The Semantic Planetary Data System J. Steven Hughes 1 , Daniel J. Crichton 1 , Sean Kelly 1 , and Chris Mattmann 1 1 Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena, CA 91109 USA {steve.hughes, dan.crichton, sean.kelly, chris.mattmann}@jpl.nasa.gov Abstract. The Planetary Data System (PDS) data model was developed in the late 1980’s and models the entities and relationships of interest within the Planetary Science Community. It was developed to both prescribe the metadata to be collected for the planetary science data archive and to design the PDS Catalog, a high level inventory of the data holdings in the archive. This catalog, an inventory of over one thousand data sets and related entities, represents a planetary science ontology. Since the advent of the Web, most of the information on the Web has been designed for human consumption using HTML and the http protocol. Semantic Web languages now allow computer processing and reasoning of web information by computer software. This paper will describe the use of these languages and other semantic web technologies to build the Semantic PDS prototype, an application that allows facet- and text -based search of PDS Catalog information. 1 Introduction The Planetary Data System (PDS) data model was developed in the late 1980’s to model the various entities and relationships of interest within the Planetary Science Community. It was developed to both prescribe the metadata to be collected for the planetary science data archive and to design the data set catalog, a high level inventory of the data holdings in the archive. The data model, implemented in a relational schema for the catalog database, supports sophisticated constraint-based searches for data sets based on their relationships to other modeled entities such as the spacecraft instruments and target bodies that were involved in the collection of the data. Since the advent of the Web, most of the information on the Web has been designed for human consumption using web technologies such as HTML and the http protocol. The Semantic Web now provides technologies to allow information to be easily read and consumed by computer software. These new technologies such as the XML language, the Resource Description Framework (RDF), and RDF Schema (RDFS) support computer processing and reasoning of web information. This capability however is dependent on the existence of domain ontologies.