Ephemeris Theories JPL DE, INPOP, and EPM

In this paper, we have provided an overview and description of three leading sources of planetary ephemerides: the ephemerides from the Jet Propulsion Laboratory (JPL) and their developed ephemeris theory DE; the ephemerides from the Institute of Celestial Mechanics and Ephemeris Calculation (IMCCE) and their developed theory INPOP; and the ephemeris theory EPM developed at the Institute of Applied Astronomy, Russian Academy of Sciences (IAA RAS). The methods and observational data sets used in constructing each of the theories have been described. A comparison of the ephemerides computed within these theories has been made using examples from future space missions. It has been shown that the differences in computed positions do not exhibit systematic characteristics and represent rather random discrepancies caused by variations in dynamic models and the observational data taken into account. The overall conclusion from the comparison of the ephemerides has been that none of the considered options (JPL DE, EPM, and INPOP) has an advantage in terms of accuracy. All three options have been equally valid, and any of the three ephemeris options can be used in practice.