NASA's Curiosity Rover Measures Intriguing Carbon Signature On Mars (nasa.gov) 22
After analyzing powdered rock samples collected from the surface of Mars by NASA's Curiosity rover, scientists today announced that several of the samples are rich in a type of carbon that on Earth is associated with biological processes. From a report: While the finding is intriguing, it doesn't necessarily point to ancient life on Mars, as scientists have not yet found conclusive supporting evidence of ancient or current biology there, such as sedimentary rock formations produced by ancient bacteria, or a diversity of complex organic molecules formed by life. In a report of their findings to be published in the Proceedings of the National Academy of Sciences journal on January 18, Curiosity scientists offer several explanations for the unusual carbon signals they detected. Their hypotheses are drawn partly from carbon signatures on Earth, but scientists warn the two planets are so different they can't make definitive conclusions based on Earth examples.
The biological explanation Curiosity scientists present in their paper is inspired by Earth life. It involves ancient bacteria in the surface that would have produced a unique carbon signature as they released methane into the atmosphere where ultraviolet light would have converted that gas into larger, more complex molecules. These new molecules would have rained down to the surface and now could be preserved with their distinct carbon signature in Martian rocks.
Two other hypotheses offer nonbiological explanations. One suggests the carbon signature could have resulted from the interaction of ultraviolet light with carbon dioxide gas in the Martian atmosphere, producing new carbon-containing molecules that would have settled to the surface. And the other speculates that the carbon could have been left behind from a rare event hundreds of millions of years ago when the solar system passed through a giant molecular cloud rich in the type of carbon detected.
The biological explanation Curiosity scientists present in their paper is inspired by Earth life. It involves ancient bacteria in the surface that would have produced a unique carbon signature as they released methane into the atmosphere where ultraviolet light would have converted that gas into larger, more complex molecules. These new molecules would have rained down to the surface and now could be preserved with their distinct carbon signature in Martian rocks.
Two other hypotheses offer nonbiological explanations. One suggests the carbon signature could have resulted from the interaction of ultraviolet light with carbon dioxide gas in the Martian atmosphere, producing new carbon-containing molecules that would have settled to the surface. And the other speculates that the carbon could have been left behind from a rare event hundreds of millions of years ago when the solar system passed through a giant molecular cloud rich in the type of carbon detected.
Re: (Score:3)
i thoughts that was bad
I have a carbon removal clinic that you might like to visit. They can remove your excess carbon with a single visit.
Covid19 (Score:2, Funny)
It gets everywhere!
Re: Covid19 (Score:3)
I told them it was a mistake to have the Mars Rover transmit back using 5G, but they did not listen.
It is not aliens (Score:5, Interesting)
Life barely appeared on Earth. All life, bacteria, fungi, plants, animals, you name it .. all life on Earth can be traced back to a single common ancestor cell. We all evolved from that one cell. It seems unlikely that that one cells descendent a hunted and destroyed other lifeforms that emerged on Earth. I mean none do the other life managed to sneak into some niche someplace? Only descendent of LUCA (Last Universal Common Ancestor â" Google it) managed to do that? That seems implausible, that LUCAs descendent managed to so efficiently wipe out other forms of life. So anyway, my point is that if life emerged so improbably on Earth, what chance did it have on Mars?
Re: (Score:3)
So anyway, my point is that if life emerged so improbably on Earth, what chance did it have on Mars?
Back when Mars had oceans? About the same as Earth.
Re: (Score:2)
So anyway, my point is that if life emerged so improbably on Earth, what chance did it have on Mars?
Back when Mars had oceans? About the same as Earth.
That is far from clear, because the energy flux from the sun is vastly less on Mars than on Earth.
Re: (Score:3)
That is far from clear, because the energy flux from the sun is vastly less on Mars than on Earth.
The sun would have been dimmer back then as well at about 75% of today's brightness 4 billion years ago. However, that still would have been enough for liquid water with the right atmospheric conditions. It's not clear that high levels of sunlight would have been necessary for life to evolve also. There are theories that UV light was necessary, but it may not have needed to be super bright.
Another thing to consider is that we don't really know what kind of orbit Mars was in 4 billion years ago. Probably it
Re: (Score:2, Informative)
Re: (Score:1)
Re: (Score:2)
Panspermia.
https://en.wikipedia.org/wiki/... [wikipedia.org]
i.e. in this case, the exchange of meterorites between Earth and Mars
Re: (Score:3)
According to the theories of Alexander Oparin, life formed out of organic substances that spontaneously form under the radiation of the sun. Such substances form slowly, but stick together into droplets that can already be subject to evolution to become more stable organic structures. From there, it is still a giant leap to organelles and complete cells, but it should not be surprising that organic substances exist on a dead planet.
His "Origin of Life" is quite an interesting book.
