SEIS: Insight’s Seismic Experiment for Internal Structure of Mars

By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight will deploy onto Mars’ surface the SEIS (Seismic Experiment for Internal Structure) instrument; a six-axes seismometer equipped with both a long-period three-axes Very Broad Band (VBB) instrument and a three-axes short-period (SP) instrument. These six sensors will cover a broad range of the seismic bandwidth, from 0.01 Hz to 50 Hz, with possible extension to longer periods. Data will be transmitted in the form of three continuous VBB components at 2 sample per second (sps), an estimation of the short period energy content from the SP at 1 sps and a continuous compound VBB/SP vertical axis at 10 sps. The continuous streams will be augmented by requested event data with sample rates from 20 to 100 sps. SEIS will improve upon the existing resolution of Viking’s Mars seismic monitoring by a factor of ∼ 2500 at 1 Hz and ∼ 200 000 at 0.1 Hz. An additional major improvement is that, contrary to Viking, the seismometers will be deployed via a robotic arm directly onto Mars’ surface and will be protected against temperature and wind by highly efficient thermal and wind shielding. Based on existing knowledge of Mars, it is reasonable to infer a moment magnitude detection threshold of Mw ∼ 3 at 40◦ epicentral distance and a potential to detect several tens of quakes and about five impacts per year. In this paper, we first describe the science goals of the experiment and the rationale used to define its requirements. We then provide a detailed description of the hardware, from the sensors to the deployment system and associated performance, including transfer functions of the seismic sensors and temperature sensors. We conclude by describing the experiment ground segment, including data processing services, outreach and education networks and provide a description of the format to be used for future data distribution

Bio oil synthesis by coupling biological biomass pretreatment and catalytic hydroliquefaction process

International audienceThe bio-oil synthesis from a mixture of wastes (7 wt.% straw, 38 wt.% wood, and 45 wt.% grass) was carried out by direct liquefaction reaction using Raney Nickel as catalyst and tetralin as solvent. The green wastes were biologically degraded during 3 months. Longer the destructuration time; higher the yield into oil is. Biological pretreatment of green wastes promotes the liquefaction process. Among the components of degraded biomass, Humin, the major fraction (60-80 wt.%) that was favored by the biological treatment, yields to a bio oil extremely energetic with a HHV close to biopetroleum (40 MJ kg−1), contrariwise, Fulvic acids (2-12 wt.%), the minor fraction is refractory to liquefaction reaction

The silicon drift detector for the IXO high-time resolution spectrometer

The High Time Resolution Spectrometer (HTRS) is one of six scientific payload instruments of the International X-ray Observatory (IXO). HTRS is dedicated to the physics of matter at extreme density and gravity and will observe the X-rays generated in the inner accretion flows around the most compact massive objects, i.e. black holes and neutron stars. The study of their timing signature and in addition the simultaneous spectroscopy of the gravitationally shifted and broadened iron line allows for probing general relativity in the strong field regime and understanding the inner structure of neutron stars. As the sources to be observed by HTRS are the brightest in the X-ray sky and the studies require good photon statistics the instrument design is driven by the capability to operate at extremely high count rates. The HTRS instrument is based on a monolithic array of Silicon Drift Detectors (SDDs) with 31 cells in a circular envelope and a sensitive volume of 4.5 cm2 × 450 μm. The SDD principle uses fast signal charge collection on an integrated amplifier by a focusing internal electrical field. It combines a large sensitive area and a small capacitance, thus facilitating good energy resolution and high count rate capability. The HTRS is specified to provide energy spectra with a resolution of 150 eV (FWHM at 6 keV) at high time resolution of 10 μsec and with high count rate capability up to a goal of 2 ·106 counts per second, corresponding to a 12 Crab equivalent source. As the HTRS is a non-imaging instrument and will target only point sources it is placed on axis but out of focus so that the spot is spread over the array of 31 SDD cells. The SDD array is logically organized in four independent 'quadrants', a dedicated 8-channel quadrant readout chip is in development

MICROSCOPE Mission: Final Results of the Test of the Equivalence Principle

International audienceThe MICROSCOPE mission was designed to test the weak equivalence principle (WEP), stating the equality between the inertial and the gravitational masses, with a precision of 10-15 in terms of the Eötvös ratio η. Its experimental test consisted of comparing the accelerations undergone by two collocated test masses of different compositions as they orbited the Earth, by measuring the electrostatic forces required to keep them in equilibrium. This was done with ultrasensitive differential electrostatic accelerometers onboard a drag-free satellite. The mission lasted two and a half years, cumulating five months worth of science free-fall data, two-thirds with a pair of test masses of different compositions—titanium and platinum alloys—and the last third with a reference pair of test masses of the same composition—platinum. We summarize the data analysis, with an emphasis on the characterization of the systematic uncertainties due to thermal instabilities and on the correction of short-lived events which could mimic a WEP violation signal. We found no violation of the WEP, with the Eötvös parameter of the titanium and platinum pair constrained to η(Ti,Pt)=[-1.5±2.3(stat)±1.5(syst)]×10-15 at 1σ in statistical errors