The carbon and nitrogen stable isotope geochemistry of two lunar meteorites: ALHA-81005 and Y-86032

The carbon and nitrogen stable isotope geochemistry of two lunar meteorites, ALHA-81005 and Y-86032 has been compared with that of an Apollo 16 regolith breccia, 60016. Although much of the carbon present in all three samples is terrestrial organic contamination, the meteorites have higher carbon abundances and lighter isotopic compositions than 60016. The non-contaminant carbon in ALHA-81005 and Y-86032 occurs as two distinct components, combusting between 550-700℃ and 900-1100℃. Since these components are absent from the pristine lunar breccia, they must have been added (i) from the impactor which ejected the meteorites from the Moon; (ii) in the Antarctic or (iii) be representative of a lunar environment not sampled by Apollo missions. At temperatures over 1100℃, spallogenic carbon combusts, with elevated δ^C, greater than 0‰. Nitrogen systematics are less-well resolved than carbon, partly due to the lower amounts of nitrogen gas liberated by the meteorites. Nitrogen abundance of ALHA-81005 and Y-86032 fall in the range of values from lunar breccias and δ^N values follow the heavy-light-heavy pattern characteristic of such samples. Spallogenic carbon and nitrogen are more abundant in ALHA-81005 than Y-86032,in keeping with its longer exposure age. Nitrogen data are consistent with identification of ALHA-81005 and Y-86032 as lunar highland breccias compacted from immature regolithic material

Re-Assessment of "Water on the Moon" after LCROSS

The LCROSS Mission has produced information about the possible presence of water in a permanently shaded regions of the Moon. Without the opportunity to have a controlled impact into a sun-lite site on the Moon, the LCROSS information must be carefully evaluated. The Apollo samples have provided a large amount of information on the nature of lunar hydrogen, water and other volatiles and this information must be considered in any interpretation of the observed data from the LCROSS and other lunar missions. Perhaps the volatiles seen by the LRO/LCROSS mission might be identical to lunar volatiles within ordinary lunar equatorial materials. Until the control experiment of having an impactor strike an equatorially site is carried out, caution must be taken when interpreting the results from the LCROSS mission

Volatile Analyzer for Lunar Polar Missions

One of the major questions remaining for the future exploration of the Moon by humans concerns the presence of volatiles on our nearest neighbor in space. Observational studies, and investigations involving returned lunar samples and using robotic spacecraft infer the existence of volatile compounds particularly water [1]. It seems very likely that a volatile component will be concentrated at the poles in circumstances where low-temperatures exist to provide cryogenic traps. However, the full inventory of species, their concentration and their origin and sources are unknown. Of particular importance is whether abundances are sufficient to act as a resource of consumables for future lunar expeditions especially if a long-term base involving humans is to be established. To address some of these issues requires a lander designed specifically for operation at a high-lunar latitude. A vital part of the payload needs to be a volatile analyzer such as the Gas Analysis Package specifically designed for identification quantification of volatile substances and collecting information which will allow the origin of these volatiles to be identified [1]. The equipment included, particularly the gas analyzer, must be capable of operation in the extreme environmental conditions to be encountered. No accurate information yet exists regarding volatile concentration even for sites closer to the lunar equator (because of contamination). In this respect it will be important to understand (and thus limit) contamination of the lunar surface by extraneous material contributed from a variety of sources. The only data for the concentrations of volatiles at the poles comes from orbiting spacecraft and whilst the levels at high latitudes may be greater than at the equator, the volatile analyzer package under consideration will be designed to operate at the highest specifications possible and in a way that does not compromise the data

The distribution of carbon in C1 to C6 carbonaceous chondrites

The carbon content and δ^C of carbon in ten carbonaceous chondrites, spanning petrologic grades 1 to 6,have been determined. There is a gradual change in the nature of the major carbonaceous components from C1 to C6 chondrites : C1 and C2 samples contain carbon as organics, whereas in higher petrologic types, carbon is predominantly amorphous or graphitic. This transition is consistent with carbon in C3 and C4 samples being formed either by dehydrogenation of organic materials during metamorphism on the parent body, or nebular heating followed by accretion at higher temperatures than prevailed during formation of C1-2 meteorites. In addition to a major carbonaceous component, ^C-rich interstellar grains are found in C1 and C2 samples and, to a much lesser extent, CV3 meteorites. CO3 and C4-6 meteorites do not appear to contain ^C-rich materials, a distribution controlled by primary accretion processes and not a result of secondary effects on parent-bodies. However, among the C1 to C3 meteorites aqueous activity might have acted to re-distribute ^C-rich grains by either concentrating them into C1 meteorites, or alternatively by transporting them into the source region of CV3 samples

