Most of the attacks I've seen Barry make focus on the other experiments which seemed to contradict the LR results. I don't recall much on the questionable nature of the LR results themselves. Barry's argument in a nut shell seems to me to be that if you trow out flawed contradictory results from other instruments Levin's LR conclusively indicated life. That is not the case.

Some relevant comments from the article Alex provided. To be fair I disagree with the comment amount the specificity of nutrients indicating a nonbiological origin. Chemical reactions are in general less specific than biological ones especially with regard to specific classes of compounds. I'd have to see the composition of the actual nutrients and proposed reaction mechanisms to buy that argument. It is quite clear that Klein disagreed with Levin as opposed to the misleading picture Barry tried to paint above.

"In a 1998 paper Klein questioned whether there were, as claimed by Levin, terrestrial organisms that could produce the LR results under the conditions encountered on Mars. If organisms were present in the Martian soil they came from extremely cold, dry conditions with no atmospheric oxygen. They were heated to about 10 degrees Celsius and held at that temperature for several days before a small amount of broth was added. Radioactive gas was detected almost immediately and increased quickly before tapering off after about two hours. After the initial reaction died down a second quantity of broth was added. There was an initial drop in radioactive gas readings -- possibly the moistened soil reabsorbed it. After this no substantial release of radioactive gas was observed. These were not results that are usually associated with micro-organisms on Earth. Klein also pointed out that the process which produced the gas was highly selective in the type of carbon compounds that it consumed -- a result that was more likely with a selective chemical reaction than a biological process.

From experience on Earth, if organisms were present in the Martian soil samples they were either dormant, and waiting for the "right" conditions to start the life processes, or they were extremely hardy organisms that managed to live normally in the harsh Martian conditions. If dormant, it seems surprising that they "awoke" so quickly when the nutrient was added. Levin refers to tests of Earthly lichen that gave a vigorous initial response and then apparently died from too much water. He suggests this might have occurred with Martian organisms. However, Klein noted that only a small quantity of broth was added in the Viking experiment so that a large portion of the soil was not drenched with the broth. Why didn't micro-organisms in the unaffected soil survive to produce gas in later experiments? The other puzzle is that the surface of Mars typically has not changed for millions of years so where did the dormant spores come from?

If the organisms were adapted to the Martian conditions it is surprising that they also found the much warmer and wetter conditions in the Viking chamber comfortable. Most organisms on Earth do not respond well to being heated to more than 40 degrees Celsius above their usual temperature. This does not rule out a remarkably tough Martian organism but is another reason to be cautious about the Viking results.

The other lingering question is the composition of the gas that was released. Radioactive carbon was present. This was probably carbon dioxide but could have been methane, some other gas or a mixture of gases. Earthly organisms generally require atmospheric oxygen to produce carbon dioxide but other sources of oxygen would be needed on Mars."

Regards,
Mark