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Lunar minerals and impact glasses, convert the polyatomic beam of solar wind (SW) ions into a flux of small molecules ( e.g. , H 2 , N 2 , H 2 O, CO, CO 2 , CH 4 , C 2 H 4 , C 2 H 6 , HCN, metal carbides and deuterides, etc.). They thus behave as “Solid State Molecular Reactors”. Moreover, ~100–200 μ m size micrometeoroids ( μ Ms) have also been exposed to the SW in the zodiacal cloud, before being captured by the Earth and recovered as Antarctic micrometeorites. They are mostly composed of a PAH-rich hydrous-carbonaceous material, which amplifies their power as molecular reactors. In particular, during the first ~200 Myr of the post-lunar period, about 75% of the μ Ms have been melted and/or volatilized upon atmospheric entry. The release of their volatile species triggered a cosmic volcanism around the mesopause that ruled the formation of the early Earth’s atmosphere and climate. Furthermore, a fraction of the μ Ms that survive unmelted upon atmospheric entry did settle on the proto-oceans floors. Upon further burial in sediments their constituent PAH-rich kerogen was cracked into abiotic oil, which generated giant oil slicks that fed prebiotic chemistry. Many stars, of all ages and types, are embedded into a secondary debris-disk loaded with ion implanted μ Ms. Some of them are expelled to the interstellar medium (ISM) where they behave first as “dormant-invisible” molecular reactors, until they became reactivated by various processes to synthesize interstellar molecules. This short paper only focus on some highlights of this research dealing with the synthesis of important interstellar molecules, including the most abundant ones (H 2 and CO) and H 2 O, HCN and PAHs, all involved in prebiotic chemistry.

We recovered micrometeorites from surface snow layers near the French-Italian station CONCORDIA. The unique weather and isolation conditions of Dome C allowed us to recover micrometeorites that are much better preserved than those extracted from blue ice fields. We have identified a new population of friable fine-grained micrometeorites; the absence of such particles in previous collections can be explained by their destruction by mechanical processes. In contrast to previous collections of micrometeorites, the particles from CONCORDIA Collection are characterized by a high content of Fe-sulfides and an undepleted CI elemental abundance pattern of their fine-grained matrix. These features suggest that micrometeorites from Dome C snow have endured much lower alteration from terrestrial weathering, unlike the micrometeorites recovered from near the margin of the Antarctic ice sheet (Adelie Land). The CONCORDIA particles have well constrained terrestrial ages and, given the low Dome C precipitation rate, the central regions of Antarctica provide a unique opportunity to search for particles from historical meteor showers.

The contribution of the accretion of “juvenile” micrometeorites to the volatile inventory of the Martian atmosphere had to mostly occur during the period of the late heavy bombardment of the inner solar system, prior to about 3.5 Ga ago, when the flux of micrometeorites was much higher than today. To assess this contribution, a micrometeorite accretion formula, developed and validated for the Earth, and based on the variation of lunar cratering rates with time, is extrapolated to Mars. This extrapolation suggests that the history of Martian volatiles was more complex than on the Earth. It is described with a two “shots” scenario involving the two last giant impacts on Mars separated by a time interval of about 500 Ma. The first one was triggered by the last planetary embryo that did merge to Mars thus closing its formation time interval and blowing up its complex pre-impact atmosphere. Thus, a new niche was formed for the accumulation of a dominant micrometeoritic atmosphere during the first 200 Ma of the post-merging period, when the partial pressures of H2O, CO2 and N2 reached about 60, 34 and 0.3 bars, respectively (in water equivalent). This huge amount of water was probably not frozen because an early greenhouse effect was triggered during the simultaneous injection of huge amounts of three strong micrometeoritic greenhouse gases (SO2, H2O and CO2) in the Martian atmosphere. Therefore, early microorganisms could have thrived on early Mars, because micrometeorites likely opened a surprising variety of reaction channels in the prebiotic chemistry of life. But they got likely extinguished a few 100 Ma later, when the last giant impactor, which was probably associated with the spike of bodies that invaded the inner solar system around 4 Ga ago, blew off the earlier massive micrometeoritic atmosphere of Mars and all ingredients of the early greenhouse effect. It thus produced the last “niche” that allowed the accumulation of the thin and sterile present day Martian atmosphere, and threw the Martian regolith and the in falling micrometeorite water and SO2 into a deep freeze.

We have investigated the texture, bulk chemistry, mineralogy, as well as the anhydrous minerals oxygen isotopic composition of 67 small Antarctic micrometeorites (AMMs) collected at Cap Prudhomme, Antarctica, and belonging to the currently poorly studied size fraction 25-50 μm. When compared to larger (50-400 μm) micrometeorites collected at the same site in Antarctica with the same techniques, no significant differences are found between the two populations. We therefore conclude that the population of Cap Prudhomme AMMs is homogeneous over the size range 25-400 μm. In contrast, small AMMs have different textures, mineralogy, and oxygen isotopic compositions than those of stratospheric interplanetary dust particles (IDPs). Because small AMMs (

We launched a program to recover cosmic dust (micrometeorites) from Dome C surface snow near the French-Italian station CONCORDIA. The Dome C snow is uniquely shielded from both morainic debris and aeolian dust within the micrometeorite size range ( ≥ 25 μ m). The average temperature at Dome C ranges from -20°C to -75°C throughout the year. Once trapped in a cold and clean snow, the micrometeorites are expected to stay much better preserved from mechanical constraints and less altered by terrestrial weathering than those of previous collections (mainly from Antarctic blue ice fields). We carried out 2 field expeditions in January 2000 and January 2002 using a new collection technique at Dome C. We successfully recovered micrometeorites from surface snow layers. By contrast with previous collections of micrometeorites, the particles from the CONCORDIA-Collection have suffered very little from terrestrial weathering. They have well constrained terrestrial ages. Their periods of fall overlap the ones of the particles found in the stratospheric interplanetary dust collections (IDPs) made by NASA. Because the precipitation rate is extremely low at Dome C, it is technically possible to exploit large areas (several tens of m 2 year) of annual snow layers formed up to 3 centuries ago, which allows searching for cometary particles from historical meteor showers.

