Barry DeGregorio, in his various guises here, continues to advance his case that Gil Levin found life on Mars and this life is too dangerous to bring to earth. His belief that the Viking Labeled Release Experiment produced incontrovertible evidence of life on Mars permeates everything else he says about Mars. But lets be clear:

Gil Levin did not find life on Mars. The reactions observed with his labeled release experiment have been properly attributed to non-organic chemical processes. Does this mean that there is no life on Mars? No. It only means that Mr. Levin didn't find any. The story of extant or extinct life on Mars remains unfinished.

Perhaps the most significant challenge to assertions that microbial life might exist on the surface of Mars is the apparent complete absence of organic compounds there. Neither Viking, Pathfinder/Sojourner, nor MGS have detected the presence of any such compounds at the surface. This doesn't mean they do not exist, only that we haven't found any. But unless and until we do, the case that organics are there cannot be made.

Nor have we yet found the elixir of life, liquid water, on Mars. There are tantalizing suggestions that perhaps, below the surface, liquid acquifers may exist. We also know that for very brief periods of time in some locations on Mars, triple point conditions are hypothetically possible. But one simple fact remains, we've yet to find a single drop of liquid water on Mars. This does not mean that liquid water does not exist on Mars. But unless and until we detect and/or observe its presence, we cannot say that it is there.

And, we've found no evidence of current hydrothermal activity on Mars. Perhaps its there, but until and unless we find it we can't say its there.

Finally, proponents of life on Mars frequently speak of life we find here on earth thriving in hostile extreme environments. The inference is that this means we should be able to find similarly hardly forms of life on Mars. But lets be clear...there is no hostile extreme environment with life on earth that is as hostile and extreme as the environment on Mars. More importantly, Mars has no apparent active biosphere within which these extreme environments may niche. Indeed, all of Mars is a hostile and extreme environment. It is bathed in radiation. Its geochemistry is highly oxidizing. It is desperately cold. Its atmsophere is 10,000 time drier than our own atmosphere. And it possesses 4,000,000 times less chemical energy upon which to power the processes of life.

BD/Me ignores all of this, instead, preferring to cite selective articles and papers that he uses to give the impression that there is evidence of life on Mars. It is a deceptive tactic that attempts to offer "proof" by association without actually offering proof. It is little different that the psuedo-science of UFOs, crop circles and ancient astronauts. Perhaps a little more sophisticated, but psuedo-science just the same.

None of this means that there is no life on Mars. But the simple fact of the matter is until and unless we actually find it, we can't say its actually there.