Gilbert Levin

Palomar · 2004-08-03 08:05:04

http://www.space.com/scienceastronomy/m … html]Click

*IIRC, Dr. Levin is a hero of Shaun's. He's definitely pro-life on Mars. He thinks the whitish residual left in MER tracks is water squeezed up by the weight of the MER, then freezing.

He is apparently pro-return to the Moon, establishing a human presence there, and having Mars sample returns taken to Lunar facility rather than back to Earth.

--Cindy

atomoid · 2004-08-04 03:59:18

As much as I like Gilbert Levin's maverick stance (and I agree the LR experiment results were unwisely dismissed by NASA, especially with no plans even for a follow-up!), i'm just not impressed by those four http://www.space.com/scienceastronomy/m … tml]images highlighted in the sidebar of that space.com article that seems to suggest mud flows, mud puddles and white sheens in those images (is it just me or are these captions just not very convincing at all?):

IMHO:
- the airbag bounce-mark puddles: really its just dust disturbed and perhaps maybe even electrostatically aggrivated by the airbag materials. after all, after the bigger grains and blueberries get punched down below the surface, leaving only the dust layer, which being composed of exteremely fine particles with no humidity to glom the particles together must act quite differently than what were used to on earth. if it were really wet enough to glop like that, wouldnt the whole crater just slump into a flat blop on its own under the influence of eons of gravity?
- and the mossbauer indentation of course is not partially covered by a mudflow, it just didnt make perfect perpedicular contact and left only a partial circle...
- The white sheen in the tracks and mossbauer impression is really just compacted soil which reflects more light (and camera exposure effects as well) since the compacted soil is flatter and lighter-toned fines have been concentrated at the surface since they're smaller (larger basalt and shadow-casting grains get pressed below the surface), especially when the lighter (lighter because its less-radiated?) stuff underneath the top layer gets mixed in when the rover disturbs it. i remember seeing many different closeups of wheel marks and it had looked as if larger grains had been crushed into a lighter powder and pressed in with the darker soil. perhaps the lightness is due to light wavelength reflectance due to particle size, the surface soil being darker due to the smaller dusts having been blown away. nevertheless, it sure looked dry.

The idea of water being "squeezed-out" of the soil by the weight of the rover seems to suggest that the topsoil is so wet that there should be collections of it in all the pits and undulations in the landscape, after all, it would have to not be bound up so tight in brine that it would stay "stuck between the grains" and not flow under the influence of gravity. somehow, it would seem that such amounts of water would have serious affects on the surface and there should be widespread and obvious evidence of it just about everywhere we look. Wouldnt all this water, if it were so close to the surface and so easily pressed out of the soil, also continually evaporate into the atmosphere? how long could such a scenario be expected to last if there were no acquifer recharge?

On the counterpoint, ok so maybe this water is the source of the clouds over meridiani and maybe its the last escaping gasp of an acquifer that has now dried-out down to a few meters below the surface.

Or maybe im thinking inside the wrong box, but i digress, i really do believe that Mars is host to a quite a signifficant variety of slow metabolizing organisms that are the less-interesting surviving descendants from some much more interesting ones that well find fossil evidence of someday, okay maybe just single-celled, but i do hold out hope), i just hate to see such radical interpretations put forth in such an unconvincing way... :band:

Rxke · 2004-08-04 05:53:03

if it were really wet enough to glop like that, wouldnt the whole crater just slump into a flat blop on its own under the influence of eons of gravity?

Good point. Also we'd see pingo's and other permafrost surface effects if there really was a significant amount of water very near the surface.

Gil Levin is also some kind of hero of mine, or rather: he was... Lately, he seems to be grasping at straws to make his point. His Viking analysis was pretty convincing, but this 'white stuf=water' doesn't make sense... the Mossbauer should be able to disprove this, or am i wrong?

I'm a bit afraid he's starting to make a fool of himself by jumping to conclusions...

rgcarnes · 2004-08-04 07:27:37

atomoid,

Finer particles scatter more because of their fine particle size. They do not reflect more than coarse particles, although in certain cases the effects might seem similar.

RXKE,

The Mossbauer spectrometer only provides information relative to iron atoms and their bonds, nothing more.

