Solar System Exploration Division

Vishnu Viswanathan


Vishnu Viswanathan's Contact Card & Information.
Phone: 301.614.6466
Org Code: 698
Mail Code 698
Greenbelt, MD 20771

Missions & Projects

Brief Bio

Dr. Vishnu Viswanathan’s research is focused on the analysis of tracking data such as radio, laser and images, to determine the geophysical, orbital, and rotational properties of planetary bodies. In 2017, Dr. Viswanathan improved the orbital-rotational dynamical model of the Moon and fitted it to over five decades of lunar laser ranging (LLR) data with gravity field constraints from the NASA GRAIL mission. This model is one of the three primary references in the world that provides high-precision planetary and lunar ephemerides. In 2018, Dr. Viswanathan used this model to perform a fundamental physics test of the universality of free fall using the Earth-Moon system as test bodies, improving upon previous constraints on the principle of equivalence. In 2019, Dr. Viswanathan further expanded the capabilities of this model resulting in the strongest constraint known for the shape and size of the lunar core-mantle boundary. In 2020, Dr. Viswanathan published two white papers submitted to the Committee on the Planetary Science Decadal Survey (2023-2032) of the National Academies of Sciences/USA, and to the Artemis III Science Definition Team, representing the interests, objectives and goals of the global LLR instrument, data analysis and observer community. In 2022, Dr. Viswanathan founded a Lunar Data Analysis Center at UMBC/NASA GSFC affiliated with the International Laser Ranging Service, and he is involved in inter-agency activities related to the US Lunar Reference System components. Dr. Viswanathan is currently at NASA GSFC employed by UMBC under the CRESST II cooperative agreement.

Personal webpage

Research Interests


Asst. Research Scientist

NASA Goddard Space Flight Center | UMBC CRESST II - Greenbelt, MD, USA

August 2021 - Present

Post-doctoral Research Associate

NASA Goddard Space Flight Center | UMBC CRESST II - Greenbelt, MD, USA

April 2019 - August 2021

Post-doctoral Researcher

Institut de Méchanique Céleste et de Calcul des Éphéphérides (IMCCE), Observatoire de Paris - Paris, France

November 2017 - March 2019

Research Engineer

Centre National de la Recherche Scientifique (CNRS) - Sophia Antipolis, France

October 2017 - November 2017

Doctoral researcher

Observatoire de Paris & Observatoire de la Côte d'Azur - France

October 2014 - September 2017


Ph.D. 2017, Astronomy and Astrophysics, Observatoire de Paris - France, "Improving the dynamical model of the Moon using lunar laser ranging (LLR) and spacecraft data", Supervisors: Prof. Agnès Fienga and Prof. Jacques Laskar

M.S. 2013, Space Systems Engineering, Institut Supérieur de l'Aéronautique et de l'Espace, Toulouse - France, "Emulation of a geostationary channel using software-defined radio platform", Supervisor: Prof. Laurent Franck

B.Tech. 2011, Electronics and Communication Engineering, National Institute of Technology, Trichy - India

Professional Societies

American Geophysical Union


2019 - Present

European Geophysical Union


2016 - Present

Division for Planetary Science


2021 - Present

International Laser Ranging Service

Associate member

2022 - Present

Professional Service

Reviewer for ApJL, A&A, ASR, CMDA, ESS, Icarus, JGeod, JGR:Pla, PSJ, Remote Sensing, Universe

Reviewer for NASA HQ’s ROSES and EONS programs as Panel Chair/Panelist/External Reviewer


Independent Measurement of Saturn's Dissipation using Cassini Astrometric Data

Cassini Data Analysis Program - NASA HQ Science Mission Directorate (NNH20ZDA001N) - Awarded: 2020-09-28

Dates: 2021-03-01  - 2024-02-29

Study of the interior structure of the Moon using lunar laser ranging data

Post-doctoral research grant - LABEX Exploration Spatiale des Environments Planétaires - France - Awarded: 2017-11-15

