A BSMRA Critique: Stardust Glycine-13C Contamination BEFORE
(and Probably AFTER) Satellite Launch;
NASA’s Unwillingness
to Admit a STARDUST Procedural Error
How Does One Distinguish Cometary 13C From Earth 13C Without Invoking
Unnecessary (and Unscientific) Assumptions?
http://www.nasa.gov/mission_pages/stardust/main/index.html
NASA Stardust Mission
and Experimental Integrity
http://en.wikipedia.org/wiki/Stardust_mission
Stardust is an American interplanetary mission of the NASA Jet Propulsion Laboratory,
whose primary purpose was to investigate the makeup of the comet Wild 2 and its coma.
It was launched on February 7, 1999 by NASA, travelled nearly 3 billion miles (5·109
km), and returned to Earth on January 15, 2006 to release a sample material capsule.[1] It
is the first sample return mission to collect cosmic dust and return the sample to Earth.
Integrity of the STARDUST Mission…On Earth
http://en.wikipedia.org/wiki/Carbon-13
http://www.biology.duke.edu/bio265/sga/leaf.html
http://stardust.jpl.nasa.gov/news/news115.html
Elsila of NASA:
"We actually analyzed aluminum foil from the sides of tiny chambers that hold the
aerogel in the collection grid," said Elsila. "As gas molecules passed through the aerogel,
some stuck to the foil. We spent two years testing and developing our equipment to make
it accurate and sensitive enough to analyze such incredibly tiny samples."
Earlier, preliminary analysis in the NASA Goddard labs detected glycine in both the foil
(BSMRA: this is contamination since glycine molecules would have been vaporized
on impact with the aluminum wall, which is of course the reason for the
requirement of the aerogel on the STARDUST mission) and a sample of the aerogel.
However, since glycine is used by terrestrial life, at first the team was unable to rule out
contamination from sources on Earth. "It was possible that the glycine we found
originated from handling or manufacture of the Stardust spacecraft itself," said Elsila.
The new research used isotopic analysis of the foil (BSMRA: aluminum) to rule out
(BSMRA: this is an unwarranted assumption since 1.1% of carbon on Earth IS 13C)
thatpossibility…
…A glycine molecule from space will tend to have more of the heavier Carbon 13 atoms
in it than glycine that's from Earth (BSMRA: Incorrect since displacement through the
solar plasma field (solar wind) precludes the possibility of intact glycine. 13C within
the solar wind plasma field would be dissociated into its component forms; not
remaining in glycine form.) That is what the team found. (BSMRA: The NASA
astrobiology team found 13C contamination).
"We discovered that the Stardust-returned glycine has an extraterrestrial (BSMRA:
another NASA assumption) carbon isotope signature, indicating that it originated on the
comet," said Elsila. Elsila is not admitting an otherwise mishandled experiment via
unnecessary contamination of the STARDUST mission, and attempting to turn the
mistake to the benefit NASA; essentially by covering a contamination occurrence of
a multi-million dollar NASA effort.
EARTH RELATIVE ABUNDANCE OF CARBON 13
http://www.biology.duke.edu/bio265/sga/leaf.html
Leaf Level: Carbon 13/Carbon 12 and 1.1% Abundance on Earth
Introduction:
All terrestrial plants alter the ratio of 13C/12C from the atmospheric concentration. These
altered ratios vary among individual plant species; C3, C4, and CAM plants; various plant
tissues; and under various environmental conditions. The changes can be measured either
by calculating the change in outgoing carbon dioxide ratios or by analyzing the actual
plant material and comparing it with an atmospheric standard. According to the equation
below:
 13C= 13C(atmosphere) - 13C(plant) x 1000
1000 + 13C(plant)
A machine called a mass spectrograph will give you the 13C parts per mil ratio
(13C/12C).
As a general introduction into the major terms used to describe isotope effects, following
is a short summary of the three major terms R, and .The isotopic composition of a
substance is commonly expressed as the ratio (R) between two isotopes. In the case of
carbon:
R = 13C/12C
Measuring this directly however is rather difficult because the difference can be minimal.
