Stephen Merkowitz is a scientist and project manager at NASA Goddard Space Flight Center. His research interests include space geodesy, Earth Science, lunar and interplanetary laser ranging, and fundamental tests of General Relativity. He received his Ph.D. in Physics from Louisiana State University working on gravitational wave antennas, and continued this research for two years in Frascati, Italy, on a National Institute for Nuclear Physics (INFN) fellowship. In 1998 he became a Research Associate at the University of Washington where he performed experimental tests of General Relativity and broke the records for the most precise measurements of Newton's gravitational constant G and the mass of the Earth. In 2000, he moved to NASA Goddard to serve as Deputy Project Scientist for the LISA Project, a space based gravitational wave mission. In 2009, Merkowitz went on a yearlong detail to the Executive Office of the President, covering Physical Science and Engineering for the Office of Science and Technology Policy, followed by a detail at NASA Headquarters as Assistant Director of the Astrophysics Division. He returned to Goddard in 2011 and now manages NASA's Space Geodesy Project, is Principal Investigator for the Global Positioning System Laser Retroreflector Array (GPS-LRA) and Project Scientist for Geodetic Reference Instrument Transponder for Small Satellites (GRITSS), and leads the implementation of a Laser Retroreflector Array on the European Space Agency/Surrey Satellite Technology Ltd (SSTL)'s Lunar Pathfinder mission.
Space Geodesy Project (SGP)
Project Manager for the Space Geodesy Project (SGP) that develops, operates, and maintains the global NASA Space Geodesy Network of Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), and Global Navigation Satellite Systems (GNSS) ground stations, and produces and disseminates the data products for the International Terrestrial Reference Frame and Earth Orientation Parameters. Responsible for managing:
- The operation and maintenance of the NASA Space Geodesy Network and associated analysis systems,
- The development and delivery of Space Geodetic data products,
- The planning and implementation of the next generation NASA Space Geodesy Network,
- Coordination with over two-dozen domestic and international partners in Space Geodesy, and the development of new NASA partnerships.
Global Positioning System Laser Retroreflector Array (GPS-LRA)
Principal Investigator for the Global Positioning System Laser Retroreflector Array (GPS-LRA), a NASA provided instrument for the next generation of GPS satellites. Provides guidance and oversight of all elements of the instrument implementation and responsible for coordination with US Space Command and US Space Force.
Geodetic Reference Instrument Transponder for Small Satellites (GRITSS)
Project Scientist for Geodetic Reference Instrument Transponder for Small Satellites (GRITSS), a flight instrument designed to improve the International Terrestrial Reference Frame (ITRF), the foundation for geolocating all Earth Observations.
Lunar Laser Ranging
Technology & Missions
Lead several activities related to Lunar Laser Ranging, including the implementation of a Laser Retroreflector Array on the European Space Agency/Surrey Satellite Technology Ltd (SSTL)'s Lunar Pathfinder mission, development of next-generation lunar laser retroreflectors, and managing NASA's Apache Point Lunar Laser Ranging Station.
Space Geodesy Project Manager
NASA Goddard Space Flight Center - Greenbelt, Maryland
2011 - Present
Project Manager for the Space Geodesy Project and Principal Investigator for the Global Positioning System Laser Retroreflector Array.
Assistant Director for Policy and Planning
NASA Headquarters - Washington, D.C.
2010 - 2011
Developed policy and strategic plans for the Astrophysics Division at NASA Headquarters. Developed the strategic and tactical plans for implementing the recommendations of the 2010 Astrophysics Decadal Survey. Supported the development of the Astrophysics Division’s inputs into the President’s budget requests. Led and supported interagency discussions with the Department of Energy, National Science Foundation, Office of Science and Technology Policy, and Office of Management and Budget. Supported and participated in bilateral international discussions with the European Space Agency, Japan, and other international partners. Prepared and reviewed presentations to the NASA Advisory Council’s Science Committee and Astrophysics Subcommittee; the Astronomy and Astrophysics Advisory Committee; and other public presentations by the Division Director. Worked with the National Research Council on Astrophysics related topics and studies.
