Description Data set of MESSENGER's periapsides' & apoapsides' times, positions (X, Y, Z) in Mercury Solar Orbital (MSO) coordinates in units of Mercury radii, distance from Mercury (units of Mercury radii), time from previous periapsis, and orbit number, over the entire MESSENGER mission from March 2011 to April 2015.MSO coordinates are defined with the origin located at the centre of Mercury. The X-axis points from Mercury toward the Sun. The Z-axis is normal to Mercury's orbital plane, oriented toward the north (positive ecliptic pole direction). The Y-axis completes the right-handed system, pointing opposite to Mercury's orbital velocity (i.e., roughly toward dusk). Distances are typically expressed in units of Mercury radii (R_M = 2439.7 km). Data Column Description Column name Description UTC Timestamp of apoapsis/periapsis in Coordinated Universal Time (UTC) in the format YYYY-MM-DD Hour:Minute:Second X MSO X position of the MESSENGER spacecraft in units of Mercury radii in MSO coordinates. Y MSO Y position of the MESSENGER spacecraft in units of Mercury radii in MSO coordinates. Z MSO Z position of the MESSENGER spacecraft in units of Mercury radii in MSO coordinates. |R| Total magnitude of the position vector of the MESSENGER spacecraft in units of Mercury Radii in MSO coordinates Orbit Length Orbit length in hours, i.e time from previous apoapsis/periapsis to next apopapsis/periapsis. Starts from zero, as the first entry has no previous entry. Orbit Number Orbit number. Starts from zero as the orbit is defined from the previous apoapsis/periapsis to the following, i.e., the first entry is the start of the first orbit. This data was constructed using SPICE kernels and the hermpy Python package (https://github.com/daraghhollman/hermpy). The code can be located in the data handling directory of the GitHub linked below.