PDA

View Full Version : Levin going a bit too far in his zealotry?



Grizzly
2004-Aug-03, 02:20 PM
I've a lot of respect for Gilbert Levin and his work, but I wonder if he might be pushing things a bit too far with his latest claims about life on Mars.

Space.com article here (http://www.space.com/scienceastronomy/mars_microorganisms_040803.html)

I know, I know, it's hard to restrain oneself when faced with the wealth of data coming back from Mars, but these experiments are not designed to make the determination as to whether what we are seeing is, in fact, water. And it's a leap between water and life...

He's not being heard, except by the woo-woo fringe now.

----
LUKE SUM IPSE PATREM TE
Luke, I am your father.

ToSeek
2004-Aug-03, 02:34 PM
If there were water, couldn't the rovers detect it?

Daffy
2004-Aug-03, 05:26 PM
If there were water, couldn't the rovers detect it?

Only if it were in their vicinity. I don't think anyone is suggesting it is everywhere.

RGClark
2004-Aug-03, 05:49 PM
I've a lot of respect for Gilbert Levin and his work, but I wonder if he might be pushing things a bit too far with his latest claims about life on Mars.

Space.com article here (http://www.space.com/scienceastronomy/mars_microorganisms_040803.html)

I know, I know, it's hard to restrain oneself when faced with the wealth of data coming back from Mars, but these experiments are not designed to make the determination as to whether what we are seeing is, in fact, water. And it's a leap between water and life...

He's not being heard, except by the woo-woo fringe now.

----
LUKE SUM IPSE PATREM TE
Luke, I am your father.

It is no different than what he has always been saying. I don't see why you would say he going to far *now*, as oppposed to before.

This article shows Mars and extremophile expert Penny Boston is taking seriously the idea that life currently exists on Mars:

Posted 8/3/2004 4:56 AM
Researchers: Water could mean Mars hills were alive
The Associated Press
"These hills might date back to some of the earliest history on Mars," said Larry Crumpler, a Mars Exploration Rover team member and curator at the New Mexico Museum of Natural History and Science. "It looks like a river channel might have flowed through there. In fact, the case is building that lots of standing water streams, maybe ponds, existed in the planet's history."
"Water is important to Crumpler and fellow scientists because it indicates life might have evolved on the planet.
"If so, it was most likely microscopic. But still, the idea is thrilling, said Penny Boston, a planetary scientist and Mars expert at New Mexico Tech in Socorro.
"Is there a chance that life still exists on Mars? I sure hope so," Boston said.
"With the new evidence of water, she thinks there is about a one-in-three chance that life still exists based on estimates that are part faith and supposition and part science. "If you asked me that 10 years ago, though, I would have said one in 100," she added."
http://www.usatoday.com/tech/news/2004-08-03-mars-hills_x.htm

More on Dr. Boston's research:

Life in the Extremes: An Interview With Dr. Penelope Boston.
http://www.ibiblio.org/astrobiology/index.php?page=interview09



Bob Clark

ToSeek
2004-Aug-03, 06:20 PM
If there were water, couldn't the rovers detect it?

Only if it were in their vicinity. I don't think anyone is suggesting it is everywhere.

Levin seems to be suggesting that the rovers are driving across moist soil. You'd think one of the instruments like the mini-TES could detect water.

Demigrog
2004-Aug-03, 08:24 PM
If there were water, couldn't the rovers detect it?

Only if it were in their vicinity. I don't think anyone is suggesting it is everywhere.

Levin seems to be suggesting that the rovers are driving across moist soil. You'd think one of the instruments like the mini-TES could detect water.

Not to mention that if there was anything approaching surface water or frost, you'd better believe NASA would be holding a press conference (especially with their budget under review as we speak). I'd say NASA was holding back until they were 100% sure, but Levin was making these claims months ago.

Grizzly
2004-Aug-03, 09:35 PM
See... I don't think that they can discern that. I thought that the question had been raised earlier in Opportunity's mission when the white substance was dredged up by one of the trenching exercises.

IIRC the trenches were Mossbauered (is that even a word?) and mini-tessed and signatures of salts were discovered. The question was raised as to whether it was brine or not and the response was (I thought) that there was no way of telling with the equipment.

Perhpas I'm wrong in that.

True, the pictures do raise some interesting questions - frost from mositure released by the digging, RATting and pressure. But to make the conjecture that there's water that close is unsupported and perhaps unsupportable by the scientific equipment on board. Or am I wrong?

For the record, I'm inclined to believe that Levin's experiments may have discovered life. But until we have a probe on site with sophisticated enough experiments, I'm going to have to be a doubting Thomas.

----
Me dilectissima! Farrago thunni!
My favourite! Tuna-noodle casserole!

Alpha_Tauri
2005-Mar-08, 12:25 PM
IIRC the trenches were Mossbauered (is that even a word?) and mini-tessed and signatures of salts were discovered. The question was raised as to whether it was brine or not and the response was (I thought) that there was no way of telling with the equipment.


The Mini TES is fully capable of detecting frost or any free water or brine on the surface of Mars. Free water would appear on the TES spectra as a peak at 1640cm-1. The paper by Gilbert Levin is so badly flawed that it would be laughable if it were not so sad. The sad part is that some of the general public are taking it seriously.

It totally misses the point that water is unstable on the Martian surface. The following peer reviewed paper discusses the question of the stability of water on a much more rigorous basis:

http://www.agu.org/pubs/pip/2004JE002367.pdf

"While the total surface pressure on Mars is near 610kPa, the triple point vapor pressure is defined in terms of the water vapor partial pressure and thus contraray to popular perception, liquid water is far from stable on Mars) in fact, it is incorrect to state that the Martian environment is close to the triple point for water - It is not)."

It then goes on to explain how ephemeral transient monofilms of water may be possible under very special conditions on the Martian surface, for example under a protective ice sheet capable of trapping vapour and allowing the pressure to build.

All of these cases are transient, and depend on recharge of water.

Grizzly
2005-Mar-08, 02:38 PM
7 months is a looong time. I wondered who'd taken my user name.

----
Nunc dimittis
Let thy servant depart in peace...

ToSeek
2005-Mar-08, 03:16 PM
IIRC the trenches were Mossbauered (is that even a word?) and mini-tessed and signatures of salts were discovered. The question was raised as to whether it was brine or not and the response was (I thought) that there was no way of telling with the equipment.


The Mini TES is fully capable of detecting frost or any free water or brine on the surface of Mars. Free water would appear on the TES spectra as a peak at 1640cm-1. The paper by Gilbert Levin is so badly flawed that it would be laughable if it were not so sad. The sad part is that some of the general public are taking it seriously.

It totally misses the point that water is unstable on the Martian surface. The following peer reviewed paper discusses the question of the stability of water on a much more rigorous basis:

http://www.agu.org/pubs/pip/2004JE002367.pdf



The paper seems to be talking about pure water (correct me if I'm wrong), but what about brine?

