The MARVEL gravity and reference frame mission proposal

Mass Change ◽

Earth System ◽

Polar Orbit ◽

Laser Tracking ◽

The Earth ◽

Gravity Sensor ◽

Mass Transfers ◽

Leo Satellite

The "MARVEL gravity and reference frame mission" proposal has been selected by CNES for the start of a pre-phase A study.&#160; MARVEL aims at reaching in one single mission two major and complementary goals: - The monitoring of mass transfers within the Earth system with increased precision, - The realization, at the millimeter level, of the terrestrial reference frame.In the nominal configuration, a LEO satellite (400 - 450 km) in polar orbit, acting as a gravity sensor, performs optical ranging measurements on two MEO satellites (7000 km) orbiting on the same plane. The MEO satellites are equiped with the four geodetic techniques (GNSS, SLR, DORIS, VLBI), in order to meet the GGOS Earth reference frame accuracy objectives.We also propose two alternative (and less costly) configurations, where only the first goal is fully reached: - one by replacing the MEO satellites by two or more cubesats on the same orbit, - the second one by using specially equipped GNSS satellites as targets for the LEO optical ranging measurements.In any case, the goal of monitoring mass change with enhanced precision is attained through the use of high-low SST laser tracking.We will present in detail the different configurations proposed and present the simulation plan for this pre-phase A study.

A Terrestrial Reference Frame realised on the observation level using a GPS-LEO satellite constellation

Journal of Geodesy ◽

10.1007/s00190-018-1121-7 ◽

2018 ◽

Vol 92 (11) ◽

pp. 1299-1312 ◽

Cited By ~ 2

Author(s):

Daniel Koenig

Keyword(s):

Reference Frame ◽

Observation Level ◽

Satellite Constellation ◽

Leo Satellite Constellation ◽

Leo Satellite

On the Adoption of a Terrestrial Reference Frame

International Astronomical Union Colloquium ◽

10.1017/s0252921100081197 ◽

1980 ◽

Vol 56 ◽

pp. 145-153

Author(s):

Dennis D. McCarthy

Keyword(s):

Reference Frame ◽

Polar Motion ◽

Center Of Mass ◽

Fixed Frame ◽

The Earth ◽

International Polar ◽

Definition Of ◽

Observational Techniques ◽

Fixed System

AbstractThe report of the IAU Working Group on Nutation endorsed by Commissions 4, 8, 19 and 31 at the 1979 General Assembly points out that “… the complete theory of the general nutational motion of the Earth about its center of mass may be described by the sum of two components, astronomical nutation, commonly referred to as nutation, which is nutation with respect to a space-fixed coordinate system, and polar motion, which is nutation with respect to a body-fixed system …”. Unlike the situation for the space-fixed frame, there is not an adequate, formally accepted, body-fixed system for this purpose. The Conventional International Origin (CIO) as it is presently defined is no longer acceptable because of recent improvements in observational techniques. The effective lack of this type of terrestrial reference frame limits the complete description of the general nutational motion of the Earth. In the absence of a terrestrial reference frame suitable for specifying the orientation of the Earth, it is suggested that a body-fixed system could be represented formally in a manner analogous to that used to represent the space-fixed frame. This procedure would be quite similar to methods employed currently by the International Polar Motion Service and the Bureau International de l’Heure, and would allow for the use of observations from new techniques in the definition of a terrestrial reference frame to be used to specify the complete nutational motion of the Earth.

