scholarly journals The Ganymede Laser Altimeter (GALA) for the Jupiter Icy Moons Explorer (JUICE): Mission, science, and instrumentation of its receiver modules

2021 ◽  
Author(s):  
Keigo Enya ◽  
Masanori Kobayashi ◽  
Jun Kimura ◽  
Hiroshi Araki ◽  
Noriyuki Namiki ◽  
...  
Keyword(s):  
Laser Altimeter ◽  
Icy Moons

scholarly journals Measuring Ganymede’s Librations with Laser Altimetry

Geosciences ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 320 ◽  
Author(s):  
Gregor Steinbrügge ◽  
Teresa Steinke ◽  
Robin Thor ◽  
Alexander Stark ◽  
Hauke Hussmann
Keyword(s):  
Expansion Method ◽  
Laser Altimetry ◽  
Satellite Mission ◽  
Laser Altimeter ◽  
Radio Science ◽  
Icy Moons ◽  
B Splines ◽  
Subsurface Ocean ◽  
The Individual ◽  
Ice Shell

Jupiter’s moon Ganymede might be in possession of a subsurface ocean located between two ice layers. However, from Galileo data it is not possible to unambiguously infer the thickness and densities of the individual layers. The upcoming icy satellite mission JUICE (JUpiter ICy moons Explorer) will have the possibility to perform more detailed investigations of Ganymede’s interior structure with the radio science experiment 3GM and the GAnymede Laser Altimeter (GALA). Here we investigate the possibility to derive the rotational state of the outer ice shell by using topography measured by laser altimetry. We discuss two different methods to invert synthetic laser altimetry data. Method 1 is based on a spherical harmonics expansion and Method 2 solves for B-splines on a rectangular grid. While Method 1 has significant limitations due to the omission of high degrees of the global expansion, Method 2 leads to stable results allowing for an estimate of the in-orbit measurement accuracy. We estimate that GALA can measure the amplitude of Ganymede’s librations with an accuracy of 2.5–6.6 μ rad (6.6–17.4 m at the equator). This allows for determining the thickness of an elastic ice shell, if decoupled from the deeper interior by a subsurface ocean, to about an accuracy of 24–65 km.

Exploring the icy moons of Jupiter: The Ganymede Laser Altimeter (GALA) for ESA’s JUICE Mission

2020 ◽  
Author(s):  
Fabian Luedicke ◽  
Hauke Hussmann ◽  
Kay Lingenauber ◽  
Reinald Kallenbach ◽  
Keigo Enya ◽  
...  
Keyword(s):  
Laser Altimeter ◽  
Icy Moons

scholarly journals Tides on Jupiter's moon Ganymede and their relation to its internal structure

2016 ◽  
Vol 95 (2) ◽  
pp. 191-201 ◽  
Author(s):  
H.M. Jara-Orué ◽  
B.L.A. Vermeersen
Keyword(s):  
Radial Deformation ◽  
Laser Altimeter ◽  
Radio Science ◽  
Icy Moons ◽  
Surface Displacements ◽  
Subsurface Ocean ◽  
Explorer Mission ◽  
Jovian System ◽  
Ice Shell ◽  
Tidal Response

AbstractOne of the major scientific objectives of ESA's JUICE (JUpiter ICy moons Explorer) mission, which is scheduled for launch in 2022 and planned to arrive at the Jovian system in 2030, is to characterise the internal water ocean and overlying ice shell of Jupiter's largest moon Ganymede. As part of the strategy developed to realise this objective, the tidal response of Ganymede's interior will be constrained by JUICE's measurements of surface displacements (by the Ganymede Laser Altimeter (GALA) instrument) and variations in the gravitational potential (by the 3GM radio science package) due to the acting diurnal tides. Here we calculate the tidal response at the surface of Ganymede for several plausible internal configurations in order to analyse the relation between the tidal response and the geophysical parameters that characterise Ganymede's interior. Similarly to the case of Jupiter's smallest icy satellite Europa, the tidal response of Ganymede in the presence of a subsurface ocean, which could be as large as about 3.5 m in terms of the induced radial deformation, mostly depends on the structural (thickness, density) and rheological (rigidity, viscosity) properties of the ice-I shell. Nevertheless, the dependence of the tidal response on several geophysical parameters of the interior, in particular on the thickness and rigidity of the ice-I shell, does not allow for the unambiguous determination of the shell thickness from tidal measurements alone. Additional constraints could be provided by the measurement of forced longitudinal librations at the surface, as their amplitude is more sensitive to the rigidity than to the thickness of the shell.

