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Comment by pacman2 | Hacker News Reader

"Similarities in morphology are not proof of life. It is possible that all the specimens presented here are abiotic. We cannot completely rule out minerals, weathering, and unknown geological forces that are unique to Mars and unknown and alien to Earth. However, growth, movement, alterations in location and shape, constitute behavior, and coupled with life-like morphology, strongly support the hypothesis there is life on Mars."

They really should put more focus on the first sentence. Extraordinary claims need extraordinary data, which they don't have. They should have phrased it otherwise around. While abiotic phenomenons are more likely, we can not rule out a biological background. Further investigation should be undertaken.

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Did you read the paper or at the very least examine all of the photo sequences in the full text article? The examination of the spheres in the rover treads and their reappearance is significant, as is the positional analysis of various spheres as they grow in size over a 3 day period. It isn't just morphology, there are some dynamics at work that point to a fungal-like growth as the simplest explanation.

Crystal growth?

No, they point to growth as an explanation, and the authors dismiss one possible geological process known from earth. There is no reason to dismiss unknown geological and chemical processes that can happen at the extremes of low pressure and temperature found on the Martian surface.

Jumping straight to multicellular life, one of the most complex structures that we've ever seen in the universe, is absurd.

NASA itself investigated similar spherules [0] they called "blueberries" and determined they were hematite-rich "mineral concretions" [1]. Evidence of water in the environment long ago, but not of life. This ResearchGate paper has only one reference to "spherules" and none of "blueberries".

[0] https://en.wikipedia.org/wiki/Martian_spherules

[1] https://mars.nasa.gov/resources/6944/martian-blueberries/

If you read the paper instead of ctrl-fing they spend a lot of time discrediting the hematite hypothesis.

I guess my point is that they are, at minimum, not in the mainstream in discussing this phenomena. That is not a refutation of their research or logic but gives context to what other serious scientists have concluded. Even this article [1] on NASA's astrobiology site (a.k.a. "Life in the universe") concurs that they are hematite mineral concretions and that the only real implication to life is the ancient presence of a large volume of water.

[1] https://astrobiology.nasa.gov/news/check-type-iron-blueberri...

You know what is really mind blowing ? I remember Kim Stanley Robinson's character(s) discussing spherical, shell(?)-looking volcanic pebbles first mistaken for fossils in his book The Martians. Which came out 5 years before this study !!

The paper discusses hematite and NASA's conclusions directly. I don't know the paper's reasoning is sound, but it's not right to suggest they don't consider this explanation.

Is "life on mars", really an extraordinary claim? I guess I have a hard time seeing a solar system where Earth is so unique that biological life only happened here. I agree more proof is needed of Martian life, but what we're imagining here is bacteria/fungus like life, not green spacemen.

Yes it is an extraordinary claim. All prior evidence shows that life is nonexistent on all planets that are not Earth. So to suggest that the planet closest to us has life is far out side the norms of our current beliefs about how frequently life appears.

Attempting to extrapolate off a sample size of n=1 is dangerous. I think that puts this in the “requires extraordinary proof” bucket. Especially when considering how many times we’ve looked but failed to find proof of extraterrestrial life.

But the Earth is entirely unique in the solar system for almost everything we know is important for life - especially liquid water (maybe with some exceptions on a few moons of Jupiter) and temperatures above freezing.

The Earth is not only unique in the solar system. We are located in a radioactively calm corner of the Milky Way, in a single-star system (not that common) with planets rotating in stable, non-intersecting orbits. And that's just the beginning of the factors that make the Earth so unique.

So the next time you take that sip of coffee in the morning, just know that you can't do that for millions of light years around you - or maybe anywhere.

Actually it is, since we've seen zero evidence of it that can't be explained away by other means. So yeah it would fucking huge, pardon my french.

All previous evidence of life on Mars (which there have been a lot of claims about) have proven false. (Including similar claims about potential evidence based on rovers). That is what makes this an extraordinary claim.

That depends on the expertise as well. Extraordinary claims need that proof, of course, but it seems they took a lot of factors into account that seems to skew it towards their hypothesis.

A lot of this just makes me think of precipitate. I’m sure there are papers on the Mars environment, I.e. low temperature low pressure geology and physics, but I didn’t immediately see any references.

I recall reading another paper indicating there is an unresolved increase and decrease of methane ? in the Martian atmosphere as well. But I’m still inclined to think this is geological not biological.

"Life" may be the simplest hypothesis. Not clear its obvious which side of "Is there life on Mars?" is the extraordinary claim.

No, it's very clear that life on Mars is the extraordinary claim. We don't know of any abiotic structure that would be even half as complex as bacteria, and multicellular life is an absurdly complex possibility to take as 'the simpler one'

Not arguing for parallel evolution in this one.

There are pieces of Mars on Earth. Possibly there are pieces of Earth on Mars. If they didn't contain spores, that would be unusual.

So if its possible for fungi to grow in a Mars environment, it seems the more likely outcome. That's the question - can they grow there? Then, they are likely growing there.

There is no reason to expect life to survive an asteroid impact. The sheer force would likely be enough to crush delicate cells, and the heat of the impact would likely sterilize any remnants.

Also, there are no fungi living off frozen water at -50 to -70 C or below on Earth, and an asteroid impact doesn't really provide time for evolution to work its magic. Perhaps extremeophiles could be found that would survive, though even that is shaky without some form of liquid water, and they would be extremely unlikely to evolve to something approaching fungi (remeber that extremeophiles are prokaryotes, while fungi are eukaryotes, and as far as we can tell eukaryotes arose from prokaryotes only once in the history of life on Earth, so it was literally a once in 2 billion years event).

Edit to add: Mars' surface is also extremely toxic to essentially all Earth-based life.

Overall, it is very hard to imagine that any form of Earth-based life would have survived the series of events you suggest: an asteroid impact with Earth which propelled a chunk of rock to space, being exposed to space, then burning through the Martian atmosphere, crashing into Mars, then encountering the extreme cold, low pressure, missing oxygen and CO2, high radiation, the toxic soil of Mars, and not just surviving, but growing and thriving from this.

No. Not no reason. Science: https://www.sciencedaily.com/releases/2013/09/130912092731.h... A portion may well survive.

Thank you for the study, I was surprised to find that (though I will note that it seems the impact speed on Mars can be larger than on Earth, depending on the size of chunk - I found antoher study that gave an upper bound of 8.52 km/s for large meteors with mass > 10^10 kg).

They discuss exactly this, from both angles, in section 5: Pareidolia and the Denial of Diverse Evidence of Martian Life.

They don't discuss it as much as dismiss it out of hand, with a 'no, you have pareidolia!' style argument.

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