Background/Aims: The ultraviolet (UV) portion of sunlight is involved in the induction and development of skin cancers against which a limited photoprotection may be provided by reduced time of exposure, clothing, and sunscreen applications. The concept of an effective, safe, systemic photoprotection will circumvent many of the shortcomings. The UV-induced oxidative stress is a cause of DNA damage and a few publications have shown, in humans, minimal benefits, if any, of the oral intake of antioxidant complex, contrasting with the large literature showing beneficial effects in vitro or in animal models. Methods: We investigated, in 25 healthy individuals, the capacity of an antioxidant complex (AOC) – vitamins (lycopene, β-carotene, α-tocopherol), selenium – to reduce UV-induced damages. The AOC was administered orally, daily during 7 weeks. Before and after irradiations, before and after the intake of the product, six parameters were studied: skin color by chromametry, minimal erythemal dose and, on skin biopsies, sunburn cells (SBCs), p53 detected by immunohistochemistry, pigmentation index, and levels of lipoperoxides (thiobarbituric acid reaction). Results: After the oral intake of AOC, we observed an elevation of the actinic erythema threshold (+20%, P=0.01) and a general reduction of the UV-induced erythemas, a reduction of the UV-induced p53 expression (P

Autonomous navigation of a rover on Mars surface can improve very significantly the daily traverse, particularly when driving away from the lander, into unknown areas. The autonomous navigation process developed at CNES is based on stereo cameras perception, used to build a model of the environment and generate trajectories. Multiple perception merging with propagation of the locomotion and localization errors have been implemented. The algorithms developed for Mars exploration programs, the vision hardware, the validation tools, experimental platforms and results of evaluation are presented. Portability and the evaluation of computing resources for implementation on a Mars rover are also addressed. The results show that the implementation of autonomy requires only a very small amount of energy and computing time and that the rover capabilities are fully used, allowing a much longer daily traverse than what is enabled by purely ground-planned strategies.

— Depending on their velocity, entry angle and mass, micrometeorites suffer different degrees of heating during their deceleration in the Earth's atmosphere, leading, in most cases, to significant textural, mineralogical and chemical modifications. One of these modifications is the formation of a magnetite shell around most micrometeorites, which until now could not be reproduced, neither theoretically nor experimentally. The present study was designed to better understand the entry heating effects on micrometeorites and especially the formation of the magnetite shell. Fragments of the Murchison and Orgueil meteorites were used as analogue material in flash-heating experiments performed in a high-temperature furnace; effects of temperature, heating duration, and oxygen fugacity were investigated. These experiments were able to reproduce most of the micrometeorites textures, from the vesicular fine-grained micrometeorites to the totally melted cosmic spherules. For the first time, the formation of a magnetite shell could be observed on micrometeorite analogues. We suggest that the most plausible mechanism for the formation of this shell is a peripheral partial melting with subsequent magnetite crystallization at the surface of the micrometeorite. Furthermore, with this study, it is possible to estimate the atmospheric entry conditions of micrometeorites, such as the peak temperature and the duration of flash-heating.

— The D/H ratios and water contents were measured by ion microprobe analysis in 52 individual Antarctic micrometeorites (AMMs) and 10 Antarctic cosmic spherules (ACSs) containing nuggets of iron hydroxide (COPS phase). In AMMs, δD values vary from −366 to +249%‰ and water contents lie between 0.4-3.7 wt%. The COPS nuggets in cosmic spherules have high water contents (2 to 8 wt%) and exhibit δD values from −144 to +167%‰, which is indicative of an extraterrestrial origin of their constituent water. The silicate portion of ACSs also contain extraterrestrial H equivalent to ∼0.l to 1.2 wt% water. Deuterium-exchange experiments were performed with isotopically spiked water. These experiments demonstrate that water in mineral phases of AMMs and ACSs is indigenous and does not result from contamination during residence in Antarctic ice. The frequency distribution of D/H ratios in AMMs allows us to further narrow the relationship between AMMs and carbonaceous chondrites to CM and CI chondrites but contrasts with that of stratospheric interplanetary dust particles (IDPs) of similar sizes (from −10 to 50 μm). The relatively narrow range of D/H ratios measured in AMMs as well as in ACSs (which are more resistant and thus less susceptible to collection biases) suggests that D-rich IDP-like particles are very rare in our AMMs collections. This indicates that these D-rich grains might constitute a minor fraction of the micrometeorite flux in the interplanetary medium and that possible collection biases in Antarctica would not be responsible for their strong depletion in the AMMs collections.

Over 100 000 large interplanetary dust particles in the 50-500 micrometers size range have been recovered in clean conditions from approximately 600 tons of Antarctic melt ice water as both unmelted and partially melted/dehydrated micrometeorites and cosmic spherules. Flux measurements in both the Greenland and Antarctica ice sheets indicate that the micrometeorites deliver to the Earth's surface approximately 2000x more extraterrestrial material than brought by meteorites. Mineralogical and chemical studies of Antarctic micrometeorites indicate that they are only related to the relatively rare CM and CR carbonaceous chondrite groups, being mostly chondritic carbonaceous objects composed of highly unequilibrated assemblages of anhydrous and hydrous minerals. However, there are also marked differences between these two families of solar system objects, including higher C/O ratios and a very marked depletion of chondrules in micrometeorite matter; hence, they are "chondrites-without-chondrules." Thus, the parent meteoroids of micrometeorites represent a dominant and new population of solar system objects, probably formed in the outer solar system and delivered to the inner solar system by the most appropriate vehicles, comets. One of the major purposes of this paper is to discuss applications of micrometeorite studies that have been previously presented to exobiologists but deal with the synthesis of prebiotic molecules on the early Earth, and more recently, with the early history of the solar system.

