This chapter reviews the present-day composition of the continental crust, the methods employed to derive these estimates, and the implications of the continental crust composition for the formation of the continents, Earth differentiation, and its geochemical inventories. We review the composition of the upper, middle, and lower continental crust. We then examine the bulk crust composition and the implications of this composition for crust generation and modification processes. Finally, we compare the Earth's crust with those of the other terrestrial planets in our solar system and speculate about what unique processes on Earth have given rise to this unusual crustal distribution.

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Composition of the Continental Crust

[1] The Shuttle Radar Topography Mission produced the most complete, highest-resolution digital elevation model of the Earth. The project was a joint endeavor of NASA, the National Geospatial-Intelligence Agency, and the German and Italian Space Agencies and flew in February 2000. It used dual radar antennas to acquire interferometric radar data, processed to digital topographic data at 1 arc sec resolution. Details of the development, flight operations, data processing, and products are provided for users of this revolutionary data set.

/pdf/the-shuttle-radar-topography-mission-4x49lt5xnj.pdf

The Shuttle Radar Topography Mission

Investigating soil moisture-climate interactions in a changing climate: A review

3.01 – Composition of the Continental Crust

[1] EGM2008 is a spherical harmonic model of the Earth's gravitational potential, developed by a least squares combination of the ITG-GRACE03S gravitational model and its associated error covariance matrix, with the gravitational information obtained from a global set of area-mean free-air gravity anomalies defined on a 5 arc-minute equiangular grid This grid was formed by merging terrestrial, altimetry-derived, and airborne gravity data Over areas where only lower resolution gravity data were available, their spectral content was supplemented with gravitational information implied by the topography EGM2008 is complete to degree and order 2159, and contains additional coefficients up to degree 2190 and order 2159 Over areas covered with high quality gravity data, the discrepancies between EGM2008 geoid undulations and independent GPS/Leveling values are on the order of ±5 to ±10 cm EGM2008 vertical deflections over USA and Australia are within ±11 to ±13 arc-seconds of independent astrogeodetic values These results indicate that EGM2008 performs comparably with contemporary detailed regional geoid models EGM2008 performs equally well with other GRACE-based gravitational models in orbit computations Over EGM96, EGM2008 represents improvement by a factor of six in resolution, and by factors of three to six in accuracy, depending on gravitational quantity and geographic area EGM2008 represents a milestone and a new paradigm in global gravity field modeling, by demonstrating for the first time ever, that given accurate and detailed gravimetric data, asingle global model may satisfy the requirements of a very wide range of applications

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2011JB008916

The development and evaluation of the Earth Gravitational Model 2008 (EGM2008)

A Technology Development, Infusion, and an interleaved joint cal/val opportunity plan is described for the VLBI GLOBAL OBSERVING SYSTEM (VGOS), and Earth Science satellite missions that measure water vapor such as Global Precipitation Measurement (GPM) Core Observatory that covers the Earth from 65°S to 65°N. The Jason Continuity of Service (Jason-CS) mission that will extend global sea-level records to 2030 and beyond is also a beneficiary and potential partner.The Space Geodesy Project (SGP) technique known as Very Long Baseline Interferometry (VLBI) is already deployed worldwide, and there are technology returns on investment to be gained by looking at the water vapor (wet) delay calibration in a 5year plan that serves to improve atmospheric models for Global Precipitation Measurement (GPM), Jason-CS, and the higher spatial resolution International Terrestrial Reference Frame (ITRF), a primary mission of SGP.

5 Year Technology Roadmap for VLBI Global Observing System (VGOS)

Using 4-way Doppler tracking with relay satellite OKINA, KAGUYA obtained the first precise gravity field of the lunar farside. Multi-frequency differential VLBI observation using OKINA and OUNA improved the accuracy of gravity, through precise determination of OKINA's orbit. The current gravity model is SGM100i involving VLBI data. Laser altimeter (LALT) on board KAGUYA obtained the first precise global topography of the Moon with range accuracy of 5m. The correlation of spherical harmonics coefficients between gravity and topography become higher than that of the previous model. Gravity signatures of far-side impact basins are mostly explained by topography except for the central high. Combined with topography data, we estimate Bouguer anomaly and the crustal thickness variation of the Moon.

The first precise global gravity and topography of the Moon by KAGUYA (SELENE) mission

In this work, we present a status update and results of the designated research and development VLBI Intensive program VGOS-INT-S, observed between MACGO12M and WETTZ13S for the rapid determination of the Earth's phase of rotation, expressed via UT1-UTC. The main novelty of these sessions is the use of a special observation strategy, rapidly alternating between high- and low-elevation scans, enabling an improved determination of delays caused by the neutral atmosphere. Since 2021, 25 Intensive sessions have been observed successfully. In early 2022, VGOS-INT-S was among the most accurate Intensive programs with an average formal error $\sigma_{UT1-UTC}$ of 3.1 $\mu$s and a bias w.r.t. IERS C04 of 1.1 $\mu$s. Later, the session performance decreased due to multiple technical difficulties.

VGOS VLBI Intensives between MACGO12M and WETTZ13S for the rapid determination of UT1-UTC

The Mercury Laser Altimeter, an instrument onboard
the MESSENGER spacecraft, is currently providing
precise, high-resolution measurements of the
topography of the northern hemisphere of Mercury as
the spacecraft executes its orbital mapping mission.
The altimeter data are contributing to studies of
planetary shape, crater and basin structure, tectonics,
volcanism and internal structure. Collectively these
observations will inform studies to reconstruct
Mercury’s geological and thermal evolution.

Orbital Observations of Mercury with the Mercury Laser Altimeter

This study focuses on utilizing the increasing availability of satellite trajectory data from global navigation satellite systemenabled low-Earth orbiting satellites and their precision orbit determination (POD) solutions to expand and refine thermospheric model validation capabilities. The research introduces an updated interface for the GEODYN-II POD software, leveraging highprecision space geodetic POD to investigate satellite drag and assess density models. This work presents a case study to examine five models (NRLMSIS2.0, DTM2020, JB2008, TIEGCM, and CTIPe) using precise science orbit (PSO) solutions of the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2). The PSO is used as tracking measurements to construct orbit fits, enabling an evaluation according to each model’s ability to redetermine the orbit. Relative in-track deviations, quantified by in-track residuals and root-mean-square errors (RMSe), are treated as proxies for model densities that differ from an unknown true density. The study investigates assumptions related to the treatment of the drag coefficient and leverages them to eliminate bias and effectively scale model density. Assessment results and interpretations are dictated by the timescale at which the scaling occurs. JB2008 requires the least scaling ( ̃-23%) to achieve orbit fits closely matching the PSO within an in-track RMSe of 9 m when scaled over two weeks and 4 m when scaled daily. The remaining models require substantial scaling of the mean density offset ( ̃30-75%) to construct orbit fits that meet the aforementioned RMSe criteria. All models exhibit slight over or under sensitivity to geomagnetic activity according to trends in their 24-hour scaling factors.

Frank G. Lemoine

Papers

5 Year Technology Roadmap for VLBI Global Observing System (VGOS)

The first precise global gravity and topography of the Moon by KAGUYA (SELENE) mission

VGOS VLBI Intensives between MACGO12M and WETTZ13S for the rapid determination of UT1-UTC

Orbital Observations of Mercury with the Mercury Laser Altimeter

Assessing Thermospheric Neutral Density Models using GEODYN’s Precision Orbit Determination