13 Things That Don't Make Sense (11 page)

We live on a hunk of rock and metal that circles a humdrum star that is one of 400 billion other stars that make up the Milky
Way Galaxy which is one of billions of other galaxies which make up a universe which may be one of a very large number, perhaps
an infinite number, of other universes. That is a perspective on human life and our culture that is well worth pondering.

As the author George Johnson put it, we have learned to “revel in our insignificance.” At present, however, the anomaly of
life spoils our revelry a little. So, while we wait to see if we can explain life, or at least re-create it from scratch to
rob it of all mystery, what are we going to do about it?

One obvious answer is to find it elsewhere in the solar system. Perhaps we are finding life so difficult to make because it
isn’t as obvious a process as Rasmussen, Venter, and company would like to imagine; perhaps life got established so quickly
on Earth not because it is straightforward but because it arrived, ready-formed, from outer space. Though that would make
us the descendants of aliens, this is not a particularly contentious idea, scientifically speaking. In the early 1990s NASA
funded a study into what happens when a rock hits Mars, Venus, or Mercury. The study took several years, using a few desktop
computers to simulate the trajectory of rocks as they were thrown out into space; it was eventually published in
Science
in 1996. The result was clear: planets and moons of the inner solar system must have been trading rocks for billions of years.
The researchers showed that, because of the way Earth’s gravitational field attracts debris, about 4 percent of the stuff
flung off the surface of Mars will land on our planet.

That certainly fits with the facts. Dozens of meteorites found in the pristine preservative environment of the Antarctic ice
fields have a geology that says they came from Mars. And if the rocks have been coming from Mars since the era when Mars was
wet and well suited to growing life—an era that came before Earth was habitable—why would we doubt that Martian life could
have hitched a rather sudden (and unsolicited) ride to our planet and started a branch right here?

The journey from Mars to Earth can take up to 15 million years—there’s no guarantee of a direct path—and would expose any
traveling microbes to huge doses of radiation. But we know that terrestrial microbes can shut themselves down and survive
millennia without respiring or metabolizing. What’s more, the “extremophile” bacteria we have found in sulphurous springs,
deep ocean vents, and radioactive debris show us we shouldn’t underestimate what conditions a microbe can enjoy. The Earth
is teeming with bacteria that can survive the harsh irradiation they would experience on the journey to Earth.

Given this information, it’s hard to argue that life couldn’t have come here from elsewhere in the solar system. So maybe
life seems so strangely hard to make because we have no idea how it started; maybe Earth’s conditions did not generate life
but merely provided a good home. It is an especially attractive hypothesis when we have two more life-related anomalies to
consider: a possible contact with alien intelligence and an experiment that seems to have discovered life on Mars.

6

VIKING

NASA scientists found evidence for life on Mars. Then they changed their minds.

A
ny discussion about the origin of life, the nature of life, the inevitability of life, has to confront a set of experimental
results gathered by Gilbert Levin in 1976. Thirty years on, they are still the subject of debate in the scientific literature.

Today, Levin’s company, Spherix, has its headquarters in an anonymous suburban business park that is a forty-minute cab ride
out of Washington, D.C. According to its Web site, Spherix has “managed some of the largest pharmaceutical launches and recalls
in the industry” and oversees “one of the country’s most advanced, affordable e-government solutions for state parks.” Apparently,
Spherix has processed nearly seven hundred thousand camping reservations for Indiana’s state parks, mostly through a call
center. Somehow, these accomplishments are less than dazzling when you know that the man in charge of this operation once
used his expertise to investigate other worlds.

Not that Levin’s origins were particularly glamorous. He started his career as a sanitary engineer; the thesis he wrote for
his PhD, from Johns Hopkins University, is titled “Metabolic Uptake of Phosphorus by Sewage Organisms.” As unappealing a read
as this seems, it set him on a path to the red planet. While working in the public health department of the District of Columbia,
Levin invented a new way to detect the presence of microorganisms. His technique speeded up the process of testing samples
by making the organisms breathe radioactive carbon that could be detected by a Geiger counter. It was the same technique that,
when he was working for NASA, later allowed Levin to attempt the detection of extraterrestrial life.

When the results first came in from the Viking mission that carried his experiment, Carl Sagan, the face of cosmic exploration
and the hero of every space-loving child in America, phoned to offer Levin his congratulations: Levin, he said, had made the
first discovery of life beyond Earth. A couple of days later, to Levin’s enormous disappointment, Sagan took his congratulations
back; it had all been a mistake. Ten years passed before Levin found the courage to stand up for his results. And despite
the toll of the passing years—he is now eighty-one—Levin is still insistent that he found life on Mars.

