PLANET TOPERS: Planets, Tracing the Transfer, Origin, Preservation, and Evolution of their ReservoirS.

The Interuniversity Attraction Pole (IAP) 'PLANET TOPERS' (Planets: Tracing the Transfer, Origin, Preservation, and Evolution of their Reservoirs) addresses the fundamental understanding of the thermal and compositional evolution of the different reservoirs of planetary bodies (core, mantle, crust, atmosphere, hydrosphere, cryosphere, and space) considering interactions and feedback mechanisms. Here we present the first results after 2 years of project work.

Mars environment and magnetic orbiter scientific and measurement objectives.

In this paper, we summarize our present understanding of Mars' atmosphere, magnetic field, and surface and address past evolution of these features. Key scientific questions concerning Mars' surface, atmosphere, and magnetic field, along with the planet's interaction with solar wind, are discussed. We also define what key parameters and measurements should be performed and the main characteristics of a martian mission that would help to provide answers to these questions. Such a mission--Mars Environment and Magnetic Orbiter (MEMO)--was proposed as an answer to the Cosmic Vision Call of Opportunity as an M-class mission (corresponding to a total European Space Agency cost of less than 300 Meuro). MEMO was designed to study the strong interconnection between the planetary interior, atmosphere, and solar conditions, which is essential to our understanding of planetary evolution, the appearance of life, and its sustainability. The MEMO main platform combined remote sensing and in situ measurements of the atmosphere and the magnetic field during regular incursions into the martian upper atmosphere. The micro-satellite was designed to perform simultaneous in situ solar wind measurements. MEMO was defined to conduct: * Four-dimensional mapping of the martian atmosphere from the surface up to 120 km by measuring wind, temperature, water, and composition, all of which would provide a complete view of the martian climate and photochemical system; Mapping of the low-altitude magnetic field with unprecedented geographical, altitude, local time, and seasonal resolutions; A characterization of the simultaneous responses of the atmosphere, magnetic field, and near-Mars space to solar variability by means of in situ atmospheric and solar wind measurements.

The structure of Venus' middle atmosphere and ionosphere.

The atmosphere and ionosphere of Venus have been studied in the past by spacecraft with remote sensing or in situ techniques. These early missions, however, have left us with questions about, for example, the atmospheric structure in the transition region from the upper troposphere to the lower mesosphere (50-90 km) and the remarkably variable structure of the ionosphere. Observations become increasingly difficult within and below the global cloud deck (<50 km altitude), where strong absorption greatly limits the available investigative spectrum to a few infrared windows and the radio range. Here we report radio-sounding results from the first Venus Express Radio Science (VeRa) occultation season. We determine the fine structure in temperatures at upper cloud-deck altitudes, detect a distinct day-night temperature difference in the southern middle atmosphere, and track day-to-day changes in Venus' ionosphere.

Frequency transfer using GPS carrier phases: influence of temperature variations near the receiver.

We have used carrier phase data from geodetic GPS receivers, driven by atomic clocks, and belonging to the IGS network, to demonstrate the capabilities of the GPS carrier phases for frequency transfer. On a regional baseline, we obtained frequency stabilities of 2.10(-16) over 4 h through a proper modeling of the tropospheric refraction and by keeping ambient temperature variations under control.

[Reproducibility of venous occlusion plethysmography. Value of a computerized system of calculation]. / Reproductibilité de la pléthysmographie à occlusion veineuse. Intérêt d'un système de calcul automatisé.

The manual interpretation of identical occlusive venous plethysmography curves by different technicians is subject to a wide variation. The object of this study is to verify this state of affairs and to propose an automatic calculation of the different parameters usually used: the percentage volume increase (delta V), the time taken to half empty (t V/2) and the maximal venous outflow (MVO). We compared the variations, due to the operators, in the measurement of the parameters characterising identical curves obtained by occlusive venous plethysmography. Sixty curves from 30 patients, were photocopied and each was measured independently by four different operators. The results were compared with the measurements obtained automatically from a micro-computer connected to the plethysmograph. The measurements of the percentage volume increase and the time taken to half empty differed among the operators and the computer by less than 2%. However, the maximal venous outflow was subject to very large variations amongst the operators (up to 60%). This uncertainty is due to the operators choice of the point on the curve where the tangent is measured. The micro-computer, by fixing this point at 0.3 second after releasing the cuff allows a standardisation of this parameter.