- Oct 13, 2009
- 2,852
- 3,872
- 53
- Country
- India
- Faith
- Christian
- Marital Status
- Celibate
EU and Russia will send probe to Mars specialized to searching for martian life, in 2020.
If you're suggesting that looking for Earth-like life may mean that we'll miss other forms of life because it may not be Earth-like, that's been taken seriously in trying to come up with a definition of life that captures the essence of what we mean by it. The other problem is detection - with only Earth-like life as an example, we only have one example of the kinds of detectable byproducts characteristic of life; in this respect, a broad definition of life makes little difference.The ambiguous results returned by the Viking life experiment instrument suite provided many lessons for NASA. The ambiguous results, themselves, provided the precedent/evidence for arguing for restraint when it came to the question of sending repeat 'Levin' experiment packages (L/R, GEx, Pyrolytic Release).
The underlying notion of searching the (local) universe specifically for Earth-like life however, has nonetheless persisted, (as is evidenced by ESA's Exo Mars astrobiology, NASA's Mars 2020 Rover programmes).
The strategy of pursuing directed (local) searches which specifically target finding Earth-like life, makes zero impact on finding Earth-like life in the case where such life turns out to be a product of only Earth's environmental evolution .. Which is of course, overlooked and completely ignored in the frenetic hunt for astrobiology's own 'Holy Grail'.
The scientific definition and its associated meaning is predicated on the context of evidence sourced only from earth's singular (inter-related) biosphere. Anything extrapolated beyond that contextual basis is thus speculative or hypothetical (at best). There is no evidence of any instances beyond our own instance .. and that is not to say that other forms of life should be ruled out, either.If you're suggesting that looking for Earth-like life may mean that we'll miss other forms of life because it may not be Earth-like, that's been taken seriously in trying to come up with a definition of life that captures the essence of what we mean by it.
There is no evidence of any examples beyond Earth-life in the first place .. therefore the notion that there are other examples 'of detectable byproducts characteristic of life', is speculative. (Hence the Holy Grail miraculously makes its appearance, yet again).FrumiousBandersnatch said:The other problem is detection - with only Earth-like life as an example, we only have one example of the kinds of detectable byproducts characteristic of life;
Agreed .. therefore 'the Hunt' is also then seen again pursuing the belief in its existence. The belief in its existence will not make it appear in the case(s) where it is beyond detection limits/uncertainties, or the case where it doesn't exist at all within detection limits/uncertainties.FrumiousBandersnatch said:.. in this respect, a broad definition of life makes little difference.
NASA in this instance (and most unfortunately I might add), is the chief protagonist in the pursuit of the Holy Grail. It even holds it as a strategic goal. The chances of success in its pursuit, by way of its directed searches, are directly proportional to the degree of intensity in the belief held .. which is a rather sad indictment for a scientific organisation.FrumiousBandersnatch said:Here's a NASA discussion of the problem, and one of their definitions: "A self-sustaining chemical system capable of Darwinian evolution."
Yes; I can't help wondering why they didn't follow up. Was it politics or internal competition for mission objectives?I have long felt* that NASA were precipitate in rejecting the positive results of some of the Viking experiments. The results were certainly ambiguous and the conclusion - no life - is more probable than not. However, in my opinion, follow up experiments, designed to test the abiotic explanations for the results, coupled with a more sensitive GC-MS, should have been part of the next lander programme.
If it turns out life was detected I trust Levin will receive appropriate recognition. (An apology would not go amiss.)
*i.e. four decades
Levins experiment and its procedures were quite sound. Thus far, the lack of GCMS sensitivity is seen as the main flaw. The GCMS was not developed to complement the aim of his various biology experiments. Unless the GCMS could detect bio-organics at the multiple various sites the Landers were deployed at, his results were seen as isolated, unsupported findings.That's what it sounds like.
I'm not so sure they outright 'rejected' the positive results. Results of any correctly designed experiments are always accepted as valid. The problem was that (at the time) all of the L/R, GEx, P/R and GCMS results were taken as being valid, yet they did not concur with eachother .. which then more or less forced the 'ambiguous' conclusion.I have long felt* that NASA were precipitate in rejecting the positive results of some of the Viking experiments. The results were certainly ambiguous and the conclusion - no life - is more probable than not. However, in my opinion, follow up experiments, designed to test the abiotic explanations for the results, coupled with a more sensitive GC-MS, should have been part of the next lander programme.
I wholeheartedly agree.Ophiolite said:If it turns out life was detected I trust Levin will receive appropriate recognition. (An apology would not go amiss.)
I could never figure it out, or find a satisfactory explanation in journals or the NASA site. The two decade gap between Viking and Pathfinder may have contributed - new research team accepting the conclusions of the Viking team up front. Not good science, but perhaps sound politics.Yes; I can't help wondering why they didn't follow up. Was it politics or internal competition for mission objectives?
What 'theory' do you mean here? Levin's experiments were very sound but were based on the assumption that Earth-like metabolism must be present in order 'to prove' that it exists. That is a philosophical assumption and not a scientific 'truth'. My point is that testing hypotheses to prove their underlying assumptions is not a scientific approach. Following the data is. And so the 'ambiguous' result is actually the appropriate data led conclusion (much to the chagrin of the believers in martian life).The article shows him not to be sure of this theory himself,
What 'idea being pushed here' do you mean?Albion said:.. and his superiors didn't support the idea that is being pushed here.
Remember, at the time, the cost of the Viking probes was very, very high. The results were ambiguous. The question had to be asked (probably behind closed doors): "Was that a good return on investment?"The NASA argument seemed to be "We've found a non-life explanation for the experimental results, so that's the one we are running with." My conclusion remains "We have ambiguous results that could be explained by living organisms, or by abiotic chemical reactions. We should investigate further to determine which is responsible."