[X] My Assistant

[Guest_AlexBlackwell_*]

Gil Levin has a new document on the Spherix website: Modern myths of Mars (1.3 Mb PDF).

[ElkGroveDan]

Interesting. I think I've read this guy's arguments before. I assume there are people who can adeptly take issue with his reasoning. I'd be interested in reading some of that.

I do recall that as a high school lad of 15 in those days, I did study these experiments ahead of time and was aware of what they would be looking for. I'm not sure I accepted the oxidizing soil theory. Not sure what I think now. I'd like to read more give and take on this.

As an aside, having been to both Death Valley and the sumit of White Mountain I can vouch for them being seemingly devoid of all earthly life.

[nprev]

Levin's arguments are always compelling if obviously biased, but I believe that final resolution of the issue can only come from direct (human) analysis of actual Martian samples.

It's difficult to conceive of an automated experiment that could run the full gamut of possible tests needed to conclusively prove or disprove the presence of microbial life, especially if it's radically different in any significant particular from terrestrial microorganisms (insert a confused shrug icon here...really, who knows what might be?)....the ALH meteorite notwithstanding. General metabolic patterns like nutrient consumption rates may exhibit far more diversity than we know.

Time to confess my secret fear: What if there are indeed Martian microcritters, and what if they've evolved to exploit scarce organic resources much more efficiently than terrestrial bugs? I have this nightmare vision of something like the nanotechie's "gray goo" coming from a DTE surface sample return...would much rather have a Mars surface sample return mission designed to be recovered & analyzed by the ISS or its evolute, and thereby provide an isolation barrier for our ecosystem.

As a cautionary tale, my high-school biology teacher back in the '70s flatly stated that there was life on Mars after Mars 2 crashed, native or not. He was an early adherent of extremophiles after studying the bugs in the hot springs of western Montana, and believed that absolute sterilization was impossible; life would always find a niche in which it could survive. Perhaps this perspective would be wise to remember when importing samples from potentially habitable extraterrestrial locales.

[ElkGroveDan]

Perhaps this perspective would be wise to remember when importing samples from potentially habitable extraterrestrial locales.

Biology is perhaps the science where my background is weakest. However I heard a very compelling and simple argument a while ago to alleviate fears of invading alien organisms, by someone schooled in the field. It goes something like this:

The human body has a very powerful immune system. The more unlike our body an organism is, the more likely our immune system will identify and destroy such an organism before it can do damage.

Conversely the most dangerous organisms are ones that recognize our immune system - organisms such as the endless strain of rhinovirouses or influenza strains that have been adapating and evolving with our bodies and the vectors in our environment for millions of years.

I found those two points to be very convincing.

Imagine an organism on Mars that has been adapted to that cold, hositle oxidizing environment for millions of years. Such an organism has never encounterd a complex immune system, let alone a large body with a 37 degrees ambient temperature. Based on what we know about the Martian environment, I am abundantly confident that anything living there would find warm mammalian bodies with their complex immune systems to be the most inhospitable places in the solar system.

[nprev]

Actually, Dan, I'm not worried about a plague; I agree that it's extremely unlikely that a "conventional" extraterrestrial bug would infect humans or anything else in the way that disease processes work on Earth.

What I am worried about is just what sort of microorganisms might have survived on Mars in such an austere environment. If organic compounds are indeed scarce, something might have evolved there that is ruthlessly efficient at assimilating organics & water wherever and whenever they are found and reproducing as rapidly as possible when conditions are favorable. Perhaps such an organism could remain dormant for thousands, even millions of years. Terrestrial extremophiles occupy niche environments because they can't handle Earth's "baseline" conditions; the Martian baseline is considerably more demanding.

Under this hypothesis, it's probable that the immune systems of most terrestrial life would handle the bug with no problem exactly as you described. However, organics that are NOT part of a living system and water are everywhere on Earth, and the stuff might just keep growing and growing...filling the oceans...eating the plastics off of our shelves...ultimately destroying Earth's ecosystem. This is a direct analogy to the "gray goo" scenario in nanotechnology in which microscopic Von Neumann machines reproduce without control (or predation) and convert the accessible surface of the Earth into a mass of themselves.

I freely admit that this is a highly unlikely scenario, but the potential risk to the Earth is so horrendous that I think it needs to be seriously considered.

[Guest_DonPMitchell_*]

... I believe that final resolution of the issue can only come from direct (human) analysis of actual Martian samples.

I think a very intersting problem would be the design of an advanced remote laboratory. Drop a rover somewhere on Mars, then drop the laboratory nearby. Let the rover collect samples and bring them to the lab. Then operators on Earth look at the stuff under microscopes, select from a large battery of tests, examine results, make more tests, publish some results, get feedback, do some more tests, send the rover out to look for some particular samples. I think you could do exciting science this way.

[nprev]

Sounds like a good approach, but I shudder at the price tag.

Additionally, you'd have to find an in situ way to discriminate between imported terrestrial bugs (which there will definitely be) and any prospective natives. Postulating for the sake of argument that Martian life exists, if it will eat what we give it how can we ascertain whether it is in fact native, or terrestrial contamination?

Obviously there would have to be close biochemical similarities in any culturing scenario for the experiment to work at all, but unless the bugs have little tattoos on them that say "Mars native & proud of it" that we can see under the microscope or that there are initially so many that they couldn't possibly be contaminants the results would remain inconclusive.

