glass chips coated with different kinds of antibodies. Each antibody recognizes in a rock different life-specific molecules—like nucleotides (the building blocks of DNA), amino acids, proteins, or certain carbon isotopes—and when it finds them, it glows. Steele says the chips will be used on NASA’s next big rover project, the 2009 Mars Science Laboratory (MSL). The MSL, part of NASA’s larger Mars Exploration Program, plans to send a nuclear-powered rover to Mars, much larger than the golf-cart sized Spirit and Opportunity rovers that are up there now. In their two years of exploring, Spirit and Opportunity have each traveled about three miles. By comparison, the MSL is a tank; it will travel up to 90 miles per hour, roll over obstacles 30 inches high, and will have a full on-board laboratory for testing climate changes and geological samples.

But to gain a true understanding of the landscape and really probe for life, Steele says, rovers aren’t enough; you need men. “Rovers are pretty easy now, we could send rovers all over the place for about $900 million a shot,” he says. “But a human being is a thousand times more capable than any robot.” Rovers have to stay on a horizontal plane, for instance, so they often don’t have the right visual perspective to find subtle-yet-important geological features, like bedrock. Also, their controllers on Earth can’t manipulate the machines in real time; they’re eight minutes behind. But the biggest problem, according to Steele, is that a rover doesn’t have object recognition. “An elephant could run in front of it,” he says, “and it wouldn’t know the difference.”

To make his point, Steele cites one rover story NASA hasn’t released. A few months ago, a wire broke on Spirit’s arm.  “So the engineering team spent a few days fixing it, slowly working the arm to loosen the dust they thought got into the motors,” he explains. Since Spirit was immobile for a few days, the scientist team decided to take high-resolution photographs of the landscape, instead of the usual low-resolution ones. And the result was amazing: Steele says the new photos gave them an incredible view of the surrounding geological features, including those that might indicate an ancient flow of liquid water.  As he explains: “They said, ‘oh my god, those crossbeds are fantastic. This is just brilliant,’ but normally, the rovers would never have caught all of that detail. A human would have seen it right away.” And the detail, in this case, was crucial: “it was evidence,” Steele says, “of water-induced features in the rocks.”

In addition to tweaking the rover machines, Steele’s also working on what he calls the next generation of gadgets: those that would allow planet exploration by astronauts.  “We’re making computing technology, like GPS and camera systems, and a barcode system that automatically labels samples,” he explains. This would have been nice for the astronauts of the Apollo missions because, as Steele says “the geezers don’t have time to get everything—on the Moon they often forgot to record locations and label properly.” But with the new toys, he says, “the astronaut merely needs to bag it, tag it, and the rest is done.”

This emphasis on creating technology for astronauts spurs Steele to visit extreme environments like Svalbard over and over again. He plans to go back for the next three Augusts, until the MSL is launched.  “It’s good for the scientists to think they’re on Mars,” he says, “because you think: where is my next meal coming from? It makes you realize you have to make the science as easy as possible for the astronauts, because they’ve got to concentrate on staying alive.”



Detecting “Habitable” Worlds

Iain Neill Reid is an astronomer at NASA’s Space Telescope Science Institute in Baltimore, the birthplace of the Hubble Telescope.  Though Reid had been using the Hubble to study dwarf stars for many years, in 2003, he switched gears.  “A few of us here just started looking at how we could work in astrobiology,” he says, “partly because the emphasis was switching at NASA, but also because at that time there was a lot of effort going into thinking about the Terrestrial Planet Finder.”

The Terrestrial Planet Finder (TPF), a telescope project conceived by the brains at NASA’s Jet Propulsion Laboratory, is new, and hasn’t been built yet. It was only in 1995, after all, that astronomers used high-powered telescopes to discover that solar systems besides our own even exist. Since then, astronomers have found over 100 planets orbiting other stars. But the TPF won’t look for just for any old planet. Its job is to look for habitable planets like Earth. A planet like the Earth, Reid says, is about 100 million times fainter than its star. So to make a planet visible, you need to use telescopes (very elaborate, expensive telescopes) that block the light from the star. And once an astronomer can see clearly the planet in question, Reid says, “we could tell the microbiologists ‘here’s what the conditions might be like,’ and then, they could tell us what could live there.”  

In 2003, Reid joined Frank Robb and a few other extremophile experts at the Center of Marine Biotechnology and submitted a proposal to the NASA Astrobiology Institute (NAI). He says they wanted to “ask if there are particular places in the galaxy that are more favored to life than others.” But the NAI Committee at the time, Reid recalls, said the project—searching the entire universe for Earth-like planets—was too ambitious. So for the next couple of years, Reid’s group funded what they could themselves. “We had a small amount of research money here at Space Telescope, only like 50 or 60K,” Reid says, “but it was enough to pay for a grad student and get equipment.” The shoestring operation became the basis of a new, scaled-back NAI proposal the team submitted in October of last year, where they suggested to look only at stars within 25 parsecs of our Sun.

