What does SSD do?

JPL’s Solar System Dynamics (SSD) group is part of Mission Design and Navigation section. The SSD group focuses on determining the motion and physical parameters of natural planetary objects and our primary products, services, and charter are described below.

• Solar System Dynamics Website
• Planetary Ephemerides
• Satellite Ephemerides
• Asteroid & Comet Ephemerides
• Gravity/Radio Science
• Center for Near Earth Object Studies (CNEOS)

Charter

The SSD group generates accurate position and velocity histories (ephemerides), gravity fields, and rotational parameters for solar system bodies including the planets, planetary satellites, asteroids and comets. The SSD group also performs scientific research and provides science support and leaders to mission studies involving gravity science, celestial mechanics, relativity, and other areas of dynamical science. Specific responsibilities of the group are to:

• Continually update and improve the ephemerides using new data and new data types.
• Export ephemerides to flight projects of all space faring nations and to an international community of scientists.
• Maintain up-to-date orbit and physical data files for planets, satellites, asteroids, and comets for mission design work.
• Assume lead role in defining fundamental coordinate systems and physical constants for solar system bodies.
• Coordinate ground-based observing programs for solar system bodies that may become future mission targets.
• Help plan future missions to study the asteroids and comets of the solar system and investigate fundamental gravitational theory.
• Conduct research and plan missions to probe the interior of planetary bodies by determining the gravity field, shape, and rotational parameters.
• Conduct research and plan missions to test certain areas of fundamental physics including the equivalence principle and gravitational waves.

Acknowledgements

For referencing the data downloaded from the SSD website, please use the following citation:

“Solar System Dynamics. (Downloaded Year, Month, Date). (Title of the Page). https://ssd.jpl.nasa.gov”

Most of the JPL Solar System Dynamic group’s ephemeris development, maintenance, and improvement tasks are part of NASA’s Advanced Multi-Mission Operations System, which is funded by NASA’s Science Mission Directorate, Planetary Sciences Division.

Many individuals were involved in the creation, maintenance, and services provided by this website. Below is a list of people who made (and/or continue to make) significant contributions to the website.

Alan Chamberlin	-	Website design, implementation, general maintenance, and overall project management. Small-body orbit determination and database maintenance.
Javier Roa Vicens	-	Implementation of several small-body tools including Mission Design, Identification, Observability, Custom Orbit Visualization, and Three-Body Periodic Orbits.
Jon Giorgini	-	Horizons system and radar astrometry.
Ryan Park	-	Planetary ephemeris data production, gravity visualization design and data maintenance, and official website manager.
Robert Jacobson & Marina Brozović	-	Planetary satellite ephemeris production and physical-characteristics data.
Davide Farnocchia	-	Small-body orbit determination and database maintenance.
Shantanu Naidu	-	Small-body orbit determination and small-body satellite-data maintenance.