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Dr. John Ries
RESEARCH INTERESTS
Precision Orbit Determination, Space Geodesy, Global Reference Frames, Satellite Laser Ranging (SLR), Relativity.
CURRENT RESEARCH THRUSTS (October 2018)
- Satellite Geodesy
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- Precision orbit determination in support of mm-level positioning with SLR
- Determine reliable estimates of geocenter motion from SLR
- Investigate the cause of the persistent frame scale offset between SLR and VLBI
- Investigate limitations to the determination of the Earth’s gravitational constant from SLR
- Improve the processing of SLR data by refining estimates of range and timing biases in the data
- Global gravity model determination from space, with additional emphasis on the variations in the lowest degree coefficients
- Relativity
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- Continue to improve the test of the General Relativity prediction of the Lense-Thirring effect on satellite orbits using SLR and GRACE gravity models
ACTIVE CONTRACT/GRANTS
MEaSUREs (https://podaac.jpl.nasa.gov/) - Through the Making Earth Science Data Records for Use in Research Environments Program, NASA is continuing its commitment to expand understanding the Earth system using consistent records of Earth science data products. This effort provides medium and long-term time series of the low-degree geopotential coefficients .
Augmenting GRACE and GRACE Follow-on with Long Wavelength Variations of the Earth's Gravity Field from Satellite Laser Ranging Data (ftp://podaac.jpl.nasa.gov/allData/grace/docs/TN-11_C20_SLR.txt) - This effort provides monthly C20 coefficient and geocenter motion to supplement GRACE Level-2 products. Because long-period variations tend to corrupt the estimates of C20 from GRACE, an independent and more accurate estimate derived using SLR has been essential for the best use of the GRACE science products.
McDonald Space Geodesy Services and Data Analysis (https://www.csr.utexas.edu/mlrs/ - This effort focuses on the quality of the International Laser Ranging Service network tracking data in general as well as the specific data quality provided by the McDonald Laser Ranging Station (MLRS).