The Estimation and Prediction of Geocenter Motion Based on GNSS Weekly Solutions

10.5194/egusphere-egu2020-2504 ◽

2020 ◽

Author(s):

Chunmei Zhao ◽

Lingna Qiao ◽

Tianming Ma

Keyword(s):

Reference Frame ◽

Prediction Accuracy ◽

Center Of Mass ◽

Science Research ◽

Small Contribution ◽

The Earth ◽

Term Prediction ◽

Geocenter Motion

The development of satellite space geodesy technology makes the establishment of global terrestrial reference frame based on the Earth&#8217;s center of mass become reality. Precise and stable terrestrial reference frame is the foundation of the Earth science research, while determination and analysis of the position of the Earth's center of mass and its change is an important part to build high precision terrestrial reference frame. Based on GNSS weekly solutions provided by IGS, the geocenter motion (GM) time series between 2007 and 2017 are obtained by means of net translation method. Then the amplitude of the annual term of geocentric motion is 2.27mm, 1.84mm and 2.13mm in the direction of X, Y and Z respectively, and the amplitude of the half-year term is 0.1mm, 0.20mm and 0.15mm respectively. In addition, some other inter-annual changes with relatively small contribution rate are found. Finally, in order to get reliable GM prediction ,two kinds of methods are used, which are ARMA and SSA+ARMA. In the short-term prediction, the accuracy of the two methods is the same, both can reach the millimeter level of prediction accuracy, but SSA+ARMA is more stable. SSA+ARMA algorithm is much better in the medium and long-term scale, and it can provide 1mm medium term prediction accuracy and 1.5mm long term prediction accuracy.

Unconstrained Estimation of VLBI Global Observing System Station Coordinates

Advances in Geosciences ◽

10.5194/adgeo-55-23-2021 ◽

2021 ◽

Vol 55 ◽

pp. 23-31

Author(s):

Markus Mikschi ◽

Johannes Böhm ◽

Matthias Schartner

Keyword(s):

Reference Frame ◽

Baseline Length ◽

Radio Telescopes ◽

Earth Orientation Parameters ◽

The Earth ◽

Station Coordinates ◽

International Vlbi Service ◽

Orientation Parameters

Abstract. The International VLBI Service for Geodesy and Astrometry (IVS) is currently setting up a network of smaller and thus faster radio telescopes observing at broader bandwidths for improved determination of geodetic parameters. However, this new VLBI Global Observing System (VGOS) network is not yet strongly linked to the legacy S/X network and the International Terrestrial Reference Frame (ITRF) as only station WESTFORD has ITRF2014 coordinates. In this work, we calculated VGOS station coordinates based on publicly available VGOS sessions until the end of 2019 while defining the geodetic datum by fixing the Earth orientation parameters and the coordinates of the WESTFORD station in an unconstrained adjustment. This set of new coordinates allows the determination of geodetic parameters from the analysis of VGOS sessions, which would otherwise not be possible. As it is the concept of VGOS to use smaller, faster slewing antennas in order to increase the number of observations, shorter estimation intervals for the zenith wet delays and the tropospheric gradients along with different relative constraints were tested and the best performing parametrization, judged by the baseline length repeatability, was used for the estimation of the VGOS station coordinates.

Relativistic effects in geodynamics

10.1017/s0074180900148260 ◽

1986 ◽

Vol 114 ◽

pp. 241-253 ◽

Cited By ~ 2

Author(s):

C. Boucher

Keyword(s):

Gravity Field ◽

Reference Frame ◽

Relativistic Effects ◽

The Earth ◽

Lunar Laser ◽

Time Variations ◽

Satisfactory Answer ◽

Definition Of ◽

Theories Of Gravitation

Geodesy has now reached such an accuracy in both measuring and modelling that time variations of the size, shape and gravity field of the Earth must be basically considered under the name of Geodynamics. The objective is therefore the description of point positions and gravity field functions in a terrestrial reference frame, together with their time variations.For this purpose, relativistic effects must be taken into account in models. Currently viable theories of gravitation such as Einstein's General Relativity can be expressed in the solar system into the parametrized post-newtonian (PPN) formalism. Basic problems such as the motion of a test particle give a satisfactory answer to the relativistic modelling in Geodynamics.The relativistic effects occur in the definition of a terrestrial reference frame and gravity field. They also appear widely into terrestrial (gravimetry, inertial techniques) and space (satellite laser, Lunar laser, VLBI, satellite radioelectric tracking …) measurements.