While Reid and his team were searching for planets, others were looking for stars—stars that would be best suited to host a planet with intelligent life. Though intelligent alien life has long been the stuff of popular science fiction, a large group of scientists, involved in a project called the Search for ExtraTerrestrial Intelligence (SETI), is seriously hunting for real ETs beyond our solar system. This February in St. Louis, a panel of astrobiologists from SETI and elsewhere held a press conference at the meeting of the American Association of the Advancement of Science (AAAS). The panel explained how to go about looking for intelligent life—that is, how to send messages to beings that could, in turn, send messages back to us.

The task is a big one: 100 billion galaxies are thought to exist, each with 100 billion stars—a gazillion places that could potentially receive and acknowledge our messages. Astronomer Maggie Turnbull of the Carnegie Institute is starting to narrow down the astronomical list. As she announced at AAAS, Turnbull has identified a mere 19,000 stars whose solar systems might provide a “habitable zone”, and of these, has made a top-five list from which to begin searches.

“When I was given the charge of making the target list for SETI,” Turnbull explained to National Public Radio, “I asked myself, just what is it about the Sun that makes it a good parent to life forms on Earth?” Most important, she said, is stability—she sought stars that didn’t change their level of brightness too “quickly” (sometimes quickly meant billions of years) for life to evolved on their surrounding planets. This requirement ruled out all of the massive stars in the galaxy, because they don’t live long enough. Because SETI is interested in intelligent life, Turnbull’s second requirement for a good “star parent” was a practical one: “Close stars are better than further stars,” she explained, because we wouldn’t be able to send radio signals to stars too far away. These eliminations brought the list down to 19,000. “Obviously 19,000 is quite a lot of stars and it will take quite a long time to go through all of those,” Turnbull explained. So she then arbitrarily whittled 19,000 to five, “for the purposes of communicating it to the public.”

With the star list thus narrowed, SETI has set up the Allen Telescope Array (named for and mostly funded by billionaire Paul Allen, co-founder of Microsoft), a cluster of 350 radio antennas in northern California. The antenna network, which should be built by 2008, is designed to “listen” for radio transmissions sent from intelligent civilizations in the solar systems of Turnbull’s chosen stars. Jill Tartar, head of the SETI Institute, says that old systems were able to scan about 1,000 stars in a decade; in the next ten years, the Allen Array will scan at least a million.

These searches are based on finding life as we know it—i.e., self-sustaining chemical systems that undergo evolution at the molecular level. But some scientists and philosophers think this is the wrong approach. “What we really need to do is to search for physical systems that challenge our current concept of life,” says Carol Cleland, a philosophy professor and fellow at the NASA-funded CU-Boulder Center for Astrobiology, “systems that both resemble familiar life and differ from it in provocative ways.” Cleland says looking for life different from ours may not be as difficult as one might think. Life on Earth works using only about 20 basic proteins (called amino acids), even though nature provides more than 100. This means that, as Cleland argues in the January 16 issue of the International Journal of Astrobiology, an “alternative microbial life” could exist on Earth, and therefore, could also exist on other planets.

Cleland says the latest life-detection instruments, based on our current definition of life, limit our ability to find life on other planets. “If the DNA in an alien organism was even slightly different than the DNA in life on Earth,” she says, “we probably wouldn’t be able to recognize it. Instead of looking for life as we know it, scientists may be better served to look for anomalies, which amounts to looking for life as we don’t know it.”

NASA Pulls the Plug

No matter what kind of life they’re looking for, all of these scientist-hunters recognize that some of the biggest mysteries are found right here on Earth.  Steele says of finding Martian life: “If we find it—fantastic! Brilliant! Superb! Let’s go get it, let’s study the hell out of it, let’s classify it. But actually, I’d be more interested if we don’t find life on Mars, and then why there isn’t life there. What went wrong? Why is Earth special? For me, that’s the biggest reason for going.”

On January 14, 2004, following reports of the success of Spirit and Opportunity, President Bush made a speech outlining his new “Vision for Space Exploration.” Reminiscent of Kennedy’s 10-year Moon challenge in 1960, Bush proclaimed that rovers were necessary, at first, to serve as “trailblazers,” and “the advance guard to the unknown.” But ultimately, he said, we need to go the next step: “The human thirst for knowledge ultimately cannot be satisfied by even the most vivid pictures or the most detailed measurements. We need to see and examine and touch for ourselves.” Bush’s exact plan called for the development of a new spacecraft, called the Crew Exploration Vehicle, which would fly by 2014, carry men to the Moon no later than 2020, and then eventually, carry them to Mars.  Bush said the main purpose of the Crew project is to take astronauts beyond our orbit, “to other worlds.”

All of this life-detection work—Steele’s life-detection chips, Reid’s TPF telescopes, Turnbull’s Earthshine—began, and continues, on the promise of financial support from Uncle Sam. But this February, two years after announcing his new vision, the President’s budget didn’t give NASA as much money as it was hoping for, causing NASA head Michael Griffin to funnel money into manned space flight and out of astrobiology. Consequently, all three of these life-detection projects have been put on hold.  

Which begs the question: If a manned missions does find life on Mars, will the Earthlings in charge then put more funding into astrobiology? “Maybe, maybe not,” Reid says wryly. “We might get cut off for getting the wrong answer.”

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