Dates: 2017-11-15  - 2018-11-15

Coverage: 1.0

Improving the dynamical model of the Moon using lunar laser ranging (LLR) and spacecraft data

Doctoral research grant - Ministry of Higher Education, Research and Innovation - France - Awarded: 2014-10-01

Dates: 2014-10-01  - 2017-09-30

Coverage: 3.0



2022. "The Contribution of Small Impact Craters to Lunar Polar Wander." The Planetary Science Journal 3 217 [10.3847/PSJ/ac8c39] [Journal Article/Letter]

2021. "A Recipe for the Geophysical Exploration of Enceladus." The Planetary Science Journal 2 (4): 157 [10.3847/psj/ac06d2] [Journal Article/Letter]

2020. "First Two-way Laser Ranging to a Lunar Orbiter: infrared observations from the Grasse station to LRO’s retro-reflector array ." Earth, Planets and Space [Full Text] [10.1186/s40623-020-01243-w] [Journal Article/Letter]

2019. "Observational constraint on the radius and oblateness of the lunar core-mantle boundary." Geophysical Research Letters 46 [10.1029/2019GL082677] [Journal Article/Letter]

2018. "The new lunar ephemeris INPOP17a and its application to fundamental physics." Monthly Notices of the Royal Astronomical Society 476 1877-1888 [10.1093/mnras/sty096] [Journal Article/Letter]

2017. "Lunar laser ranging in infrared at the Grasse laser station." Astronomy & Astrophysics 602 A90 [10.1051/0004-6361/201628590] [Journal Article/Letter]


2023. "Recent Developments at the Apache Point Lunar Laser Ranging Station." Proceedings of the 22nd International Workshop on Laser Ranging [Full Text] [Proceedings]

2021. "A Recipe for Geophysical Exploration of Enceladus." Bulletin of the American Astronomical Society 53 (4): [10.3847/25c2cfeb.b65f2c4c] [Journal Article/Letter]

2021. "Extending Science from Lunar Laser Ranging." Bulletin of the American Astronomical Society 53 (4): [10.3847/25c2cfeb.3dc2e5e4] [Journal Article/Letter]

2017. "INPOP17a planetary ephemerides." Notes Scientifiques et Techniques de l'Institut de mécanique céleste S108 [Full Text] [10.13140/RG.2.2.24384.43521] [Book]

2017. "Satellite and lunar laser ranging in infrared." Proceedings of the SPIE Conference on Photon Counting Applications, 2017 10229 UNSP 102290K [10.1117/12.2270573] [Proceedings]

Talks, Presentations and Posters


Recommendations on the Data, Models and Parameterization for Planning a Unified Lunar Geodetic System

August 18, 2024

In-depth presentation and discussion on Task #1 deliverable of the National Geospatial-Intelligence Agency (NGA)-NASA Inter-Agency Agreement (IAA) during the IAA close-out meeting held at NGA's Moonshot Labs, St. Louis, MO.

GRAIL-LLR Principal Axes Reference Frames

November 2023

Invited by the National Geospatial-Intelligence Agency's (NGA) Office of Geomatics (Space Branch) to present work and lead a discussion related to lunar reference frames realized from the analysis of GRAIL gravity and LLR data to members of the Lunar Geodetic System Working Group, consisting of ~180 members across USGOV, academia, and industry.

LLR and Lunar Reference Frames

July 2023

Invited by the National Geospatial-Intelligence Agency's (NGA) Office of Geomatics (Space Branch) for discussions regarding the realization of a lunar reference frame using LLR data analysis.

Lunar Laser Ranging Data Analysis

April 2023

Invited by the National Geospatial-Intelligence Agency's (NGA) Office of Geomatics (Space Branch) to present work on LLR data analysis to the Lunar Reference System Working Group.