Giant micrometeorites (sizes ranging from ≈>50 to 500 μm), such as those that were first recovered from clean pre-industrial Antarctic ices in December 1987, represent by far the dominant source of extraterrestrial carbonaceous material accreted by the Earth's surface, about 50 000 times the amount delivered by meteorites (sizes ≥ a few cm). They correspond to large interplanetary dust particles that survived unexpectedly well their hypervelocity impact with the Earth's atmosphere, contrary to predictions of theoretical models of such impacts. They are related to relatively rare groups of carbonaceous chondrites (≈2% of the meteorite falls) and not to the most abundant meteorites (ordinary chondrites and differentiated micrometeorites). About 80% of them appear to be highly unequilibrated fine-grained assemblages of mineral grains, where an abundant carbonaceous component is closely associated on a scale of ≤0.1 μm to both hydrous and anhydrous minerals, including potential catalysts. These observations suggest that micrometeorites could have functioned as individual microscopic chemical reactors to contribute to the synthesis of prebiotic molecules on the early Earth, about 4 billions years ago. The recent identification of some of their complex organics (amino acids and polycyclic aromatic hydrocarbons), and the observation that they behave as very efficient ‘cosmochromatographs’, further support this ‘early carbonaceous micrometeorite’ scenario. Future prospects include identifying the host phases (probably ferrihydrite) of their complex organics, evaluating their catalytic activity, and assessing whether synergetic interactions between micrometeorites and favorable zones of the early Earth (such as submarine hydrothermal vents) accelerated and/or modified such synthesis.

Antarctic micrometeorites (AMMs) in the 100-400 microns size range are the dominant mass fraction of extraterrestrial material accreted by the Earth today. A high performance liquid chromatography (HPLC) based technique exploited at the limits of sensitivity has been used to search for the extraterrestrial amino acids alpha-aminoisobutyric acid (AIB) and isovaline in AMMs. Five samples, each containing about 30 to 35 grains, were analyzed. All the samples possess a terrestrial amino acid component, indicated by the excess of the L-enantiomers of common protein amino acids. In only one sample (A91) was AIB found to be present at a level significantly above the background blanks. The concentration of AIB (approximately 280 ppm), and the AIB/isovaline ratio (> or = 10), in this sample are both much higher than in CM chondrites. The apparently large variation in the AIB concentrations of the samples suggests that AIB may be concentrated in rare subset of micrometeorites. Because the AIB/isovaline ratio in sample A91 is much larger than in CM chondrites, the synthesis of amino acids in the micrometeorite parent bodies might have involved a different process requiring an HCN-rich environment, such as that found in comets. If the present day characteristics of the meteorite and micrometeorite fluxes can be extrapolated back in time, then the flux of large carbonaceous micrometeorites could have contributed to the inventory of prebiotic molecules on the early Earth.

Two-step laser desorption/laser ionization mass spectrometry (μL2MS) was used to establish the nature and mass distribution of polycyclic aromatic hydrocarbons (PAHs) in fragments of fifteen ‘giant’ (∼200 μm) carbonaceous Antarctic micrometeorites (AMMs). Detectable concentrations of PAHs were observed in all AMMs showing a fine-grained matrix. The range of integrated PAH signal intensities varied between samples by over two orders of magnitude. No evidence of contamination whilst in the Antarctic environment could be found. The dramatic variation of both PAH signal intensities and mass distributions between AMMs along with comprehensive contamination checks demonstrates that particles are not exposed to terrestrial PAHs at or above detection limits, either subsequent, during or prior to collection. Comparison of the observed PAH distributions with those measured in three carbonaceous chondrites [Orgueil (CI1), Murchison (CM2) and Allende (CV3)] under identical conditions demonstrated that marked differences exist in the trace organic composition of these two sources of extraterrestrial matter. In general, AMMs show a far richer distribution of unalkylated ‘parent’ PAHs with more extended alkylation series (replacement of -H with -(CH2)_-H; n = 1, 2, 3 ...). The degree of alkylation loosely correlates with a metamorphic index that represents the extent of frictional heating incurred during atmospheric entry. A search for possible effects of the chemical composition of the fine-grain matrix of host particles on the observed PAH distributions reveals that high degrees of alkylation are associated with high Na/Si ratios. These results, in addition to other observations by Maurette, indicate that ‘giant’ micrometeorites survive hypervelocity (≥11 km s_1) atmospheric entry unexpectedly well. Because such micrometeorites are believed to represent the dominant mass fraction of extraterrestrial material accreted by the Earth, they may have played a significant role in the prebiotic chemical evolution of the early Earth through the delivery of complex organic matter to the surface of the planet.

Teleoperation will be used for rover control during lunar missions. However the interesting places for scientific investigations are located in difficult areas: the south pole, or deep craters in which communications to the earth will be limited and possibly interrupted. To investigate the feasibility of such missions, a testbed has been built in order to check the feasibility of remote control of the rover in the presence of important time delays with low-rate communications, as well as to demonstrate the capability of autonomous motion during communications blackout periods. The testbed consists of a 6x6 vehicle able to move on a moon-representative terrain, either in an autonomous mode or in low-communication-rate teleoperation called TESA. This paper describes the vehicle, its control and the results obtained during the tests.

