Geodesy and Geophysics Working Group

Primary Questions

• What is the thickness and density of the crust?

• What has shaped the surface of Mercury?

• What are the relative roles of tectonism, volcanism and impacts with respect to Mercury’s surface?

• How strong was the contraction and when did it occur?

• What are the regions in the southern hemisphere that present crustal magnetization?

• What is the structure and rheology (i.e, viscosity, rigidity) of the mantle?

• What is the size, density and physical state (liquid, solid) of the core?

• What is the relative amount of volatiles in the core?

• What is Mercury’s deviation from hydrostatic state?

• What is the level of precision of Einstein’s theory of General Relativity?

• Are any violations of the Strong Equivalence Principle (SEP) in the weak-field?

• How does the solar inter- nal evolution affect planetary ephemerides?

• How and when did Mercury get captured in the 3:2 spin-orbit resonance?

Science Objectives

• Local and global mapping of gravity and topographic relief
• Local and global measurements of the magnetic field
• Accurate global determination of Mercury’s degree 2 shape and gravity
• Gravitational and surface tides measured by the Love numbers k₂ and h₂, including phase lags.

• Polar moment of inertia of the outer layers (crust and mantle) by measuring librations with altimetric data.

• Internal magnetic field magnitude and structure (i.e., dipole and equatorial offset)

• Accurate measure of the offset between the center of mass and the center of figure

• Mercury rotation from altimetry and orbital period from radio science

• Parameterized PostNewtonian (PPN) γ, β,  α₁, and α₂. Nordvedt's parameter η.

• Sun’s J₂, and GM and its temporal variation due to solar mass loss rate.

Meetings (most recent first)

Virtual Meetings: 

1^st GGWG virtual meeting on Friday 18 June. Two science talks: 

• Jurrien S. Knibbe, "Mercury's Interior Structure Constrained by Density and P-Wave Velocity Measurements of Liquid Fe-Si-C Alloys"

• Gregor Steinbrügge "Challenges on Mercury's Interior Structure Posed by the New Measurements of its Obliquity and Tides"" 

and final discussion.

2^nd GGWG virtual meeting on Friday 24 September. Two science talks: 

• Csilla Orgel, "Re‐examination of the population, stratigraphy, and sequence of Mercurian basins: Implications for Mercury's early impact history"

• Nicola Tosi "Inferring Mercury’s evolution from impact basins and crustal thickness"" 

and final discussion.

3^rd GGWG virtual meeting on Friday 26 November. Two science talks: 

• Valentina Galluzzi, "Asymmetric Magnetic Anomalies Over Young Impact Craters on Mercury"

• Alain Plattner "Mercury's Northern Rise Core‐Field Magnetic Anomaly"" 

and final discussion.

4^th GGWG virtual meeting on Friday 21 January 2022. Two science talks: 

• Agnes Fienga, "INPOP Planetary Ephemerides and BepiColombo : from Orbit Improvements to GR and Alternative Theories tests"

• Clifford M. Will, "Zombie Alert!  Solar System Tests of General Relativity are Still Alive"" 

and final discussion.

5^th GGWG virtual meeting on Friday 25 March 2022. Two science talks: 

• Mathieu Dumberry, "The influence of a fluid core and a solid inner core on the Cassini state of Mercury"

• Sander Goossens, “Evaluation of recent measurements of Mercury’s moments of inertia and tides using a comprehensive Markov Chain Monte Carlo method" 

and final discussion.

6^th GGWG virtual meeting on Friday 17 June 2022. One science talk: 

• Ingo Wardinski, "Mercury's Interior Structure Inferred from Magnetic Field Measurements"

and final discussion.

GGWG meeting on July 11 June 2022 with the following agenda: 

• 2:00-2:20pm BELA report + 10-min discussion
• 2:30-2:50pm ISA report + 10-min discussion
• 3:00-3:20pm MORE report + 10-min discussion
• 3:30-3:50pm MPO-MAG report + 10-min discussion
• 4:00-5:00pm Short presentations on the first results with Venus and Mercury flybys

^7th GGWG virtual meeting on Friday 24 March 2023. The science talk: 

• Laura Lark, "Sulfides in Mercury's Mantle: Implications for Mercury's Interior as Interpreted From Moment of Inertia"

• Sophia Zomerdijk-Russell, "Modeling the Time-Dependent Magnetic Fields That BepiColombo Will Use to Probe Down Into Mercury's Mantle"

and final discussion.

^8th GGWG virtual meeting on Friday 9 June 2023. The meeting is focused on: 

• BepiColombo Perihelion Science Strategy

• TMX

and final discussion.

^9th GGWG virtual meeting on Friday 15 November 2024. The meeting is focused on: 

• Geophysical measurements derived from MESSENGER data analysis.

• Interior modeling and experimental measurements.

• General discussion on mission-related issues.

Resources

• LiveLink Geodesy and Geophysics Working Group document repository ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​