MARS
is Earth’s sister planet. It may be a frozen waste with a thin, wispy atmosphere, but at least it has something we can work
with when hypothesizing over the existence of life on its surface. Venus’s atmosphere has a crushing deep sea–like pressure;
Mercury and Pluto have no atmosphere; and Jupiter, Saturn, Uranus, and Neptune don’t even have a surface we could stand on.
In comparison, Mars seems positively welcoming. People have even come up with ideas for “terraforming” Mars; there are ways
we could transform it into a planet that is habitable for humans. While this idea was once science fiction, now NASA researchers
are drawing up work schedules.

Terraforming Mars is the culmination of centuries of human fascination with the red planet. The Babylonians knew it as the
“fire-star,” an angry, bloodthirsty sky-god, and the ancient Chinese, the Aztecs, the Greeks, and the Romans all felt similarly.
We became a little more dispassionate about the planet for a while when we invented telescopes; in the seventeenth century
Galileo Galilei and Christopher Huygens brought it down off its pedestal and charted its astronomical properties. Then, toward
the end of the nineteenth century, it became mystical again as Percival Lowell tried to convince the world the planet harbored
an intelligent civilization.

As soon as the march of technology made it possible, probe after probe was sent to examine Mars at close quarters. By the
end of 1964 the Soviet Union had launched six craft toward the red planet. None of them made it, however; some rocket scientists
joke about the “curse of Mars” because less than half of the thirty-seven craft we have sent there in the last half century
have succeeded in their missions. At the time of the first Viking launch, there had been only six fully successful Mars missions
in twenty-one attempts. Viking 1 reached Mars orbit on June 19, 1976. The next challenge, the next attempt to sidestep the
curse, was to land a probe on the surface.

The first Viking lander was meant to touch down on Independence Day, but there was no safe site at which to land. In Puerto
Rico the one-thousand-foot dish of the Arecibo telescope, later to become the backdrop for the Hollywood adaptation of Carl
Sagan’s bestseller
Contact
, was scanning the Martian surface and showed the proposed landing site to be littered with enormous rocks. The lander eventually
went down on July 20, landing on the Plains of Gold. Nineteen minutes later, its signal reached Earth. Everything was go.

If the navigation team had done their preparation well, so had the team that would look for signs of life. As the mission
was being designed, the life-seeking experiments were selected, honed, and then picked apart to eliminate all possibility
the scientists would be fooled. The researchers were under no illusions about the importance of the task; these experiments
had the potential to revolutionize our view of ourselves. Find life on Mars, and our perspective would be altered, suddenly
and forever.

The mission team, together with four NASA-appointed review committees, had agreed on what would constitute success. If any
of the tests showed a positive result, a duplicate sample of Martian soil would be heated to 160 degrees Celsius, a temperature
that would kill any microbes, then tested again. If that test came up negative, the researchers could safely assume they had
detected life, not chemistry.

It was only afterward—after Gil Levin’s experiment met the agreed criteria—that they changed their minds.

On the face of it, Levin’s achievements are extraordinary. Detecting life in your city’s sewage is one thing; detecting microbial
life using a robot scientist on a planet 200 million miles away is quite another. But Levin’s “Labeled Release” experiment,
sixteen years in the making, performed almost without fault.

The experiment gained its name through the radioactive carbon it used to “label” the gas released by anything that metabolized
it. To produce a culture of microorganisms, you generally put some into a soup of nutrients in a Petri dish; they feed on
the nutrients and begin to multiply. Levin tweaked this idea in a very simple way: by adding radioactive isotopes to the nutrients.
The metabolism of microorganisms means that they will release gas derived from whatever they’ve been feeding on. If they’ve
been feeding on radioactive carbon, a Geiger counter above the gas should go crazy. The plan was simple: add radioactive nutrients
to a soil sample containing microbes, and watch for a rising graph from the radiation detector. Then, if it works, heat the
soil sample to 160 degrees Celsius, killing the microbes, and repeat. You can add all the radioactive nutrients you like,
but you won’t get radioactive gas. It worked for finding microbes in suspect water, and it worked when tested on Earth, using
California soil. And then it worked on Mars.

It was July 30 when Levin saw the first graph showing that Martian soil is just like California soil. A day earlier, the robot
arm on the Viking lander had scooped Mars dirt into a box that distributed a little of it among four chambers. Each one contained
half a cubic centimeter of soil. The chambers were sealed, and for the next twenty-four hours, the radiation detector monitored
the background radiation in the air above the soil. It was a flat line.

Then the nutrient went in. It was a microbe’s perfect lunch—with an extra kick from a little radioactive carbon-14. Fifteen
hours later, the flat line shot upward. Radioactive gas was filling the microbe chamber. To start with, the assembled scientists
were startled by the similarity to Earthbound data; they had seen this signature hundreds of times in their tests. Then they
got over their shock and had a party. Levin went out and bought some champagne. He even got himself a cigar. They printed
the graph, then everyone on the team signed it. The big hit show of the time was
West Side Story
, and Levin wrote the title of one of its songs—“Tonight!”—on the top of the printout.

