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Dr. Srinivas Bettadpur
GENERAL RESEARCH INTERESTS
Space Geodesy and Spaceflight Mechanics; Earth System Science from space.
CURRENT RESEARCH THRUSTS (January 2022)
Some are mature, others are nascent - all of these feature dynamics, modeling, estimation and interpretation...
- Dynamics of the Earth system from satellite gravity measurements
- Solve the challenges of mass flux estimation, validation and interpretation in near real-time
- Use of the global, space-based methods to solving problems at the smallest regional scales
- Best representation of gravity information for diverse Earth sciences & applications
- What does this tell us about the dynamics of the Earth system?
- Global Space Geodesy and Orbit Determination
- Global reference frames for precision Earth system science and for Positioning, Navigation and Timing (PNT).
- Do the next generation needs require that we integrate Terrestrial and Lunar geodesy? What challenges remain?
- Can we achieve the 1-mm precision orbits? How can we even tell?
- Regional Applications of Global Methods
- Using remote sensing for understanding the water cycle in Texas and northern Mexico
- A Gulf of Mexico reference frame for natural (inundation) hazards
- How do we apply tomorrow's technologies for space-based gravity & Earth system science?
- Explore innovative concepts and methods for gravity field sensing at all spatio-temporal scales from space.
- Use of laser interferometry, cold-atom technologies, precise clocks, drag-free flight, etc...
ACTIVE RESEARCH PROJECTS
Gravity Field & Earth System Science: Projects in this theme are intended to seamlessly bridge between science and space mission architecture.
The Next Mass Change Mission(s) NASA has initiated pre-Phase-A studies to evaluate options for the next mission intended to measure mass change through global measurements of gravity. Such a mission responds to the consensus community needs articulated in the 2018 Earth Science Decadal Survey. At the same time, NASA and ESA together explore constellation gravity mission concepts to obtain order of magnitude improvements in mass change measurements with twin pair mission concepts. We join in these activities as we study the links between theory, observation concepts, and technology trade studies for the full range of gravity field (and mass change) observation concepts.
GRACE Follow-On (https://gracefo.jpl.nasa.gov/) - The NASA/GFZ GRACE-FO mission launched on May 22, 2018. We are now focused on research into the estimation of Earth gravity models from GRACE-FO microwave and laser-ranging interferometer data; assessing its quality and continuity with respect to the 15-year data record from GRACE-FO; and improvements of methods and models for Earth gravity field determination in near real time. An important component of this research is also the development and operation of the Global Flux eXploratory (GFX), where we run the MITgcm, forced by CFS/GDAS atmospheric fields to reproduce the non-tidal variations in the atmosphere and ocean, for real-time applications.
Cold-Atom Interferometry & the Gravity Field -These projects study the development of science applications and space mission architectures for mass change measurement using cold atom interferometer techniques. Two projects fund this activity - First is a JPL/SURP grant, now in its third year, which focuses on architectural technical trade studies, and science applications. The Second is a NASA Earth Science Instrument Incubator Program (IIP) slated to start in June 2022, for TRL advancement of the atom interferometric gravity gradiometer. Of particular interest is research into the angular motion estimation and control for separating gradients of gravitational and inertial accelerations. We also continue to study this technique for applications other than mass change measurement.
Reference Frames and Space Geodesy: This theme addresses precise positioning for local and global reference frames, for driving applications in sea-level science and precision PNT. Ongoing research includes metrology, field work, and analytical science components. This work is intimately associated with the establishment and growth of the McDonald Geodetic Observatory (MGO - https://www.csr.utexas.edu/mgo/).
Terrestrial Reference Frames (TRF) and mm-Metrology at McDonald Observatory -This project is currently funded under the NGA University Research Initiative (NURI, 2020-22), studying scale instability in multi-technique reference frames, and related topics in fundamental science and metrological techniques for the TRF. The work started through a NASA-ROSES grant, which ended in Feb 2019, which looked at mm-precision laser metrology to aid the realization of next generation terrestrial reference frames.
Following projects are now concluded, but my hope is that the accomplishments from these projects will lead to more interesting work in these areas in the future.
GRACE (http://www2.csr.utexas.edu/grace/) - The NASA/DLR GRACE mission ended in late 2017.
GSFC/Drought & Flood - This collaboration with Matt Rodell (Hydrological Sciences Branch at GSFC) deals with the use of GRACE and GRACE-FO data with the lowest possible latency, tuned for North American flood and drought applications.
Water Cycle in Texas & Northern Mexico - In collaboration with MAGIC group at (UTCSR), we are expanding research into the joint use of GRACE/GRACE-FO, NDVI (from MODIS), precipitation and other available remote sensing resources for the characterization and understanding of the water cycle in Texas and Northern Mexico. A post-doc joined in 2016 and is helping us take this to the next phase of expansion.
Bangladesh & GRACE - This collaboration with colleagues at LDEO (Columbia University) is completed, and led to us testing the smallest spatio-temporal resolutions to which water loads could be meaningfully extracted from the GRACE data.
Drag-Free Systems for Satellite Gravity - A collaboration with colleagues at JPL, this project is wrapping up a study on the specification of requirements for a drag-free system for next generation gravity field measurement missions. The outcomes should inform future space mission design studies.
OGMOC - With this collaboration with TU-Munich and DTU, lasting through mid-2017, we looked at optimal combination of GRACE and GOCE data for the purpose of obtaining the best estimates of geostrophic ocean currents using satellite altimetry and the geoid.