  In the Virtual Observatory era, where we intend to expose scientists (or
software agents on their behalf) to a stream of observations from all existing
facilities, the ability to access and to further interpret the origin,
relationships, and processing steps on archived astronomical assets (their
Provenance) is a requirement for proper observation selection, and quality
assessment. In this article we present the different use cases Data Provenance
is needed for, the challenges inherent to building such a system for the ESO
archive, and their link with ongoing work in the International Virtual
Observatory Alliance (IVOA).
