Timeline and the Timeline eXchange Infrastructure: A framework for exchanging temporal information

The concept of a timeline is used ubiquitously during space mission design and development to specify elements of flight and ground system designs; it is used also during testing and operations to describe mission plans and system state trajectories, for example. In this paper we introduce our Timeline Ontology. The Timeline Ontology is grounded in mathematical formalism, thus providing concrete semantics. We also describe our ontology-based Timeline eXchange Infrastructure (TXI), a framework that provides a means to exchange time-varying information among various tools and algorithms with semantic correctness. To further ground the needs for Timeline and the TXI, we examine the tools used in the Mission Operations Systems (MOS) at the Jet Propulsion Laboratory (JPL). To illustrate the versatility of the formalism, we also describe a use of Timelines during the early design phase of a project lifecycle. Finally, we look at future extensions to this work, including creating a user interface for Timeline instance editing, integrating with ontology validation tools, and extending the Timeline concept to include relationships to other pre-existing JPL ontologies.