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Space Pole Publications Server latest documentsenSat, 12 Oct 2024 05:47:18 GMTInvenio 1.2.1sarah@oma.be36050125https://publi2-as.oma.be/img/site_logo_rss.pngSpace Pole Publications Server
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About the improvement in Mars Polar Motion determination from radio tracking of two landers
https://publi2-as.oma.be/record/7073
Goli, MartaMon, 07 Oct 2024 10:15:08 GMThttps://publi2-as.oma.be/record/70732024Simulations In Support Of Mars Polar Motion Estimation Using Radio Data From Multiple Landers
https://publi2-as.oma.be/record/6649
The polar motion of Mars is defined as the movement of the rotation axis with respect to a fixed frame tied to the crust. Composed of annual, seasonal and free wobble periods, it provides information on the atmospheric dynamics and seasonal mass exchanges, as well as on the interior structure, making it an attractive study target for investigations using radiometric data. We investigate the uncertainties associated with Mars pole motion (PM) parameters estimation using Doppler, Range and Same-Beam Interferometry (SBI) observables between multiple landers on the surface of Mars and the Deep Space Network (DSN) on Earth. We use the MONTE astrodynamics and measurement simulation suite from JPL to evaluate the improvement enabled by combining data from multiple landers, identify the optimal mission architectures for PM estimation, and analyze them by considering the influence of respective mission parameters on the estimation uncertainty. In particular, we consider the effects of absolute and relative locations of the landers, observation scheduling considerations, and noise level. We re-evaluate the possibility of estimating the polar motion using data from landers in proximity to the equator, and apply our considerations to existing past, present and future missions such as InSight or the planned Mars Sample Return lander. We also consider the possible improvement in the estimation of the period of the pole’s free Chandler Wobble, which has recently been detected for the first time using orbiter radio tracking (Konopliv et al 2020).Goli, MartaWed, 24 Jan 2024 15:03:38 GMThttps://publi2-as.oma.be/record/66492023Simulations In Support Of Mars Polar Motion Estimation Using Radio Data From Multiple Landers.
https://publi2-as.oma.be/record/6623
The polar motion of Mars is defined as the movement of the rotation axis with respect to a fixed frame tied to the crust. Composed of annual, seasonal and free wobble periods, it provides information on the atmospheric dynamics and seasonal mass exchanges, as well as on the interior structure, making it an attractive study target for investigations using radiometric data. We investigate the uncertainties associated with Mars pole motion (PM) parameters estimation using Doppler, Range and Same-Beam Interferometry (SBI) observables between multiple landers on the surface of Mars and the Deep Space Network (DSN) on Earth. We use the MONTE astrodynamics and measurement simulation suite from JPL to evaluate the improvement enabled by combining data from multiple landers, identify the optimal mission architectures for PM estimation, and analyze them by considering the influence of respective mission parameters on the estimation uncertainty. In particular, we consider the effects of absolute and relative locations of the landers, observation scheduling considerations, and noise level. We re-evaluate the possibility of estimating the polar motion using data from landers in proximity to the equator, and apply our considerations to existing past, present and future missions such as InSight or the planned Mars Sample Return lander. We also consider the possible improvement in the estimation of the period of the pole’s free Chandler Wobble, which has recently been detected for the first time using orbiter radio tracking (Konopliv et al 2020).Goli, Marta Tue, 23 Jan 2024 08:51:27 GMThttps://publi2-as.oma.be/record/66232023DETECTION OF THE LIQUID CORE SIGNATURE IN MARS NUTATIONS FROM INSIGHT-RISE DATA: IMPLICATIONS FOR MARS INTERIOR STRUCTURE
https://publi2-as.oma.be/record/6599
Le Maistre, Sébastien Mon, 22 Jan 2024 11:00:18 GMThttps://publi2-as.oma.be/record/65992023La mission JUICE À la découverte des lunes de glace de Jupiter
https://publi2-as.oma.be/record/6517
Yseboodt, MarieTue, 07 Nov 2023 14:51:14 GMThttps://publi2-as.oma.be/record/65172023De JUICE-missie
