New Evidence Presented For Ancient Fossils In Mars Rocks

azoblue passes along a story in the Washington Post, which begins: "NASA's Mars Meteorite Research Team reopened a 14-year-old controversy on extraterrestrial life last week, reaffirming and offering support for its widely challenged assertion that a 4-billion-year-old meteorite that landed thousands of years ago on Antarctica shows evidence of microscopic life on Mars. In addition to presenting research that they said disproved some of their critics, the scientists reported that additional Martian meteorites appear to house distinct and identifiable microbial fossils that point even more strongly to the existence of life. 'We feel more confident than ever that Mars probably once was, and maybe still is, home to life,' team leader David McKay said at a NASA-sponsored conference on astrobiology."

Comments

Skeptical

[Foobar of Borg]

If any fossilized life they find their has the same four nucleotides in its dna sequence (assuming anything like DNA can be recovered), then it is far more likely that the fossils are from Earth and have contaminated the sample. If, however, some sort of dna material can be obtained and there are different base nucleotides, then we have a winner.

Re:Skeptical

[Misanthrope]

Actually I'd be a little surprised if the nucleotides were different, current studies seem to suggest that the nucleotides had selective pressure. Here's a video that summarizes some current work on abiogenesis by Dr. Jack Szostak. http://www.youtube.com/watch?v=U6QYDdgP9eg

Re:Skeptical

[Cyberax]

It's quite possible that the Martian life used different nucleotids. For example, even on Earth uracil is used instead of thymine in RNA. Also, parts of DNA can be methylated.

And it's certainly conceivable that some other substances can be used for genetic information. Maybe even from non-organic elements (metals, for example).

Consequences of discovery

[Larson2042]

While it may be cool to find life on Mars, it would present some additional problems for future colonization (or even just future missions, robotic or otherwise). If we do find life, do we quarantine Mars so that we don't contaminate the native life there? Do we bar ourselves from any terraforming efforts whatsoever so that we don't disrupt possible existing life? You all must realize that that would be the position of at least some people; what percentage of the public that might be, and the influence they would have is another question.

Generally, I think it would be much simpler if we never found life on Mars, and could in fact say with a fair amount of certainty that it is completely dead. That would remove a (possibly significant) reason to oppose human colonization and terraforming.

Re:Consequences of discovery

[khallow]

While it may be cool to find life on Mars, it would present some additional problems for future colonization (or even just future missions, robotic or otherwise). If we do find life, do we quarantine Mars so that we don't contaminate the native life there? Do we bar ourselves from any terraforming efforts whatsoever so that we don't disrupt possible existing life? You all must realize that that would be the position of at least some people; what percentage of the public that might be, and the influence they would have is another question.

I think here that we'll just have to take it as the universe gives it to us. If there is life on Mars, we will probably establish some sort of barrier so that Earth life doesn't necessarily contaminate Mars life and vice versa. Even if Mars colonization turns out to be obstructed by regulation or other means to prevent contamination, the obstacles will be reasonable or someone will find a way to get around the regulations in question (say by totally ignoring them and deliberately contaminating Mars and/or Earth).

Re:Consequences of discovery

[Thinboy00]

What are you talking about? The prime directive was the Vulcans' idea, not ours.

Re:Consequences of discovery

[Anonymous Coward]

I used to be naive and idealistic like you, then I learned about panspermia. It is fairly certain by now that all planets are being bombarded by asteroids filled with random organisms. Earth and Mars have almost certainly been recipients of foreign material. Any bacteria, etc. that we might transfer to Mars should cause us no worries. Organisms from Earth should be just as valid as random organisms from panspermia. In fact the very organisms that we might take there could have been derived from our own exposure to panspermia.

I would suggest that we should enact our own panspermia missions. We can drop our own organisms on planets and moons. Imagine in only a few hundred years that Mars could have large areas covered with many varieties of lichens, including those nifty ones that blow around in the wind. We could start with extremophiles, and work our way up from there. I would guess that the lunar missions left human biological material on the moon as they would want to reduce weight as much as possible before returning to Earth. What is NASA's answer to this? And now ice has been found on the surface of the moon. My high school science teacher lied to me, I was told it was impossible due to sublimation.

Re:Consequences of discovery

[ChatHuant]

Panspermia doesn't really answer where life comes from. It just sort of shifts the question off of Earth.

It's true, it doesn't answer where life comes from, but it's more than turtles all the way down. Shifting the question off Earth changes the question, because off Earth the conditions are different! Panspermia removes all objections related to the specific conditions of primeval Earth. If you postulate that life has appeared on Earth, your theory has to explain it given a lot of constraints: a certain chemical composition, a certain gravity, certain temperature ranges and so on. With panspermia that's not the case any more - it vastly expands the range of environments, processes, time frames and resources available for life to arise.

Life from Earth

[PineHall]

It is my understanding that bacteria could survive a trip through space from Earth to Mars (or vice versa). I wonder if a chunk of earth made it to Mars and seeded Mars with bacterial life. That could mean that the bacterial life on Mars could have the same characteristics as bacterial life on Earth because they originated from Earth. It makes the contamination issue a little more complex.

Panspermia

[sdo1]

If it's true, it's actually not a huge deal. I could mean that life spontaneously started on both Earth and Mars (Panspermia). But it's probably more likely (Occam's razor and such) that life started on either Earth or Mars and was transported via meteor to the other planet. I would be very cool if life on Earth actually started on Mars, but it's not clear to me how we could prove which came first. -S