RGClark
2005-Mar-08, 04:16 PM
If there were water, couldn't the rovers detect it?

Only if it were in their vicinity. I don't think anyone is suggesting it is everywhere.

Levin seems to be suggesting that the rovers are driving across moist soil. You'd think one of the instruments like the mini-TES could detect water.

Not to mention that if there was anything approaching surface water or frost, you'd better believe NASA would be holding a press conference (especially with their budget under review as we speak). I'd say NASA was holding back until they were 100% sure, but Levin was making these claims months ago.

Now Opportunity HAS detected surface frost at least on the landers.

Next question?


Bob Clark

RGClark
2005-Mar-08, 04:55 PM
IIRC the trenches were Mossbauered (is that even a word?) and mini-tessed and signatures of salts were discovered. The question was raised as to whether it was brine or not and the response was (I thought) that there was no way of telling with the equipment.


The Mini TES is fully capable of detecting frost or any free water or brine on the surface of Mars. Free water would appear on the TES spectra as a peak at 1640cm-1. The paper by Gilbert Levin is so badly flawed that it would be laughable if it were not so sad. The sad part is that some of the general public are taking it seriously.

It totally misses the point that water is unstable on the Martian surface. The following peer reviewed paper discusses the question of the stability of water on a much more rigorous basis:

http://www.agu.org/pubs/pip/2004JE002367.pdf

"While the total surface pressure on Mars is near 610kPa, the triple point vapor pressure is defined in terms of the water vapor partial pressure and thus contraray to popular perception, liquid water is far from stable on Mars) in fact, it is incorrect to state that the Martian environment is close to the triple point for water - It is not)."

It then goes on to explain how ephemeral transient monofilms of water may be possible under very special conditions on the Martian surface, for example under a protective ice sheet capable of trapping vapour and allowing the pressure to build.

All of these cases are transient, and depend on recharge of water.

Levin is aware that liquid water on the surface would eventually evaporate. His point is that microorganisms could survive on liquid water available for only minutes in a day, and then go into a long suspended date during the period when conditions are too cold.
Experiments have shown that liquid water can exist from minutes to hours on the Martian surface:

==============================*=======
Office of University Relations
University of Arkansas


CONTACT:
Derek Sears
Professor, chemistry and biochemistry, Fulbright College;
Director, Arkansas-Oklahoma Center for Space and Planetary Sciences
(479) 575-5204, dse...@uark.edu


Melissa Blouin
Science and research communications manager
(479) 575-5555, blo...@uark.edu


EMBARGOED FOR RELEASE AT 2 P.M. WEDNESDAY, SEPTEMBER 3, 2003


SURFACE WATER POSSIBLE UNDER MARS-LIKE CONDITIONS


FAYETTEVILLE, Ark. -- A team of researchers from the University of
Arkansas has measured water evaporation rates under Mars-like
conditions, and their findings favor the presence of surface water on
the planet. Water on the planet's surface makes the existence of past
or present life on Mars a little more likely, according to the group.
Derek Sears, director of the Arkansas-Oklahoma Center for Space and
Planetary Sciences, and his colleagues graduate student Shauntae Moore
and technician Mikhail Kareev reported their initial findings at the
fall 2003 meeting of the Division of Planetary Sciences of the AAS.
The researchers have brought on-line a large planetary environmental
chamber in which temperature, pressure, atmosphere, sunlight and soil
conditions can be reproduced. Sears and his colleagues use the chamber
to investigate the persistence of water under a range of physical
environments and to study its evaporation.
For their first experiments, reported at the DPS meeting, the group
chose to measure one of the most important properties of water on a
planetary surface, the rate at which it evaporates.
"Physicists have long argued that Mars is currently a sterile desert,
completely unsuited to life," Sears said. "This conclusion is based on
their belief that water would evaporate very quickly, as soon as it
appeared on the surface."
The University of Arkansas group examined the effect of Mars'
atmospheric conditions -- temperature and wind -- on the evaporation
rate. The movement of the atmosphere close to the surface is a crucial
factor in the survival of water on Mars. Water evaporates more slowly
when evaporated molecules build up over the water's surface, but wind
sweeps away evaporated molecules, allowing more water molecules to
escape the surface and increasing evaporation rates.
"These findings suggest that even under worst case scenarios, where
wind is maximizing evaporation, evaporation rates on Mars are quite
low," Sears said. This implies that surface water could indeed exist,
or have existed recently, under the given conditions on Mars.
In addition to the evaporation experiments, the group examines the
ways in which water-ice behaves when frozen at depth and how it reacts
when covered with layers of frost or dust. They also explore how ice
behaves when exposed on the surface, and whether it can exist in a
transient liquid phase that could harbor life.
The subtle balance between the input of heat from the Sun and
subsurface sources and the strength of the surface atmospheric motions
determines the fate of the water; whether it remains as ice, becomes
liquid, and if so how long it remains as a liquid, or how quickly it
evaporates.
"The environmental chamber will enable us to gain new insights into
the behavior of water on Mars and reduce much of the speculation on
this topic," said Barney Farmer, principal investigator for the
atmospheric water vapor mapping experiment during the Viking missions
and a member of the Arkansas research group.


EDITORS NOTE: Dr. Sears will be at the Doubletree Monterey during the
meeting. The number there is (831) 649-4511.
==============================*=======


Here is an abstract to this month's LPSC discussing this:


STABILITY OF WATER AND GULLY FORMATION ON MARS.
Derek Sears1,2, Larry Roe1,3, and Shauntae Moore1,2.
1W. M. Keck Laboratory for Space Simulation, Arkansas Center for Space and Planetary Sciences, University of Arkansas, Fayetteville, AR 72701, 2Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701,
3Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR 72701.
Lunar and Planetary Science XXXVI (2005) 1496.pdf
"We measured evaporation rates at 7 mb under
conditions much closer to martian than previous
work and eight determinations yielded a value of
1.04 0.14 mm/h [7]."
http://www.lpi.usra.edu/meetings/lpsc2005/pdf/1496.pdf


Bob Clark

Alpha_Tauri
2005-Mar-08, 07:17 PM
The paper seems to be talking about pure water (correct me if I'm wrong), but what about brine?

Read it in more detail. Brines are also discussed.

Alpha_Tauri
2005-Mar-08, 07:52 PM
Levin is aware that liquid water on the surface would eventually evaporate. His point is that microorganisms could survive on liquid water available for only minutes in a day, and then go into a long suspended date during the period when conditions are too cold.


I have no problem with the fact that ephemeral liquid water can theoretically exist on Mars for extremely brief periods. That was also the conclusion of the paper I cited. Levin jumps one stage further and claims that not only is water possible, but that it can be proven to exist from the Pancam data. Let's stick to my original assertion that the paper is seriously flawed without bringing in other papers.

In particular, I am referring to this paper:

http://mars.spherix.com/5555-14.PDF

Specifically it is using nonsensical data to 'prove' that we are seeing mud in some of the images from the Meridiani landing site.