Levin was the happiest man in the solar system, but his joy wasn’t to last. As agreed, the Labeled Release team later carried
out a control experiment, heating one of the soil samples to 160 degrees before adding the nutrient. The line stayed flat,
making the initial indication of life a strong scientific result. The Labeled Release team had met the four criteria that
NASA had agreed signaled the presence of life on the red planet. By that time, however, the results of another experiment
were in. And that one said there simply couldn’t be life on Mars.

The two Viking landers each carried apparatus for four experiments. The second, the “Pyrolitic Release” experiment, seemed
to give a positive result. During a five-day test, organic molecules, the basis of biology, were created by
something
in collected Martian soil. The scientists’ best guess was that some kind of algae was responsible.

The “Gas Exchange” experiment gave a negative. It mixed a scientist’s version of chicken soup—a broth of nutrients—with Martian
soil. Analyzing the gases given off, the researchers concluded the soil contained nothing that had thrived on the nutrients.

Gilbert Levin’s Labeled Release experiment, on the other hand, gave positive indications of microbial activity. In a way,
the fourth experiment, the Gas Chromatograph Mass Spectrometer, which would test the soil for organic—that is, carbon-based—compounds,
held the casting vote. Which is a pity, because it didn’t work properly.

The thinking behind the GCMS experiment was, if there were organisms on Mars, the soil would be littered with decaying bodies:
assemblies of carbon molecules. The experiment would take soil samples from Mars, roast them, and analyze the gases given
off. If there was any carbon present, the experiment would detect the presence of volatile carbon-based chemicals.

Unfortunately, the experiment had problems. They had started en route: while Viking 1 was cruising toward Mars, a test showed
that one of the three ovens in the GCMS apparatus, used to heat soil samples so they would give off gases, wasn’t working.
Then, on Mars, it turned out that the indicator showing a soil sample had been successfully delivered to the second oven didn’t
work either. Two out of three ovens had failed. And that was before Levin’s experiment had even run. After its successful
run, with the outcome of the mission resting on the GCMS’s result, Levin held his breath while the GCMS’s third oven was fed
a sample. Six Martian days after the sample failed to register in the second oven, the same thing happened again. Not wanting
to risk heating an empty oven, they went through the emptying routine—just in case—and waited for the next soil dig to come
around. That was seventeen Martian days later. There was still no indication of whether the sample had been delivered, but
the GCMS team went ahead anyway. The only data that came from the instrument showed that the oven still contained microscopic
traces of the cleaning solvent used by NASA engineers prior to launch.

The GCMS experiment was run four times in total. The Viking 2 attempts, housed in an identical lander that followed Viking
1, at least registered samples in the ovens. But no trace of organic material was detected in any of the four runs. And no
organic material, in the team leaders’ interpretation, meant no life.

Naively speaking, it is inconceivable that there are no organics on Mars. After all, even our sterile Moon is littered with
carbon that arrives in meteorite impacts. The solution put forward by the Viking team leaders was that some chemical in the
Martian surface must break up organic compounds. It would, they suggested, do the same to Levin’s nutrient, explaining his
“positive” signal. The chief suspect was hydrogen peroxide.

The thing is, hydrogen peroxide has never been found on Mars—despite at least four extensive searches in the atmosphere and
on the Martian surface. What’s more, Levin points out, it is stable to temperatures of more than 160 degrees Celsius (320
degrees Fahrenheit). If hydrogen peroxide in the soil was breaking up the nutrient and releasing radioactive gas, it would
have continued to do so after the soil samples were baked.

Nevertheless, the hydrogen peroxide argument fit with the negative result from the GCMS experiment. Thirty years on, the argument
would still benefit from someone actually finding some.

AT
the risk of muddying the waters, it has to be said that the GCMS result was not the only problem for Levin’s Labeled Release
experiment. A further procedure, carried out by Levin and his coworker Pat Straat, gave a puzzling result during experiments
with the second Viking lander.

The consensus that chemical processes could explain the negative GCMS results was growing among the mission team; the prevailing
idea was that ultraviolet rays from the Sun would produce hydrogen peroxide in the soil, which would then destroy all organic
matter. So Levin and Straat asked the team controlling the sampler arm to move a rock and dig into the soil underneath, where
there would be no hydrogen peroxide. The resulting sample gave another positive result in the Labeled Release experiment,
punching a hole in the hydrogen peroxide argument. It also demonstrated, however, that a lack of light was not a problem to
Martian microbes; they could live happily under a rock. Unfortunately for Levin and Straat, they already had evidence to the
contrary.

On Martian day thirty-six, the team had put a sample of Martian soil into the chamber of the Labeled Release experiment. When
the nutrient went in, something in the soil reacted, releasing radioactive gas just as in all the previous experiments. Then
the chamber was covered over and left alone for seven days.

After a week in the dark, the team injected some more nutrient. Every time they had done this with microbe-infested soil samples
on Earth, the Geiger counter had registered another increase; the microbes had gulped down the second helping. On Mars, nothing
happened.