Senior Policy Analyst for Physical Science and Engineering
Office of Science and Technology Policy, Executive Office of the President - Washington, D.C.
2009 - 2010
Provided advice and support to the President’s Science Advisor on a variety of physical science and engineering issues. Worked closely on a day-to-day basis at the very highest levels of government to develop policy recommendations on a wide variety of technical and scientific topics, and coordinated across all parts of the Executive Branch to implement and monitor those policies. In particular, worked directly with senior officials from the Department of Energy, the National Science Foundation, and the National Aeronautics and Space Administration, in addition to coordinating with other offices within the Executive Office of the President such as the Office of Management and Budget.
NASA Goddard Space Flight Center - Greenbelt, Maryland
2000 - 2009
Deputy Project Scientist and Acting Mission Systems Engineer for the international LISA Project, a space based gravitational wave mission. Work on all aspects of the LISA mission, including: scientific activities, technology development, detailed engineering, and management. Lead a group of nearly 30 engineers and scientists solving some of the most challenging aspects of the LISA mission. Collaborate routinely with scientists throughout the US and Europe. Examples include: ESTEC (Netherlands), University of Trento (Italy), Instituto de Ciencias del Espacio (Spain), and the University of Hannover (Germany). Work closely and interact daily with managers, engineers, and scientists at the European Space Agency.
Principle Investigator for the “Precision Lunar Laser Ranging” project and Co-Investigator for the NASA Lunar Science Institute node “Lunar University Node for Astrophysics Research (LUNAR): Exploring the Cosmos From the Moon.” These efforts are aimed at developing the next generation of lunar laser ranging instruments and deriving the science they will produce. Collaborate with scientists at the University of Colorado, University of California at San Diego, and the University of Maryland, among others.
Member of the Goddard “LaserComm” development team, which is building a photon counting instrument for space based laser communications. Member of the MLA-Earthlink experiment team, which is attempting to perform laser ranging and communications over interplanetary distances using the laser altimeter on the MESSENGER spacecraft and the Goddard observatory.
Chair of the Astrophysics Science Division Colloquium Committee and member of the Lunar Exploration Science Working Group Steering Committee. Member of the Advanced LIGO Project Advisory Panel, which reports directly to the director of the NFS funded LIGO Project.
Nuclear Physics Laboratory, University of Washington - Seattle, Washington
1998 - 2000
Member of Professors Eric Adelberger’s and Jens Gundlach’s Eöt-Wash group, pioneering new techniques in high-precision studies of gravity. Performed a measurement of Newton’s gravitational constant G with unprecedented precision. This measurement remains the world’s most precise measurement of “big G” and is used to set the standard value. Also led the implementation of a new continuously rotating torsion balance for testing the Equivalence Principle (the equivalence between gravitational mass and inertial mass). Responsible for all aspects of the experiment, including designing and building the apparatus, writing the data acquisition and control system, and analyzing the data.
Master of Science, Louisiana State University, 1994. Program in Physics. Major in General Relativity, Minor in High Energy Physics.
Bachelor of Arts, University of Colorado at Boulder, 1989. Major in Physics.
2023-Present, Member of the United Nations Global Geodetic Centre of Excellence Advisory Committee
2023-Present, Chair of the International Laser Ranging Service (ILRS) Governing Board
2019-2022, Chair of the International Laser Ranging Service (ILRS) Missions Standing Committee (MSC)
2017-Present, Member of the US Delegation to the United Nations Global Geospatial Information Management (UN-GGIM) and member of the Geodetic Infrastructure Working Group of the UN-GGIM Subcommittee on Geodesy.
2017-Present, International Laser Ranging Service (ILRS) Governing Board Member
- 2019 Robert H. Goddard Exceptional Achievement Award
- 2014 Robert H. Goddard Exceptional Achievement Award
- 2005 Robert H. Goddard Exceptional Achievement Award
- Goddard Space Flight Center Special Act Award in 2001, 2003, and 2004.
