The distribution of asteroids: evidence from Antarctic micrometeorites

The relative abundances of types amongst 550 AMMs are reported. These suggest that C-type asteroids vary from petrologic type 1 to 3.2 and that the majority of S-type asteroids are chondrule-rich

Exploring Mars with Returned Samples

The international Mars Exploration community has been planning to return samples from Mars for many years; the next decade should see the plans becoming a reality. Mars Sample Return (MSR) requires a series of missions, first to collect the samples, then to return them to Earth, whilst preventing the contamination of both Earth and Mars. The first mission in the campaign, Mars 2020, will land at Jezero Crater in early 2021; samples should return to Earth sometime after 2032. The information to be derived from analysis of martian samples in terrestrial laboratories equipped with state-of-the-art instrumentation is more than recompense for the difficulties of the MSR campaign. Results from analyses of returned samples will enable increased understanding of martian geological (and possibly biological) evolution. They will facilitate preparations for human exploration of Mars and by providing a second set of absolute ages for a planetary surface will validate (or otherwise) application of the lunar crater-age scale throughout the Solar System

Microbial D/H fractionation in extraterrestrial materials: application to micrometeorites and Mars

High D/H terrestrial alteration of micrometeorites is described and suggested to be a result of microbial isotopic fractionation by methanogens. Applications to other planetary materials, including martian meteorites, are also considered

Spectroscopy of Stardust from 200nm to 16µM (with a gap in the middle)

UV/Vis and IR spectroscopy are complementary, non-destructive techniques that can be used to identify the presence of a range of organic and inorganic, hydrated and anhydrous minerals within micron-sized grains. We look forward to applying these techniques to the Stardust materials

A study of the morphology, composition and mineral associations of Fe-Ni sulphides in CM carbonaceous chondrites

A study of the compositional and textural variations between Fe-Ni sulphides in a suite of pristine to extensively aqueously altered CM chondrites, using SEM and EMP techniques

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

Alteration of the Nakhlite Lava Pile: was water on the surface, seeping down, or at depth, percolating up? Evidence (such as it is) from carbonates

We present carbon and oxygen isotope data on carbonates in five nakhlites and use the results to interpret the martian weathering processes

Euromet Ureilite Consortium: A preliminary report on carbon and nitrogen geochemistry

The first Euromet expedition to the Frontier Mountain in Antarctica in December 1990 recovered two ureilites, FRO 90036 (34.6g) and FRO 90054 (17.5g). Preliminary classification indicated that the specimens had very different textures and mineral chemistries, and hence were not paired. A third ureilite, Acfer 277 (41.0 g), has also recently been returned from the Sahara. Due to the small sample sizes of the meteorites, and the unusual mineralogy of FRO 90054, a consortium was established to ensure the most effective study of these samples; this abstract reports on the carbon and nitrogen stable isotope geochemistry of two of the three ureilites issued to the consortium

Biologically–induced elemental variations in Antarctic sandstones: a potential test for Martian micro-organisms

Lichen-dominated cryptoendolithic communities from the Dry Valleys of Antarctica have been the subject of much research over recent years owing to their potential as analogues of Martian life forms. Their ability to mobilize iron compounds and organize themselves into distinct coloured biotic zones suggests that they may alter the chemistry of their host rock. By conducting a major, minor and trace element study utilizing inductively coupled plasma atomic emission spectroscopy (ICP-AES) and mass spectrometry (ICP-MS) techniques, we have been investigating the relationship between the microbes and the chemistry of the sandstones. Different layers within a suite of sandstones collected from six localities in the Dry Valleys have been analysed to establish if or how the microbes influence or directly affect the chemical composition of the rocks. Background petrographic studies have shown significant differences in mineralogical maturity between rocks colonized by the communities and those that are not, and the chemistry results have shown significant elemental disparity between colonized and uncolonized rocks. By obtaining accurate percentages of the minerals present in each sample the differences in elemental concentrations could be construed to be caused by the differences in mineralogy between samples. The nature and extent of the concentration differences has led to the conclusion that either the cryptoendolith communities are able to alter their host rock by the solubilization and mobilization of elements that are then subsequently removed or that the organisms are simple opportunists that can only successfully colonize rocks that provide the ideal substrate, being mineralogically mature with ample pore space and less concentrated in the elements tested for