His sole argument is that the Absorption coefficient of water increases with increasing wavelength over the range of the Pancams.

"Figure 8b taken at 753nm shows darker darks than Figure 8a taken at 535nm............but the increasing darkness indicating water, is obvious:"

The source of the data is from raw images taken from the NASA site. Not only is this uncorrected for exposure, but the assertion is made that because it gets darker with increasing wavelength, it is 'obviously water'.

As has been pointed out elsewhere, there are a number of substances commonly found on Mars that exhibit a similar spectrum over this range.

That is by no means the only flaw in the paper, but let's concentrate on that one for now.

"Levin is aware that liquid water on the surface would eventually evaporate. "

I'm not sure exactly what Levin is aware of, but Bob, how can you honestly defend such a flawed paper? I'm sure that the reputable researchers that you cited would not thank you for the association.

Alpha_Tauri
2005-Mar-08, 08:05 PM
Now Opportunity HAS detected surface frost at least on the landers.

Next question?
Bob Clark

I agree that surface frost has been detected on the solar panel of Opportunity, and there is a chance that it could have been present on the surface. However, how do you get from short lived frost deposits which subliminate during the earliest part of a mid-winter's Sol, to mud ?

That frost would have been detectable using the Mini TES instrument if it were activated during this period, however that instrument is not normally used until later in the Sol.

Free water in the form of mud or brine would be detectable using the Mini TES. If this had been detected, NASA would have been the first to announce it, just as they announced the frost on the panels.

RGClark
2005-Mar-09, 07:13 AM
Levin is aware that liquid water on the surface would eventually evaporate. His point is that microorganisms could survive on liquid water available for only minutes in a day, and then go into a long suspended date during the period when conditions are too cold.


I have no problem with the fact that ephemeral liquid water can theoretically exist on Mars for extremely brief periods. That was also the conclusion of the paper I cited. Levin jumps one stage further and claims that not only is water possible, but that it can be proven to exist from the Pancam data. Let's stick to my original assertion that the paper is seriously flawed without bringing in other papers.

In particular, I am referring to this paper:

http://mars.spherix.com/5555-14.PDF

Specifically it is using nonsensical data to 'prove' that we are seeing mud in some of the images from the Meridiani landing site.

His sole argument is that the Absorption coefficient of water increases with increasing wavelength over the range of the Pancams.

"Figure 8b taken at 753nm shows darker darks than Figure 8a taken at 535nm............but the increasing darkness indicating water, is obvious:"

The source of the data is from raw images taken from the NASA site. Not only is this uncorrected for exposure, but the assertion is made that because it gets darker with increasing wavelength, it is 'obviously water'.

As has been pointed out elsewhere, there are a number of substances commonly found on Mars that exhibit a similar spectrum over this range.

That is by no means the only flaw in the paper, but let's concentrate on that one for now.

"Levin is aware that liquid water on the surface would eventually evaporate. "

I'm not sure exactly what Levin is aware of, but Bob, how can you honestly defend such a flawed paper? I'm sure that the reputable researchers that you cited would not thank you for the association.

You were referring to more than just that paper. You were making the blanket contention that liquid water wouldn't exist on Mars. Actual experiments wouldn't support that claim.
I can tell you that in the papers themselves where he discusses his labeled release experiment he specifially mentions that liquid water would be temporary but he says that is all microorganisms would need to survive.
The reputable researchers I cited would have no problem with Levin's contention that liquid water could exist for short times on Mars, since that is what their research shows.
I did a search within the Levin article you mentioned:

Interpretation of new results from Mars with respect to life.
http://mars.spherix.com/5555-14.PDF

and no where does he use the word *prove* in regards to liquid water at the MER landing sites. The only time he uses the word *prove* is in relation to his contention that his experiment on the Viking mission prove life on Mars.
I believe what Levin is saying in regard to liquid water using the PANCAM images is that they are *consistent with* liquid water.


Bob Clark

Alpha_Tauri
2005-Mar-09, 07:27 AM
I believe what Levin is saying in regard to liquid water using the PANCAM images is that they are *consistent with* liquid water.


Bob Clark


...and on the basis on the information presented, he can't even say that in any sort of meaningful way. The data has not even been corrected for exposure for the various filters.

Even looking at the spectrum over this narrow range, it is also consistent with olivine and/or hydrated salts.

"and no where does he use the word *prove* in regards to liquid water at the MER landing sites."

Perhaps not, but to say, "but the increasing darkness indicating water, is obvious" is getting pretty close. It goes much further than saying that it's merely consistent with liquid water.


What I'm saying is that the paper rings alarm bells all over the place. If it is consistent with anything, it is consistent with very little knowledge of scientific principles. And a little knowledge is a dangerous thing.

JonClarke
2005-Mar-09, 09:53 AM
It is quite understandable that Levin, who surely is pushing 80, wants to see his experiment vindicated before he shuffles off this mortal coil. However the facts have not changed since Viking. A both sites, multiple tests of the top 10 cm saw that:

The pyrolic release results gave results consistent with oxidative chemistry and not biology

The gas exchange experiment gave results consistent with the same chemistry and not biology

The labeled release experiment gave results consistent with both biology or the same chemistry as the others.

The gas chromatograph-mass spectrometer showed that simple organics were absent at ppm levels and above, complex organics at ppb levels and above. This is consistent with oxidative chemistry.

Furthermore, the camera showed no sign of motile macroscopic organisms.

The most likely conclusion has to be that the soil at both sites contains no biology but a strong oxidant that actively destroys incoming organic matter including meteorites. Because this material shows global distribution it is likely the same results would be repeated globally.

If there is life on Mars it is most probable in either the subsurface or at rare oases. Nothing has happened since Viking to change this.

Jon

Alpha_Tauri
2005-Mar-09, 10:10 AM
It is quite understandable that Levin, who surely is pushing 80, wants to see his experiment vindicated before he shuffles off this mortal coil.

I have nothing against Levin himself, but I will argue against pseudoscience masquerading as science regardless of who wrote it. The problem is that there are too many people quoting this paper, at least on forums such as this (although virtually nobody in the mainstream takes him seriously) and too few people have had the guts to debunk this nonsense. It needs to be debunked once and for all.


If there is life on Mars it is most probable in either the subsurface or at rare oases. Nothing has happened since Viking to change this.


I agree. If there is life to be found, perhaps some underground refuge that is still heated by vestigial geothermal energy would be the place to look.

JonClarke
2005-Mar-09, 10:32 AM
I think it is fair to say that LR was a great experiment and the original conclusions by Levin were that the results were consistent with life but also other explanations well justified. The problem has been he has become more strident with time and completely ignored the other experiments. In the absence of new data Levin can only publish in non-mainstream journals and on the web. It is quite sad really.