- Current record holder for the most precise measurement of Newton’s gravitational constant and the mass of the Earth.
Varghese, T., R. L. Ricklefs, E. C. Pavlis, M. Kuzmicz-Cieslak, and S. M. Merkowitz. 2019. Transitioning the NASA SLR network to Event Timing Mode for reduced systematics, improved stability and data precision Journal of Geodesy 93 (11): 2345-2355 [10.1007/s00190-019-01326-x]
Merkowitz, S. M., S. Bolotin, P. Elosegui, et al. J. Esper, J. Gipson, L. Hilliard, E. Himwich, E. D. Hoffman, D. D. Lakins, R. C. Lamb, F. G. Lemoine, J. L. Long, J. F. McGarry, D. S. MacMillan, B. P. Michael, C. Noll, E. C. Pavlis, M. R. Pearlman, C. Ruszczyk, M. D. Shappirio, and D. A. Stowers. 2019. Modernizing and expanding the NASA Space Geodesy Network to meet future geodetic requirements Journal of Geodesy 93 (11): 2263-2273 [10.1007/s00190-018-1204-5]
Preston, A. M., and S. M. Merkowitz. 2013. Next-generation hollow retroreflectors for lunar laser ranging Applied Optics 52 (36): 8676
Merkowitz, S. M. 2010. Tests of Gravity Using Lunar Laser Ranging Living Reviews in Relativity 13 7
Merkowitz, S. M. 2009. Current LISA spacecraft design J. Phys.: Conf. Ser. 154 012021
Merkowitz, S. M., P. Dabney, J. C. Livas, et al. J. L. Mcgarry, G. A. Neumann, and T. W. Zagwodzki. 2007. Laser Ranging for Gravitational, Lunar and Planetary Science International Journal of Modern Physics D 16 2151 [10.1142/S0218271807011565]
Merkowitz, S. M., A. Ahmad, T. T. Hyde, et al. T. Sweetser, J. Ziemer, S. Conkey, W. I. Kelly, and B. Shirgur. 2005. LISA propulsion module separation study Classical and Quantum Gravity 22 413 [10.1088/0264-9381/22/10/037]
Hyde, T. T., P. G. Maghami, and S. M. Merkowitz. 2004. Pointing acquisition and performance for the laser interferometry space antenna mission Class. Quant. Grav. 21 S635
Merkowitz, S. M. 2004. Structural, thermal, optical and gravitational modelling for LISA Class. Quant. Grav. 21 S603
Merkowitz, S. M. 2003. The LISA integrated model Class. Quant. Grav. 20 S255
Merkowitz, S. M. 2002. A µNewton thrust-stand for LISA Class. Quant. Grav. 19 1745
Gundlach, J. H., and S. M. Merkowitz. 2000. Measurement of Newton's Constant Using a Torsion Balance with Angular Acceleration Feedback Phys. Rev. Lett. 85 2869
Merkowitz, S. M. 1999. Final isolation stage for a spherical gravitational wave antenna Rev. Sci. Instrum. 70 1553
Pavlis, E. C., M. R. Pearlman, C. C. Carabajal, et al. R. Ricklefs, C. Schwatke, M. Wilkinson, G. Kirchner, V. Luceri, T. Otsubo, J.-M. Torre, U. Schreiber, D. Kurchaski, C. Course, M. Blossfeld, J. Ventura-Traveset, P. Delva, S. M. Merkowitz, R. Sherwood, J. Rodriguez, and F. G. Lemoine. 2023. International Laser Ranging Service Travaux 43 825-858
Colmenares, N. R., J. B. Battat, D. P. Gonzales, et al. E. D. Hoffman, F. G. Lemoine, R. M. McMillan, S. M. Merkowitz, T. W. Murphy, S. S. Sabhlok, and V. Viswanathan. 2023. Recent Developments at the Apache Point Lunar Laser Ranging Station Proceedings of the 22nd International Workshop on Laser Ranging
