HAL (Le Centre pour la Communication Scientifique Directe), May 1, 2022
En 1923, Camille Flammarion reçut comme présent de l'astronome turc Ahmed Ziya, un astrolabe-quad... more En 1923, Camille Flammarion reçut comme présent de l'astronome turc Ahmed Ziya, un astrolabe-quadrant calculé pour l'Observatoire de Juvisy. Cet instrument rare, de facture ottomane, présente des courbes complexes liées à la détermination des heures de prières. L'étude suivante analyse dans le détail cet astrolabe-quadrant inédit.
HAL (Le Centre pour la Communication Scientifique Directe), 2019
In this work, we demonstrate the possibility to determine the true North direction on Mars by usi... more In this work, we demonstrate the possibility to determine the true North direction on Mars by using a gnomon on the InSight mission. The Sun local coordinates are computed using the analytical solution VSOP87 for the planetary ephemeris. The Sun position in the sky induce specific gnomon shadow orientation and length that can be read on a target. By comparing the images of the shadow with the expected position of the Sun, we can determine the true North direction with an accuracy up to 1 • , well within the seismic requirement of 5 • , even if the lander position or the gnomon verticality are not accurate. To achieve this result, we determine the best periods of observation during the SEIS deployment phase in December 2018. A total period of 5 hours has been identified on mornings and evenings on Mars, during which the impact of errors on position and verticality on the true North direction are minimised.
HAL (Le Centre pour la Communication Scientifique Directe), Oct 1, 2016
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
In this work, we demonstrate the possibility to determine the true North direction on Mars by usi... more In this work, we demonstrate the possibility to determine the true North direction on Mars by using a gnomon on the InSight mission. The Sun local coordinates are computed using the analytical solution VSOP87 for the planetary ephemeris. The Sun position in the sky induce specific gnomon shadow orientation and length that can be read on a target. By comparing the images of the shadow with the expected position of the Sun, we can determine the true North direction with an accuracy up to 1 • , well within the seismic requirement of 5 • , even if the lander position or the gnomon verticality are not accurate. To achieve this result, we determine the best periods of observation during the SEIS deployment phase in December 2018. A total period of 5 hours has been identified on mornings and evenings on Mars, during which the impact of errors on position and verticality on the true North direction are minimised.
HAL (Le Centre pour la Communication Scientifique Directe), 2023
Mots clefs Résumé Compendium ; convertisseur horaire ; italiques, babyloniques, planétaires. Le c... more Mots clefs Résumé Compendium ; convertisseur horaire ; italiques, babyloniques, planétaires. Le compendium astronomique construit au XVI e par Érasme Habermel est un chef d'oeuvre d'orfèvrerie destiné à la conversion des différents types d'heures à l'aide d'abaques munis d'ostenseurs.
HAL (Le Centre pour la Communication Scientifique Directe), Oct 1, 2021
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight wi... more 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 M w ∼ 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.
HAL (Le Centre pour la Communication Scientifique Directe), May 1, 2022
En 1923, Camille Flammarion reçut comme présent de l'astronome turc Ahmed Ziya, un astrolabe-quad... more En 1923, Camille Flammarion reçut comme présent de l'astronome turc Ahmed Ziya, un astrolabe-quadrant calculé pour l'Observatoire de Juvisy. Cet instrument rare, de facture ottomane, présente des courbes complexes liées à la détermination des heures de prières. L'étude suivante analyse dans le détail cet astrolabe-quadrant inédit.
HAL (Le Centre pour la Communication Scientifique Directe), 2019
In this work, we demonstrate the possibility to determine the true North direction on Mars by usi... more In this work, we demonstrate the possibility to determine the true North direction on Mars by using a gnomon on the InSight mission. The Sun local coordinates are computed using the analytical solution VSOP87 for the planetary ephemeris. The Sun position in the sky induce specific gnomon shadow orientation and length that can be read on a target. By comparing the images of the shadow with the expected position of the Sun, we can determine the true North direction with an accuracy up to 1 • , well within the seismic requirement of 5 • , even if the lander position or the gnomon verticality are not accurate. To achieve this result, we determine the best periods of observation during the SEIS deployment phase in December 2018. A total period of 5 hours has been identified on mornings and evenings on Mars, during which the impact of errors on position and verticality on the true North direction are minimised.
HAL (Le Centre pour la Communication Scientifique Directe), Oct 1, 2016
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
In this work, we demonstrate the possibility to determine the true North direction on Mars by usi... more In this work, we demonstrate the possibility to determine the true North direction on Mars by using a gnomon on the InSight mission. The Sun local coordinates are computed using the analytical solution VSOP87 for the planetary ephemeris. The Sun position in the sky induce specific gnomon shadow orientation and length that can be read on a target. By comparing the images of the shadow with the expected position of the Sun, we can determine the true North direction with an accuracy up to 1 • , well within the seismic requirement of 5 • , even if the lander position or the gnomon verticality are not accurate. To achieve this result, we determine the best periods of observation during the SEIS deployment phase in December 2018. A total period of 5 hours has been identified on mornings and evenings on Mars, during which the impact of errors on position and verticality on the true North direction are minimised.
HAL (Le Centre pour la Communication Scientifique Directe), 2023
Mots clefs Résumé Compendium ; convertisseur horaire ; italiques, babyloniques, planétaires. Le c... more Mots clefs Résumé Compendium ; convertisseur horaire ; italiques, babyloniques, planétaires. Le compendium astronomique construit au XVI e par Érasme Habermel est un chef d'oeuvre d'orfèvrerie destiné à la conversion des différents types d'heures à l'aide d'abaques munis d'ostenseurs.
HAL (Le Centre pour la Communication Scientifique Directe), Oct 1, 2021
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight wi... more 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 M w ∼ 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.
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Papers by Denis Savoie