This directory contains SPK kernels for the US-German Helios 1 and 2 missions
(also known as Helios A and B), launched in 1974 and 1976, respectively.

The Helios orbits have been reconstructed from tabulated daily positions
available from NSSDC.

For Helios 1, the trajectory information is split into two kernels,
100528R_helios1_74345_81272.bsp which contains a reconstruced orbit
for the times for which tabulated daily positions are available, and
160707AP_helios1_81272_86074.bsp which contains a predicted orbit
based on the same orbital solution.

For Helios 2, the available tabulated daily positions on which the
orbit reconstruction was based cover the whole mission, so there is
only one kernel, 100607R_helios2_76016_80068.bsp.

There is an extensive description of how these files were produced found
inside the comment area of each kernel. You can use either the “commnt”
(note the unfamiliar spelling) or the “spacit” utility to read those
comments. Both are included in the SPICE Toolkit, and both are available
under the Utilities web page (http://naif.jpl.nasa.gov/naif/utilities.html).