[ldd-msn] Addition of orbit_number attribute to MSN DD

[CSeyb]

Issue Type ENHANCEMENT

Describe the issue identified (if applicable) Mission-specific DDs, such as JUNO and MRO, include the attribute ‘orbit_identifier’ while the mission information commons discipline DD does not.

Considering that more than 1 mission project may need an attribute to assign an orbit value to (often, but not always a number), 'orbit_identifier' should be created for the msn dd.

See samples of JUNO and MRO_CTX PDS3 labels:

Per the JUNO SIS for ‘orbit_number’: ‘The orbit_number element identifies the number of the orbital revolution of the spacecraft around a target body. This value is N/A for cruise images.’

Per the MRO CTX SIS for ‘orbit_number: ‘The orbit number from the start of the mapping phase as defined by the MRO Project.’

Per notes below, '...Cassini orbits are labeled 000, 00A, 00B, 00C, 003, 004, ... then continuing up to 293', so 'identifier' is more useful than 'number'.

Describe the solution you'd like Create the attribute ‘orbit_identifier’ to add to the msn DD.

Here are examples of PDS4 JUNO and MRO CTX labels using an ‘orbit_identifier’ attribute:

Describe alternatives you've considered None

LDD Dictionary Version msn

PDS4 IM Version 1.21

Need-by Date Non-urgent

[matthewtiscareno]

If the eventual vision would be for this attribute to supplant all similar attributes that are currently in mission-specific LDDs, then please be advised that Cassini orbits are labeled 000, 00A, 00B, 00C, 003, 004, ... then continuing up to 293.

[rgdeen]

given the Cassini usage, perhaps it should be orbit_identifier as a string rather than number as an int?