Instead the ratio of the sample is compared against a standard. For carbon the standard is
a fossil from the Pee Dee geologic formation in South Carolina (PDB), whose R is
0.011238. The standard is then related to the R of the sample in terms of the isotope ratio
().
 = (Rsample/Rstandard - 1) * 1000‰
The unit ‰ denotes per mil, or parts per thousand. Its a little counterintuitive and needs
to be thought through several times at, if Rsample < Rstandard then  is negative.  is often
used when examining fossils to determine ancient climactic conditions, and as the first
line in representing current conditions.
Another way to express isotopic composition by looking at the discrimination () of a
plant to various isotopes either by physical processes, diffusion or more biological i.e.
enzymatic discrimination.
 = Rsource/Rproduct - 1
Converting between  and :
 = (source - product)/(1 + product)
Fractionation of Carbon during Photosynthesis:
The discrimination of a plant between heavy and light isotopes is called fractionation.
There are two main ways a plant discriminates against 13C: by diffusion and by enzymatic
discrimination. Because 13C is a larger atom, it is heavier and diffuses more slowly
through the air. CO2 that contains heavy 13C will not move as often or as rapidly into the
stomata of a plant and will therefore not be used as readily as light fast moving 12C. This
type of diffusion discrimination typically is smaller then enzymatic discrimination at
about +4.4 ‰(Gillion 1998).
Enzymatic discrimination of 13C is mainly a function of the first enzyme to come in
contact with carbon dioxide, in C3 plants, RUBISCO (ribulose-1,5-biphosphate
carboxylase oxygenase) and in C4 and CAM plants, PEPC (phophoenol pyruvate
carboxylase) only later does the CO2 come in contact with RUBISCO. These enzymes are
the initial carbon fixers. RUBISCO takes carbon dioxide from the atmosphere and
attaches it to a short sugar chain with five carbon atoms. RUBISCO then cleaves the
molecule into two three carbon phosphoglycerates. PEPC, which is much more efficient
at carbon dioxide fixation fixes it first as four-carbon oxaloacetate which can be fed into
the Calvin Cycle. Enzymatic discrimination is larger varying from +30 to -6 ‰
depending on the type of plant (Gillion 1998). Below is a diagram of cross section of a C3
plant's stomata to illustrate the two main fractionation effects of CO2. On the left of the
diagram is a useful equation that models the integration of both diffusion and enzymatic
discrimination in C3 plants. Where a is the fractionation due to diffusion and b is the
fractionation due to the combined effects of RUBISCO and PEPC on enzymatic effects.
Using standard values for diffusion discrimination and enzymatic discrimination the
typical plant will have a 13
13
= 4.4‰ + (22.6‰) x ci/ca (Farquhar 1991)
The observed 13C value, however is generally due to various factors that the equation
does not take into account such as diffusion effects inside the cell across the aqueous
spaces to the chloroplasts, respiration affects, boundary effects of the leaf, and fixation of
carbon by enzymes other then RUBISCO. There are various different models of 13C
discrimination which take into account some of these omissions from the standard
formula, but at best the equation is a good approximation of discrimination of 13C.
C4 Discrimination:
C4 represent a minority of plants, and are constructed in such a way that photorespiration
is minimized. Photorespiration occurs because RUBISCO can bind to CO2 as well as
oxygen. When it binds to oxygen the plant must use both energy and already fixed carbon
dioxide to remove it, making photorespiration highly inefficient. C4 plants avoid this
inefficiency by using a different pathway. CO2 first encounters not RUBISCO, but PEP
carboxylase which unlike RUBISCO does not bind to oxygen. It is then converted to the
four carbon intermediate, malate, and transported to special cells called the bundle sheath
cells. In the bundle sheath cells, malate is converted back to CO2 and only then is it fixed
by RUBISCO in the C3 photosynthetic pathway. Because the concentration of carbon
dioxide in bundle sheath cells is made very high, and the concentration of oxygen is low,
photorespiration is minimized. Isotopically this means that the 13C/C12 is also very
different as seem below.