Viswanathan, V., E. Mazarico, S. Merkowitz, et al. J. G. Williams, S. G. Turyshev, D. G. Currie, A. I. Ermakov, N. Rambaux, A. Fienga, C. Courde, J. Chabé, J.-M. Torre, A. Bourgoin, U. Schreiber, T. M. Eubanks, C. Wu, D. Dequal, S. Dell'Agnello, L. Biskupek, J. Müller, and S. Kopeikin. 2021. Extending Science from Lunar Laser Ranging Bulletin of the American Astronomical Society 53 (4): [10.3847/25c2cfeb.3dc2e5e4]
Lyons, P., J. J. Lyons, P. J. Dogoda, et al. J. Golder, D. Lindler, S. Merkowitz, E. Hoffman, D. Steinfeld, J. Crow, G. Gao, and K. Dymond. 2020. Alignment and verification testing of the GPS LRA test bed Proceedings Volume 11488, Optical System Alignment, Tolerancing, and Verification XIII; 114880 [10.1117/12.2569160]
Merkowitz, S. M., J. Esper, L. M. Hilliard, et al. E. D. Hoffman, J. E. Horvath, F. G. Lemoine, J. L. Long, C. Ma, D. McCormick, J. L. Mcgarry, B. P. Michael, C. E. Noll, J. Sager, M. D. Shappirio, and S. L. Wetzel. 2016. The NASA Space Geodesy Network 20th International Workshop on Laser Ranging, Potsdam Germany, October 9-14, 2016
Pearlman, M. R., A. Ipatov, F. G. Lemoine, et al. J. Long, C. Ma, S. M. Merkowitz, R. Neilan, C. E. Noll, E. C. Pavlis, V. Shargorodsky, D. Stowers, and S. L. Wetzel. 2014. The Role of Core and Co-location Sites, and the Activities Underway to Improve the Global Space Geodesy Network Proceedings of the 19th International Workshop on Laser Ranging, Annapolis, Maryland, U.S.A., October 27-31, 2014
Mcgarry, J. L., S. M. Merkowitz, M. Shappirio, et al. S. Butani, J. W. Cheek, C. B. Clarke, J. J. Degnan, H. Donavan, F. Hall, J. E. Horvath, D. R. Lamb, T. Mann, J. Marzouk, A. Nelson, D. Patterson, M. Torrence, T. Varghese, S. L. Wetzel, J. Woo, and T. W. Zagwodzki. 2014. Developing and Deploying NASA’s Space Geodesy Satellite Laser Ranging (SGSLR) Systems Proceedings of the 19th International Workshop on Laser Ranging, Annapolis, Maryland ,USA October 27 – 31, 2014
Ma, C., S. M. Merkowitz, and B. Luzum. 2014. The Impact of NASA’s SGP and USNO on VGOS Proceedings of the 8th IVS General Meeting, “VGOS: The New VLBI Network”
Mcgarry, J. L., S. M. Merkowitz, H. L. Donavan, et al. J. E. Horvath, J. J. Degnan, J. W. Cheek, A. Nelson, D. Patterson, A. Mann, F. Hall, R. L. Ricklefs, T. Varghese, T. W. Zagwodzki, and E. C. Pavlis. 2013. The Collocation of NGSLR with MOBLAS-7 and the Future of NASA Satellite Laser Ranging Proceedings of the 18th International Workshop on Laser Ranging, Fujiyoshida, Japan, November 11-15, 2013
Krainak, M. A., J. R. Chen, P. W. Dabney, et al. J. F. Ferrara, W. H. Fong, A. J. Martino, J. F. McGarry, S. M. Merkowitz, C. M. Principe, X. Sun, and T. W. Zagwodzki. 2008. Direct-detection free-space laser transceiver test-bed Proceedings of the Free-Space Laser Communication Technologies XX SPIE.6877 687703 [10.1117/12.758654]