Filling out the SPICE Kernel Files Class

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The SPICE_Kernel_Files class is used to cite the specific SPICE kernel files used in calculating the associated geometry. Since SPICE kernels are also archivable products, they will usually be referenced by their PDS logical identifier and version ID by the time (i.e., LIDVID) by the time the associated data are archived. If referencing by LIDVID presents a problem, you should let PDS node consultant know ASAP, and use the various names and IDs that are included optionally in this class to help link early mission data to its final SPICE kernels after the fact.

<SPICE_Kernel_Identification>

REQUIRED

You are required to identify at least one SPICE kernel in your <SPICE_Kernel_Files> class. You will repeat this class for each kernel file you need to reference.

Note that if you reference a meta-kernel, you do not need to reference all the kernel files that the meta-kernel references. Make sure you include the appropriate version ID in the kernel reference, though.

Usage Note

In an ideal world, you would only ever need to provide the <kernel_type> and <Internal_Reference> attributes of this class to link directly to the URI of the SPICE kernel product on which the geometry is based. But if the SPICE kernel products do not exist yet, you will need to use the other, optional attributes of this class to provide enough information for future users to find the corresponding kernels by these other parameters.

<kernel_type>

REQUIRED

This is the standard NAIF/SPICE abbreviation used to identify kernels in that toolkit. It must have one of the following values:

  • CK
  • DBK
  • DSK
  • EK
  • FK
  • IK
  • LSK
  • MK
  • PCK
  • SCLK
  • SPK

<file_name>

OPTIONAL

This is the name of the file containing the SPICE kernel, as assigned by NAIF. Do not include path information (it is unlikely to be correct in the archive), but do include the correct extension.

<frame_spice_id>

OPTIONAL

This attribute contains the numeric identifier assigned by NAIF to the reference frame associated with the data.

<frame_spice_name>

OPTIONAL

This attribute provides the specific name string assigned by NAIF to the reference frame corresponding to the frame_spice_id value.

<body_spice_id>

OPTIONAL

This attribute contains the numeric identifier assigned by NAIF to some physical entity - a planet, a spacecraft, a system barycenter, etc.

<body_spice_name>

OPTIONAL

This attribute contains the name string assigned by NAIF to correspond to the body_spice_id.

<local_spice_kernel_name>

OPTIONAL

This attribute contains the name of the kernel file as it was identified in the local mission disk space.

<Internal_Reference>

OPTIONAL

Use this class to identify your SPICE kernels by their PDS URI (LIDVID, in particular). This allows the kernels to be programmatically linked to this data product.

Note, however, that the elements in this class are considered to be in the PDS4 core namespace, not the geometry dictionary namespace. So you will need to provide the PDS4 core namespace reference when using the elements. There are two ways to do that: by using a pre-defined namespace prefix, or by specifying the PDS4 core namespace URI via an xmlns XML-attribute in each of the tags. For this page, we're using the namespace abbreviation as a prefix on the tag.

If that all sounds like gibberish to you, you might want to check the Namespace Reference topic on the "Schema Referencing" page on this wiki.

<pds:lid_reference> or <pds:livid_reference>

REQUIRED

One or the other of these is required to be present. In most cases, version matters and you should reference your SPICE kernel products by LIDVID rather than just LID.

<pds:reference_type>

REQUIRED

This must have a value of data_to_spice_kernel.

Note: Type carefully, this value is not currently being validated.

<pds:comment>

OPTIONAL

If you have anything else you'd like to say about the particular kernel product being referenced, here would be the place to do it.

<comment>

OPTIONAL

If you have any additional comments to make about the SPICE kernels you've referenced as a group, this is the place to do it.