Is there another major constituent in the atmosphere of Mars?

In view of the possible finding of several tens percent of inert gas in the atmosphere of Mars by an instrument on the descent module of the USSR's Mars 6 spacecraft, the likelihood of the correctness of this result was examined. The basis for the well-known fact that the most likely candidate is radiogenic argon is described. It is shown that, for the two important methods of investigating the atmosphere, earth-based CO2 is infrared absorption spectroscopy and S-band occultation, within the estimated 1 standard deviation uncertainties of these methods about 20% argon can be accommodated. Within the estimated 3 standard deviation uncertainties, more than 35% is possible. It is also stated that even with 35% argon the maximum value of heat transfer rate on the Viking 75 entry vehicle does not exceed the design value

Plasma accelerator Patent

Crossed-field plasma accelerator for laboratory simulation of atmospheric reentry condition

A Coronal Hole's Effects on CME Shock Morphology in the Inner Heliosphere

We use STEREO imagery to study the morphology of a shock driven by a fast coronal mass ejection (CME) launched from the Sun on 2011 March 7. The source region of the CME is located just to the east of a coronal hole. The CME ejecta is deflected away from the hole, in contrast with the shock, which readily expands into the fast outflow from the coronal hole. The result is a CME with ejecta not well centered within the shock surrounding it. The shock shape inferred from the imaging is compared with in situ data at 1 AU, where the shock is observed near Earth by the Wind spacecraft, and at STEREO-A. Shock normals computed from the in situ data are consistent with the shock morphology inferred from imaging.Comment: to appear in The Astrophysical Journa

Gas analyzer for bi-gaseous mixtures Patent

Gas analyzer for bi-gaseous mixtures suitable for use in test facilitie

Values of the photometric parameters of Mars and their interpretation

Photometric data for the Martian disk obtained by Thorpe from television-camera pictures taken by Mariner 9 were used to derive values for the parameters in the photometric function. The photometric function can be applied to Mars and to the design of cameras for photography of Mars. Values of the parameters are for one wavelength only, 0.56 micros and are average or effective values for the Martian disk. The values derived were interpreted to provide semi-quantitative information on the soil. The results do not disagree with other indications that the effective mean diameter of the surface particles is about 400 micros. Another result is that the mean intercenter spacing of adjacent particles may be about 4/3 of the mean diameter

The minimum free-stream wind speed for initiating motion of surface material on Mars

Estimates of the minimum free-stream wind speed that is required for initiating the motion of surficial material on Mars have ranged from 30 to about 200 meters per second. Thus the best value for this quantity is not well established. Graphical comparison of much of the pertinent data taken in the laboratory and in the field on Earth provides a minimum value for the Bagnold coefficient of 0.08 and this in turn provides a minimum value for the threshold friction velocity of 1.3 meters per second for initiating motion of particulate matter on Mars at low elevations where the pressure is 7 millibars. The most appropriate value of the ratio of friction velocity to free-stream velocity for putative unstable condition appears to be 0.026. Thus the minimum free-stream wind speed for initiating motion is obtained as 50 meters per second. If the surface material on Mars, however, is less cohesive than that on earth, the minimum value may be smaller

Comprehensive Observations of a Solar Minimum CME with STEREO

We perform the first kinematic analysis of a CME observed by both imaging and in situ instruments on board STEREO, namely the SECCHI, PLASTIC, and IMPACT experiments. Launched on 2008 February 4, the CME is tracked continuously from initiation to 1 AU using the SECCHI imagers on both STEREO spacecraft, and is then detected by the PLASTIC and IMPACT particle and field detectors on board STEREO-B. The CME is also detected in situ by ACE and SOHO/CELIAS at Earth's L1 Lagrangian point. The CME hits STEREO-B, ACE, and SOHO on 2008 February 7, but misses STEREO-A entirely. This event provides a good example of just how different the same event can look when viewed from different perspectives. We also demonstrate many ways in which the comprehensive and continuous coverage of this CME by STEREO improves confidence in our assessment of its kinematic behavior, with potential ramifications for space weather forecasting. The observations provide several lines of evidence in favor of the observable part of the CME being narrow in angular extent, a determination crucial for deciding how best to convert observed CME elongation angles from Sun-center to actual Sun-center distances.Comment: 27 pages, 10 figures, AASTEX v5.2, accepted by Ap

Material flow during the extrusion of simple and complex cross-sections using FEM

This paper deals with the extrusion of rod and shape sections and uses a 3D finite element model analysis (FEM) to predict the effect of die geometry on maximum extrusion load. A description of material flow in the container is considered in more detail for rod and shape sections in order to fully comprehend the transient conditions occurring during the process cycle. A comparison with experiments is made to assess the relative importance of some extrusion parameters in the extrusion process and to ensure that the numerical discretisation yields a realistic simulation of the process. The usefulness and the limitation of FEM are discussed when modelling complex shapes. Results are presented for velocity contours and shear stress distribution during the extrusion process. It is shown that for most of the shapes investigated, the material making up the extrudate cross-sections originates from differing regions of virgin material within the billet. The outside surface of the extrudate originates from the material moving along the dead metal zone (DMZ) and the core of the extrudate from the central deformation zone. The FE program appears to predict all the major characteristics of the flow observed macroscopically

Material flow during the extrusion of simple and complex cross-sections using FEM

This paper deals with the extrusion of rod and shape sections and uses a 3D finite element model analysis (FEM) to predict the effect of die geometry on maximum extrusion load. A description of material flow in the container is considered in more detail for rod and shape sections in order to fully comprehend the transient conditions occurring during the process cycle. A comparison with experiments is made to assess the relative importance of some extrusion parameters in the extrusion process and to ensure that the numerical discretisation yields a realistic simulation of the process. The usefulness and the limitation of FEM are discussed when modelling complex shapes. Results are presented for velocity contours and shear stress distribution during the extrusion process. It is shown that for most of the shapes investigated, the material making up the extrudate cross-sections originates from differing regions of virgin material within the billet. The outside surface of the extrudate originates from the material moving along the dead metal zone (DMZ) and the core of the extrudate from the central deformation zone. The FE program appears to predict all the major characteristics of the flow observed macroscopically