Gravity and precisE ORBit determination system

GEORB is a software package for Precise Orbit Determination (POD) of Low Earth Orbiters (LEOs) and satellite gravity missions, gravity field recovery and design of future space missions.

Released as open source in 2022 while it has been developed by Thomas since 2007.

GEORB has supported the Gravity Recovery And Climate Experiment (GRACE), and Gravity Field and Steady-State Ocean Circulation (GOCE) missions. The current release delivers data products of precise orbits, calibrated accelerometer data and gravity field models for the GRACE Follow-On mission launched by NASA and GFZ in 2018.

Data Products (major):

• Precise Orbit data
• Gravity Field models
• Calibration of on-board accelerometer data

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Cite GEORB:

Thomas Loudis Papanikolaou (2023). GEORB: Release for precise orbit determination of low Earth orbiters and satellite gravity missions, Software Impacts, doi: https://doi.org/10.1016/j.simpa.2023.100502.

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Data Products:

Thomas Loudis Papanikolaou (2023b). Precise orbit data and Gravity field models for GRACE Follow-On mission. VBN. doi: https://doi.org/10.5278/8b4d5e8d-0010-4461-a58e-b5b39637bd51

Thomas Loudis Papanikolaou (2023c). DORUS time-variable gravity field models. VBN. doi: https://doi.org/10.5278/b9644d2d-697f-4b73-bf73-c79582e6572b

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Guide: Instructions for configuration and data requirements

GEORB can be executed through applying the following steps:

1. Set the configuration files located in the folder '../config/'. Description of the configurable parameters is provided within the config files.

main_config.in :: Master Configuration file for setting the basic modes

orbit_model.in :: Configuration file for the orbit modelling and methods

ic_config.in :: Initial Consditions file for setting the list of the Satellites/Objects along with the Initial Epoch per object

cd config/
edit main_config.in
cd ..

cd config/
edit orbit_model.in
cd ..

cd config/
edit ic_config.in
cd ..

2. Download the models' data required by executing the script file georb_data_models.m stored in the folder '../scripts/'. The data will be save in the folder '../data/'.

cd scripts/
georb_data_models

3. Satellite Missions data are required when operating in the 'orbit missions mode' and other modes requiring satellite data.

The current release supports the GRACE missions.

Data of the GRACE Follow-On and GRACE missions can be accessed from the official data centers servers as follows:

JPL/NASA: https://podaac.jpl.nasa.gov/GRACE-FO

GFZ: https://isdc.gfz-potsdam.de/grace-fo-isdc/

The GRACE/GRACE-FO data need to be stored in the folder '../data/'

4. Execute the GEORB main script georb_main.m in the folder '../main/'

cd main/
georb_main

5. The computed restuls are written to output data (ascii) files saved in the folder '../data_output/'

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