Shaun Barrett · 2004-08-04 08:12:25

I tend to agree with Atomoid, at least to some extent.
While I can see Dr. Levin's point of view about the the surface features looking like they might be mud or ice, I've looked long and hard at the pictures too and I can't be sure it's not all just dust! I can imagine very fine, very dry dust, perhaps cloying together under electrostatic influences, appearing and even behaving somewhat like mud.
While the photographic evidence is tantalising, on balance I don't think it's conclusive enough to say categorically that we're looking at mud.
Atomoid's points, while superficially damning for the water argument, don't necessarily rule out mud. Mars may be more hydrologically active than we realise and aquifers may indeed be slowly recharging as outbreaks of water and general evaporation/sublimation occur at the surface to drain them. The amount of evaporation of surface water has been shown by Dr. Levin to be less copious than might be imagined. On Mars, it's as though the stratosphere starts at about 1 metre above the ground. The solar-heated ground warms the air only very near the surface and, although that near-surface air may reach 20 deg.C on a warm day, a metre or so higher, the air may be well below freezing. That cold air at 1 metre altitude is unable to carry significant quantities of water, which means the warmer air below it quickly becomes saturated. This saturated layer can then accept no more water vapour from any liquid water on the surface. Thus evaporation and/or sublimation is slowed dramatically. This effect would probably be most noticeable in craters, where winds would be less likely to disturb the layering of saturated and dry air. In fact, it's quite likely that the near-surface environment on warm days in martian craters could be quite moist and balmy for hours at a time. Bacteria, specially adapted to the diurnal/seasonal cycle, could easily use these relatively clement interludes for metabolism and reproduction, closing down during the frigid nights and local winters.

I'm on record as saying I think Mars is alive and I've seen nothing that dissuades me from that point of view. I agree with Dr. Levin that it's harder to imagine a sterile Mars than a living Mars!
But I don't think these photos are conclusive evidence of mud, however much I wish they were!
We still need an astronaut on the surface to get the evidence we need ... and my bag is packed!!

Rxke · 2004-08-04 10:51:20

The Mossbauer spectrometer only provides information relative to iron atoms and their bonds, nothing more.

Yes, i know, i'm being too stunted with my English again: i should've written:
So it should be possible to point at at an ice-mass, and get 'zero' result, no? abscence of any metal-ions would be significant at that spot, so telling us at least something, or am i wrong?

(later i thought: 'duh, the ice would probably be mixed with iron-salts or sulfates... (FeCl2 &FeSO4))

C M Edwards · 2004-08-04 13:24:58

The Mossbauer spectrometer only provides information relative to iron atoms and their bonds, nothing more.
So it should be possible to point at at an ice-mass, and get 'zero' result, no? abscence of any metal-ions would be significant at that spot, so telling us at least something, or am i wrong?

(later i thought: 'duh, the ice would probably be mixed with iron-salts or sulfates... (FeCl2 &FeSO4))

All essentially correct, but it does depend on the mixture.

The alpha XRF spectrometer on the MER's also cannot detect water, although it can sense most salts. A lot of water gives a weaker signal, which distinguishes it from solid rock.

This lack of ability to detect water directly means that a sample has to be mostly water to be identified as water.

rgcarnes · 2004-08-04 15:20:47

CM Edwards and RXKE,

I see your points about weak signals implying water in both instruments, but find these methods underwelming as a means of positively detecting water.

If NASA found it impossible to admit to the presence of surface moisture in the face of the Viking image showing a transient overnight accumulation of apparent snow, how could they possibly admit that weak signals from instruments not designed to detect water imply the presence of water?

Let's, however, continue to keep a close eye on them. The best to you all!

atomoid · 2004-08-04 21:03:10

No special instruments shoudl be necessary to detect ice...
I'd have to say that if the white sheen were ice, it would be pretty obvious if NASA chose to take a closeup picture of it (wouldnt it tend to crytalize and form a quite different texture than the dust?), and NASA certainly has taken many pictures to investigate the wheel-disturbed areas. But, perhaps these are only look-alike areas, and arent the areas Gil is talking about, and freshly-pressed-out-of-the-soil mars ice may just look like white dust from a couple feet away! but I really doubt that. I choose to be somewhat gullible about the potential for life on mars (at worst, the power of wishful thinking keeps us looking harder!), but about this mud, im just not coerced. Dont get me wrong i hope we find liquid water or at least exposed ice or brine at Mars, and I really do think well see some surface water at Meridiani, but it will probably be in the form of frost as the winter progresses, at least there are the clouds that suggest water vapor closely overhead here.