I just don't see how to reach a definitive finding one way or the other without extremely detailed DNA analysis (esp. if Martians don't use DNA, but instead use some other mega-molecule...that would be a slam-dunk right there!)

[EDIT]: Found this pic of a Mars critter from Disney's "Mars & Beyond"...gotta have a thread mascot!

[edstrick]

The Phoenix lander is going to have a quite sophisticated wet-analysis instrument for characterizing soil and icy-soil samples. It will go a long way toward providing meaningful information on the soil-moisture and soil-nutrient-solution interactions observed with Viking's biology experiments.

I've personally had a couple run-ins with Gil Levin as a grad student, and he's an expert evidence cherry-picker and insinuated-inference-maker. I have not exhaustively investigated the soil analysis results and modeling work to understand his viewpoints and how it clashes with other team and research group viewpoints, but I take his opinions with a bagfull of side-walk-ice-melting salt, rather than a grain of salt. One thing I don't recall him ever DIRECTLY, head-on addressing is the total lack of evidence of GROWTH in his instruments results, rather than a heat-sterilizable one-shot chemical reaction.

[Bill Harris]

Nonetheless, with the prevalence of organic compunds in the Universe,
I'd be concerned about the infinitesimally remote possibility of an incompatable DNA being present. And much more worried about a compatable virus or viral organism, which would be simple, adaptable and deadly.

Whatever...

--Bill

[nprev]

The Phoenix lander is going to have a quite sophisticated wet-analysis instrument for characterizing soil and icy-soil samples. It will go a long way toward providing meaningful information on the soil-moisture and soil-nutrient-solution interactions observed with Viking's biology experiments.

I've personally had a couple run-ins with Gil Levin as a grad student, and he's an expert evidence cherry-picker and insinuated-inference-maker. I have not exhaustively investigated the soil analysis results and modeling work to understand his viewpoints and how it clashes with other team and research group viewpoints, but I take his opinions with a bagfull of side-walk-ice-melting salt, rather than a grain of salt. One thing I don't recall him ever DIRECTLY, head-on addressing is the total lack of evidence of GROWTH in his instruments results, rather than a heat-sterilizable one-shot chemical reaction.

That's some good info, Ed; thanks for the insight!

The absence of detectable organics was what troubled me (and everyone else, of course) the most. Frankly, that's why I have this concern about a superbug that can eat like crazy. If the VL results were in fact caused by life yet there weren't enough cells to be detected by the GCMS, then that might imply an extraordinarily high level of activity by individual organisms.

Hmm. Although, as you say, there was no evidence for growth. I don't know; maybe Mars life is selfish & doesn't want to have kids in order to maintain its lifestyle? Seriously, though, we assume that rampant reproduction is inevitable for microorganisms, but this may not be a universal truth, especially if a given organism has no predators, competition or threats other than environmental variables. Martian bugs might encounter food so rarely that they reproduce only when truly prolonged favorable circumstances are present, remaining dormant for extended periods. (Sounds unlikely to me too, but I'm just throwin' it out there for consideration).

[Guest_DonPMitchell_*]

Sounds like a good approach, but I shudder at the price tag.

I don't see how this would be more expensive than a rover mission. I think a sample-return mission would be more expensive, but we should also think hard about trying that too someday. And of course, sending a man to Mars would be orders of magnetude more expensive.

[nprev]

Might not be so bad if it was a single mission instead of two launches...sort of a Pathfinder on steroids thing. There's a lot of implicit risk involved trying to get two spacecraft to the same place on Mars at the same time, and obviously neither vehicle would be able to complete the prime mission objectives on its own.

My shudder was based on thinking of the cost required to mitigate the risks as described.

[Guest_DonPMitchell_*]

I wonder if there might be some value to landing multiple different types of missions to one place. The risks would be amortized then, and you might get some very useful synergy from having a couple robotic Mars Base, with rovers, chemical and biologcial laboratories, specialized stations, a sample-return platform, etc.

[nprev]

Interesting idea, but it would have to be one heck of a site to justify that kind of dedicated activity. Perhaps MRO will find one (or ten, or thousands...)

[Stephen]

Nonetheless, with the prevalence of organic compunds in the Universe,
I'd be concerned about the infinitesimally remote possibility of an incompatable DNA being present. And much more worried about a compatable virus or viral organism, which would be simple, adaptable and deadly.

Whatever...

A "compatable virus or viral organism" would imply compatible DNA (or RNA).

Viruses function by capturing control of a host cell through capturing control of its DNA or RNA then using that to get the cell to churn out more viruses. A virus which had incompatible DNA (or RNA) would be unable to link in to the DNA or RNA of its intended host, which in turn would prevent it reproducing.

It may well kill the host cell in trying, but so long as no baby viruses were produced it would be unable to spread; or at least spread very widely.

A far more deadly alien organism would be one which:

• got everything it needed from the environment, whether the natural environment or the gut of another organism;
• could reproduce quickly and spread widely; and
• could survive in or hide from (eg inside another organism) Earth's oxygen-rich atmosphere.

The first item would imply more the equivalent of a bacterium than a "virus or viral organism". The last seems unlikely if the organism came from (largely oxygen-free) Mars.

======
Stephen