The petrology and geochemistry of twentythree chondritic dust particles with masses of 1–47 μg (sizes 100–400 μm) were recovered from blue ice near Cap Prudhomme, Antarctica, and studied by INAA, ASEM, EMPA, and optical microscopy. Sample selection criteria were irregular shape and (for a subsample) black color, with the aim of studying as many unmelted micrometeorites (MMs) as possible. Of thirteen unmelted MMs, six were phyllosilicate-dominated MMs, and seven were coarsegrained crystalline MMs consisting mainly of olivine and pyroxene. The remaining ten particles were largely melted and consisted of a foamy melt with variable amounts of relic phases (scoriaceous MMs). Thus, of the black particles selected, an astonishing portion, 40% (by number), consisted of largely unmelted MMs. Although unmelted, most phyllosilicate MMs have been thermally metamorphosed to a degree that most of the phyllosilicates were destroyed, but not melted. The original preterrestrial mineralogy is occasionally preserved and consists of serpentine-like phyllosilicates with variable amounts of cronstedtite, tochilinite-like oxides, olivine, and pyroxene. The crystalline MMs consist of olivine, low-Ca pyroxene, tochilinite-like oxides, and occasional Ni-poor metal. Relics in scoriaceous MMs consist of the same phases. Mineral compositions and the coexistence of phyllosilicates with anhydrous phases are typical of CM and CR-type carbonaceous chondrites. However, the olivine/pyroxene ratio (~ 1) and the lack of carbonates, sulfates, and of very Fe-poor, refractory element-rich olivines and pyroxenes sets the MMs apart from CM and CR chondrites. The bulk chemistry of the phyllosilicate MMs is similar to that of CM chondrites. However, several elements are either depleted (Ca, Ni, S, less commonly Na, Mg, and Mn) or enriched (K, Fe, As, Br, Rb, Sb, and Au) in MMs as compared to CM chondrites. Similar depletions and enrichments are also found in the scoriaceous MMs. We suggest that the depletions are probably due to terrestrial leaching of sulfates and carbonates from unmelted MMs. The overabundance of some elements may also be due to processes acting during atmospheric passage such as the recondensation of meteoric vapors in the high atmosphere. Most MMs are coated by magnetite of platy or octahedral habit, which is rich in Mg, Al, Si, Mn, and Ni. We interpret the magnetites to be products of recondensation processes in the high (>90 km) atmosphere, which are, therefore, probably the first refractory aerominerals identified.

A new type of meteoritic material, intermediate in size between meteorites and interplanetary dust particles (IDPs), is described. Melting and filtering of about 100 tons of blue ice near Cap Prudhomme, Antarctica, yielded 7500 or more irregular, friable particles and about 1500 melted spherules, about 100 microns in size, both showing a 'chondritic' composition suggestive of an extraterrestrial origin. Analyzed irregular particles appear to be unmelted and have similarities with the fine-grained matrix of primitive carbonaceous chondrites, but are extremely diverse in composition. Isotopic analysis of trapped neon confirms an extraterrestrial origin for 16 of 47 irregular particles and 2 of 19 spherules studied and strongly suggests that they were exposed in space as micrometeoroids. These large Antarctic micrometeorites constitute a new family, or at least a new population, of solar system objects, in a mass range corresponding to the bulk of extraterrestrial material accreted by the earth today.

About 5000 unmelted and well preserved “giant” chondritic micrometeorites with sizes ≈50–200 μ have been extracted from ≈100 tons of antarctica blue ice. They have been unexpectedly well shielded against both terrestrial weathering and frictional heating in the atmosphere. Mineralogical studies indicate that they are all related to primitive “unequilibrated” meteorites (mostly carbonaceous chondrites). About 50% of them are made of friable and porous aggregates of submicron-sized grains, that represent a highly desequilibrated assemblage of minerals, including hydrous silicates and anhydrous clasts, metal oxides and sulfides, and some carbonaceous material related to the broad family of “hydrogenated refractory carbon.” Each carbon-rich micrometeorite might have behaved as a “minicenter” of prebiotic synthesis on the early Earth, through the “in-situ” catalyzed hydrolysis of this carbonaceous material.

Brain death results in various changes in circulation haemostasis, acid-base balance and glycoregulation. This study was carried out between February 1988 and December 1988 in 91 patients with brain death. Age range was between 6 and 58 years. The cause of brain death was brain trauma (71%) and vascular malformations (26%). In all patients a cardio-vascular collapse occurred at the moment of brain death, requiring an intravascular loading (466.3 +/- 240.3 ml.h-1) with crystalloids and albumin. Dopamine was used in 70% of cases at the dose of 3 micrograms.kg.min-1 to improve kidney and splanchnic perfusion. No alterations of acid-base balance were observed in these patients who admitted for organ donation in a short delay (17.1 +/- 6 h). Haemostasis was modified in all patients but the alterations occurred before the brain death and were related to brain injury. Further investigations are required for a better understanding of glycoregulation changes as they could influence pancreatic transplant survival. Hormonal changes have also to be more extensively studied for possible physiopathologic causes of the variations. A better understanding of these alterations will be of benefit for management of patients in brain death and potential organ donors.

The International Rosetta Mission is set for a rendezvous with Comet 67 P/Churyumov-Gerasimenko in 2014. On its 10 year journey to the comet, the spacecraft will also perform a fly-by of the two asteroids Stein and Lutetia in 2008 and 2010, respectively. The mission goal is to study the origin of comets, the relationship between cometary and interstellar material and its implications with regard to the origin of the Solar System. Measurements will be performed that shed light into the development of cometary activity and the processes in the surface layer of the nucleus and the inner coma. The Micro-Imaging Dust Analysis System (MIDAS) instrument is an essential element of Rosetta's scientific payload. It will provide 3D images and statistical parameters of pristine cometary particles in the nm-μm range from Comet 67P/Churyumov-Gerasimenko. According to cometary dust models and experience gained from the Giotto and Vega missions to 1P/Halley, there appears to be an abundance of particles in this size range, which also covers the building blocks of pristine interplanetary dust particles. The dust collector of MIDAS will point at the comet and collect particles drifting outwards from the nucleus surface. MIDAS is based on an Atomic Force Microscope (AFM), a type of scanning microprobe able to image small structures in 3D. AFM images provide morphological and statistical information on the dust population, including texture, shape, size and flux. Although the AFM uses proven laboratory technology, MIDAS is its first such application in space. This paper describes the scientific objectives and background, the technical implementation and the capabilities of MIDAS as they stand after the commissioning of the flight instrument, and the implications for cometary measurements.