https://publi2-as.oma.be/record/6516
Yseboodt, MarieTue, 07 Nov 2023 14:49:20 GMThttps://publi2-as.oma.be/record/65162023Mars orientation and rotation angles
https://publi2-as.oma.be/record/6515
The rotation and orientation of Mars is commonly described using two different sets of angles, namely (1) the Euler angles with respect to the Mars orbit plane and (2) the right ascension, declination, and prime meridian location angles with respect to the Earth equator at J2000 (as adopted by the IAU). We propose a formulation for both these sets of angles, which consists of the sum of a second degree polynomial and of periodic and Poisson series. Such a formulation is shown here to enable accurate (and physically sound) transformation from one set of angles to the other. The transformation formulas are provided and discussed in this paper. In particular, we point that the quadratic and Poisson terms are key ingredients to reach a transformation precision of 0.1 mas, even 30 years away from the reference epoch of the rotation model (e.g., J2000). Such a precision is required to accurately determine the smaller and smaller geophysical signals observed in the high-accuracy data acquired from the surface of Mars. In addition, we present good practices to build an accurate Martian rotation model over a long time span ( years around J2000) or over a shorter one (e.g., lifetime of a space mission). We recommend to consider the J2000 mean orbit of Mars as the reference plane for Euler angles. An accurate rotation model should make use of up-to-date models for the rigid (this study) and liquid (Le Maistre et al., Nature 619, 733–737 (2023)) nutations, relativistic corrections in rotation (Baland et al., Astron. Astrophys. 670, A29 (2023)), and polar motion induced by the external torque (this study). Our transformation model and recommendations can be used to define the future IAU solution for the rotation and orientation of Mars using right ascension, declination, and prime meridian location. In particular, thanks to its quadratic terms, our transformation model does not introduce arbitrary and non-physical terms of very long period and large amplitudes, thus providing unbiased values of the rates and epoch values of the angles.Yseboodt, MarieTue, 07 Nov 2023 14:46:15 GMThttps://publi2-as.oma.be/record/65152023Spin state and deep interior structure of Mars from InSight radio tracking
https://publi2-as.oma.be/record/6500
Rivoldini, Attilio Fri, 29 Sep 2023 10:04:26 GMThttps://publi2-as.oma.be/record/65002023Spin state and deep interior structure of Mars from InSight radio tracking
https://publi2-as.oma.be/record/6491
Knowledge of the interior structure and atmosphere of Mars is essential to understanding how the planet has formed and evolved. A major obstacle to investigations of planetary interiors, however, is that they are not directly accessible. Most of the geophysical data provide global information that cannot be separated into contributions from the core, the mantle and the crust. The NASA InSight mission changed this situation by providing high-quality seismic and lander radio science data1,2. Here we use the InSight's radio science data to determine fundamental properties of the core, mantle and atmosphere of Mars. By precisely measuring the rotation of the planet, we detected a resonance with a normal mode that allowed us to characterize the core and mantle separately. For an entirely solid mantle, we found that the liquid core has a radius of 1,835 $\pm$55 km and a mean density of 5,955--6,290 kg m−3, and that the increase in density at the core--mantle boundary is 1,690--2,110 kg m−3. Our analysis of InSight's radio tracking data argues against the existence of a solid inner core and reveals the shape of the core, indicating that there are internal mass anomalies deep within the mantle. We also find evidence of a slow acceleration in the Martian rotation rate, which could be the result of a long-term trend either in the internal dynamics of Mars or in its atmosphere and ice caps.Le Maistre, SébastienWed, 30 Aug 2023 14:47:14 GMThttps://publi2-as.oma.be/record/64912023The deep interior of Mars from nutation measured by InSight RISE.
https://publi2-as.oma.be/record/6243
Le Maistre, SébastienFri, 27 Jan 2023 12:59:22 GMThttps://publi2-as.oma.be/record/62432022Mars rotational elements: how to explain the long period terms in the IAU standard?
