NASA'S Phoenix Mars Lander Checking Soil Properties.
"June 07, 2008 The arm of NASA's Phoenix Mars Lander released a handful of clumpy Martian soil onto a screened opening of a laboratory instrument on the spacecraft Friday, but the instrument did not confirm that any of the sample passed through the screen."
http://phoenix.lpl.arizona.edu/news.php
This confirms an argument I've been making for years now. That the reason the Viking GCMS failed to detect organics in the Martian soil probably was due to low amounts of sample being delivered to the instrument. The key point is the "sample full" detector for the GCMS at BOTH Viking sites failed to give sample full indications. This is curious because there were similar sample full detectors on the biology experiments that did properly show full samples were delivered. I concluded that the sample full detectors for the GCMS were in fact operating correctly and correctly indicated that only below registering amounts of sample were delivered.
I copied below a post to sci.astro were I discuss this argument. The Mars Phoenix scientists have given an explanation in the Phoenix case that it might be the clumpiness of the soil that prevents it from passing through the sieving grid. I considered this as the possible reason also in the Viking case but another possibility I think should be investigated using Mars simulant soil is that the extreme low humidity of Mars creates a great amount of static electricity that causes the soil to stick to the sieving grid.
I've highlighted the most relevant passage in bold.
===========================================
Newsgroups: sci.astro, alt.sci.planetary, rec.arts.sf.science, sci.bio.misc
From: Robert Clark <rgcl>
Date: 2000/02/25
Subject: Odds of Hazard of the Mars Sample Return Mission.
From the MSNBC Space bbs, http://bbs.msnbc.com/bbs/msnbc-
space/index.asp :
************************************************** *****
Subject: Re: Odds of Hazard (was: Re: Disagree with...
From: Robert Clark
Host: isp15a-21.pha.adelphia.net
Date: Thu Feb 24 12:38:47
I think the low odds frequently given for the
likelihood of back contamination of Mars organisms is due
to the assumption that the likelihood of life on the
surface of Mars is virtually nonexistent. There are
reasons to doubt this conclusion. The Antaeus report gave
some plausible scenarios where life could still exist on
Mars despite the results of the Viking missions.
Unfortunately this is no longer available on the
Astrobiology Web site in the Planetary Protection
section,
http://www2.astrobiology.com/astro/protection.html
Another paper discussing possibilities for life on Mars
after Viking is by Thomas and Schimel:
D. J. Thomas and J. P. Schimel, 1991. Mars after the
Viking missions: is life still possible? Icarus,
91:199-206,
http://www.lyon.edu/webdata/users/dt...9-206_1991.pdf
Also discussed in the Antaeus report are some known
situations where organisms taken out of their natural
environment had flourished and out-competed the organisms
already there. Their conclusion essentially was this was
not the usual state of affairs but it was known to occur
on Earth. This was important since I had not seen this
consideration discussed in any detail in any of the other
NASA reports on possible back contamination by Mars
samples. This gave some useful information to address the
claims frequently made that Mars organisms would be
unlikely to thrive outside their natural environment.
It has been also asserted that it is unlikely that Mars
life and Earth life would even be compatible. However,
recent research suggests that Earth and Mars as well as
the other terrestrial planets have been exchanging
material through impact ejecta throughout the life of the
solar system. Experiments suggest that some microbes
would be able to survive the trip through space encased
in the meteorites. Experiments also show that some very
hardy Earth microbes should be able to survive on the
surface of Mars. So it is likely that Earth and Mars have
exchanged some biological material. Since they have
exchanged biological material should we be concerned with
introducing new material? An analogous question to ask is
since they have exchanged biological material should we
be concerned with introducing new material with our
spacecraft we send to Mars? I think most scientists would
say yes. If we arbitrarily introduced new material to
Mars we could not determine the extent of naturally
occurring life we found there at some later time when
extensive, perhaps human, exploration takes place. Also,
over millennia the Earth life transferred there may have
evolved to their new environment to be as well adapted to
Mars as has life that evolved there independently. In the
case of possible life already transferred to Earth from
Mars via meteorites, it is impossible to tell how much
this life has been damaging to the life present in the
area in which it arrived. It may be that over time the
Mars life and Earth life accommodated each other with
some adaptations to each. Arguing that we need not be
concerned with introducing new Mars life since it has
happened before is a little like saying since we have
introduced new life from one region on Earth to another
region without deletious effects, we need not be
concerned with introducing ANY new life from one region
to another, clearly not a legitimate argument.
Now in my opinion there are also other reasons to doubt
the prevailing opinion that the Viking missions detected
no life on Mars. All three life experiments detected life
signs on Mars and two of them the Labeled Release and
Pyrolytic Release experiments also satisfied the
criterion of getting no life signs after sterilization by
heating. The third the Gas Exchange experiment is
frequently said to be incompatible with life since some
gas was still released after heating to 145 degrees C.
However, it is usually not mentioned that the amount of
gas relesed was reduced to 45% after heating and as
discussed again in the Antaeus report as many as 10%
of some organisms will survive heating even to 160
degrees C.
The primary reason for the conclusion of no life on
Mars were the results of the Viking GCMS which could
detect no organics on the surface of Mars. Back in 1976
this might have seemed a reasonable conclusion to accept.
However, I believe it no longer is so. Astronomical
observations show organics to be ubiquitous in the
universe. They've been found on the Moon, comets,
meteorites, asteroids, interstellar clouds,
interplanetary dust grains that fall to Earth (and
presumably other planets), Titan, Pluto and Charon, and
the moons of Jupiter, Ganymede and Callisto. These last
two are important because it shows organics are able to
survive the intense radiation environment in the vicinity
of Jupiter. This has relevance to the situation on Mars
since the UV flux on Mars had been argued to limit the
possibility of organics on the surface. However, a recent
paper by Chris Chyba in Nature has argued that radiation
itself may create organics on the Jovian moon Europa:
Jovian Radiation Could Heat Up Europan Soup
http://www.spacedaily.com/spacecast/news/life-00e.html
It is possible the same mechanism occurs on Mars to
create organics.