scholarly journals Alignment determination of the Hayabusa2 laser altimeter (LIDAR)

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Hirotomo Noda ◽  
Hiroki Senshu ◽  
Koji Matsumoto ◽  
Noriyuki Namiki ◽  
Takahide Mizuno ◽  
...  
Keyword(s):  
Altimeter Data ◽  
Gravity Assist ◽  
Laser Altimeter ◽  
Trajectory Error ◽  
Flight Data ◽  
Camera Image ◽  
Operation Period ◽  
The Cross ◽  
Along Track

AbstractIn this study, we determined the alignment of the laser altimeter aboard Hayabusa2 with respect to the spacecraft using in-flight data. Since the laser altimeter data were used to estimate the trajectory of the Hayabusa2 spacecraft, the pointing direction of the altimeter needed to be accurately determined. The boresight direction of the receiving telescope was estimated by comparing elevations of the laser altimeter data and camera images, and was confirmed by identifying prominent terrains of other datasets. The estimated boresight direction obtained by the laser link experiment in the winter of 2015, during the Earth’s gravity assist operation period, differed from the direction estimated in this study, which fell on another part of the candidate direction; this was not selected in a previous study. Assuming that the uncertainty of alignment determination of the laser altimeter boresight was 4.6 pixels in the camera image, the trajectory error of the spacecraft in the cross- and/or along-track directions was determined to be 0.4, 2.1, or 8.6 m for altitudes of 1, 5, or 20 km, respectively.

scholarly journals Geodesy, Geophysics and Fundamental Physics Investigations of the BepiColombo Mission

2021 ◽  
Vol 217 (2) ◽  
Author(s):  
Antonio Genova ◽  
Hauke Hussmann ◽  
Tim Van Hoolst ◽  
Daniel Heyner ◽  
Luciano Iess ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Surface Composition ◽  
Current Knowledge ◽  
Laser Altimeter ◽  
Fundamental Physics ◽  
Radio Science ◽  
Nasa Mission ◽  
Gravity And Magnetic ◽  
Working Groups ◽  
Science Investigations

AbstractIn preparation for the ESA/JAXA BepiColombo mission to Mercury, thematic working groups had been established for coordinating the activities within the BepiColombo Science Working Team in specific fields. Here we describe the scientific goals of the Geodesy and Geophysics Working Group (GGWG) that aims at addressing fundamental questions regarding Mercury’s internal structure and evolution. This multidisciplinary investigation will also test the gravity laws by using the planet Mercury as a proof mass. The instruments on the Mercury Planetary Orbiter (MPO), which are devoted to accomplishing the GGWG science objectives, include the BepiColombo Laser Altimeter (BELA), the Mercury orbiter radio science experiment (MORE), and the MPO magnetometer (MPO-MAG). The onboard Italian spring accelerometer (ISA) will greatly aid the orbit reconstruction needed by the gravity investigation and laser altimetry. We report the current knowledge on the geophysics, geodesy, and evolution of Mercury after the successful NASA mission MESSENGER and set the prospects for the BepiColombo science investigations based on the latest findings on Mercury’s interior. The MPO spacecraft of the BepiColombo mission will provide extremely accurate measurements of Mercury’s topography, gravity, and magnetic field, extending and improving MESSENGER data coverage, in particular in the southern hemisphere. Furthermore, the dual-spacecraft configuration of the BepiColombo mission with the Mio spacecraft at higher altitudes than the MPO spacecraft will be fundamental for decoupling the internal and external contributions of Mercury’s magnetic field. Thanks to the synergy between the geophysical instrument suite and to the complementary instruments dedicated to the investigations on Mercury’s surface, composition, and environment, the BepiColombo mission is poised to advance our understanding of the interior and evolution of the innermost planet of the solar system.

Description of the Mass Spectrometer for the Jupiter Icy Moons Explorer Mission

2021 ◽  
Author(s):  
Martina Fohn ◽  
Andre Galli ◽  
Audrey Vorburger ◽  
Marek Tulej ◽  
Davide Lasi ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Icy Moons ◽  
Explorer Mission
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