(Ehleringer 1991)
Because these bundle sheath cells are almost totally impermeable to diffusion, extra
terms are added to the initial equation for 13 in C3 plants. b4 is the discrimination of the
enzyme PEPC of 5.7‰, which is much lower than the value for Rubisco, or b3, of 30‰.
f is the fraction of CO2 that leaks out of the bundle sheath cells; this value is typically
near 0.2, very low. Thus, we can also use isotopic discrimination to gain information on
CI/ca and the factors that control it in C4 plants, which are less enriched in 13C than C3
plants. Typical  values for C4 plants are -12 to -15‰.
13
 = a + (b4 - b3f - a)*CI/ca (Farquhar 1991)
Water Use Efficiency:
Stable isotopes can be used to gauge water use efficiency in plants. This is useful for a
number of reasons. As this trait is genetically determined trees can be sampled for their
water use efficiency and bred to increase it (Farceur 1989). Also, long range plant
metabolism and transpiration rates can be determined through this method (Ehleringer
1992). Integrating this information over long time scales can further give insight into
general climactic changes especially those brought about by the industrial revolution and
continuing into the present (Bert 1997).
As noted above the concentration of CO2 inside the leaf (CI) depends on the rate of
photosynthesis and the opening of the stomatal pores, these two terms influence isotopic
discrimination. This is best illustrated by looking at extreme cases. On the one hand if
stomates are completely closed, no carbon dioxide can diffuse into the leaf. Thus all
available CO2 will be used during photosynthesis. Not allowing RUBISCO to
discriminate against 13CO2. The cell ci is closer to zero, thus ci/ca is closer to zero. Thus
the only discrimination value that applies is the diffusional discrimination of 4.4‰,
oRUBISCO discrimination being zero. As atmospheric 13C is typically -8‰, the plant
material with totally closed stomata will have a this hypothetical  of -8 - 4.4 = -12.4‰
(Farquhar 1991).
On the other hand if the stomates are totally open the carbon concentration inside the cell
CI is more like the CO2 concentration of the atmosphere i.e. CI/ca is closer to one. Here
the diffusional discrimination becomes negligible against a background of RUBISCO
fractionation which is much higher. RUBISCO will now bind almost much more often to
the available 12CO2. The plant tissue produced through this process will thus carboy an
isotope signature of approximately 30 (max RUBISCO discrimination) + 8 (atmospheric
concentration) = -38‰. As both of these options are impractical for a typical plant, values
fall in the middle, and by gauging these values one can find how efficient the plant is at
using water.
The relationship between water use efficiency and stable isotopes is found by looking at
that between photosynthesis and transpiration.
Photosynthesis = ca - CI = A(ssimilation) (mol CO2 x m-2 x s-1)
transpiration
1.6v
E(mol H2)O x m-2 x s-1
where v is the water vapor concentration difference outside and inside the leaf, and 1.6 is
the ratio of diffusion coefficients, or rates of diffusivity, of water vapor and CO2
molecules in air.
Transpiration is a result of water from the plant evaporating through the open stomata
without being used in photosynthesis. Approximately 99% of the root water taken up by a
plant eventually leaves through in this way, wasting much water that in dry times could
spell doom for a plant. By looking at the carbon isotope index of plant material a general
outline of how often the stomata are open can be determined.
This information can tell something about the general efficiency of a single plant, or can
tell about the climatic conditions the plant lived in. As stemmata conductance (amount of
time stomates are open to absorb carbon dioxide) varies under different temperature,
humidity, carbon dioxide concentration, and water stress conditions. By looking at the
signature in plant tissues one can gauge the conditions under which the plant lived,
thereby indicating past climactic conditions.
This method has been used to look at recent changes in climate brought about by the
burning of fossil fuels on a massive scale starting during the industrial revolution. As
fossil fuels are the byproducts of organic material they are depleted in 13C with a value of
about -26‰. This continual dilution of the 13C pool can be seen in tree ring analysis. For
example, a recent study assembled and analyzed an array of stable-carbon isotope data
for 23 different sets of trees scattered throughout western North America. For the period
1800 to 1985, over which time the air's CO2 concentration rose by approximately 62
ppm, the intrinsic water use efficiencies of the 23 groups of trees rose from 10 to 25%, or
by a mean of 17.5%, which is equivalent to an increase of approximately 85% per 300
PPM increase in the air's CO2 concentration (Sherwood 2002).