The Seismic Experiment for Interior Structure (SEIS): Experiment Data Distribution

The six sensors of SEIS (The Seismic Experiment for Interior Structure) [- one of three primary instruments on NASA's Mars Lander Insight] cover a broad range of the seismic bandwidth, from 0.01 hertz to 50 hertz, with possible extension to longer periods. Data are transmitted in the form of three continuous VBB (Very Broad-Band) components at 2 samples per second (sps), an estimation of the short period (SP) energy content from the SP at 1 sps, and a continuous compound VBB/SP vertical axis at 10 sps. The continuous streams are augmented by requested event data with sample rates from 20 to 100 sps. SEIS data products are downlinked from the spacecraft in raw CCSDS (Consultative Committee for Space Data Systems) packets and converted to both the Standard for the Exchange of Earthquake Data (SEED) format files and ASCII tables (GeoCSV) for analysis and archiving. Metadata are available in dataless SEED and StionXML. Time series data (waveforms) are available in miniseed and GeoCSV. Data are distributed according to FDSN (Federation of Digital Seismograph Networks - http://www.fdsn.org) formats and interfaces. Wind, pressure and temperature data from the Auxiliary Payload Sensor Suite (APSS) will also be available in SEED format, and can be used for decorrelation and diagnostic purposes on SEIS

The ambident electrophilic behavior of 5-nitro-3-X-thiophenes in σ-complexation processes

International audienc

Influence of solvent mixture on nucleophilicity parameters: the case of pyrrolidine in methanol–acetonitrile

International audienceThe course of organic chemical reactions is efficiently modelled through the concepts of “electrophiles” and “nucleophiles” (meaning electron-seeking and nucleus-seeking reactive species). On the one hand, an advanced approach of the correlation of the nucleophilicity parameters N and electrophilicity E has been delivered from the linear free energy relationship log k (20 °C) = s(N + E). On the other hand, the general influence of the solvent mixtures, which are very often employed in preparative synthetic chemistry, has been poorly explored theoretically and experimentally, to date. Herein, we combined experimental and theoretical studies of the solvent influence on pyrrolidine nucleophilicity. We determined the nucleophilicity parameters N and s of pyrrolidine at 20 °C in CH3OH/CH3CN mixtures containing 0, 20, 40, 60, 80 and 100% CH3CN by kinetic investigations of their nucleophilic substitution reactions to a series of 2-methoxy-3-X-5-nitrothiophenes 1a–e (X = NO2, CN, COCH3, CO2CH3, CONH2). Depending on the resulting solvation medium, the N parameters range from 15.72 to 18.32 on the empirical nucleophilicity scale of Mayr. The nucleophilicity parameters N first evolve linearly with the content of acetonitrile up to 60% CH3CN by volume, but is non linear for higher amounts. We designed a general computation protocol to investigate the solvent effect at the atomistic scale. The nucleophilicity in solvent mixtures was evaluated by combining classical molecular dynamic (MD) simulations of solvated pyrrolidine and a few density functional theory (DFT) calculations of Parr nucleophilicity. The pyrrolidine theoretical nucleophilicity 1/ω obtained in various CH3OH/CH3CN mixtures are in excellent agreement with Mayr's nucleophilicity (N) parameters measured. Analyses of the molecular dynamic trajectories reveal that the decrease of the nucleophilicity in methanol rich mixtures arises predominantly from the solvation of the pyrrolidine by methanol molecules through strong hydrogen bonds. Last, we proposed a simple model to predict and accurately reproduce the experimentally obtained nucleophilicity values

The SEIS InSight VBB Experiment

Introduction: The SEIS experiment is the primary payload of the Interior Structure Investigation using Seismology and Heat Transport (InSight) mission selected by NASA in August 2012 to be the next Mars mission. The objective of the InSight SEIS experiment is the determination of the deep internal structure of Mars. In particular, geophysical parameters of first importance, such as the state (liquid/solid) and size of the core, structure of the mantle, shape of discontinui-ties and thickness of the crust will be determined by the experiment. It will measure seismic activity over a very broad frequency band, from tidal frequencies (0.05 mHz) up to high frequencies (50 Hz), to address a wide range of scientific questions, from the state of the core to the meteoritic impact rate, marsquake rate and the response of the planet to the Phobos tide. Description of the instrument: The instrument includes notably a Very Broad Band (VBB) 3 axis seis-mometer which is developed by the ';Institut du Globe de Paris' (IPGP) under the funding of CNES. The sensor assembly, which also contains a MEMS short-period seismometer, will be deployed on the Martian ground by a robotic arm from a Phoenix-type lander platform and will be protected by a wind and thermal shield. The wind and thermal shield,together with a vacuum sphere and a passive compensation system will achieve a very high protection of the VBB against temperature and pressure variations, allowing the sensor to operate in the rough Martian thermal environment while reaching a detection threshold below 10-9 ms-2 Hz-1/2 in the VBB bandwidth. Conclusion: Performance has been demonstrated with previous prototypes and the SEIS experiment of the InSight mission will therefore provide high-quality seismic signal acquisition and associated seismic information during one martian year. The delivery of the payload is planned for the end of 2014 and the launch is in March 2016 SEIS deployed on the ground next to the lande

Resonances of the InSight Seismometer on Mars

(InSight) seismometer was deployed to the surface of Mars in December 2018- February 2019. The specific deployment conditions, which are very different from those of a standard broadband instrument on the Earth, result in resonances caused by different parts of the sensor assembly (SA) that are recorded by the seismometer. Here, we present and characterize the resonances known to be present in the SA and their causes to aid interpretation of the seismic signals observed on Mars. Briefly, there are resonances in the SA at about 2.9, 5.3, 9.5, 12, 14, 23-28, and 51 Hz. We discuss various methods and tests that were used to characterize these resonances, and provide evidence for some of them in data collected on Mars. In addition to their relevance for the high frequency analysis of seismic data from InSight, specifically for phase measurements near the resonant frequencies, the tests and observations described here are also of potential use in the further development of planetary seismometers, for example, for Mars, th