https://publi2-as.oma.be/record/6238
Yseboodt, MarieFri, 27 Jan 2023 11:39:57 GMThttps://publi2-as.oma.be/record/62382022Relativistic variations in Mars rotation
https://publi2-as.oma.be/record/6237
Baland, Rose-MarieFri, 27 Jan 2023 11:37:06 GMThttps://publi2-as.oma.be/record/62372022Relativistic contributions to the rotation of Mars
https://publi2-as.oma.be/record/6236
Context: The orientation and rotation of Mars, which can be described by a set of Euler angles, is estimated from radioscience data and is then used to infer Mars internal properties. The data are analyzed using a modeling expressed within the Barycentric Celestial Reference System (BCRS). Aims: We provide new and more accurate (to the 0.1 mas level) estimations of the relativistic corrections to be included in the BCRS model of the orientation and rotation of Mars to avoid a misinterpretation of the data. Methods: There are two types of relativistic contributions in Mars rotation and orientation: (i) those that directly impact the Euler angles and (ii) those resulting from the time transformation between a local Mars reference frame and BCRS. The former correspond essentially to the geodetic effect. We compute them assuming that Mars evolves on a Keplerian orbit. As for the latter, we compute the effect of the time transformation and compare the rotation angle corrections obtained using realistic orbits as described by ephemerides. Results: The relativistic correction in longitude comes mainly from the geodetic effect and results in the geodetic precession (6.754mas/yr) and the geodetic annual nutation (0.565 mas amplitude). For the rotation angle, the correction is dominated by the effect of the time transformation. The main annual, semi-annual, and ter-annual terms have amplitudes of 166.954 mas, 7.783 mas, and 0.544mas, respectively. The amplitude of the annual term differs by about 9 mas from the estimate usually considered by the community. We identify new terms at the Mars-Jupiter and Mars-Saturn synodic periods (0.567 mas and 0.102 mas amplitude) that are relevant considering the current level of uncertainty of the measurements, as well as a contribution to the rotation rate (7.3088 mas/day). There is no significant correction that applies to the obliquity. Baland, Rose-MarieFri, 27 Jan 2023 11:24:26 GMThttps://publi2-as.oma.be/record/62362023Soapbox Science Brussels, voor de eerste keer in België
https://publi2-as.oma.be/record/5630
Pham, Lê Binh SanFri, 28 Jan 2022 10:47:42 GMThttps://publi2-as.oma.be/record/56302021Soapbox Science Brussels, une première en Belgique
https://publi2-as.oma.be/record/5629
Pham, Lê Binh SanFri, 28 Jan 2022 10:45:00 GMThttps://publi2-as.oma.be/record/56292021Soapbox Science Brussels: an outreach platform for the promotion of Women in Sciences in Belgium
https://publi2-as.oma.be/record/5628
Bingen, ChristineFri, 28 Jan 2022 10:39:59 GMThttps://publi2-as.oma.be/record/56282021Promotion of women in science: the Soapbox Science outreach platform in Belgium
https://publi2-as.oma.be/record/5627
Bingen, ChristineFri, 28 Jan 2022 10:37:49 GMThttps://publi2-as.oma.be/record/56272021Martian Rotation and Orientation Angles: transformation between the Euler angles and the Earth equatorial coordinates
https://publi2-as.oma.be/record/5615
Mars rotation models are regularly updated based on the precise radioscience data coming from Martian orbiters and landers and new theoretical developments. Two precise radio-science experiments are ongoing or will arrive soon: the RISE experiment on board the InSight mission (Folkner et al., 2018) and the future LaRa experiment on ExoMars 2022 (Dehant et al., 2020). Two different sets of angles are commonly used in the rotation matrix transforming the coordinates from the body frame to an inertial frame: the Euler angles versus the IAU formulation with the Earth equatorial coordinates. We present the transformations between the 2 sets. We compute the initial values of the angles, their temporal drift (diurnal rate or precession rate) and their quadratic term, and their periodic variations (nutations and length-of-day LOD variations). The objective is to have a rotation matrix difference smaller than less than 1 mas. The improvements proposed in the transformations mostly affect the rotation angle (or LOD) variations and the quadratic terms.Yseboodt, MarieTue, 25 Jan 2022 11:15:03 GMThttps://publi2-as.oma.be/record/56152021The rotation of Ganymede and Callisto
https://publi2-as.oma.be/record/5614
The rotation rates of Ganymede and Callisto, the two largest satellites of Jupiter, are on average equal to their orbital mean motion but cannot be constant as a result of the varying gravitational torque exerted by Jupiter on the satellites. For a Keplerian orbit, the period of the torque and of the rotation variations is equal to the orbital period. Gravitational interaction with the other Galilean satellites and the Sun induces deviations from a purely Keplerian orbital motion, leading to changes in the gravitational torque of Jupiter on the satellites with respect to the mean Keplerian orbital motion and therefore to additional rotation variations. Here we discuss small variations from the average rotation on different time scales and assess the potential of using rotation as a probe of the interior structure. The ESA JUICE (JUpiter ICy moons Explorer) mission will measure the rotation and tides of Ganymede and Callisto in the early 30s, and will in particular very accurately determine those quantities for Ganymede during the orbital phase of the spacecraft around that satellite starting in 2032. We report on different theoretical aspects of the rotation for realistic models of the interior of the satellites, include tidal deformations and take into account the low-degree gravity field and topography of Ganymede and Callisto. We assess the advantages of a joint use of rotation and tides to constrain the satellite's interior structure, in particular its ice shell and ocean.Van Hoolst, Tim Tue, 25 Jan 2022 11:09:47 GMThttps://publi2-as.oma.be/record/56142021The Structure of the Martian Core Revealed by RISE