In the present study we investigated the influence of two different antioxidant supplements composed of carotenoids, vitamin E and selenium on parameters related to skin health and skin aging. Thirty-nine volunteers with healthy, normal skin of skin type 2 were divided into 3 groups (n = 13) and supplemented for a period of 12 weeks. Group 1 received a mixture of lycopene (3 mg/day), lutein (3 mg/day), beta-carotene (4.8 mg/day), alpha-tocopherol (10 mg/day) and selenium (75 microg/day). Group 2 was supplemented with a mixture of lycopene (6 mg/day), beta-carotene (4.8 mg/day), alpha-tocopherol (10 mg/day) and selenium (75 microg/day). Group 3 was the placebo control. Upon supplementation serum levels of selected carotenoids increased in both verum groups. Skin density and thickness were determined by ultrasound measurements. A significant increase for both parameters was determined in the verum groups. Roughness, scaling, smoothness and wrinkling of the skin were determined by Surface Evaluation of Living Skin (Visioscan). Roughness and scaling were improved by the supplementation with antioxidant micronutrients. In the placebo group no changes were found for any of the parameters.

The ultraviolet (UV) portion of sunlight is involved in the induction and development of skin cancers against which a limited photoprotection may be provided by reduced time of exposure, clothing, and sunscreen applications. The concept of an effective, safe, systemic photoprotection will circumvent many of the shortcomings. The UV-induced oxidative stress is a cause of DNA damage and a few publications have shown, in humans, minimal benefits, if any, of the oral intake of antioxidant complex, contrasting with the large literature showing beneficial effects in vitro or in animal models.We investigated, in 25 healthy individuals, the capacity of an antioxidant complex (AOC) - vitamins (lycopene, beta-carotene, alpha-tocopherol), selenium - to reduce UV-induced damages. The AOC was administered orally, daily during 7 weeks. Before and after irradiations, before and after the intake of the product, six parameters were studied: skin color by chromametry, minimal erythemal dose and, on skin biopsies, sunburn cells (SBCs), p53 detected by immunohistochemistry, pigmentation index, and levels of lipoperoxides (thiobarbituric acid reaction).After the oral intake of AOC, we observed an elevation of the actinic erythema threshold (+20%, P=0.01) and a general reduction of the UV-induced erythemas, a reduction of the UV-induced p53 expression (P0.05) and of SBCs (P0.01), and a parallel reduction of the lipoperoxide levels (P0.01). The pigmentation was increased (P0.01).After the oral intake of an antioxidant complex, many parameters of the epidermal defense against UV-induced damages are significantly improved. The oral intake of AOC could provide a safe, daylong and efficient complement to photo-protective measures provided by topical and physical agents and may contribute to reduce the DNA damages leading to skin aging and skin cancers.

— An inventory of 1991 EUROMET Antarctic micrometeorite (AMM) collection is presented. Fifty grams of sediments were collected by filtration of 260 tonnes of melted ice water. Four sieve fractions were obtained and material from these is available from the EUROMET group. The few hundred milligrams of the 50–100 μm fraction are the most productive ones, in which 10% of the grains are AMMs. Input for planning a 1994 expedition to collect AMMs is also invited.

Large interplanetary dust particles (micrometeorites) with sizes of 100– 200 μm , recovered from the Greenland and Antarctica ice sheets, represent by far the dominant source of primitive extraterrestrial material accreted by the Earth today. Comparisons of mineralogical, chemical and isotopic analyses of micrometeorites and meteorites indicate that micrometeorites are mostly related to the relatively rare group (2% of the meteorite falls) of the primitive hydrous-carbonaceous meteorites, and not to the most abundant classes of the ordinary chondrites and differentiated meteorites. But there are differences between these two classes of extraterrestrial objects, such as a high pyroxene to olivine ratio, a strong depletion in chondrules, a much smaller size of the most refractory components, and a much higher AIB (α-isobutyric amino acid) to isovaline ratio in micrometeorites as compared to meteorites. They indicate that micrometeorites represent a new population of solar system objects, not represented as yet in the meteorite collections. The major objective of this work is to predict various effects of the accretion of early micrometeorites on the Earth during the period of heavy bombardment suffered by the Earth–Moon system ⩾3.9 Ga ago. The application of a simple arithmetics of accretion to a selection of measurements (average contents of neon, carbon, nitrogen and water in micrometeorites, and isotopic composition of their Ne and H), shows that during the peak of this cataclysmic epoch (sterilization period) which occurred just after the formation of the young Earth (4.45 Ga ago), the accretion of early micrometeorites did play a major role in the formation of the terrestrial atmosphere and oceans. Later on, during the early life period (around 4 Ga ago), when liquid water and organics could condense and/or survive, micrometeorites were possibly functioning as tiny chemical reactors to synthesize the prebiotic molecules required for the origin of life. Efforts were made to start reducing the number of major speculations in this “early-micrometeorite-accretion” scenario (EMMAC), which is finally extended with some confidence to Mars, where the survival of micrometeorites upon atmospheric entry looks even more favorable than on the Earth.

