Are Martians within reach? A model of a Viking lander (Image: NASA/JPL-Caltech)

GILBERT LEVIN aims to appropriate the Mars Science Laboratory for his own ends. “Since NASA has disdained any interest in MSL looking for life, I’m taking over,” he says. “I claim it.”

He is only half joking. If MSL’s rover Curiosity finds carbon-based molecules in the Martian soil, Levin – who led the “labelled release” experiment on NASA’s 1976 Viking mission – will demand that his refuted discovery of life on Mars is reinstated.

Levin, a former sanitary engineer, will make this call next week at the annual SPIE convention on scientific applications of light sources in San Diego, California. He wants an independent reanalysis of the data.


The experiment mixed Martian soil with a nutrient containing radioactive carbon. The idea was simple: if bacteria were present in the soil, and metabolised the nutrient, they would emit some of the digested molecules as carbon dioxide. The experiment did indeed find that carbon dioxide was released from the soil, and that it contained radioactive carbon atoms.

Levin’s team went out and bought champagne. He even took a congratulatory phone call from Carl Sagan. However, the party was ruined by a sister experiment. Viking’s Gas Chromatograph Mass Spectrometer (GCMS) was looking for carbon-based molecules and found none. NASA chiefs said that life couldn’t exist without these organic molecules, and declared Levin’s result moot. “NASA powers that be concluded that the lack of organics trumped the positive labelled release experiment,” says Robert Hazen, a geophysical scientist at the Carnegie Institution for Science in Washington DC.

Since then, some of the GCMS team have admitted that their experiment was not sensitive enough to detect organic molecules even in terrestrial soils known to contain microbes.

That is why Levin wants a reanalysis of his original data if Curiosity finds organic molecules. “I’m very confident that MSL will find the organics and possibly that the cameras will even see something,” he says. Taken with his 36-year-old results, that would constitute a discovery of life on Mars, Levin says.

It’s not a crank claim, says Hazen. “Levin’s experiment showed a surprising and as yet not well explained effect that, at least prior to the Viking mission, the experts said would indicate microbial metabolism. If you can’t explain that through an obvious inorganic process, then it follows that microbial life is a real possibility.”

New Scientist tried to reach NASA for comment on Levin’s claim, but without success.