Seminar - Measuring Earth’s Time-Variable Gravity with Future Satellite Constellations: From MAGIC to Orbiting Optical Clocks and Beyond - Sept. 4

Khosro Ghobadi-Far
Assistant Professor, Smead Aerospace
Friday, Sept. 4 | 10:40 A.M. | AERO 111

Abstract: Measuring temporal changes in Earth’s gravity field provides a unique way to monitor redistribution of water and ice associated with processes such as icesheet mass loss, groundwater depletion, and floods. The NASA GRACE (2002-2017) and GRACE Follow-On (2018-present) missions have demonstrated this capability by using ultra-precise inter-satellite ranging to track changes in the distance between two co-orbiting satellites. 

However, their ability to resolve smaller-scale and more rapidly changing signals is limited by a spatial resolution of about 300 km and typical monthly sampling. Future satellite gravimetry missions offer an exciting opportunity to overcome these limitations. 

In this talk, I will first demonstrate the potential of the future dual-pair MAGIC satellite constellation, consisting of the NASA polar GRACE-C pair and the ESA inclined NGGM pair, to improve spatial and temporal resolution of mass change estimates. I will then explore orbiting optical clocks as a new approach to satellite gravimetry and evaluate their performance for different satellite formation flying architectures. 

A comparison of optical-clock and inter-satellite ranging approaches, including their performance against MAGIC, will highlight the strengths and limitations of each technique and provide insights into promising architectures for future missions. These results highlight the potential of future satellite gravimetry to provide more detailed observations of Earth system dynamics at various spatial and temporal scales.

Bio: Dr. Khosro Ghobadi-Far is an Assistant Professor in the Ann and H. J. Smead Department of Aerospace Engineering Sciences and a Fellow of CIRES. His fundamental research focuses on modeling Earth’s gravity field using current and future satellite constellations, while his applied research focuses on remote sensing of freshwater resources. 

He received his B.S. in Civil Engineering-Geomatics from the University of Tabriz, an M.S. in Geodesy from the University of Tehran, and a Ph.D. in Geodesy from the University of Newcastle. He was a postdoctoral scholar at Virginia Tech before joining the University of Colorado Boulder.