Life on Mars

MORE: There has been speculation that evolution on earth took a different path from that on other planets when mitochondria, which were originally free-living organisms like Rickettsia, developed a symbiotic relationship with eukaryotes (cells with a nucleus) and made possible multi-celled organisms. This crucial step may have occurred only once. Or, it may occur in any oxygen rich atmosphere. We should not be surprised to find single cell life on Mars but multicellular life might very, very rare.

I have already posted on the new developments in bacteriology and life forms like Archea. Now, we are starting to see evidence that Mars may host similar organisms. Here is evidence of methane on Mars.

At a NASA news conference this afternoon, a team of scientists led by Michael Mumma of the Goddard Space Flight Center announced the discovery of plumes of methane emanating from the surface of Mars during the planet’s late spring and early summer. Methane is a key component of natural gas, and much of the Earth’s supply of the chemical comes from organisms that release it as they digest nutrients. But the five scientists were cautious to avoid claiming the methane spouts as evidence of life, saying that geologic activity could also put pressure on the methane and blast it through cracks in the surface. Either way, Mumma said, the plumes show that Mars is not merely a dead planet that once may have hosted life or liquid water. “We are entering a new era,” he said. “Now we’re looking at an active Mars.”

I have previously commented on extremophiles and other organisms that might survive in the Martian environment. Here and here.

There is more on this topic here.

To learn whether life could exist in a barren landscape such as that seen on the surface of Mars, where any water present is mostly present in the frozen state, some microbiologists have journeyed to a part of Earth that resembles Mars in some respects: the polar deserts of Antarctica.

Antarctica proves that microbes survive in barren landscapes.

This region of Antarctica has very little water, and most of the year what little water there is exists in the form of ice.

The hole in the ozone layer that has developed over Antarctica allows high levels of ultraviolet radiation to reach Earth’s surface, a condition that would be experienced by any creatures located on the Martian surface.

The level of radiation encountered in Antarctica is not nearly as high as that encountered on the surface of Mars, but it is higher than that encountered on most other parts of Earth’s surface.
Is there life in the polar desert of Antarctica? The answer is an unequivocal Yes. Bacteria and fungi have been found in the Antarctic deserts, not only in the soil of the region but also inside rocks. Scientists speculate that bacteria enter the porous matrix of rocks as a means of protecting themselves from radiation.

The atmosphere on Mars is much thinner than Earth’s.
A major difference between the environment found in the high deserts of Antarctica and that encountered on the surface of Mars is the atmosphere. The Martian atmosphere is much thinner than that of Earth. It consists mostly of carbon dioxide, or CO2 (about 95%), and contains virtually no oxygen (O2). Because many bacteria, archaea, and algae can use inorganic carbon dioxide as their source of carbon (used to build proteins and other cell components), the predominance of carbon dioxide would be a plus. Also, as noted earlier, many of Earth’s microbes do not require O2, so the lack of O2 does not preclude life.

So all these points are permissive. Life could exist on Mars. There is a problem, though.

A more troubling feature of the Martian atmosphere is the very low level of nitrogen (N2). On Earth, N2 makes up 78% of atmospheric gases. On Mars it only composes 3%. Many bacteria can use N2 as a sole source of the nitrogen they need for proteins, nucleic acids, and other cell components, but the low level of N2 would certainly limit the amount of microbial growth. Thus, if there is microbial life on Mars, it is unlikely to be as abundant and as widespread as on Earth and may thus be harder to find.

Different compositions and concentrations of gases may exist in some areas under the Martian surface. Such a possibility would be difficult to prove—unless it is proved indirectly the presence of life in the subsurface regions and in greater abundance than expected.

We may have to consider a life form that does not use Nitrogen. Phosphorus and Arsenic are members of the family of Nitrogen in the periodic table. on Earth, Nitrogen is a gas and a large part of the atmosphere. On Mars, it is a small part. One problem is thinking about Exobiology, the biology of other systems. Phosphorus is abundant on Mars. What does this mean ? I don’t know.

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8 Responses to “Life on Mars”

  1. Eric Blair says:

    Dr. K.

    I LIKE this post, of course. Thanks for writing it.

    I’m pretty sure that microbial life exists subsurface on Mars. Remember that anywhere on this planet that has liquid water, life occurs. I don’t expect Mars to be different.

    I also don’t think that Mars is quite as nitrogen starved as NASA does. The problem is the UV-generated peroxides on the surface, that pretty much degrade most nitrogeneous compounds. What you are describing is life as we do NOT know it, which would be deeply exciting. Please check out the work of this scientist (he has a recent book worth your time):

    I expect that we will find our archaean friends on Mars, personally. And I think that they will be relatives, phylogenetically speaking. Mars cooled before Earth did, after all, and had oceans of water and a thick, warm atmosphere then.

    Earth was still pretty darned hot (to the point of being molten). In fact, life originated on Earth in a very short span after our planet cooled.

    Me? I think we are all the descendants of Martians, brought here by meteorite a few billion years ago. And we may find our long lost cousins once we explore Mars.

    But if it is life as we DO NOT know it, that is even cooler!

  2. I wonder if we could see life with other chemistry or is our chemical system the only one compatible with life. I am too far from my biochemistry anymore to make intelligent speculation but I do expect that the elements are universal but maybe a nitrogen-free world would have alternative pathways.

  3. Eric Blair says:

    If you like this subject, Dr. K., try this out:

    This one is good, too:

    Life as we do NOT know it is a very, very interesting concept. As a joke, talking with an SF writer friend of mine, I gave him a phrase that appears in most of his fiction these days: “…the thing about aliens is, they’re alien.”

    The original Viking results, by the way, were not as unequivocal as “not-life” as NASA says. For example, dumping radioactively labeled sugar into Martian soil released hot carbon dioxide. Just like microbes would do on Earth. The problem is that low concentration of organic material…and that the effect was not totally removed by heating the soil sample.

    But when radioactive carbon dioxide was added to those soil samples, it was removed….again, as autotrophic microbes would do on Earth.

    NASA claimed that this was all chemical, powered by peroxides. Except we don’t know of any such peroxide, in a single sample, that can do both fixation and release of carbon dioxide. Living things can.

    Unfortunately, the only way to be sure is to bring back a sample or send someone with the proper training and equipment to go look.

    Carbon based life is possible, again, wherever liquid water and entropic differences exist.

    Life other that C-N based life would have interesting and different characteristics. Silicon based life would require high temperatures, for example.

    Anyway, those two books are a start. Fascinating subject!

  4. Eric Blair says:

    And here is the book for you, Dr. K.:

    Dirk Schulze-Makuch and Louis N. Irwin. 2008. “Life in the Universe: Expectations and Constraints.” Springer.

    It has some great discussion of different molecules for “life.” Smart fella.

  5. Bradley, I accidentally deleted a comment of yours while deleting spam. Sorry. The finger twitch was faster than the thought process.

  6. Eric, I’m backed up with a new Steven PInker book I picked up this weekend. I will read one of them. LOvely weather makes me want to get out, too. In the 80s this weekend.

  7. Eric Blair says:

    You might be very interested in the the Schultz-Makuch book in particular. But I surely do know the “so many books, so little time” issue.