The Viking landers and its possible discovery of extraterrestrial life

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Link here. One of the scientists involved in the Viking project has written a memoir of her experience, and the article interviews her.

Patricia Straat served as co-experimenter on one of the most controversial experiments ever sent to Mars: the Labeled Release instrument on the Viking Mars landers. The experiment’s principal investigator, Gilbert Levin, insists to this day that the project found extraterrestrial life. Most scientists doubt this interpretation, but the issue has never been fully settled.

Read it. It illustrates how uncertain science can be, even when an experiment produces a result that everyone involved dreamt of. As Straat notes,

The results met the pre-mission definition of a positive life response. But of course as soon as we got it everyone came up with alternative proposals to account for the results nonbiologically.

The problem was that though their experiment found evidence of life, none of the other Viking experiments did. Most significant was the apparently complete lack of organic material (based on carbon) in the soil.

To this day, no one has a good explanation for these results on Viking. The results remain a mystery, one that really will only be solved when we can return to Mars in force, and find out what it is really like.



  • Ryan Lawson

    I am amazed I have never heard about this other than generic statements about how Viking tested for signs of life but they all came back negative or ambiguously unlikely. After reading this article I am stunned there was never a follow-up on this with something like Phoenix to include a simple digital microscope to look at the sample. You don’t have to see the individual microbes, give them enough time and you will see the aggregate structures they form like fuzz on a rotting fruit.

  • Ryan Lawson: You’ve been reading the mainstream science press too much. :)

    I have reported on these Viking results since the 1990s, when I first became a science journalist. It didn’t take much research to learn about them, just a willingness to do it.

  • Ian C.

    What would it take to replicate the experiments on Mars with today’s means? Assume I’d put things together in a somewhat hackerish approach, what equipment would I need, energy, communication, remote controlled actuators etc.? Could I do it rather low cost (just materials and engineering, excluding qualification, launch etc.)? Any idea how much mass and volume it would require?

    And would it even make sense or would it just satisfy the curiosity of people involved at that time?

  • John

    I recall, that at the time, the preponderance of opinions was that the detection of CO2, originally designed to be an indicator of biological respiration, was generated by planetary chemical peroxides when contacting the experiment’s liquid growth substrate. It was thought the intense solar radiation levels at the Martian surface would cause and maintain such forms of reactive peroxides. It was such an emotional letdown; similar to the initial photographs released showing vast fields of green and blue landscapes, later to be color corrected to the harsh reddish environment we frequently see today.

  • John: This was the explanation offered. Gil Levin, principal scientist for the labeled release experiment, never bought it, and offered many reasonable objections to it.

    There are too many uncertainties here. The truth is that we really do not understand what happened. It was likely a chemical reaction of some sort, but that is not certain by any means.

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