What is a Meta-Kernel?

A meta-kernel, also known as a "furnsh kernel," is a specially-formatted listing of a set of kernels applicable to a particular mission phase or time span. For each SPICE data set archived on the NAIF server the NAIF Team has created one or more meta-kernels. This allows the SPICE user to load into her/his own application program only the one or more meta-kernels applicable to the time span(s) of interest, rather than having to select and load each of the individual kernels referenced in the meta-kernel.

• For shorter missions such as Deep Space 1, Clementine, and Stardust, a single meta-kernel is provided, covering the entire data set.
• For longer missions, such as Mars Global Surveyor, Mars Odyssey, Mars Reconnaissance Orbiter and Cassini, there is a series of meta-kernels, each one covering a defined time span—usually a calendar year.
• In some cases, such as Mars Exploration Rovers (MER), there are multiple sets of meta-kernels based on other discriminators.

In some cases there are multiple versions of a particular meta-kernel. Unless you have a particular reason to select an earlier version—perhaps to be consistent with calculations made in the past—you should select the latest version.

In all cases there is an mkinfo.txt file included in the meta-kernel folder that describes the naming convention and the purpose of these meta-kernels. Users should read this important information.

The meta kernel(s) and mkinfo.txt are always found under the .../extras/mk/ folder of the archived SPICE data set.