Giant micrometeorites (sizes ranging from approximately 50 to 500 micrometers), such as those that were first recovered from clean pre-industrial Antarctic ices in December 1987, represent by far the dominant source of extraterrestrial carbonaceous material accreted by the Earth's surface, about 50,000 times the amount delivered by meteorites (sizesor = a few cm). They correspond to large interplanetary dust particles that survived unexpectedly well their hypervelocity impact with the Earth's atmosphere, contrary to predictions of theoretical models of such impacts. They are related to relatively rare groups of carbonaceous chondrites (approximately 2% of the meteorite falls) and not to the most abundant meteorites (oridinary chondrites and differentiated micrometeorites). About 80% of them appear to be highly unequilibrated fine-grained assemblages of mineral grains, where an abundant carbonaceous component is closely associated on a scale ofor = 0.1 micron to both hydrous and anhydrous minerals, including potential catalysts. These observations suggest that micrometeorites could have functioned as individual microscopic chemical reactors to contribute to the synthesis of prebiotic molecules on the early Earth, about 4 billion years ago. The recent identification of some of their complex organics (amino acids and polycyclic aromatic hydrocarbons), and the observation that they behave as very efficient 'cosmochromatographs', further support this 'early carbonaceous micrometeorite' scenario. Future prospects include identifying the host phases (probably ferrihydrite) of their complex organics, evaluating their catalytic activity, and assessing whether synergetic interactions between micrometeorites and favorable zones of the early Earth (such as submarine hydrothermal vents) accelerated and/or modified such synthesis.

The aim of the study was to evaluate the efficacy of polysaccharides from fish cartilage with regard to their skin aging properties. An application test was carried out during the intake of cartilage tablets as a nutritional supplement. The study was designed as a monocentric, double-blind, randomized, placebo-controlled application test. 28 healthy female volunteers (35–60 years) with dry skin were included in the study. They were divided into two groups. Group 1 received tablets containing placebo and group 2 the verum treatment (cartilage hydrolysate combined with vitamin C). The duration of the study was 12 weeks. The focus of interest was to find out about the hydration properties, and to see whether the skin barrier and structure were influenced by the test formulation compared with placebo. Hydration measurements were made before and during the study, and the transepidermal water loss (barrierer function of the skin) was measured. The thickness and density of the skin of all volunteers were determined by means of ultrasound measurements during the study. Statistical analysis was based on Wilcoxon signed rank test. The following results were obtained in this study: there was a significant improvement in the hydration properties, a significant decrease in transepidermal water loss and a significant increase in the skin density in the verum group (cartilage extract). No or minor improvements could be detected in the placebo group.

Micrometeorites (MMs) represent the most common interplanetary dust particles (50-500 μm). They are similar to carbonaceous chondrites (CCs) but do not match, mineralogically and chemically, known CC types.

Since the Apollo missions, we have emphasized the following points, which are based on theoretical calculations and on laboratory studies of the properties of evaporated silicate deposits and of lunar samples. The mass of vapor generated by impacts on the lunar surface is comparable in magnitude to the mass of impact melt glasses; the physics of impact into a porous regolith requires that much of this vapor be retained in the soil rather than lost to space (as is widely believed); experimental coatings made from vaporized or sputtered lunar basalt contain abundant inclusions of submicroscopic, super paramagnetic metallic Fe; and this Fe may explain the magnetic signature, low albedo, reddened spectrum, and subdued absorption bands of lunar regolith. Our conclusions have been generally rejected by the lunar geochemical community for two reasons: there seemed to be no direct evidence for vapor deposits in Apollo samples, and it seemed that the lunar optical properties could be explained by the presence of impact melt glasses alone. However, advances in our understanding of the optical properties of glasses and of light scattering by planetary regoliths, and now the direct detection of vapor deposits, show that these objections are not valid. Vapor phase transport is a major process on the lunar surface, and unless its effects are taken into account, the chemical, magnetic, and optical properties of the regolith cannot be understood.

Upon melting or sublimating Greenland and Antarctica ice yields a sandy material which is very rich (up to ∼10% by weight in the 50–100 size fraction) in unmelted and partially melted micrometeorites. These polar micrometeorites are remarkably unweathered despite having lost unknown amounts of soluble sulfates and carbonates and having ‘‘accreted’’ some trace elements during their settling time in the Earth’s atmosphere. Although they mainly bear similarities with the rare class of CM and CR chondrites, some of the characteristics of their primary minerals strongly suggests that they are composed of a material not yet represented in meteorite collections. This paper describes improved methods for collecting micrometeorites in Greenland and Antarctica, and ways to study the past variations of the micrometeorite flux over a time scale ≳200,000 years.

"Interplanetary Dust Particles" with sizes approximately 10 micrometers collected in the stratosphere (IDPs), as well as much larger "giant" micrometeorites retrieved from Antarctic ice melt water (AMMs), are mostly composed of unequilibrated assemblages of minerals, thus being related to primitive unequilibrated meteorites. Two independent evaluations of the mass flux of micrometeorites measuring approximately 50 micrometers to approximately 200 micrometers, recovered from either the Greenland or the Antarctic ice sheets have been reported (approximately 20,000 tons/a). A comparison with recent evaluation of the flux of meteorites reaching the Earth's surface (up to masses of 10,000 tons), indicates that micrometeorites represent about 99.5% of the extraterrestrial material falling on the Earth's surface each year. As they show carbon concentrations exceeding that of the most C-rich meteorite (Orgueil), they are the major contributors of extraterrestrial C-rich matter accreting to the Earth today. Moreover they are complex microstructured aggregates of grains. They contain not only a variety of C-rich matter, such as a new "dirty" magnetite phase enriched in P, S, and minor elements, but also a diversity of potential catalysts (hydrous silicates, oxides, sulfides and metal grains of Fe/Ni composition, etc.). They could have individually functioned on the early Earth, as "micro-chondritic-reactors" for the processing of prebiotic organic molecules in liquid water. Future progress requires the challenging development of meaningful laboratory simulation experiments, and a better understanding of the partial reprocessing of micrometeorites in the atmosphere.

The authors report a case of wave burst arrhythmia in a young immigrant woman of Laotian origin aged 32. The main cause of the arrhythmia was related to potassium deficiency of dietary origin. Some contributory factors may have had a promoting effect: theophylline treatment, beta-mimetics and adrenaline (epinephrine). This case can therefore be related to the cases of wave burst arrhythmia and hypokalemia previously reported in anorexic subjects. This case suggests that special attention should be paid to the diet of some ethnic groups who have been displaced by economic causes. Their very unusual dietary habits may induce or aggravate hypokalemia, which may also be promoted in some cases by drugs. Some treatments should therefore be introduced with caution in this context due to the potential risk of inducing severe arrhythmia.

