SPICE Kernels Contents:

- Planet, satellite, comet, or asteroid ephemerides, or more generally, location of a target body, given as a function of time.
The ephemeris data for spacecraft and target bodies are normally combined in a single file called the SPICE SPK file. (But either target ephemerides alone or a spacecraft ephemeris alone can be held in an SPK file; it is not necessary that both types be present.)
The P kernel also logically includes certain physical, dynamical and cartographic constants for target bodies, such as size and shape specifications, and orientation of the spin axis and prime meridian. These target body physical and cartographic constants are found in the SPICE PCK file.

- Instrument description kernel, containing descriptive and operational data peculiar to a particular scientific instrument, such as mounting alignment, internal timing relative to the spacecraft clock, and field-of-view model parameters. This instrument information is contained in the SPICE IK file.

- Pointing kernel, containing a transformation traditionally called the C-matrix which essentially yields time-tagged pointing (orientation) angles for a spacecraft structure upon which science instruments are mounted. Attitude data is contained in the SPICE CK file.

- Events kernel, the principal contents of which are derived from the integrated sequence of events used to produce actual spacecraft commands. Events data are contained in the SPICE EK file set (there are three components to the EK).

Several miscellaneous kernel files - spacecraft clock (SPICE SCLK file) and leapseconds (SPICE LSK file) - are also part of SPICE; these are used in converting time tags between various time measurement systems.