NASA has always denied that its Viking spacecraft discovered Life on Mars in 1976. But the truth may be very different…

by Heather Couper and Nigel Henbest

On finding the right unit, a tall, gangly man in his seventies ushers us into the conference room. He is driven; he still has fire in his belly. "I'm Gil Levin, founder, President and CEO of Biospherics Incorporated. I was also a member of the Viking spacecraft team. On Viking, I was an investigator on the Labelled Release experiment. That's the one that got a positive indication for life on Mars - and has kept me in trouble ever since".

The dispute dates back to July 1976, when the first Viking lander settled down on the dusty-pink world with its salmon-pink skies. But there was nothing rosy about the Red Planet. It was bitterly cold, and almost airless. Drifts of fine Martian soil stretched for miles, as powdery as Antarctic snow. Rocks and boulders of all shapes and sizes littered the scene. Many were rough and volcanic in appearance, and some had small holes where gas had once bubbled through - like pumice.

The Viking 2 mission arrived at Mars a couple of months after its twin, and both landers continued to perform flawlessly for many years. Each returned weekly weather reports, analyses of the Martian atmosphere, wind-speed readings, and thousands of pictures of the surface of Mars in all its moods.

Stunning though the images undoubtedly were, it was the life experiments that captured the imagination of the world. Each lander carried a miniature laboratory, the size of a wastepaper basket, to perform the life-detection experiments on the surface by remote control. Nothing as sophisticated had ever flown to another world.

With its 10-foot-long arm, each Viking lander fed soil samples into its laboratory to be tested. There were four main experiments. Three looked at biological or chemical reactions with the soil, and one - the GCMS - broke down the soil into its basic atoms.

Two of the experiments gave negative or inconclusive results. Any reactions that took place, agreed the researchers, were down to chemistry rather than biology. But the third experiment had everyone sitting up and taking a considerable amount of notice. It was the Labelled Release experiment of 'sanitary engineer' Gil Levin.

CREDIT: Hencoup Enterprises Lift-off of Viking 2 atop a Titan/Centaur launch vehicle on 9th September, 1975

Levin explains his technique. "It's very simple. The standard method of culturing micro-organisms is to put them in some kind of nutrient soup, and wait several days until they start multiplying and you can see them. My technique simply added radioisotopes to those nutrient compounds. This meant that as soon as the micro-organisms started metabolising them, they would expire radioactive gas - which would be detected much more quickly than waiting around for a visible bubble. So the whole thing reduced about two days of waiting for evidence of life to about 15 or 30 minutes".

Geologist Mike Carr recalls the feeling in the Control Room when Levin's experiment yielded up copious quantities of radioactive gas. "I mean, we initially thought, my God, my God - there may be life there. And then, of course, it all kind of waned".

Ever since then, NASA's official line on the Labelled Release experiment is that it, too, discovered chemistry rather than biology. But Gil Levin absolutely refuses to take this assessment lying down.

His problems with NASA started, he explains, long before Viking even flew. "My problem is that I'm an engineer. I'm an engineer in a small company, and when my experiment began to work, NASA called me down and said, we have a problem. It looks as though your experiment might be selected - it looks awful damn good - and you're just an engineer. What's more, you don't have a Ph.D. - so how can you, if successful, go and talk to the National Academy of Sciences, go abroad to distinguished universities and report? So we want you to take on a senior investigator, and he will report it".

"I absolutely refused, and said, I'm not going to give up this experiment. I'll go get myself a Ph.D. So I went to school and I worked - did both full-time for three years - took all the sciences and got my Ph.D in engineering".

After the Viking landing, everything seemed to bode well for Levin's experiment. He recalls the excitement in Mission Control at the time. "When my experiment came up - it was about 7.30 at night - the results clattered out of the computer, and we saw this curve and were amazed. We'd tested the Labelled Release experiment hundreds of times on Earth, with thousands of different micro-organisms. We knew what those curves of response looked like, and here was one staring us in the face. We were astounded, and I sent out for a bottle of champagne".

CREDIT: Hencoup Enterprises This panoramic view of Mars was the first picture taken by the Viking 1 Lander on 23rd July 1976. The large rock (centre) was dubbed 'Big Bertha' - but later renamed 'Big Joe' after howls of protest from feminists.

No experiment can be validated without controls, so Levin's team decided to 'kill off the bugs' in their sample by heating it to 160 degrees. "We waited, and finally the computer started spitting out again", recounts Levin. "There was zilch. A flat control line".

But Levin's problems were just about to start. Results from the GCMS experiment began to come in shortly afterwards. It found many familiar chemical elements - including iron, silicon and oxygen. But there was absolutely no trace of carbon - the basic building block of life. How could Levin's experiment have detected life if there was no organic matter on Mars to make it?

Worse was to come. As geologist Bruce Jakosky observes, Mars must be kept topped up by carbon from meteorites. "You find organics on the Moon from meteorites. So something must be breaking apart the organics on Mars. The suggestion that's been pretty much accepted is that there must be oxidising agents, like hydrogen peroxide, in the Martian soil that would attack the organics and break them apart".