I think we can and should give an old man with considerable achievements some slack. But other people need to be constantly reminded that overal Viking did not discover life and that this conclusion is entirely reasonable. The results of the PR, GX and GCMS experiments must constantly be brought back into people's attention. It is simply not the case that NASA and the astrobiology community has ignored or suppressed Levin, despite what people we both know maintain :wink:

Cheers

Jon

RGClark
2005-Mar-09, 06:25 PM
It is quite understandable that Levin, who surely is pushing 80, wants to see his experiment vindicated before he shuffles off this mortal coil.

I have nothing against Levin himself, but I will argue against pseudoscience masquerading as science regardless of who wrote it. The problem is that there are too many people quoting this paper, at least on forums such as this (although virtually nobody in the mainstream takes him seriously) and too few people have had the guts to debunk this nonsense. It needs to be debunked once and for all.


If there is life on Mars it is most probable in either the subsurface or at rare oases. Nothing has happened since Viking to change this.


I agree. If there is life to be found, perhaps some underground refuge that is still heated by vestigial geothermal energy would be the place to look.

ALOT has changed since Viking! We know there is several percent water/ice within centimeters of the Viking landing sites. We also have experimental evidence that liquid water could persist for minutes to hours on the surface of Mars.
We now know that the Viking GCMS could not have detected the organics contained in millions of microbes per gram. It is simply unjustified to claim there are NO organics on Mars based on this instrument.
There are plans underway and instruments already designed for more sensitive organic detection on Mars.
I don't know why you say no one debunks Levin. Most mainstream Mars scientists disagree with his stance there is active life on Mars and say so when asked.


Bob Clark

RGClark
2005-Mar-09, 06:39 PM
I think it is fair to say that LR was a great experiment and the original conclusions by Levin were that the results were consistent with life but also other explanations well justified. The problem has been he has become more strident with time and completely ignored the other experiments. In the absence of new data Levin can only publish in non-mainstream journals and on the web. It is quite sad really.

I think we can and should give an old man with considerable achievements some slack. But other people need to be constantly reminded that overal Viking did not discover life and that this conclusion is entirely reasonable. The results of the PR, GX and GCMS experiments must constantly be brought back into people's attention. It is simply not the case that NASA and the astrobiology community has ignored or suppressed Levin, despite what people we both know maintain :wink:

Cheers

Jon

There is really nothing sad about it. A scientist is supposed to give the reasons for his point of view, even if it disagrees with the mainstream view. That's how scientific revolutions occur.
EVERYBODY already knows about the Viking life experiments and their accepted explanations. And EVERBODY already knows that the life explanation is decidely outside the mainstream.
You say people need to be reminded of them I don't agree. They already know them. What people should be reminded about is the NEW information that the instrument that was used to conclude no organics on Mars did not have the sensitivity to make that determination conclusively.
You're a scientist. You know scientists are supposed to give the sensitivity levels of their instruments when quoting their results. If WHENEVER any Mars scientist or science reporter ever mentioned Viking GCMS results they ALWAYS said "the Viking instruments showed no organics on Mars except perhaps the equivalent of 1 million microbes per gram", do you think people would continue to say Viking "proved no life on Mars"?



Bob Clark

Alpha_Tauri
2005-Mar-09, 07:06 PM
Bob,

My post was about the claim that there was mud at the Opportunity landing site in the paper by Levin. I think you will agree that the argument used to justify mud in this paper was flawed.

Most mainstream workers ignore Levin for obvious reasons, such as the above. I was simply pointing out the fantastic nature of the argument used, so that I didn't have to continually rebut the reference of this paper on forums such as this.


ALOT has changed since Viking! We know there is several percent water/ice within centimeters of the Viking landing sites. We also have experimental evidence that liquid water could persist for minutes to hours on the surface of Mars.



Do we? The only information that I have seen is from the Hend instrument, and this is incapable of differentiating between water, or hydrogen in hydrated minerals and free water/ ice.

Please tell me more.

A lot has indeed changed since Viking. We also have the experimental evidence that superoxide (O3.) is produced by the action of UV radiation on Martian regolith. This confirms the finding from Viking that there are strong oxidants present on the surface of Mars.

JonClarke
2005-Mar-09, 09:16 PM
Bob

It is one thing to defend your ideas when they are against the mainstream because you think they are right it is another thing to defend them when they have been proved wrong and to keep doing so, ignoring contrary evidence. This is just pride not science. You see it all the time. Sam Carey, Tom Gold, Fed Hoyle etc.

The scientific community generally ignore Levin for good reason. There is no new relevant data, the evidence against widespread life on the surface still stands, and Levin has nothing new to say. More serious is the fact that his supporters ignore all the other data and focus on one experiment, the LR, the results of which Levin AT THE TIME acknowledged was as consistent with chemsitry as biology. The lack of complex molecules at ppb level, the experiments that produce superoxides in mars analogue materials under Mas surface conditions, the absence of surface life inthe most mars like Martian environments on earth like parts of the Atacama, these are facts that Levin's supporters ignore.

Very little of substance has changed since Viking with respect to Mars. All the recent discoveries - subsurface ice, the stability of water calculations, lake and river deposits were all known or suspected before Viking, some, like ground ice, were suspected before Mariner - indeed Arthur Wallace postulated this in the 19th century. We have more evidence for these, thanks to recent missions, that is all. ALH84001 does not contribute anything to the debate because it is inconclusive and came from beneath the surface anyway. The methane may point to subsurface life, but Viking was about surface life, so the recent methane discoveries are irrelevant. Not to mention there are a host on non-biological explanations.

This is why scientists generally don't take Levin seriously. However on the popular fringe it is He who gets the publicity, it is his experiment that is described as part of Viking. The general public who is interested in Mars often isn't even aware that the results were ambigious and the other experiments were negative. This is especially the case for the GCMS, the results of which are fatal for any widespread occurrence of life. Indeed, the evevation of Levin to the patron saint of life on Mars by woo woos and boarderline woo woos like the group against mars sample return is actually harmful to his case, making it easier for other scientists to dismiss what limit merits his arguments might still have.

Saying that Viking found life on mars and that Levin was right is flogging a very dead horse. There may be life on Mars, but the probability that Viking did not find it is very high. We need more data, data on the superoxide chemsitry, data from the subsurface, below the 10 cm or so that Viking was able to dig. It would have been nice if Beagle, Mars 96, and MPL had been a success, they would have shed some data. As it is we will have to wait until Phoenix, MSL and ExoMars.

Jim, with respect to water, there were two instruments that detect hydrogen on MO - HEND and the GRS neutron detector. Both map similar values. While it cannot differentiate between free and bound water, once you start getting water contents above 12% you have to have free ice, as no hydrated minerals have that much water. North and South of 60 degree latitudes both instruments point to water contents in the top metre of above 50%

Best

Jon.

Alpha_Tauri
2005-Mar-09, 11:57 PM
Jim, with respect to water, there were two instruments that detect hydrogen on MO - HEND and the GRS neutron detector. Both map similar values. While it cannot differentiate between free and bound water, once you start getting water contents above 12% you have to have free ice, as no hydrated minerals have that much water. North and South of 60 degree latitudes both instruments point to water contents in the top metre of above 50%

Best

Jon.