Orientation of the Moon using Lunar Laser Ranging data & GRAIL gravity field

December 2022

Invited by NASA HQ/ESD to talk at the Scripps Institution of Oceanography, La Jolla, CA during the Solid Earth Team (SET) meeting (November 7-11; consisting of ~200 participants) organized by NASA Earth Surface and Interior (ESI) focus group.

Extending Science from Lunar Laser Ranging

May 2021

Joint Seminar: Geodesy & Geophysics Laboratory; Planetary Geology, Geophysics & Geochemistry Laboratory at NASA GSFC


A Simulation Study for Extending Lunar Laser Ranging Science

April 2021

Poster presented at 52nd LPSC, #2651, 3/2021

Science Opportunities for Lunar Retro-Reflectors

August 2020

NASA Exploration Science Forum 2020, #NESF2020-078

Scientific Exploration of the Lunar South Pole with Retro-Reflectors

May 2020

Talk at Lunar Surface Science Workshop 2020

Estimating the Lunar Core Equatorial Ellipticity Using Lunar Laser Ranging

April 2020

Poster presentation at the 51st Lunar and Planetary Science Conference (2020), Texas, USA

On the GRAIL-LLR Low-Degree Gravity Field Inconsistencies


Poster presented at AGU Fall Meeting 2019, San Francisco, USA

Updates from INPOP ephemeris: From fundamental physics tests to lunar interior probe.

August 2018

Talk at 42nd COSPAR Scientific Assembly (H0.5-0006-18)

Recent updates from the INPOP lunar and planetary ephemeris team.

July 2018

Talk at Journées Scientifiques du Programme National GRAM (215219)

Multi-geodetic characterization of the seasonal signal at the CERGA geodetic reference station, France.

May 2017

Poster presented at EGU General Assembly Conference (Vol. 19, p. 7450)

Infrared Lunar Laser Ranging at Calern: Impact on Lunar Dynamics.

April 2017

Poster presented at Lunar and Planetary Science Conference (Vol. 48, p. 2329)

LLR data analysis and impact on lunar dynamics from recent developments at OCA LLR Station.

May 2016

Talk at EGU General Assembly Conference Abstracts (Vol. 18, p. 13995)

Recent developments in INPOP planetary ephemerides.


Talk at IAU General Assembly, 22, p.27116.

Teaching Experience

"Principles of Thermodynamics", Undergraduate level, ESAIP Graduate School of Engineering, Grasse - France

"Satellite systems", Graduate level, University of Nice, Sophia Antipolis


Selected Public Outreach

Science Update: From Apollo to Artemis, Get Ready for International Observe the Moon Night!

August 2024 - August 2024

Staci Tiedeken (NASA/GSFC) and I presented a talk at the Science Update webinar series hosted by the National Science Teaching Association (NSTA), highlighting the upcoming International Observe the Moon Night and the field of planetary geodesy, to a ~65-member audience consisting of teachers of science and general science enthusiasts. During the talk, I covered the critical role of lunar laser ranging data behind scientific discoveries about the Moon's interior structure and how it also goes on to help millions of people plan their trips around solar eclipses! I also had the honor of sharing updates and the excitement around NASA's Artemis missions. A recording of the event is available here.

"How bouncing lasers off the Moon paves the road to lunar science and exploration"

May 2023 - May 2023

I served as the keynote speaker for a NASA Goddard Visitor Center symposium involving nearly 110 high school students from MA/NY/NJ presenting their work on challenges in building a sustainable presence of humans on the Moon, followed by Q&A with the students and feedback on their work.

“Episode 42 – Watch a Total Lunar Eclipse”, NASA Science Live, May 15, 2022

June 2022 - June 2022

I was invited to participate along with Dr. Ryan Watkins (NASA/HQ) in this live stream organized by NASA to talk about my role and support Q&A from the public regarding lunar science and exploration in the Artemis era.  

50th Anniversary of the Apollo Moon landing, National Mall

August 2019 - August 2019

Volunteering work at the Moon Tours (Moon trek + LRO) tent using lunar topographic data, 3D prints of the lunar surface and lunar simulant samples.