A feldspar-nepheline achondrite clast in Parnallee

A feldspar-nepheline clast (FELINE) has been identified in Parnallee (LL3.6). Plagioclase is An_, Ab_ and nepheline contains 0.24-3.12wt% Cl. The calculated bulk composition is mildly alkaline, with 3.5wt% Na_2O. Plagioclase has heavy REE depletion and a positive Eu anomaly (Eu/Eu^*=65). Nepheline has lower total REE than plagioclase. On a three isotope plot, the oxygen isotope composition of FELINE falls near the Carbonaceous Chondrites Anyhdrous Minerals Line, beneath the Terrestrial Fractionation Line. This suggests that the parental material had carbonaceous chondrite affinities. It was derived from a melt with moderately enriched LREE and Eu (13.5×CI), which probably underwent an influx of Na-, Cl-rich fluids during crystallisation. This LREE-enrichment suggests that Ca-pyroxene crystallised in the parent body residue during a melt extraction event. REE abundances and the oxygen isotope signature are consistent with an origin as a lost plagiophile melt fraction complementary to the ureilites. FELINE provides further evidence that achondritic fragments with an igneous, exotic origin are an important component of chondritic meteorites

Beagle 2: Seeking the signatures of life on Mars

ESA's Beagle 2 lander will land on Mars to search for signatures of present and past life. A Gas Analysis Package (GAP) with a mass spectrometer, XRF, Mossbauer, stereo cameras, microscope, environmental sensors, rock corer/grinder, and a Mole attachment are on the lander

The CR chondrite clan

The (1) CR chondrites, (2) LEW 85332,(3) Acfer 182,(4) ALH 85085-like chondrites, and (5) Bencubbin-like chondritic breccias are five kinds of chondritic groups which have dramatically different petrographic characteristics, but have mineralogical, bulk chemical, and oxygen and nitrogen isotopic similarities that indicate they are closely related. They are all considered to be members of what we term the CR chondrite clan. Distinguishing characteristics of CR clan chondrites include : (a) reduced, Mg-rich mafic silicates, (b) hydrous matrix and/or dark inclusions (except for Bencubbin-like chondrites), (c) high modal abundances of FeNi metal, (d) FeNi metal having a solar Ni : Co ratio, (e) solar (CI) abundances of refractory and moderately volatile lithophiles, and highly depleted abundances of volatile lithophiles, (f) similar oxygen isotopic compositions of whole rocks, chondrules and matrices, which are on or near the CR mixing line, and (g) anomalously high ^N abundances. CR clan chondrites must have formed in the same local region of the nebula, from closely related reservoirs of materials. The coexistence of anhydrous chondrules with hydrous matrix (and dark inclusions) in the LEW 85332,Acfer 182,and ALH 85085-like chondrites, as well as the widely differing degrees of hydration within and between chondritic samples, implies that hydration of the components was not variable in a single locality, but took place at a variety of locales prior to final lithification of the CR clan chondrites

The Beagle 2 microscope

The Beagle 2 microscope provides optical images of the Martian surface at a resolution 5x higher than any other experiment currently planned. By using a novel illumination system it images in three colors and can also detect fluorescent materials

Reduced Martian Carbon: Evidence from Martian Meteorites

Identification of indigenous reduced carbon species on Mars has been a challenge since the first hypotheses about life on Mars were proposed. Ranging from the early astronomical measurements to analyses of samples from the Martian surface in the form of Martian meteorites. The first direct attempt to analyze the carbon species on the surface was in 1976 with the Viking GC-MS in-situ experiment which gave inconclusive results at two sites on Mars [1]. With the recognition in 1983 that samples of the Martian surface were already present on Earth in the form of Martian meteorites by Bogard and Johnson [2] new opportunities became available for direct study of Mars's samples in te rlraesbtrioalratories. Carbon isotopic compositional information suggested a reduced carbon component was present in the Martian meteorites [3-5]. Polycyclic aromatic hydrocarbons associated with carbonate globules in ALH84001 were later identified [6,7]. Jull et al [8] noted that an insoluble component was present within Nakhla and more than 75% of its C lacked any 14C, which is modern-day carbon contaminant. This carbon fraction was believed to be either indigenous (i..e. Martian) or ancient meteoritic carbon phase. Within the fractures of Nakhla and ALH84001, Fisk et al [9,10] identified reduced carbon-enriched areas. Gibson et al. [11] using a combination of NanoSIMS, Focused Electron microscopy, Laser Raman Spectroscopy and Stepped-Combustion Static Mass Spectrometry analyses the presence of possible indigenous reduced carbon components within the 1.3 Ga old Nakhla