Jon,

The last time I checked, Epsomite contains 51% water by weight, and gypsum has 21% water by weight . Both the the GRS and the Russian instrument use epithermal neutrons to detect hydrogen. In the case of the GRS, the gamma rays are a secondary effect caused by neutrons.

I have no argument with the fact that there is surface ice in the near Polar regions, however in the Equatorial regions, it is more likely that the hydrogen comes from hydrated minerals, where such minerals have been positively confirmed by both Spirit and Opportunity.

I also tend to have more credence for surface observation than remote observation in this case. Remote observation has not always been historically reliable, and other explanations can emerge.

Regards,

Jim

RGClark
2005-Mar-10, 01:58 PM
Bob

It is one thing to defend your ideas when they are against the mainstream because you think they are right it is another thing to defend them when they have been proved wrong and to keep doing so, ignoring contrary evidence. This is just pride not science. You see it all the time. Sam Carey, Tom Gold, Fred Hoyle etc.

We're not going to agree on this until another organic detector is sent to Mars that really does have the sensitivity people *believe* the Viking GCMS had.
This is a real sore point for me. And most people don't get (or agree with) how important it is. Because of this, I wrote this little hypothetical scenario:

Scene: Professor R. G. Persnickety is being interviewed about the Viking life results. Dr. Persnickety is well-known for his fastidious attention to detail.

Persnickety: We know that there is no life on Mars because of the Viking life results.

Reporter 1: I thought some of those Viking life experiments gave positive results or at least inconclusive ones.

Persnickety: Yes, some did give responses which according to the prelaunch criteria were considered to be positive. However, the reason we believe these were due to chemistry and not life is because the Viking GCMS didn't get a positive response.

Reporter 2: GCMS? Could you explain what this is?

Persnickety: Yes, it is an instrument that was shown on Earth to be sensitive to the detection of organic compounds. Organic compounds compose all life as we know it. The GCMS didn't detect any organics within its sensitivity level.

Reporter 1: Its sensitivity level?

Persnickety: Yes, of course any instrument has to be calibrated before it is used. Experiments showed it could detect the organics contained in 30 million cells per gram.

Reporter 2: 30 million cells! That sounds like alot. It must be very good!

Reporter 1: Huh?

Persnickety: Yes, actually, as far as sensitivity level is concerned you want this number to be as small as possible. But this really is very good. You see microbes are mostly just water and because microbes are so tiny the organics they contain might be only in the femtograms range, which is quadrillionths of a gram. 30 million cells really is a small amount in weight.

Reporter 1: About that 30 million number, am I understanding you correctly Professor that if a Martian sample only contained say 1 million cells in a gram, the GCMS wouldn't have detected them?

Persnickety: Er, well, yes ....

Reporter 1: That doesn't seem very sensitive to me.

Persnickety: No, that actually is very sensitive because typical fertile Earth soils might contain billions to 10's of billions of cells per gram.

Reporter 1: Fertile Professor?

Persnickety: Yes, the, uh, kinds of soils you might have in your backyard or in arable land.

Reporter 1: Wouldn't a better comparison be to soils that we know have low levels of microbes? Are there cases on Earth with soils with less than a million cells per gram?

Persnickety: Er, yes, there have been some recent samples taken from Antarctica and from Siberia with active life that had the organic content of a few million cells per gram.

Reporter 1: So if the Viking GCMS was used on these samples it would say there is no life there eventhough they did contain active life?

Persnickety: Um, yes ...

Reporter 1: Professor, it seems to me that it's not really justified to say there is no life on Mars if the GCMS instrument would give a false negative reading on known samples on Earth.

Persnickety: Hmmm. To be completely precise, it would be more accurate to say the instruments detected no definitive life within their sensitivity levels, but the possibility of life at this point can not be ruled out.

Reporters 1,2: Thank you very much for your time Professor Persnickety.

Persnickety: Thank You.

algorithms
2005-Mar-10, 03:22 PM
Simply put...Gil Levin did not find life on Mars. That doesn't mean there isn't any life on Mars. It only means that Mr. Levin's labeled release experiment didn't find any.

Of course, we know a lot more today than we did in 1976. But everything we've learned tells us not to expect to find microbial life at surface of Mars, except, perhaps in rare, well-protected micro-environments. The chemistry at the surface is essentially self-sterilizing. The more likely scenario is that we'll find microbial life beneath the surface, if its there at all.

The only folks who take Levin seriously today are the cydonuts who believe that almost every rock found in Pathfinder and Rover images is some kind of creature, piece of hardware or ancient stone artifact.

Levin may be encouraged by what the Rover missions are telling us about the prospects for extant or extinct microbial life on Mars. But he shouldn't delude himself into thinking that he'll get credit for the discovery, if it ever occurs.

ToSeek
2005-Mar-10, 03:38 PM
Simply put...Gil Levin did not find life on Mars. That doesn't mean there isn't any life on Mars. It only means that Mr. Levin's labeled release experiment didn't find any.

That's a rather high-handed statement considering that according to the pre-established criteria it did detect signs of life.


The only folks who take Levin seriously today are the cydonuts who believe that almost every rock found in Pathfinder and Rover images is some kind of creature, piece of hardware or ancient stone artifact.

Ad hominem. Not the sort of claim that is welcome on this board. Argue the facts, don't smear those you disagree with.

RGClark
2005-Mar-10, 03:59 PM
Simply put...Gil Levin did not find life on Mars.

Simply put the issue isn't decided yet.
Most scientists agree on the non-life interpretation, but that doesn't mean they arrived at that conclusion in a logical fashion.


Bob Clark

algorithms
2005-Mar-10, 04:23 PM
RGClark: "Simply put the issue isn't decided yet. Most scientists agree on the non-life interpretation, but that doesn't mean they arrived at that conclusion in a logical fashion."

The issue was decided over twenty five years ago. There are a small minority of folks who think otherwise, who, no matter how hard they try, have failed to convince the scientific community of the veracity of their arguements. To suggest that the vast majority of planetary scientists are "illogical" is "not the sort of claim that is welcome on this board."

ToSeek
2005-Mar-10, 04:57 PM
RGClark: "Simply put the issue isn't decided yet. Most scientists agree on the non-life interpretation, but that doesn't mean they arrived at that conclusion in a logical fashion."

The issue was decided over twenty five years ago. There are a small minority of folks who think otherwise, who, no matter how hard they try, have failed to convince the scientific community of the veracity of their arguements. To suggest that the vast majority of planetary scientists are "illogical" is "not the sort of claim that is welcome on this board."

There are plenty of instances in which consensus of the scientific community has eventually turned out to be wrong. And how many planetary scientists have taken the time to investigate the evidence rather than just accepting the judgment of their peers?