We go over this ground with Gil Levin. He takes some papers out of a filing cabinet, and places a computer print-out on the table. To our eyes, the Mars data does not look like a chemical reaction. Chemical activity builds rapidly, then dies away. But the Martian curve builds steadily, and looks identical to his terrestrial controls.

Levin had one last-ditch attempt to convince NASA that he was onto something. He decided to heat samples of Mars soil within a narrow range of temperatures - the range of temperatures that kill off bacteria on the Earth. "First of all, we showed that 51 degrees definitely destroyed the signal. But secondly, we showed that 46 degrees didn't destroy it - it inhibited it by 30 percent. And that's just the way that in the laboratory here we distinguish E. coli from the rest of the coliforms, because E. coli can survive beyond 37 degrees, while the others cannot".

CREDIT: Hencoup Enterprises At the Scripps Institution of Oceanography, La Jolla, Danny Glavin perfects the ultimate equipment for discovering the merest traces of amino acids - the building blocks of life.

It was all to no avail. NASA had turned its collective back on Levin. "It was political", he acknowledges. "They had to come down with a decision, and they hate to retract a decision. If you go to people from NASA and you say, what do you think of the Labelled Release Experiment, they'll say - oh, that's garbage you know. Levin keeps saying the same thing over and over again".

"In 1986, I was asked to speak at the tenth anniversary of Viking, and what I did was list, oh, maybe fifteen possible explanations of a non-biological nature for the Labelled Release Experiment results - and I showed errors in each one of those. And for the very first time, I said, it's my opinion that it's more probable than not that the Labelled Release Experiment detected life on Mars. There was an uproar. Since then, I've been essentially ostracised by the NASA-supported community".

But amongst Mars researchers around the world we have felt a tide beginning to turn - away from the official NASA line. At the Scripps Institution of Oceanography in La Jolla, California, we spoke to young chemists Danny Glavin and Oliver Botta. Their field is detecting the chemicals of life - and now they hope to take their techniques, tried and tested on Earth, to Mars. "We've recently done some really interesting experiments with this new Mars Organic Detector, the MOD," Glavin enthuses.

"What we've shown with the MOD is that you can detect amino acids with very high sensitivities. And using the detection limits of what the Viking GCMS measured for these compounds, and comparing it with our instrument, we estimate that Viking would have missed on the order of thirty million bacteria cells per gramme of soil. So there could have been cells in the soil, but the Viking GCMS wouldn't have seen them."

Oliver Botta reminds us how much our knowledge about the tenacity of life in extreme environments has advanced since Viking. "The problem with the biology package on Viking was that it was really designed to look for terrestrial analogues of life. And we have to realise that, in the Seventies, we didn't know of the variety of lifeforms we have on Earth - high temperature, low temperature, and high acid, or whatever".

Extremophile expert Jonathan Trent of NASA's Ames Research Center can even contemplate life in an environment of hydrogen peroxide. "Cells on Earth have wonderful adaptations for getting rid of peroxide. For example, there's an enzyme called catalase. When you have a wound, and put peroxide on to sterilise it, the peroxide will bubble. The catalase is transforming the peroxide into water and oxygen, and the bubbles are actually oxygen coming off. Many organisms produce catalase, and it isn't inconceivable that they could cope with the peroxide levels on the surface of Mars".

So where does the jury stand these days on the Viking life findings?

CREDIT: Hencoup Enterprises Danny Glavin (left) and Oliver Botta check out samples of meteorites for organic molecules: they hope similar equipment will discover the materials of life on Mars.

David Wynn-Williams is a geologist at the British Antarctic Survey. "When Gil Levin evaluated his system in the Antarctic, he was able to show biological activity at very low densities of micro-organisms. So he's partly right - the GCMS was not as sensitive as his system, but I need more evidence to be convinced that he did actually see microbiological activity on Mars".

'Mr. Mars', NASA-Ames's Chris McKay adds: " If Gil's experiment was the only experiment we had, its results would be consistent with a biological source. But it was inconsistent with the other experiments. Explanations relying on a chemical reaction with the soil are more plausible, but I should say that none of these explanations have been proven".

NASA's John Rummel remembers how Viking's non-detection of life cast a shadow over the Agency. "When I first got to Headquarters with the odour of what was assumed to be a negative result on Viking, there were many astrophysicists quite willing to prove to me that life couldn't exist anywhere in the Universe, including the Earth - and at days in Washington, I agreed with them".

So what is Rummel's verdict on Viking? - "Not proven".

Meanwhile, Gil Levin bides his time. He is heartened by the 'not proven' verdict. But NASA still stonewalls him, and there are a number of scientists around who doubt his competence. Does he let it get to him? "I'm not resentful", he smiles. "I'm kind of amused. I do believe that the existence of life on Mars will be established one day, and I'm sure that when it is established, whoever does it will take the credit."

But - indicating his sheaf of graphs - Levin concludes: "Nonetheless, the original data are there".