Cosmogenic Be-10 and Al-26 were measured in a suite of stony cosmic spherules derived from deep-sea sediments and the Greenland ice cap. These spherules show clear evidence of exposure to galactic cosmic ray and solar cosmic ray bombardment on time scales from a few times 100,000 years up to as much as 10 to the 7th years. The exposure took place in the inner solar system, not in highly eccentric orbits. When they reached the earth, the particles were not much larger than their present size, but it is not excluded that most of their cosmic ray exposure took place very close to the surface of an asteroidal body.

Brain death results in various changes in circulation haemostasis, acid-base balance and glycoregulation. This study was carried out between February 1988 and December 1988 in 91 patients with brain death. Age range was between 6 and 58 years. The cause of brain death was brain trauma (71%) and vascular malformations (26%). In all patients a cardio-vascular collapse occurred at the moment of brain death, requiring an intravascular loading (466.3 +/- 240.3 ml.h-1) with crystalloids and albumin. Dopamine was used in 70% of cases at the dose of 3 micrograms.kg.min-1 to improve kidney and splanchnic perfusion. No alterations of acid-base balance were observed in these patients who admitted for organ donation in a short delay (17.1 +/- 6 h). Haemostasis was modified in all patients but the alterations occurred before the brain death and were related to brain injury. Further investigations are required for a better understanding of glycoregulation changes as they could influence pancreatic transplant survival. Hormonal changes have also to be more extensively studied for possible physiopathologic causes of the variations. A better understanding of these alterations will be of benefit for management of patients in brain death and potential organ donors.

The work reported here confirms the existence of (largely) unmelted micrometeorites in sediments from seasonal lakes on the Greenland ice sheet. Approximately1/3 of the dark and irregularly shaped particles selected from disaggregated sediments had sufficient contents of Ne to permit measurement of isotopic compositions. The sediments consisted of a mixture of biologically derived contaminants and minor amounts of terrestrial minerals and extraterrestrial fragments. Although terrestrial mineral contamination varied by a factor of 20 for the two different sediments, a yield of ∼ 1000 cosmic particles/kg of wet cryoconite was found for both samples. The isotopic compositions of the Ne in both rounded and irregular (25% of total) particles that contained enough gas to measure were non-terrestrial, plotting in a field defined by solar wind (SW), solar energetic particle (SEP) and spallation. Exposure ages ranged from

Payloads to be handled by space manipulators cannot always be considered as inert bodies represented by mass and inertias. They may feature flexible appendages, liquide sloshing in tanks or kinetic momentum wheels which will make their modelling and control more complex. Modelling is considered in this paper from the point of view of the connection of a dynamic model of a payload to a general purpose multi-body simulation package. Control issues are discussed in the frame of dynamic control, where the overall control loop is split up between an inner force control loop dependent only on the manipulator parameters, and an outer payload control loop which adaptation to large inert and complex payloads is investigated.

About 260 tonnes of ultraclean blue ice were recently melted and filtered on the Antarctic ice sheet (in January 1991, at Cap-Prudhomme, near the french station of Dumont d'Urville) as to collect all grains with sizes > 25 μm. In the best size fraction (50-100μm) about 10% of the grains are unmelted antarctic micrometeorites (AMMs) with a chondritic composition. About 50% of these grains are complex aggregates of submicron-sized grains. Their characterization, which is very difficult, requires a panoply of analytical techniques allowing their analyses at all scales of magnification between 106 μm3 and 10-4 μm3. We review below analyses performed by various groups, and discuss briefly some of their preliminary implications to various fields of Science.The "large" size of the AMMs allows their multidisciplinary investigations. With a binocular we start selecting an aliquot of ≈50 dark grains showing irregular shapes, and which usually contains about 70% AMMs. Each grain is broken into about 4 fragments and their multidisciplinary analysis proceeds as follow: (1) Polished sections. The largest of these fragments are mounted in an epoxy disc and polished.

(1982). On the registration of low energy (E 1 keV/amu) ion tracks in dielectric. Radiation Effects: Vol. 65, No. 1-4, pp. 133-137.

Payloads to be handled by space manipulators cannot always be considered as inert bodies represented by mass and inertias. They may feature flexible appendages, liquide sloshing in tanks or kinetic momentum wheels which will make their modelling and control more complex. Modelling is considered in this paper from the point of view of the connection of a dynamic model of a payload to a general purpose multi-body simulation package. Control issues are discussed in the frame of dynamic control, where the overall control loop is split up between an inner force control loop dependent only on the manipulator parameters, and an outer payload control loop which adaptation to large inert and complex payloads is investigated.

This article also appears in: Proceedings of the Seventeenth Lunar and Planetary Science Conference; International audience; Instrumental neutron activation analysis was used to determine the concentrations of Ir, Fe, Ni, Co, Cr, and Sc in 16 "iron" and 8 "chondritic" magnetic deep sea spherules with sizes of about 200$\mu$m. With the exception of two iron spheres, high iridium concentrations were found in each sphere, thus confirming their extraterrestrial origin. Moreover, the "depth profile" of the residual mass of iridium was monitored in individual spheres by comparing the variations of the intensities of the $\gamma$ ray lines of iridium, cobalt, and iron during a very gradual sequential polishing. Each sharp but partial discontinuity, observed only in the Ir profiles, reflects the intersection of a polished section with a tiny Ir-rich nugget. These profiles show that such nuggets are much more common in both the iron and the chondritic spheres than previously thought. We found new types of disequilibrated clusters of micrometer-sized nuggets of platinum metals. All types of nuggets, which were characterized with a scanning electron microscope and an energy dispersive X ray spectrometer, seem to be associated with magnetite. The compositions of the nuggets, as well as the fractionation patterns for Ir, Fe, Ni, Co, and Sc in the spheres, suggest that most of the Ir-rich iron spheres originate from iron-rich bodies.