Concept for Reference Frames in Geodesy and Geodynamics: The Reference Directions

10.1017/s0074180900036202 ◽

1979 ◽

Vol 82 ◽

pp. 175-175

Author(s):

Erik W. Grafarend ◽

Ivan I. Müller ◽

Haim B. Papo ◽

Burkhard Richter

Keyword(s):

Reference Frame ◽

Reference Frames ◽

Current Knowledge ◽

Observation Point ◽

Terrestrial Reference Frames ◽

Space And Time ◽

The Earth ◽

Least Squares Adjustment ◽

Rigid Earth

Modern high accuracy measurements of the non-rigid Earth are to be referred to four-dimensional, i.e., time and space-dependent reference frames. Geodynamics phenomena derived from these measurements are to be described in a terrestrial reference frame in which both space and time-like variations can be monitored. Existing conventional terrestrial reference frames (e.g., CIO, BIH) are no longer suitable for such purposes.The ultimate goal of this study is the establishment of a reference frame, moving with the Earth in some average sense, in which the geometric and dynamic behavior of the Earth can be monitored, and whose motion with respect to inertial space can also be determined.The study is conducted in two parts. In the first part problems related to reference directions are investigated, while the second part deals with positions, i.e., with reference origins. Only the first part is treated in this paper.The approach is based on the fact that reference directions at an observation point on the Earth's surface are defined by four fundamental vectors (gravity, Earth rotation, etc.), both space and time variant. These reference directions are interrelated by angular parameters, also derived from the fundamental vectors. The interrelationships between these space and time-variant angular parameters are illustrated in a commutative diagram–tower of triads, which makes the derivation of the various relationships convenient.In order to determine the above parameters from observations (e.g., laser ranging, VLBI) using least squares adjustment techniques, a model tower of triads is also presented to allow the formation of linear observation equations. Although the model tower is also space and time variant, these variations are described by adopted parameters representing our current knowledge of the Earth. For details, see Bulletin Géodésique, end of 1978.

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

The determination of the fluctuations in the rotation of the Earth

10.1098/rsta.1984.0085 ◽

1984 ◽

Vol 313 (1524) ◽

pp. 85-94 ◽

Cited By ~ 3

Keyword(s):

Reference Frame ◽

Quality Data ◽

Operational Experience ◽

Data Set ◽

The Earth ◽

New Space ◽

Rotation Of The Earth ◽

International Services

In recent years new space techniques have been used to determine with higher precision the fluctuations in the rate of rotation of the Earth and in the motion of the pole of rotation with respect to the conventional terrestrial reference frame. The international MERIT-COTES programme of observation and analysis is now in progress and is providing a high-quality data set for use in the study of the nature and causes of the fluctuations and in the determination of the relationships between the reference systems of the different techniques. The results and operational experience gained will be reviewed to provide a basis for recommendations about the future international services for Earth-rotation and for the establishment and maintenance of a new terrestrial reference frame.

Realization of a Regional Terrestrial Reference Frame: A GPS Campaign

10.1017/s0074180900173668 ◽

1993 ◽

Vol 156 ◽

pp. 432-432

Author(s):

Ziqing Wei

Keyword(s):

Reference Frame ◽

Relative Positioning ◽

Gps Positioning ◽

The Earth ◽

The Absolute ◽

Point Positioning ◽

Basic Approaches

A terrestrial reference frame can be defined by the coordinates of a set of stations on the surface of the earth. It is possible to realize a reference frame through the GPS positioning. In this sense two basic approaches are available to realizing a terrestrial reference frame using GPS: absolute and relative. By the absolute approach we mean the point positioning, whereas by the relative approach is meant the relative positioning. At the present day the absolute approach should realize a reference frame at a meter or submeter level precision. By contrast, the relative approach could realize a reference frame with a centimeter or even better precision.