JonClarke
2005-Mar-10, 08:52 PM
There are also many occasions when the consensus view has turned out to be correct. I would say that most scientists I know of interested in Martian astrobiology have very carefully reviewed the original Viking results. All of them, not just one experiment.

Jon

JonClarke
2005-Mar-10, 08:54 PM
Bob

Please justify your statement that the Viking GC-MS did not have the specified detection limits.

Jon

JonClarke
2005-Mar-10, 09:14 PM
The last time I checked, Epsomite contains 51% water by weight, and gypsum has 21% water by weight . Both the the GRS and the Russian instrument use epithermal neutrons to detect hydrogen. In the case of the GRS, the gamma rays are a secondary effect caused by neutrons.

I have no argument with the fact that there is surface ice in the near Polar regions, however in the Equatorial regions, it is more likely that the hydrogen comes from hydrated minerals, where such minerals have been positively confirmed by both Spirit and Opportunity.

I also tend to have more credence for surface observation than remote observation in this case. Remote observation has not always been historically reliable, and other explanations can emerge.



Doh! #-o I was thinking of hydrated silicates. You are of course right. However there are caveats.

1. Sulphate deposits are relatively minor in terms of overal area on Mars and rarely pure. Hydrogen signals i most areas will be developed on basaltic regolith and so levels of >12% are flags for possible ice and about 20% for probable ice.

2. The high (>50%) hydrogen abudances also occur at mid lattitudes, not just the poles.

3. Both types of neutron detector only work to depths of 1 m, A relatively shallow blanket of dust or other surfical materia will thus obscure any subsurface ice.

4. Local low latitude ice may be present at low latitude if deposited of relatively recently. The probable ice deposits on the Tharsis volcanoes and southern Elysium are a interesting example.

5. Totally agree with the priority of ground truth. However, with the exception of Viking 2, none of the successful landers touched down in areas with strong hydrogen signals. Viking 2 did not directly detect ice, however the polygonal troughs seen at the landing site were interpreted at the time to be similar to those found in areas of ice-rich permafrost on earth.

Cheers

Jon

Alpha_Tauri
2005-Mar-10, 11:16 PM
1. Sulphate deposits are relatively minor in terms of overal area on Mars and rarely pure. Hydrogen signals i most areas will be developed on basaltic regolith and so levels of >12% are flags for possible ice and about 20% for probable ice.


Are sulphate deposits relatively minor in distribution? There is evidence that they were present at almost every landing site so far. If it was say Epsomite, it would require a concentration of 23% Epsomite by weight in the surface regolith to give a 12% signal reported as H2O.



2. The high (>50%) hydrogen abudances also occur at mid lattitudes, not just the poles.

I don't doubt what you say, but where is your source for that? It just seems extremely high compared to the figures I've seen. (and I'm a little busy right at the moment to look them up :) )

Of course ice in the elevated volcanic terrain is a special case.

I'll expand on this when I have more time.

RGClark
2005-Mar-11, 12:50 AM
Bob

Please justify your statement that the Viking GC-MS did not have the specified detection limits.

Jon

Here are some links on the topic:

State-of-the-art instruments for detecting extraterrestrial life.
PNAS | January 30, 2001 | vol. 98 | no. 3 | 797-800
"The possible presence of organic compounds on Mars is also uncertain.
Using a pyrolysis procedure, in combination with a gas
chromatograph/mass spectrometer (GCMS), Viking did not detect any
organic compounds above a level of a few parts per billion in near
surface samples at two different landing sites. However, it is now
apparent that the Viking pyrolysis GCMS instruments would not have
detected the presence of millions of bacterial cells in 1 g of soil. In
addition, oxidation reactions involving organic compounds on the
Martian surface would likely produce nonvolatile products that also
would not have been detected by the Viking GCMS."
http://www.pnas.org/cgi/conten*t/full/98/3/797

Fleshing Out Martian Proteins.
Summary (Jun 07, 2004)
"Astrobiology Magazine (AM): The project is founded on the the hypothesis that extraterrestrial life would be based on amino acid polymers, and that the evidence for such biology is remotely accessible by heating dirt. Did the 1977 Mars Viking experiments not have the required sensitivity to make a determination of whether a signal was coming from an organic source?
Richard Mathies (RM): The Viking GCMS experiment did not have sufficient sensitivity to detect even high levels of organic molecules like amino acids, and the release experiments were based on the remote possibility of the presence of bacterial cells that were alive and could grow under the available conditions."
http://www.astrobio.net/news/article1008.html

What are the best ways to look for extinct or
extant life on Mars? Thinking outside the box.
"It was claimed that the GC/MS instrument
did not detect organics above part per billion
(ppb) level.
However, the detection limit for amino acids
is now known to have been in the 10s of ppm
range.
A bacterial cell has a dry weight of 10-13
grams.
Amino acids are the major organic
component of cells.
At ppm level, amino acids from ~107 cells
per gram of Martian soil would not have
been detected!
Thus, Viking did not necessarily rule out the
possibility of Martian biology!"
http://astrobiology.berkeley.edu/PDFs_present/Life_on_Mars.pdf

Mars Organic Detector.
"The Viking GC/MS instruments did not detect any organic compounds in Martian soils above a level of several parts per billion (ppb). But this level of sensitivity is not good enough to totally rule out the possibility of biology. A single bacterial cell weighs in at a mere 10-12 grams! About two thirds of this is water, the remaining third organic compounds of which amino acids are the major component. Recent estimates indicate amino acids present in ~106 bacterial cells per gram of Martian soil would have not been detected by the Viking GC/MS."
http://exobio.ucsd.edu/MOD/mission.htm


Bob Clark

JonClarke
2005-Mar-12, 03:09 AM
Jim

There is sulphate at all the landing sites, but mainly as a fraction of the soil. Only at Merdiani are sulphates a dominant mineral phase. Layered terrains, such as at Meridiani, assuming they are all sulphate dominant, are what 10-20 of the surface? The rest of the areas will contain some sulphate in the top metre seen by neuton spectroscopy, but that is all. Soils at the Viking sites had about 10% Mg-sulphate by weight. This comes back to 5% mineral water.

I checked my numbers, which were based on my memory of preliminary data and they are indeed a bit high for the more recent estimates. There is a nice set of maps based on epithermal neutrons at http://www.lanl.gov/news/photos/mars.shtml . In summary, it is N and S of 60 degrees (approximately) that you get water abundances above ~20% by weight in the top metre. Meridiani shows up as a broad area of about 10%, Gusev at about 8%. Viking 1 & Pathfinder about 3% and Viking 2 6%.

What is interesting is the fact that areas with known geomorphic indicates of very near surface ice, such as Dao Vallis, the Tharis volcanoes, and south of Elysium, don't particularly stand out. It is very regional data.

Cheers

Jon

Alpha_Tauri
2005-Mar-12, 04:04 AM
Meridiani shows up as a broad area of about 10%, Gusev at about 8%. Viking 1 & Pathfinder about 3% and Viking 2 6%.