Re:It is not aliens (Score:4, Informative)
We all evolved from that one cell. It seems unlikely that that one cells descendent a hunted and destroyed other lifeforms that emerged on Earth
Those are almost contradictory statements in the same sentence. You're trying to imply how improbable it is that one single cell could eliminate any other fledgling form of life that started to develop while simultaneously pointing out that a single common ancestor spread to basically every niche on Earth from the edge of space down to the bottom of the ocean and the deepest we've ever drilled into the Earth and probably beyond. The simple fact that the Earth is just so full of life shows just how easy it is for that life to have "hunted and destroyed" (a somewhat dramatic term for outcompeting and, yes eating that other life over millions of years) other forms of life. Your argument is especially bizarre in light of your reference to the Last Universal Common Ancestor, the very concept of which implies a form of life that outcompeted all other forms of life that might have existed at the time. The whole idea that LUCA would have been not the first life on the Earth, but just the most recent that's a common ancestor to all life today specifically means that there were other forms of life at the time that were a dead end and eliminated by LUCA and it's descendants. Those other forms of life might have also descended from common ancestor, but there's no way to know.
The earliest life would have been very simple. There are all sorts of innovations that evolution developed at some point that improved it. That includes things like cell membranes. The earliest life is believed to not have had a cell membrane. The very earliest life may have actually been undifferentiated. Just a sort of life soup. Not the so called primordial soup, that it lived in, but basically a bunch of parts that weren't alive independently, but were when considered together, but that just sort of freely floated around. Evolution would have eventually made those things agglomerate, increasing their success at replication. In an environment with advanced cellular life present, a process like that would not really be able to happen again. The other cells would simply eat it.
So anyway, my point is that if life emerged so improbably on Earth, what chance did it have on Mars?
We don't know enough about Mars yet. So we''ll have to wait and see, but we really don't have a good idea yet of how probable the appearance of life is. As I pointed out above, once it's happened once, it's hard for it to happen again, and we don't have a lab big enough and enough time to find out. That's why checking other planets for it can be useful. Of course, with Mars, we have the panspermia problem. We know that rocks from Mars have reached Earth. While Earth has a higher escape velocity, transfer in the same direction is still entirely possible. So even if life only evolved once on Earth, it could still have hitchhiked to Mars in the distant past. So even if we actually found life on Mars, it could still be of Earth origin.
Re: (Score:2)
Life barely appeared on Earth. All life, bacteria, fungi, plants, animals, you name it .. all life on Earth can be traced back to a single common ancestor cell.
I dispute that as being an established fact. Whatever conditions may have existed for the first proto-cell -- probably wasn't a cell as we know it -- probably also gave rise to huge numbers of similar proto cells. These may have given rise to many types of life, and they may have interacted affecting each other, so that we actually descend from a soup.
Re: (Score:2)
OK, that means all of those had the same DNA based system? That doesn't add much in plausibility. Also, where are the descendents of the ones that didn't interact? Surely there had to be some. We know about LUCA because the code in all life for the certain parts of the cell such as the ribosome are almost exactly the same. There are different ways to encode the ribosome but all life chose a very similar DNA code to encode it .. that seems wonky to me. The ribosome is sort of the machine code interpreter of
Re: (Score:2)
You seriously need to read up on LUCA since you keep referencing it. It specifically refers to a common ancestor of all modern life that would have existed along with other branches of life that don't exist any more. Those other branches of life may have still evolved from a previous common ancestor, but those branches of life and any other ancestors, common or not, don't exist any more. They all vanished, and no trace of them exists any more.
This makes sense, extinctions happen all the time in the fossil r
Re: (Score:2)
You seriously need to read up on LUCA since you keep referencing it. It specifically refers to a common ancestor of all modern life that would have existed along with other branches of life that don't exist any more. Those other branches of life may have still evolved from a previous common ancestor, but those branches of life and any other ancestors, common or not, don't exist any more. They all vanished, and no trace of them exists any more.
On a more human scale, there are LOTS of people who lived in the past who have zero descendants currently living. As you go back generation after generation, it does not take long until you reach a point where almost everyone alive falls into two groups: they have zero descendants alive today or everyone today is one of their descendants. This is a pretty good exploration of it:
EVERY baby is a ROYAL baby - Numberphile
https://youtu.be/Fm0hOex4psA [youtu.be]
On the other hand... (Score:1)
If Carbon 12 isn't (only) a signature of life, on Earth as well, does that mean that the biologists' use of it for that is also now farked ?
Poor summary (Score:5, Informative)
Re: (Score:2)
How can this be so difficult? (Score:2)
Say we send up a super-duper light microscope with a digital imager. Better, we send two of them.
We send up two slides (really, a magazine full of slide pairs, but...), one is a sterile control, and one a sterile sampler. We shove the sampler outside for a while (perhaps choosing a good location where we think water has been), bring it back in, compare the slides under the microscope.
Or bring up a couple (dozen) sterile Petri dishes, paired up: control and sampler. Put some stuff in the sampler dish, treat