Italian magazine claims Phoenix contaminated Mars with terrestrial bacteria Options

[dvandorn]

But... how are we currently looking (or have any idea how to look for) non-DNA-based life?

Gets back to my earlier post. It appears that every life-detection experiment is *only* looking for life identical to that found on Earth -- DNA-based, made of organic molecules, using the ADP-ATP cycle to generate chemical energy. It's almost a slam-dunk that any life such sensors *do* detect is a result of contamination... isn't it?



-the other Doug

[01101001]

(Was Huygens sterilized?)

NASA: Frequently Asked Questions - Huygens Probe

What precautions have been taken to prevent the Huygens Probe from contaminating Titan when it lands there?
[...]
As a Category II mission, the Huygens Probe was not sterilized.

[djellison]

It appears that every life-detection experiment is *only* looking for life identical to that found on Earth

But the simple fact is that's the only form of life we understand. It's the only form of life we know of, it's the only form of life that, as of now, we know to exist. At some point, we simply end up having a debate about what constitutes life, would we be able to recognize life significantly different to 'ours'. Sulphur based or Silicon based or whatever-based life - we don't know what reactions that might involve. Will it have something like DNA, will it have something like respiration, will it have something like photosynthesis, what will it do instead of proteins, what will it 'eat', what will it 'poop' - we have absolutely no idea. We've been unable to make carbon based life in the lab - so we're a long long way from perhaps making silicon or some other chemistry based life which we could then observe, measure and understand to the point of knowing how to detect them.

Essentially - we can do the instrument measurements we know of - Xray spec, Mass Spec etc etc ( MSL is very very well equipped in that regard ),we can do that basic elemental and mineralogical characterisation - or we can look for life as we understand it using things such as the Life Marker Chip from here in Leicester. But how can we be expected to identify a different type of life that we've never seen, never measured, have no baseline for, and have no grasp of how it might work.

That's like asking me to find a cow - if I'd never ever seen a cow or heard one described or seen a picture of one. I'd walk straight past the big black and white tree with four legs stood in a field - because I don't know it's a cow.

[centsworth_II]

It appears that every life-detection experiment is *only* looking for life identical to that found on Earth .... It's almost a slam-dunk that any life such sensors *do* detect is a result of contamination... isn't it?

No.

Why would you think that "DNA-based, made of organic molecules, using the ADP-ATP cycle" life is exclusive to Earth?

[tanjent]

In order to positively identify a microscopic life form as being recently imported from Earth I think you would have to do a lot of testing, since we are nowhere near having a complete catalog of Earth species at that level. It might be tough to differentiate it from chemically similar life, based on the same fundamental constituents as our own, that could have ridden in at any time on a meteorite or maybe even originated on Mars before coming to Earth. In that case, if it is just barely holding its own on the red planet, we'd have to worry a lot about contamination, crossbreeding, displacement; maybe even disease as in a reverse "War of the Worlds". And we'd want to study that record for all it was worth because of what it could tell us about our own origins and the implications for panspermia on an even wider scale. Mars' greatest value to us would be as a huge nature preserve - forget about terraforming, colonization, exploitation for the forseeable future. So yeah, it would be a pity to find ourselves in the situation where we couldn't tell the difference between present-day contamination and a truly parallel evolution.

The implication may just be that we should hurry up and get there and do the on-site research while there are still plenty of pristine areas to study. Contamination of an entire unfriendly planet is bound to be a slow business. Life doesn't move around all that rapidly, even in a hospitable environment. Native earthworm species are still busy re-colonizing North America by a few inches each year following the retreat of the most recent glaciers.

In the case of "life" with truly alien constituents, the scope for interaction would likely be much less. If we missed it on the first pass we could probably still find it and identify it after some period of living side-by-side. Some biologists believe that even on Earth alternative life chemistries may simply be carrying on unnoticed amidst the dominant paradigm.

[vikingmars]

...That's like asking me to find a cow - if I'd never ever seen a cow or heard one described or seen a picture of one...

Doug, this is your cow : a Martian rock that resembles remnants of a cow... Well : just found it for fun on a Conspiracy website ! The caption itself worth reading for psycho studies...


[ Caption : "MARTIAN COW
Parallel evolution at work, perhaps this is the remains of a Martian cow. Could they, too, have suffered from Mad Cow Disease? Is that perhaps what killed them?" ]

[dvandorn]

To Doug et al -- what I'm really getting at, here, I think, is how the Viking results were received. At first, the gas emission results indicated that something was undergoing life-like chemical reactions which caused various liquids and nutrients to be processed and released. However, when the holy grail of organic compounds was not detected, the results were intepreted in the context of "well, since it cannot possibly be caused by any kind of living organism, what exotic chemistry can we postulate that would account for these results?"

In other words, when we placed Martian soil in an environment that would nurture life as we know it, we got results at least roughly consistent with life being present. But when we saw no organic compounds, instead of *also* trying to follow up possible life processes that could exist within the parameters of the observation, the interpretation of the results was shifted such that life-processes were taken off the table as being even remotely possible as the cause.

All I'm saying is that as long as we insist on defining life as *only* that which is based on organic compounds, as long as our definition of life automatically excludes anything except life as it is found on Earth, we are in danger of completely missing other types of life, based on different chemistries. That's really all I'm saying.

And IMHO, the "life question" is important enough that we ought to at least be aware that we're conducting our search with our heads buried in terro-centric sands.

-the other Doug

[djellison]

as long as we insist on defining life as *only* that which is based on organic compounds

I don't think anyone would. We just don't know what else to look for yet. Maybe in 100 years we'll have a wider understanding of what life can be, and then we can go looking for it.

[ilbasso]

Have we checked any of the big rocks to see if they are actually Hortas?

[BrianL]

Have we checked any of the big rocks to see if they are actually Hortas?

Can they hear a Who?

[centsworth_II]

...when we saw no organic compounds, instead of *also* trying to follow up possible life processes that could exist within the parameters of the observation, the interpretation of the results was shifted such that life-processes were taken off the table...

How does looking at the Viking reactions from a biological standpoint help? You still have to name the reactants, the reactions and the products. You still need to show that those reactants and products exist. That all can be done without addressing the question of life at all. The problem is there is not enough information.

[ElkGroveDan]

I wonder if any of these little guys hitched a ride.

[Shaka]

....the remains of a Martian cow. Could they, too, have suffered from Mad Cow Disease? Is that perhaps what killed them?" ]

Complete NONSENSE! You can clearly see the holes in the skull made by the spearpoints of Martian hunters. Just another tragic case of over-exploitation of resources, leading to extinction!

[imipak]

...rustlers!!

Time to form a posse.

[Guest_PhilCo126_*]

those bacteria (if any) will freeze to death once Heimdall crater will be covered in ice and Phoenix Lander entombed like a farao in a few feet of carbon dioxide