What is interesting is the fact that areas with known geomorphic indicates of very near surface ice, such as Dao Vallis, the Tharis volcanoes, and south of Elysium, don't particularly stand out. It is very regional data.

Cheers

Jon

Thanks for looking that up. I was (ahem) at work when I posted the last one. That _sort of_ confirms what a number of workers are saying - that the hydrogen anomaly at Meridiani could be accounted for by hydrated evaporites.

- Regards,

Jim

RGClark
2005-Mar-12, 05:55 AM
Here are some links on the topic:

State-of-the-art instruments for detecting extraterrestrial life.
PNAS | January 30, 2001 | vol. 98 | no. 3 | 797-800
"The possible presence of organic compounds on Mars is also uncertain.
Using a pyrolysis procedure, in combination with a gas
chromatograph/mass spectrometer (GCMS), Viking did not detect any
organic compounds above a level of a few parts per billion in near
surface samples at two different landing sites. However, it is now
apparent that the Viking pyrolysis GCMS instruments would not have
detected the presence of millions of bacterial cells in 1 g of soil. In
addition, oxidation reactions involving organic compounds on the
Martian surface would likely produce nonvolatile products that also
would not have been detected by the Viking GCMS."
http://www.pnas.org/cgi/conten*t/full/98/3/797
...

The correct link is:

State-of-the-art instruments for detecting extraterrestrial life.
http://www.pnas.org/cgi/content/full/98/3/797?

Another article by these researchers has been submitted to the Proceedings:

BIOPHYSICS
Development and evaluation of a microdevice for amino acid biomarker detection and analysis on Mars.
PNAS | January 25, 2005 | vol. 102 | no. 4 | 1041-1046
http://www.pnas.org/cgi/content/abstract/102/4/1041?
[abstract only]


Bob Clark

Alpha_Tauri
2005-Mar-18, 05:29 AM
I checked my numbers... Meridiani shows up as a broad area of about 10%, Gusev at about 8%. Viking 1 & Pathfinder about 3% and Viking 2 6%.=

Jon,

Remind me never again to ask a geologist to do the job of a chemist :evil:

I finally had time to check the figures myself. The MgO content at Meridiani is around 10% :

http://www.lpi.usra.edu/meetings/lpsc2004/pdf/2172.pdf

This is equivalent to about 30% as MgSO4 (Although a small proportion of that could be present as Olivine).

So the argument that the hydrogen anomalies at Meridiani and Gusev are more likely to be due to hydrated salts becomes much more valid, especially when you consider that the (Specific) Enthalpy of sublimation for Ice is about 1/3 of the enthalpy of dehydration for Epsomite.

Take it easy, mate.

- Jim

Never lend a geologist money. They consider 1 million years to be a short time.

JonClarke
2005-Mar-20, 07:55 AM
Bob

Apologies for the slow reply. I have been discussing cyclers on another forum and then life intervened.

Thank you for the links. I think they support my position that the Viking landers did not discover any evidence for life on Mars.

For reference, your statement was: "We're not going to agree on this until another organic detector is sent to Mars that really does have the sensitivity people *believe* the Viking GCMS had."

I am not sure what you meant, but this says to me that the GCMS did not have the published sensitivity, generally summarised as ppm for simple compounds and ppb for complex ones. The main source on the Viking GCMS results is Biemann et al. (1977) J geophs. res 82(28 ), 4641-4658. This gives a more detailed break down.

This sensitivity (for complex organics the ability to detect one specific grain out of a sand box a metre on a side) is supported by all the Bada links and references therein - the PNAS paper, the UCSD link, and presentation. The rest is special pleading and in some cases a smoke and mirrors act.

Equating an amount of organic matter cannot be equated to a specified number of organisms is smoke and mirrors. While 1 ppb in a gram of sample may still equate to several thousand micro-organisms, biology does not work that way. At a given level of organic matter in a sample, micro-organisms will only make up a small fraction of that material. these rest will be dispersed dead matter that provides food for the
living. At best, ppb level organic matter equates to at best a few hundred organisms, if they are present at all. Given the fact that they are not at the detected level means that the postulate them is supposition to save another hypothesis, in this case the the LR results are due to biology.

As for special pleading, there are several examples in the Baba pieces and their links. To argue that all the organic matter will somehow break down into forms that cannot be detected is highly improbable and therefore specious. Ppm is still a very low level of organic matter.

Although the argument of the GCMS is generally considered a clincher. Even without the evidence of the GCMS there is good evidence that the behaviour of the other three experiments points to chemistry rather than biology. You can't focus on highly optomistic interpretations of the LR results and a specious dismissal of the GCMS. There are the results of the other experiments as well, the PR and GX experiments all must be considered. In particular the decrease in reactivity over time in the
experiments or with repeat treatment of the same samples points to consumption of an active agent, not biology. Furthermore we know there are a range of reagents that will mimic this behaviour much better than biology, and that these agents are formed in terrestrial conditions similar to mars and in the laboratory under simulated Mars conditions.

But this does not mean we should not look for organic molecules on Mars. If if there is no life, there should be some from meteorites and even from inorganic sythenesis. More sensitive instruments will better refine the rates at which they are created and destroyed. Perhaps there is life there at very low levels. Again more sensitive tests may find it, or ones in favourable locations such as with ephemeral moisture or gas
seeps. All the tests mentioned in the links are worth sending to Mars - more sensitive mass specs, labs on a chip to look for specific compounds - amino acids, nucleic acids, and determine chirality. Equally we need to determine the chemical activity of the Martian surface. But none of this invalidates the fact that the Vikings did not find conclusive or consistent evidence for life. But they have greatly constrained the abundance and extent of any life that might be present. And that is a very important
result.

Jon

RGClark
2005-Mar-20, 04:54 PM
Bob

Apologies for the slow reply. I have been discussing cyclers on another forum and then life intervened.

Thank you for the links. I think they support my position that the Viking landers did not discover any evidence for life on Mars.

For reference, your statement was: "We're not going to agree on this until another organic detector is sent to Mars that really does have the sensitivity people *believe* the Viking GCMS had."

I am not sure what you meant, but this says to me that the GCMS did not have the published sensitivity, generally summarised as ppm for simple compounds and ppb for complex ones. The main source on the Viking GCMS results is Biemann et al. (1977) J geophs. res 82(28 ), 4641-4658. This gives a more detailed break down.

This sensitivity (for complex organics the ability to detect one specific grain out of a sand box a metre on a side) is supported by all the Bada links and references therein - the PNAS paper, the UCSD link, and presentation. The rest is special pleading and in some cases a smoke and mirrors act.

Equating an amount of organic matter cannot be equated to a specified number of organisms is smoke and mirrors. While 1 ppb in a gram of sample may still equate to several thousand micro-organisms, biology does not work that way. At a given level of organic matter in a sample, micro-organisms will only make up a small fraction of that material. these rest will be dispersed dead matter that provides food for the
living. At best, ppb level organic matter equates to at best a few hundred organisms, if they are present at all. Given the fact that they are not at the detected level means that the postulate them is supposition to save another hypothesis, in this case the the LR results are due to biology.