Since the prevalence of organics in the universe makes
it quite likely they also occur on Mars, it is my opinion
that an important fact was left out of the papers
describing the results of the Viking GCMS. In the first
report from the GCMS team in Science it is mentioned that
the sample indicator didn't get a full indication for
Viking Lander 1,
"Search for organic and volatile inorganic compounds
in two surface samples from the Chryse Planitia region of
Mars", Science, vol. 194, Oct. 1, 1976, p. 72-76.
This is also discussed in the online history of the
Viking missions:
ON MARS
Exploration of the Red Planet 1958-1978
http://www.hq.nasa.gov/office/pao/Hi...P-4212/on-mars.
html.
In Chapter 11 of ON MARS, in the section "Sampling
the Martian Surface", it states that the Viking 1
GCMS never got the signal that a sample was actually
delivered:
"The first soil samples were acquired on sol 8, 28
July. Four samples were dug, with the first being
deposited into the biology instrument distributor
assembly, the next two into the GCMS processor, and
the fourth into the funnel of the x-ray fluorescence
spectrometer. All the commands were successfully
executed, but there was no positive indication that the
gas chromatograph-mass spectrometer processor
had been properly filled. A second acquisition attempt
still did not provide a "sample level detector `full'
indication". The sampler system, having completed its
programmed sequences in a normal manner, parked the boom
as planned. On Earth, the lander performance specialists
began to analyze the possible causes of the anomaly: (1)
insufficient sample acquired in the collector head
because the same sample collection
site had also been used for the biology sample; (2)
insufficient time allowed for the sample to pass from the
funnel through the sample grinding section and then
through the fine (300-micrometer) sieve into the metering
cavity of the instrument; (3) grinder stirring spring not
contacting the sieve; or (4) sample-level-detector
circuit faulty. Since the "level-full" detector
consisted of a very fine wire stretched across the cavity
to which the sample material was
delivered, it was also possible that it had broken when
the soil was dropped into the funnel."
Ch. 11-5 SCIENCE ON MARS
http://www.hq.nasa.gov/office/pao/Hi...-4212/ch11-5.h
tml
It is therefore puzzling to read in the Journal of
Geophysical Research paper on the GCMS results from
Viking Lander 2 that there was no sample full sensor:
"The are two positions to which any of the ovens
can be moved in any sequence. The load position is
directly under the sampling system, which delivers about
1-2 cm^3 of surface material that after having been
ground is passed through a 0.3 mm sieve. A mechanical
poker pushes the material through a funnel into the oven.
This operation is timed in such a manner that the filling
of the oven is complete with any of the terrestrial test
soils (including finely ground basalt, commonly referred
to as 'lunar nominal'). However, there is no sensor
measuring the final level or completeness of the fulling
operation. Thus one has to assume that the oven is filled
to capacity, i.e., approximately 60 mm^3 of surface
material is being analyzed."
The Search for Organic Substances and Inorganic Volatile
Compounds in the Surface of Mars, Jour. Geophys. Res.,
vol. 82, no. 28, September 30, 1977, p. 4642.
This paper discusses the GCMS results from both Viking
landers. The conclusion I draw from this passage is that
in fact the Viking lander 2 GCMS also never got a sample
full indication. I discussed this via email with two
researchers who worked on the Viking missions and their
view was that since the GCMS did detect water evolved
during heating this was proof that a sample was
delivered. However, one does note the JGR paper admits it
can't be determined the size of this sample. In my
opinion if was indeed the case that the Viking GCMS never
got a sample full indication at either of the Viking
sites for any of the samples drawn by the robot arm, then
this fact should have been mentioned in the papers
describing the GCMS results. This gains even more
significance when you consider that the sample full
indicator for the biology experiments was virtually
identical, yet DID receive sample full indications. One
could argue that it was only coincidence that the sample
full indicators failed at both Viking sites for the GCMS
yet worked for the biology experiments or one could
conclude that in fact the sample full indicators were in
fact giving a correct reading for the GCMS. In that case
one would be led to consider what was the difference
between the sample full indicators for the GCMS and the
biology experiments. It turns out the only difference was
that the GCMS had a much smaller sieving grid than did
the biology experiments because it needed smaller
samples. The examination of the Viking soil led to new
(and unexpected) information on the size of soil
particles, the magnetism of the particles, the
cohesiveness (stickiness) of the particles, and, one
could conclude, the static electricity of the particles
in the dry Martian atmosphere. In my opinion, knowing
that the Viking GCMS never got sample full indications
while the biology experiments did, could have led to
experiments to reproduce the Martian soil using the new
data returned by Viking to see if in such conditions it
was possible that only minute samples would be delivered
to the GCMS.
Given these facts it is my opinion that more likely than
not, the Viking missions did indeed discover life on
Mars. So I would put the probability of life at the
surface at above 50%. I would also put the likelihood
that the hardy Martian organisms could survive in the
Earth environment at above 50%. Following the Antaeus
report the cases where new introduced organisms
out-compete native organisms are rare, but do occur. I
would say the probability of this for Earth organisms is
certainly greater than one in a million. As a guess I
would put it at one in 1,000. So the probability that a
Mars organism introduced could out-compete Earth
organisms in a region might be one in 4,000. Note that
this may only result in a change in the dominant
organisms in an area. It may not be a death of the native
organisms. Nevertheless, this is not a situation we would
like to occur inadvertently.
Bob Clark
===========================================
Reply With Quote
Originally Posted by RGClark