To help assess possible water reserves on the moon derived from the solar wind that could supply a lunar base, oligoclase, ilmenite, and simulated lunar glass have been irradiated with a beam of 2.5 keV/amu deuterium ions to simulate solar wind proton bombardment of lunar materials. For ilmenite and simulated lunar glass the areal density of deuterium D(ϕ) (D/cm2) increases with the incident ion fluence ϕ until a critical reemission fluence is reached (ϕ = 3.3–3.5×1017 D/cm2). At this point deuterium begins to be lost from both targets until D(ϕ) reaches a saturation value Ds = 2–4×1017 D/cm2 at ϕ8 = 1–2 × 1018 D/cm2. Oligoclase begins losing deuterium when the beam is turned on; D(ϕ) never reaches a saturation value up to the limit of our experiment (≈ 3×103 D/cm2). There is a small yield of ∼10−4 D2O+/Dincident during the implantation. Thermal release patterns for D2 in our targets do not correspond to those observed for H2 in lunar soils, but the differences may be explainable after further experiments. Although ilmenite stores about twice as much deuterium as the other target materials, it is unknown whether this small enrichment factor will be sufficient to make it a potential source of lunar water.

The paper discusses several discoveries made in the study of lunar material. In the examination of the effects of solar wind implantations the topics covered include (1) solar wind radiation damage parameters and their aging characteristics, (2) the theory of the ancient solar wind, (3) the solar wind sputtering erosion rate, (4) the physicochemical properties of amorphous coatings, (5) maturity indexes and the macroscopic properties of the lunar regolith, (6) solar wind gas bubbles, (7) the composition of very heavy nuclei in the contemporary solar wind, and (8) track aging processes. Conclusions are drawn from the results about other extraterrestrial features such as the parent bodies of the meteorites, early solar nebulas, and interstellar clouds.

When time delay is introduced in a remote manipulation system (RMS) due to long communication links the operator ability to perform complex tasks is decreased. A means to improve the manipulation performances is to compensate for time delay by displaying to the operator a predicted view of the system. The predictive technique is developed for a satellite grasping task that shows the two control problems time delay within the control loop inducing unstability time delay located on the reference input inducing a tracking error. In the first case a prediction algorithm is built using a dynamic model of the manipulator. in the second case the prediction of the reference input requires a model of the target movement that is real time identified. Digital simulations of the RMS where an automatic pilot is substituted to the operator have showed the efficiency of the method if the modelling is accurate enough. Then using a real teleoperator device, experiments have confirmed the previous results and have led to some basic considerations on the need to display the delayed view.

Cosmic dust grains, whatever their origin may be, have probably suffered a complex sequence of events including exposure to high doses of low-energy nuclear particles and cycles of turbulent motions. High-voltage electron microscope observations of micron-sized grains either naturally exposed to space environmental parameters on the lunar surface or artificially subjected to space simulated conditions strongly suggest that such events could drastically modify the mineralogical composition of the grains and considerably ease their aggregation during collisions at low speeds. Furthermore, combined mass spectrometer and ionic analyzer studies show that small carbon compounds can be both synthesized during the implantation of a mixture of low-energy D, C, N ions in various solids and released in space by ion sputtering.

This paper describes the dynamic modeling and fine pointing control system design for the SPOT French Earth observation satellites. The dynamic model of the vehicle includes a representation of the flexible solar array by effective mass technique. An onboard computer processes the attitude rate information provided by a gyro package and, possibly, the measurement of torque around boom axis to provide a very high angular rate accuracy with the help of reaction wheels and solar array drive motor. Several control design techniques are investigated for this multivariable control problem. Performances, including sensitivity to modal data, are checked by extensive simulations. I. Introduction E ARTH observation satellites differ mainly from other satellites (scientific, telecommunications, television) in the strong requirements on attitude rates of the spacecraft during the operational observation mode. A great deal of the control design is then directed by the short term torque disturbances; the dynamic reactions of the payload itself and of the flexible solar array give major contributions. Moreover, this array is mounted dissymmetrically on the spacecraft in order to avoid payload interaction. The control of a satellite with flexible appendages often has been investigated, the concern centering on the stability of the closed-loop control laws; in the Earth observation case, a problem of performance appears, particularly when harmonic disturbances are considered. The solar pointing mechanism of the power generator induces such disturbances and the present paper is devoted to a detailed investigation of these problems and their solutions in the frame of the SPOT French Earth observation project.1

Most insulator materials so far proposed for storing high-level radioactive wastes, such as glass and and the constituent minerals of ceramics are nuclear track detectors. Lead ion implantation experiments show that such materials should be transformed into “giant” nuclear tracks, when the internal fluence of heavy recoils emitted during the α-decay of actinide elements stored in them exceeds a critical value, which corresponds to an equivalent storage period of a few thousand years for the wastes expected from a pressurized water reactor. In contrast, actinide bearing minerals are much more stable against α-recoil damage. As nuclear tracks are extremely chemical reactive, α-recoil damage is expected to shorten the lifetime of storage materials such as glass and ceramics against dissolution in ground waters. Fortunately new nuclear track concepts are already yielding guidelines for predicting and improving the long-term stability of storage materials. The results of the present studies also bear on the physics of ion implantation phenomena an insulator targets exposed to high fluences of low energy ions.

The discussion of fossil nuclear reactors (the Oklo phenomenon) covers the earth science background, neutron-induced isotopes and reactor operating conditions, radiation-damage studies, and reactor modeling. In conclusion possible future studies are suggested and the significance of the data obtained in past studies is summarized. (JSR)