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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.


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:


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).”

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.