Rgcarnes,
Is scattering why iron oxide looks red and titanium oxide is white, something like that? maybe im misunderstanding some basics here. But anyway i was suggesting that the whiter stuff is whiter because it is made of finer and lighter powdery particles that tend to blow away leaving meridiani topsoil very dark, even if the lighter and darker materials are made of the same matter, because i didnt see any other way how the stuff below the topsoil should tend to be whiter than the stuff on top (unless it has to do with solar radiation) other than the lighter particles blowing away (like desert pavement effect), other than if they were truly different compositions and contain frozen-out brine like Levin suggests. Or perhaps dew and frost has modified the soils and concentrated salty minerals into dust-clods by capilary action or other means, now dry, the white powder comes from inside these dust-clods when they are broken up when the rover smashes them. regardless, this aspect is quite mysterious...

Shaun,
thanks for your detailed treatment on the Martian surface temps and humidities, i never know it was that extreme. That seems to suggest those beautiful clouds Opportunity snapped last month are actually very very close to the ground! However, this devils advocate, though not being a meteorologist, would think that if the saturation point is so tight, shouldnt there be lots of fog forming in many places on Mars with the generous supply of nucleating dust in these supersaturated conditions? maybe the "haze" we see in the rover photos not just dry dust, but a thin water vapor fog?

Also, those airbags sure should have picked up a heck of a lot of static electricity bouncing around on dry ground like that, and the "magic carpet" effect (electrostatics?) seemed to only occur under the airbag retraction area. i wonder if anyone knows more about this, NASA must have worked out calculations to safeguard the electronics from this static build up, maybe even measured it in situ?

Rxke · 2004-08-05 00:01:34

I see your points about weak signals implying water in both instruments, but find these methods underwelming as a means of positively detecting water.

Yes, they'd be circumstantial at best. And again: the ice will very probably be 'polluted' with salts or sulfates containing Fe... Making it hard, or rather impossible to say anything conclusive.

rgcarnes · 2004-08-05 08:03:42

Rxke,

You are obviously right in saying that the finer particles of a given substance appear lighter. This is because a larger proportion of the light coming to an observer is due to Fresnel reflections at the interface between the medium the sample is immersed in (air or near vacuum, in this case) and the substances' many surfaces.

If one has electrical engineering tendencies, one can think of this as reflectances due to impedence mismatches at the interfaces between the solid particles and the medium they are immersed in.

Most of the color of a finely divided substance which has optical absorbtion bands is given its characteristic hues by passage through small particles where the absorbed light is reduced exponentially as a function of distance through the substance before emerging, only to be scattered on to the observer from other particles or by being reflected back from the second surface of the same particle. Smaller particles can absorb light less because of the smaller distance the light must travel before emerging. If the substance is a perfect absorber, this could not take place so only the light due to Fresnel reflectances from the surfaces would reach the observer as some shade of grey.

White titanium oxide is white because it has little visible absorption and also because of it's very high index of refraction (large impedance mismatch; large Fresnel reflectances at surfaces). Iron oxide, Fe2O3, is red because of it's significant visible absorbtion bands.

tahanson43206 · 2024-04-09 07:21:53

This topic from 2004 came up when I looked for the word Fresnel.

That search was inspired by Terraformer's report on a "Fresnel"-like method of focusing photons for solar heating.

The topic itself considered the opinions of Dr. Gil Levin, whose experiments on one of the first Mars landers produced inconclusive results.

20 years have gone by I and a lot has happened in the Mars study arena since then. Overhead satellites have produced radar data that seems to indicate significant water reserves far below the surface of Mars, while other observations seem to indicate there may be water near the surface in some locations.

None of the instruments on Mars to date have found evidence of current life, as far as I know, and even past life evidence seems elusive.

It is definitely time for an update on this topic, if someone in the membership has time to investigate.

Gilbert Levin - Wikipedia
en.wikipedia.org › wiki › Gilbert_Levin
Gilbert Victor Levin (April 23, 1924 – July 26, 2021) was an American engineer, the founder of Biospherics and the principal investigator of the Viking mission ...

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#1 2004-08-03 08:05:04

Re: Gilbert Levin

#2 2004-08-04 03:59:18

Re: Gilbert Levin

#3 2004-08-04 05:53:03

Re: Gilbert Levin

#4 2004-08-04 07:27:37

Re: Gilbert Levin

#5 2004-08-04 08:12:25

Re: Gilbert Levin

#6 2004-08-04 10:51:20

Re: Gilbert Levin

#7 2004-08-04 13:24:58

Re: Gilbert Levin

#8 2004-08-04 15:20:47

Re: Gilbert Levin

#9 2004-08-04 21:03:10

Re: Gilbert Levin

#10 2004-08-05 00:01:34

Re: Gilbert Levin

#11 2004-08-05 08:03:42

Re: Gilbert Levin

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