See https://astrogreg.com/jpl-ephemeris-format/jpl-ephemeris-format.html for an
inciteful explanation of the ASCII JPL files.

The JPL ephemerides are available by ftp

ftp ssd.jpl.nasa.gov
user: anonymous
psw: email address
cd pub
cd eph
choice of planets, satellites, small_bodies, spacecraft

cd planets
cd ascii

choose: 
  de440t Mar 04  2021
  
to have time included in the data files.  The file for 1950 to 2050 and the
header file are here for your convenience, or can be downloaded from the JPL
site.  Both files (or ones of your chosing) should be in the current working 
directory when you execute jpl_ephemeris.jl