The Contribution of the IERS to Astrophysics and Geodynamics

10.1017/s0074180900173619 ◽

1993 ◽

Vol 156 ◽

pp. 406-406

Author(s):

M. Feissel ◽

Yaroslav Yatskiv

Keyword(s):

Reference Frame ◽

Global Positioning System ◽

International Earth Rotation Service ◽

Earth Orientation Parameters ◽

Long Baseline ◽

The Earth ◽

Global Positioning ◽

Orientation Parameters ◽

Celestial Reference Frame

The International Earth Rotation Service (IERS) maintains a celestial reference frame and a terrestrial reference frame based on observations in Very Long Baseline radio Interferometry, Lunar and Satellite Laser Ranging, and Global Positioning System, as well as a time series of the Earth Orientation Parameters in a system that is consistent at the level of 0.001″.

Essential Geodetic Variables: Earth Orientation Parameters

10.5194/egusphere-egu2020-2434 ◽

2020 ◽

Author(s):

Richard Gross

Keyword(s):

Reference Frame ◽

Temporal Resolution ◽

Earth Rotation ◽

International Association ◽

Global Navigation Satellite Systems ◽

Earth System ◽

Earth Orientation Parameters ◽

Earth Orientation ◽

The Earth ◽

Orientation Parameters

The Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG) provides the basis on which future advances in geosciences can be built. By considering the Earth system as a whole (including the geosphere, hydrosphere, cryosphere, atmosphere and biosphere), monitoring Earth system components and their interactions by geodetic techniques and studying them from the geodetic point of view, the geodetic community provides the global geosciences community with a powerful tool consisting mainly of high-quality services, standards and references, and theoretical and observational innovations. A new initiative within GGOS is to define Essential Geodetic Variables. Essential Geodetic Variables (EGVs) are observed variables that are crucial (essential) to characterizing the geodetic properties of the Earth and that are key to sustainable geodetic observations. Once a list of EGVs has been determined, requirements can be assigned to them such as the accuracy with which the variables need to be determined, their spatial and temporal resolution, latency, etc. These requirements on the EGVs can then be used to assign requirements to EGV-dependent products like the terrestrial reference frame. The EGV requirements can also be used to derive requirements on the systems that are used to observe the EGVs, helping to lead to a more sustainable geodetic observing system for reference frame determination and numerous other scientific and societal applications.For the Earth's rotation, the essential variables can be considered to be the five Earth orientation parameters (EOPs), namely, the x- and y-components of polar motion (xp, yp), the x- and y-components of nutation/precession (X, Y), and the spin parameter UT1. Related to these five Essential Earth Rotation Variables are the sub-variables of their time rates-of-change and the derived variables of the excitation functions (&#967;x, &#967;y, and length-of-day). The Essential Earth Rotation Variables are currently observed by the operational techniques of lunar and satellite laser ranging, very long baseline interferometry, global navigation satellite systems, and Doppler orbitography and radiopositioning integrated by satellite. In the future, the emerging techniques of ring laser gyroscopes and superfluid helium gyroscopes can be expected to routinely observe parameters related to the Essential Earth Rotation Variables. The GGOS requirements on the five Essential Earth Rotation Variables (that is, on the five EOPs) are "ERP-001-EOP: Earth Orientation Parameters will be determined with an accuracy of 1 mm, a temporal resolution of 1 hour, and a latency of 1 week; near real-time determinations of the Earth Orientation Parameters will be determined with an accuracy of 3 mm" (Plag and Pearlman, 2009, p. 223). Currently, the best-determined EOPs have an accuracy of about 1 mm, a temporal resolution of about 1 day, and a latency of about 2 weeks (Ray et al., 2017; http://www.igs.org/products). Thus, while the GGOS accuracy requirement on the Essential Earth Rotation Variables is currently being met, at least for some of the variables, the GGOS resolution and latency requirements are not being met.