ESP Definitions

The discussion of ESP can be better understood if we first define several terms.

• Experiment - In general, a collection of procedures and equipment which, when executed, contribute to the body of technological or scientific information. In ESP, the term experiment refers to the "model" or "models" corresponding to the general definition.
• Functional Objective - A large section of an experiment's procedures which accomplish a definite purpose, such as verifying equipment, collecting baseline data, etc.
• Model (Activity Model) - The database representation of an experiment or part of an experiment. A model is a collection of constraint and execution definitions. Some of the definitions apply to the whole model and some apply to the "steps" of the model.
• Step - The smallest, clearly delineated part of an activity model. Steps are usually executed in sequential order, but are not necessarily contiguous. Resource and crew requirements of a model are shown at the step level.
• Performance - An execution of an activity model. A model may be performed multiple times to collect additional data.
• Activity Timeline - A time history of experiment performances and related activities planned for a mission. These activities are represented by the start and stop times of model steps.
• Nondepletable - A resource whose availability is temporarily changed only for the duration of its usage. This type of resource may be used in fractional amounts. A negative usage will increase the availability for the duration of the step.
• Equipment - A nondepletable resource which is used only in whole number amounts. In ESP, equipment appears to be separate entities from other nondepletables resources.
• Consumable - A resource whose availability is permanently changed by its usage (e.g., camera film). A consumable can be defined to be used at a fixed amount, constant rate or based upon a nondepletable rate.
• Orbit Opportunity - An orbit opportunity data set lists the times when certain conditions exist (for example, the sun is up). Orbit opportunities are usually based on orbit geometry and timing.