https://publi2-as.oma.be/record/5571
After more than 2 years of monitoring the rotation of Mars with the RISE instrument on InSight, the effect of the planet’s core on the nutation (small periodic variations of the orientation of Mars spin axis in space) have been measured. From the acquired Doppler data we have confirmed the liquid state of the core, constrained its moment of inertia, and estimated, for the first time for a planetary body other than the Earth, the period of the Free Core Nutation (FCN) rotational normal mode. The FCN occurs because the instantaneous rotation axes of the mantle and the elliptical liquid core are misaligned. The knowledge of the FCN period provides unique insights about the moment of inertia of the core, its dynamical flattening, and its ability to deform as well as information about the coupling between the mantle and core. Mars dynamical flattening deviates significantly from that of a uniformly rotating fluid body and likewise, deviations from that state can be expected for the core. The validity of core shape predictions from models that aim to explain the dynamical shape of Mars can thus be assessed by comparing them to nutation observations. Unlike the FCN period, nutation amplitudes are less sensitive to the dynamical shape of the core. When combined with interior structure modeling, nutation data allows to deduce the radius of the core and constrain its fraction of light elements. Our inferred core radius agrees with previous estimates based on geodesy data and seismic data obtained with the InSight seismometer. The large fraction of light elements required to match the core density implies that its liquidus is significantly lower than any plausible estimate of its present-day temperature, and as such, the presence of an inner core is highly unlikely, although the presence of remelting iron-rich snow in the core cannot be excluded. An inner core would also lead to an additional rotational normal mode that could potentially be measurable, but its signature has not been detected in the RISE data. The estimated period of the FCN is best matched if the shape of the core resembles that of a rotating fluid planet or if the effective long-term rotating figure of Mars behaves like a rotating fluid overlain by an elastic shell of substantial thickness, comparable to the lithosphere thickness deduced from studies based on seismic data.Rivoldini, AttilioThu, 20 Jan 2022 11:45:17 GMThttps://publi2-as.oma.be/record/55712021Mars precession rate determined from radiometric tracking of the InSight Lander
https://publi2-as.oma.be/record/5340
The Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport (InSight) mission has provided an opportunity to improve our knowledge of Mars'interior via the Rotation and Interior Structure Experiment (RISE). RISE provides information on the rotation of Mars by measuring the Doppler shift of radio transmissions from InSight to NASA's Deep Space Network (DSN) on Earth. Through the combination of one year of Doppler data from InSight with previous data from the Viking-1 lander, Mars Pathfinder, and Opportunity missions, data spanning 43 years from 1976 to 2019 are used to estimate the Mars precession rate as −7605 $\pm$3 milliarcseconds per year. This result is consistent with the precession rate estimated from Doppler tracking of previous landers and orbiters alone.Kahan, Daniel S.Mon, 10 May 2021 12:38:38 GMThttps://publi2-as.oma.be/record/53402021The rotation and interior of Ganymede
https://publi2-as.oma.be/record/5170
The rotation rate of Ganymede, the largest satellite of Jupiter, is on average equal to its orbital mean motion but cannot be constant on orbital time scale as a result of the gravitational torque exerted by Jupiter on the moon. Here we discuss small deviations from the average rotation rate, evaluate polar motion, and discuss Ganymede's obliquity. We examine different time scales, from diurnal to long-period, and assess the potential of using rotation as probes of the interior structure. The ESA JUICE (JUpiter ICy moons Explorer) mission will accurately measure the rotation of Ganymede during its orbital phase around the satellite starting in 2032. We report on different theoretical aspects of the rotation for realistic models of the interior of Ganymede, include tidal deformations and take into account the low-degree gravity field and topography of Ganymede. We assess the advantages of a joint use of rotation and tides to constrain the satellite's interior structure, in particular its ice shell and ocean.Van Hoolst, TimMon, 25 Jan 2021 12:59:02 GMThttps://publi2-as.oma.be/record/51702020Geodesy at Mars: from gravity, rotation and tides to the deep interior of the red planet.
https://publi2-as.oma.be/record/5007
Dehant, VeroniqueSun, 22 Nov 2020 08:23:28 GMThttps://publi2-as.oma.be/record/50072020The Librations, Tides, and Interior Structure of Io.
https://publi2-as.oma.be/record/5004
Van Hoolst, TimSun, 22 Nov 2020 08:15:56 GMThttps://publi2-as.oma.be/record/50042020Contraindre la structure interne de Mars avec l'instrument LaRa
https://publi2-as.oma.be/record/4696
Péters, Marie-JulieWed, 29 Jan 2020 10:33:53 GMThttps://publi2-as.oma.be/record/46962019