Deflecting APOPHIS with a flotilla of solar shields

The possibility to use the photonic pressure from the Sun for acting upon the orbit of a man-made object is well known.     

First astrometric observations of space debris with the MéO telescope

The MéO (for Métrologie Optique) telescope is the Satellite and Lunar Laser Ranging (SLR) dedicated telescope of Observatoire de la Côte d’Azur (France) located at plateau de Calern. The telescope uses an altazimuth mount. The motorization of the mount has a capability of 6 deg/s allowing the follow up of Low Earth Orbits (LEO) satellites, as well as Medium Earth Orbits (MEO) and geostationary (GEO) satellites, and the Moon. The telescope has a primary mirror of 1.54 m. It uses a Nasmyth focus equipped with an EMCCD camera. The telescope field of view, defined by the equivalent focal length and the size of the camera, is currently 3.4 arcmin × 3.4 arcmin.     

The USSR and space power plants

The American idea of a Solar Power Satellite was proposed for the first time in 1968 by Peter Glaser in a famous article in Science. This concept has since been the subject of many theoretical studies, and of some limited practical studies (mainly about microwave energy transmission) in the USA with funding from NASA and the Department of Energy (DOE). Some evaluations have been also conducted in Western Europe, particularly within the European Space Agency (ESA). But very little is generally known about the attitude towards SPS of the second main space power: the USSR. Soviet literature on SPS is much less abundant, but it does exist. Very interesting articles on the subject have been written by leading Soviet space experts. Some of these articles are analysed here, and the practical meanings of the ex[ressed opinions, generally very favourable, are investigated in view of the growing Soviet space capability.     

Stable iron isotopes and microbial mediation in red pigmentation of the Rosso Ammonitico (mid-late Jurassic, Verona area, Italy)

The iron (Fe) isotopic composition of 17 Jurassic limestones from the Rosso Ammonitico of Verona (Italy) have been analyzed by Multiple-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). Such analysis allowed for the recognition of a clear iron isotopic fractionation (mean -0.8 per thousand, ranging between -1.52 to -0.06 per thousand) on a millimeter-centimeter scale between the red and grey facies of the studied formation. After gentle acid leaching, measurements of the Fe isotopic compositions gave delta(56)Fe values that were systematically lower in the red facies residues (median: -0.84 per thousand, range: -1.46 to +0.26 per thousand) compared to the grey facies residues (median: -0.08 per thousand, range: -0.34 to +0.23 per thousand). In addition, the red facies residues were characterized by a lighter delta(56)Fe signal relative to their corresponding leachates. These Fe isotopic fractionations could be a sensitive fingerprint of a biotic process; systematic isotopic differences between the red and grey facies residues, which consist of hematite and X-ray amorphous iron hydroxides, respectively, are hypothesized to have resulted from the oxidizing activity of iron bacteria and fungi in the red facies. The grey Fe isotopic data match the Fe isotopic signature of the terrestrial baseline established for igneous rocks and low-C(org) clastic sedimentary rocks. The Fe isotopic compositions of the grey laminations are consistent with the influx of detrital iron minerals and lack of microbial redox processes at the water-interface during deposition. Total Fe concentration measurements were performed by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) (confirmed by concentration estimations obtained by MC-ICP-MS analyses of microdrilled samples) on five samples, and resultant values range between 0.30% (mean) in the grey facies and 1.31% (mean) in the red facies. No correlation was observed between bulk Fe content and pigmentation or between bulk Fe content and Fe isotopic compositions. The rapid transformation of the original iron oxyhydroxides to hematite could have preserved the original isotopic composition if it had occurred at about the same temperature. This paper supports the use of Fe isotopes as sensitive tracers of biological activities recorded in old sedimentary sequences that contain microfossils of iron bacteria and fungi. However, a careful interpretation of the iron isotopic fractionation in terms of biotic versus abiotic processes requires supporting data or direct observations to characterize the biological, (geo)chemical, or physical context in relation to the geologic setting. This will become even more pertinent when Fe isotopic studies are expanded to the interplanetary realm.     

Is there really any duplication in Europe''s space activities?

