Eni G. Njoku
Research Scientist (retired), NASA Jet Propulsion Laboratory, 1977–2016
I spent nearly four decades asking a deceptively simple question: what can naturally-emitted microwave signals, traveling from Earth to a satellite hundreds of kilometers above, tell us about the moisture at Earth's land surface? And, further: how might that information be applied to benefit life on Earth? These questions led me from electromagnetic theory through instrument design, mission planning, and eventually to the launch of SMAP — a mission that today still maps the world's soil moisture every two to three days. Along the way, as a recent immigrant to the U.S., I had the opportunity to study and work at top technical institutions, travel widely around the world, and meet wonderful people. This site is an evolving record of that journey. If you find the contents interesting, or have questions, please contact me and let me know.
Career Milestones
1977
Employed at JPL
Fresh from MIT, I joined the Jet Propulsion Laboratory in Pasadena — not quite knowing that I would still be there nearly four decades later.
1986–1990
NASA Headquarters
A four-year stint in Washington gave me a view of the whole Earth science program — and a deeper appreciation for what it takes to turn a scientific idea into a funded mission.
2007
SMAP Project Scientist
Appointed to lead the science of the Soil Moisture Active Passive mission — the project I had, in many ways, been preparing for since 1977.
2016
Retirement
After 39 years, I retired from JPL. SMAP was still in orbit, still sending data. That felt like a good place to stop.
Research Areas
Remote Sensing Theory and Modeling
The work that started it all — developing the mathematical models that describe how microwave energy interacts with soil, vegetation, and snow. Getting the theory right was the necessary foundation for everything that came after.
Instrument and Mission Design
Science only gets you so far on paper. I spent a significant part of my career working with engineers to design the actual hardware — radiometers, antenna systems, calibration methods — that could make the measurements we needed.
Project Science
Leading a science team means translating ambitious objectives into concrete requirements that engineers can build to — and then holding the line on scientific integrity through years of trade-offs and budget pressures. It is demanding work, and I found it deeply rewarding.
SMAP Mission
The culmination of my career. As Project Scientist, I guided SMAP from its earliest concept through launch and into operations — watching it become a tool that researchers and forecasters around the world now rely on.
Selected Publications
- Njoku, E. G., and D. Entekhabi (1996). Passive microwave remote sensing of soil moisture. Journal of Hydrology, 184(1–2), 101–129.
- Njoku, E. G., T. J. Jackson, V. Lakshmi, T. K. Chan, and S. V. Nghiem (2003). Soil moisture retrieval from AMSR-E. IEEE Transactions on Geoscience and Remote Sensing, 41(2), 215–229.
- Njoku, E. G. (Ed.) (2014). Encyclopedia of Remote Sensing. Springer, New York.