Is the bar higher for scientific claims of alien life?

[Admin]

The skepticism and debate around the question of "are we alone in the universe" makes the field of astrobiology more cautious

Is the bar higher for scientific claims of alien life? : Read more

 

[Hildy]

There certainly seems to be a deep prejudice against life on Mars. It should be remembered that the first searcher for Martian life was the Viking rover and one of it's experiments (the Limited Release experiment) returned a positive result.

One wonders if the ALH84001 meteorite, shown in the photo, had been an Earth rock if it would be taken as a sign of life.

Instead, in both cases, and in the case of other Martian meteorites, the scientific community tried to create somewhat convoluted explanations as to how natural processes could explain them.

One source of this prejudice that cannot be discounted is Science Fiction which conflates life with civilization. War of the Worlds just wouldn't be the same if it were War of the Martian Microbes. Although it is Earth microbes that ultimately defeat the Martians.

 

[billslugg]

Viking experiment documented the generation of oxygen, not the presence of life. There are many ways to make oxygen, including with perchlorates which exist in Martian soil.
They can tell you when the Alan Hills meteorite was blasted off Mars, what spot on Mars it originated from, how long it was in transit.

 

[Hildy]

Viking experiment documented the generation of oxygen, not the presence of life. There are many ways to make oxygen, including with perchlorates which exist in Martian soil.
They can tell you when the Alan Hills meteorite was blasted off Mars, what spot on Mars it originated from, how long it was in transit.

You are right that the scientists' consensus is that the LR experiments were flawed but rather than launching a better experiment none of the subsequent landers had any experiments that directly searched for microbial life .

As for the meteorite, of course it is Martian. My point is that in a similar sample of Earth rock, such formations would be interpreted as signs of ancient Earth microbial life.

 

[billslugg]

The Viking interpretation was incorrect.
Morphology alone can not be taken as a sign of life.

 

[Unclear Engineer]

Scientifically speaking, if there are several possible ways for something to be caused, it is necessary to rule out all but one to prove that is the one that is correct.

That becomes a real problem for verifying life on other planets that we cannot (yet?) visit, because we do not even know the complete list of all possible ways that some indicator might be created in potentially very different environments that we also have little knowledge about.

 

[Hildy]

The LR experiment absolutely returned a positive result.

They equipment was extensively tested on Earth and never returned a false positive. No objections were made about the inclusion or suggestions about any modifications prior to launch.

The Case for Extant Life on Mars and Its Possible Detection by the Viking Labeled Release Experiment - PMC

The 1976 Viking Labeled Release (LR) experiment was positive for extant microbial life on the surface of Mars. Experiments on both Viking landers, 4000 miles apart, yielded similar, repeatable, positive responses. While the authors eventually ...

pmc.ncbi.nlm.nih.gov

 

[billslugg]

"While the authors eventually concluded that the experiment detected martian life, this was and remains a highly controversial conclusion."

You believe it, I don't. It has been hashed over for half a century. We're probably not going to settle it here.

 

[Unclear Engineer]

I think that both hypotheses are still unproven and unfalsified.

We are going to at least need a sample return to prove life was/is on Mars, and would need boots on the planet to disprove it. Even if the Viking analysis is proved to be due to inorganic reactions, that still does not disprove that there is organic material somewhere on Mars.