A Satellite, by definition, should have only one record per Business Key per Load Date. The Business Key (or the hash of the Business Key) + LOAD_DATE is the unique key for the record. BK + LOAD_DATE is the Primary of the Satellite
The exception is a Multi-Active Satellite where a Sequence Number is added to indicate the each of the active records. Sequence Number becomes part of the PK of the Multi-active Satellite.
See section 5.4 of the Data Vault Data Modeling Specification v 2.0.2
Update 05/07/2022: An exception to this rule is when a stable descriptive attribute from the source can be used as part of the Private Key for the SAT. For e.g. the Modify Timestamp from the source can be combined with the HASHKEY and the LOAD_DATE to generate the Private Key, which will be unique for all records in the SAT
HASHKEY + LOAD_DATE + MODIFY_TS