As for special pleading, there are several examples in the Baba pieces and their links. To argue that all the organic matter will somehow break down into forms that cannot be detected is highly improbable and therefore specious. Ppm is still a very low level of organic matter.

Although the argument of the GCMS is generally considered a clincher. Even without the evidence of the GCMS there is good evidence that the behaviour of the other three experiments points to chemistry rather than biology. You can't focus on highly optomistic interpretations of the LR results and a specious dismissal of the GCMS. There are the results of the other experiments as well, the PR and GX experiments all must be considered. In particular the decrease in reactivity over time in the
experiments or with repeat treatment of the same samples points to consumption of an active agent, not biology. Furthermore we know there are a range of reagents that will mimic this behaviour much better than biology, and that these agents are formed in terrestrial conditions similar to mars and in the laboratory under simulated Mars conditions.

But this does not mean we should not look for organic molecules on Mars. If if there is no life, there should be some from meteorites and even from inorganic sythenesis. More sensitive instruments will better refine the rates at which they are created and destroyed. Perhaps there is life there at very low levels. Again more sensitive tests may find it, or ones in favourable locations such as with ephemeral moisture or gas
seeps. All the tests mentioned in the links are worth sending to Mars - more sensitive mass specs, labs on a chip to look for specific compounds - amino acids, nucleic acids, and determine chirality. Equally we need to determine the chemical activity of the Martian surface. But none of this invalidates the fact that the Vikings did not find conclusive or consistent evidence for life. But they have greatly constrained the abundance and extent of any life that might be present. And that is a very important
result.

Jon

Thanks for the response. You did make a good point about the amount in organics in toto will exceed the amount in living organisms. This fact should be kept in mind when discussing the sensitivity levels of the GCMS.
My view is even taking this into account the sensitivity levels of the GCMS were not sufficient to rule out biology. We agree that more sensitive detectors need to be sent.
Until they are, I'll continue to take the decidely minority view that the Viking results do not rule out near surface life on Mars.
BTW, a good book on the Viking life experiments is by Henry Cooper:

The search for life on Mars: evolution of an idea.
Henry S. F. Cooper, Jr.
New York : Holt, Rinehart and Winston, c1980.
http://www.amazon.com/exec/obi*dos/ISBN=0030461669/


Bob Clark

RGClark
2005-Mar-21, 04:30 AM
Thanks for the response. You did make a good point about the amount in organics in toto will exceed the amount in living organisms. This fact should be kept in mind when discussing the sensitivity levels of the GCMS.
My view is even taking this into account the sensitivity levels of the GCMS were not sufficient to rule out biology. We agree that more sensitive detectors need to be sent.
Until they are, I'll continue to take the decidely minority view that the Viking results do not rule out near surface life on Mars.
BTW, a good book on the Viking life experiments is by Henry Cooper:

The search for life on Mars: evolution of an idea.
Henry S. F. Cooper, Jr.
New York : Holt, Rinehart and Winston, c1980.
http://www.amazon.com/exec/obi*dos/ISBN=0030461669/


Bob Clark

At least the book used to be there. Try this link instead:

The search for life on Mars: evolution of an idea.
Henry S. F. Cooper, Jr.
New York : Holt, Rinehart and Winston, c1980.
http://www.amazon.com/exec/obidos/tg/detail/-/0030461669/


Bob Clark

JonClarke
2005-Mar-28, 05:47 AM
Hi Bob

There is certainly a pressing need for more data on surface chemistry. These include inproved GCMS (better than ppb), surface oxidant detectors, lab on a chip technology keyed to nuclei and amino acids, chirality detectors, Raman spectometers, etc., etc., etc. Until then we are rehashing the same old data, despite the occasional new insights on things like degradation of organics into non-labile salts.

I have not read Cooper's book, although I am aware of it and have some of his others (e.g. the Apollo 13, Skylab books). I am also trying to get hold of Harold Horowitz's retrospective "To Utopia and Back: The Search for Life in the Solar System" (1986).

Best

Jon

Don J
2013-Mar-25, 07:39 PM
A lot has indeed changed since Viking. We also have the experimental evidence that superoxide (O3.) is produced by the action of UV radiation on Martian regolith. This confirms the finding from Viking that there are strong oxidants present on the surface of Mars.
Sorry to reactive a 2005 thread....
A lot have indeed changed since 2005 too.
The Rover Opportunity confirmed that the surface of Mars is not highly oxidizing contrary to your above claim.So the speculated theory that the LR positive results were caused by strong oxidants present on the surface of Mars falls apart.
Eta
This is even confirmed by the Curiosity rover.
http://www.cnn.com/2013/03/12/us/nasa-mars-rock


Powder from the drill was a gray-green color, meaning it was not highly oxidized, said David Blake, principal investigator for Curiosity's Chemistry and Mineralogy investigation at NASA's Ames Research Center. That means if there were organic material present there, it could have been preserved.

See page 5 of the PDF paper where Levin is addressing adequately all the points made on this thread.
also on page 13 you can see an image of snow or frost on Mars surface taken by a Viking camera at a landing site.
http://www.gillevin.com/Mars/THE_VIKING_MISSION_AND_LIFE_ON_MARS.pdf

Among the points covered by Levin in the PDF:

Why "Viking GCMS didn't get a positive response." Hint... the sensitivity of the GCMS instrument was eight order of magnitude lower than the LR.That the GCMS even frequently obtained negative results with live soils on Earth.See page 5- 6 and also reference number(12)(13)PDF doc
http://www.gillevin.com/Mars/THE_VIKING_MISSION_AND_LIFE_ON_MARS.pdf
That important "detail" about the in-sensitivity of the GCMS is also well described by RG Clark in post 22 and 26 of this thread .
To resume, the sensitivity of GCMS on Viking was set to detect organic content "in the kinds of soils you might have in your backyard or in arable land."but totally unable to detect organic content "in samples taken from Antarctica and from Siberia with active life that had the organic content of a few million cells per gram."

ASTRO BOY
2013-May-17, 09:47 PM
Sorry to reactive a 2005 thread....



Well I for one am glad that you did!
I wasn't around here in 2005 and as I have mentioned many times, speaking as a non professional layman, I am quite intrigued how a number of professional people all obviously connected with the industry, can be so disagreeable on what has been observed.
It is quite obvious from this vigouress debate that the issue of life on Mars certainly has not been validated one way or the other.
Which in my mind means we are duty bound to keep looking.
It wasn't so long ago we did not have any definitive proof of water on Mars at all.
Phoenix and to a lesser extent the orbital surveyors and other rovers have now validated that question in the affirmative.
It certainly gives me more confidence when debating what is and isn't science, what is and isn't good scientific speculation, and other possible ETL questions in other threads.
Great thread, great debate!