At a time of declining space budgets in Europe, and of a consequent need to make savings, accusations of wasteful duplication—resulting from the large number of national agencies pursuing programmes alongside ESA—are rife, as are calls for the space industry further to consolidate. This viewpoint argues that duplication is not really the issue, however, since most national agencies have become specialists in particular fields. Nor would industry restructuring be straightforward, given the fact that Europe cannot be satisfied with a single source of supply. What is needed is better coordination between space agencies upstream to avoid later duplication, as is now being pursued through ESA's ‘harmonisation process’. The move to create a Network of Centres could also promote worthwhile collective action. These initiatives are more realistic than the technocratic aim of completely restructuring European space.     

Focal contacts organization in osteoblastic cells under microgravity and cyclic deformation conditions.

We compared quantitatively vinculin-related adhesion parameters in osteoblastic cells submitted to opposite mechanical stresses, i.e., low deformation and frequency strain regimens (stretch condition) and microgravity exposure (relaxed condition). Cyclic deformation induced a biphasic response comprising new focal contacts formation followed by their clustering in ROS cells. Microgravity exposure induced a reduction in focal contact number and clustering in ROS cells. We previously demonstrated that 1% cyclic deformations at 0.05 Hz during a daily 10 min episode over 7 days stimulated ROS 17/2.8 growth as compared to static culture whereas relaxed ROS proliferated similarly to static culture (BC). To evaluate whether the proliferation (stretch) or the survival (relaxed) status of ROS cells influences focal contact organization, we inhibited ERKs proliferative-dependent pathway. Inhibition of proliferation by PD98059 was overcome although not fully restored by stretch. Furthermore stretch-induced clustering of vinculin-positive contacts still occurs in the presence of ERKs inhibitor, whereas the increase in focal contact number is abolished. In conclusion, we showed that focal contacts are mechanoeffectors and that hyper-mechanical stimulation could up regulate focal contacts size as compared to hypo-mechanical that down regulate clusterization.     

A liquid propulsion panorama

Liquid-propellant rocket engines are widely used all over the world, thanks to their high performances, in particular high thrust-to-weight ratio. The present paper presents a general panorama of liquid propulsion as a contribution of the IAF Advanced Propulsion Prospective Group.After a brief history of its past development in the different parts of the world, the current status of liquid propulsion, the currently observed trends, the possible areas of future improvement and a summarized road map of future developments are presented. The road map includes a summary of the liquid propulsion status presented in the “Year in review 2007” of Aerospace America.Although liquid propulsion is often seen as a mature technology with few areas of potential improvement, the requirements of an active commercial market and a renewed interest for space exploration has led to the development of a family of new engines, with more design margins, simpler to use and to produce associated with a wide variety of thrust and life requirements.     

Influence of nuclear de-excitation on observables relevant for space exploration

The composition of the space radiation environment inside spacecrafts is modified by the interaction with shielding material, with equipment and even with the astronauts’ bodies. Accurate quantitative estimates of the effects of nuclear reactions are necessary, for example, for dose estimation and prediction of single-event-upset rates. To this end, it is necessary to construct predictive models for nuclear reactions, which usually consist of an intranuclear-cascade or quantum-molecular-dynamics stage, followed by a nuclear-de-excitation stage.     

Navigating in a Virtual 3D Maze: Body and Gravity,Two Possible Reference Frames for Perceiving and Memorizing

Although recent studies have brought new insight into the mechanisms of spatial memory and cognitive strategies during navigation, most of these studies have concerned two-dimensional navigation and little is known regarding the problem of three-dimensional (3D) spatial memory. We found previously that memorizing complex 3D-structured corridors was easier with natural self-motion that included only yaw turns, and vertical translations facing the walls at vertical sections. This suggests that when only sideways (yaw) mental rotations had to be performed in order to shift from the experienced egocentric to the allocentric reference frame where recognition was tested, memorization of such corridors was improved. In the present investigation we studied the effect of tilting separately subject's body axis and self-motion's rotation axis relative to gravity. With a computerized 3D reconstruction task of the maze, we examined whether having any single rotation axis was enough to facilitate this reference shift or, if not, what aspect of the terrestrial condition-where visual displacement rotation, gravity and body axes were aligned-led to better performance. Field dependent (FD) and independent (FI) subjects, as determined by the rod and frame test, showed distinct effects of the navigation conditions. The FD group performance was markedly impaired when gravity and body axis were in conflict, independently of the rotation axis, whereas FI performance only slightly worsened when the body was tilted and the rotation axis remained aligned with gravity. Moreover, tilting the body in the control condition only worsened performance for the FD group.