Primordial matter in the outer solar system: A study of its chemical composition from remote spectroscopic analysis

Our knowledge of the primordial matter from the objects of the outer solar system has made a considerable progress over the past years, in spite of the lack of any in situ measurements of these objects at the present time. The recent progress of ground-based instrumentation and the launch of the two Voyager fly-by missions have provided a huge amount of new informations about the origin and the evolution of the primitive Solar System objects.The most significant discoveries concerning the atmospheres of the Giant Planets can be summarized as follows: (1) there does not seem to be any differentiation in the internal structure of Jupiter during the planet's history; thus, the H₂/He ratio measured on Jupiter seems to be representative of the H/He ratio of the Primordial Nebula; (2) there is some evidence for a helium differentiation, relative to hydrogen, in Saturn's interior; (3) there seems to be a carbon enrichment on both Jupiter and Saturn by a factor about 2; this result is consistent with a model in which the planetary core is formed first, and the atmosphere accreted by this core in a second stage; (4) the D/H ratio measured on Jupiter should be representative of the D/H value in the Primordial Nebula, 4.5 billion years ago; this value is 2 to 5 times larger than the mean value measured in the local interstellar medium now; (5) Titan's atmosphere is dominated by nitrogen and contains traces of organic and prebiotic molecules (HCN, C₂N₂, HC₃N); the chemical composition of Titan's atmosphere could be favorable for the early stages of life development.The small bodies of the Solar System — asteroïds and comets — are still very poorly known. However they contain a key information about the physical and chemical properties of dust in the Primordial Nebula and the interstellar medium. With the launch of expected fly-by missions towards Comet Halley and, possibly, towards asteroïds, we may hope to know a new development of our understanding of these objects, comparable to the progress we have known on the Giant Planets over the past ten years.     

Unsteady laminar separation over impulsively moved cylinders

A numerical method is employed to integrate the unsteady laminar boundary layers about circular and elliptic cylinders started impulsively from rest. An upwind differencing scheme permits the integration through thin layers of reversed flow that are embedded in the boundary layer. The results are in agreement with numerical solutions of the full Navier-Stokes equations and with small time inner-outer expansion solutions. At later times, a singularity of the Goldstein type appears; Sears and Telionis defined this singularity as unsteady boundary-layer separation. For the circular cylinder, this singularity travels upstream and for large times, arrives asymptotically at the point of steady-state separation.     

Ozone destruction by solar electrons in relation to solar variability and the terrestrial latitude

Precipitating electrons from the radiation belts with energies greater than from 150 keV to 5 MeV have been correlated with ozone data of a large number of stations located within 40–70° N. Energetic electrons have been collected by the low altitude polar Russian satellite METEOR while ozone data have been compiled from almost ninety (90) stations located all over the world within the latitude zone 40–70° N.     

Helio-geomagnetic influence in cardiological cases

The effects of the energetic phenomena of the Sun, flares and coronal mass ejections (CMEs) on the Earth’s ionosphere–magnetosphere, through the solar wind, are the sources of the geomagnetic disturbances and storms collectively known as Space Weather. The research on the influence of Space Weather on biological and physiological systems is open. In this work we study the Space Weather   impact on Acute Coronary Syndromes (ACS) distinguishing between ST-segment elevation acute coronary syndromes (STE–ACS) and non-ST-segment elevation acute coronary syndromes (NSTE–ACS) cases. We compare detailed patient records from the 2nd Cardiologic Department of the General Hospital of Nicaea (Piraeus, Greece) with characteristics of geomagnetic storms (_DST${\mathrm{D}}_{\mathit{ST}}$), solar wind speed and statistics of flares and CMEs which cover the entire solar cycle 23 (1997–2007). Our results indicate a relationship of ACS to helio-geomagnetic activity as the maximum of the ACS cases follows closely the maximum of the solar cycle. Furthermore, within very active periods, the ratio NSTE–ACS to STE–ACS, which is almost constant during periods of low to medium activity, changes favouring the NSTE–ACS. Most of the ACS cases exhibit a high degree of association with the recovery phase of the geomagnetic storms; a smaller, yet significant, part was found associated with periods of fast solar wind without a storm.     

A differential measurement of the Lyman alpha emission from the giant planets using IUE

The intensity of the resonantly scattered Ly-α line of the gian planets depends on the scattering column length of atomic hydrogen above the methane layer and on the incident solar flux. We have obtained measurements of the Ly-α brightness of Jupiter and Saturn on December 19, 1979, with a time difference of 111 minutes, which is only slightly longer than the additional travel time for solar photons scattered at Saturn compared to those from Jupiter. This observational technique eliminates two major uncertainties — the use of different instruments and solar variability — affecting previous determinations of the relative brightness of the planets. The measured ratio of the brightness of the subsolar points is 3.0 ± 0.4 which agrees well with the ratio of the incident solar flux of 3.4. This implies approximately equal scattering column lengths of H on both planets.     

From interstellar matter to comets: Elemental abundances in interstellar dust and in comet Halley

Analogies between interstellar and cometary matter can be found in their chemical compositions, both in the gaseous and solid phases, but also in the physical processes involved like evidence for ion-molecules reactions at low temperature and for ice irradiation processes. Such analogies can be observed from 3 types of measurements: interstellar spectra, cometary observations, and analyses of interplanetary dust particles, with the help of laboratory simulation experiments. Taking into account all the present available information, a compilation of the elemental abundances in interstellar matter and in comet Halley is derived, without any assumption about the dust to gas ratio. It is found that there is a significant apparent depletion of nitrogen, presently unexplained, in both interstellar and cometary materials.     

Atmospheric photochemistry above possible martian hot spots

Considering the possibility of outgassing from some localized sources on Mars, we have developed a one-dimensional photochemical model that includes methane (CH₄), sulfur dioxide (SO₂) and hydrogen sulfide (H₂S). Halogens were considered but were found to have no significant impact on the martian atmospheric chemistry. We find that the introduction of methane into the martian atmosphere results in the formation of mainly formaldehyde (CH₂O), methyl alcohol (CH₃OH) and ethane (C₂H₆), whereas the introduction of the sulfur species produces mainly sulfur monoxide (SO) and sulfuric acid (H₂SO₄). Depending upon the flux of the outgassed molecules from possible hot spots, some of these species and the resulting new molecules may be detectable locally, either by remote sensing (e.g., with the Planetary Fourier Spectrometer on Mars Express) or in situ measurements.     

The Magnetic Field of the Earth’s Lithosphere

The lithospheric contribution to the Earth’s magnetic field is concealed in magnetic field data that have now been measured over several decades from ground to satellite altitudes. The lithospheric field results from the superposition of induced and remanent magnetisations. It therefore brings an essential constraint on the magnetic properties of rocks of the Earth’s sub-surface that would otherwise be difficult to characterize. Measuring, extracting, interpreting and even defining the magnetic field of the Earth’s lithosphere is however challenging. In this paper, we review the difficulties encountered. We briefly summarize the various contributions to the Earth’s magnetic field that hamper the correct identification of the lithospheric component. Such difficulties could be partially alleviated with the joint analysis of multi-level magnetic field observations, even though one cannot avoid making compromises in building models and maps of the magnetic field of the Earth’s lithosphere at various altitudes. Keeping in mind these compromises is crucial when lithospheric field models are interpreted and correlated with other geophysical information. We illustrate this discussion with recent advances and results that were exploited to infer statistical properties of the Earth’s lithosphere. The lessons learned in measuring and processing Earth’s magnetic field data may prove fruitful in planetary exploration, where magnetism is one of the few remotely accessible internal properties.     

Telemedicine for the international space station

The medical care for the integrated crew of the International Space Station (ISS) will require close co-operation between the partner agencies in the areas of selection, medical surveillance, countermeasures, and handling of acute medical problems. Based on a commonly accepted policy of shared care and responsibilities medical guidelines, procedures, and standards for medical data and communication need to be harmonised under the responsibility of the Multilateral Medical Operations Panel (MMOP). A supporting telemedical network connecting the partners on an organisational and technical level will facilitate the harmonisation process and provide new tools for effective co-operation between medical professionals. Earth bound projects with similar application areas can profit from and contribute to this development and need to be considered for efficient implementation and exploitation.