2.1.1 Relationship to NEEDS
NASA has instituted the NASA End-to-End Data System (NEEDS) program, the goal of which is to improve the effectiveness and efficiency of the agency's data and information management methodology. NEEDS began with Phase I which addressed some very near-term data handling and processing problems. Phase II, initiated in 1978, concentrated on complete subsystems development to permit nearly real-time data management. Future Phase III will concentrate on low-cost communications and data distribution, and Phase IV will deal with integration of modular subsystems and systems techniques. NEEDS is a complex program which evolved on a problem-by-problem basis to accommodate everincreasing demands placed on it by the changing nature of the space program. A summary of Phases I and II projects appears in table 2.3.
TABLE 2.3 - NASA END-TO-END DATA SYSTEM (NEEDS) PROGRAM. Phase I 1. Synthetic aperture radar processor 2. Multispectral data processor 3. Digital data systems 4. Multipurpose user oriented software techniques 5. Resource effective data system definitions Phase II 1. Systems analysis and integration 2. Modular data transport systems 3. Information adaptive systems 4. Database management systems 5. Archival mass memory 6. Massively parallel processor
The intelligent Earth-sensing information system proposed in this report, and also the Titan mission described in chapter 3, will also place significantly increased demands on the present NEEDS program. This is not surprising as both may be viewed as parts of a natural evolution of present or near-term planned NASA missions. Moreover, with these new proposals as goals, the NEEDS program can implement Phases III and IV in a comprehensive fashion rather than on a problem-by-problem basis. The Earth-sensing mission demands are at the far extremes of present NEEDS activities, particularly in planning, scheduling, and control of satellite systems.
2.2 System Description
The system and mission goals described in this chapter are best summarized as an attempt to propose a flexible, ongoing tool of tremendous utility and sophistication. Most of the details presented are offered solely to illustrate one of many possible alternative approaches. The intent was not to prepare an encyclopedic discussion of design specifics but rather to indicate the general nature of probable solutions and provide sufficient subsystem details to permit preliminary technology assessment of the basic concept.
The Intelligent Earth-Sensing Information System (IESIS) has the following major features:
- An intelligent satellite system that gathers data in a goal-directed manner, based on specific requests for observation and on prior knowledge contained in a detailed self-correcting world model (section 2.3). The world model eliminates the processing and storage of redundant information.
- A user-oriented interface that permits natural language requests to be satisfied without human intervention from information retrieved from the system library or from observations made by a member satellite within the system.
- A medium-level onboard decisionmaking capability which optimizes sensor utilization without compromising users' requests.
- A library of stored information that provides a complete detailed set of all significant Earth features and resources, adjustable for seasonal and other identifiable variations. These features and their characteristics are accessible through a comprehensive cross- referencing scheme.
IESIS has five major components: (1) System/user interface, (2) uplink, (3) satellite sensing and processing, (4) downlink, and (5) on-ground processing. The basic- system is illustrated in figure 2.2. The user connects to the on-ground processor via a communication link and interactively defines his needs with the assistance of the system, accessing the database or directing IESIS to collect, process, and deliver information as required. The link might be a standard telephone line, and the entire transaction could occur in keyed natural language. Often, the user request should be answerable entirely from information already available in the system database, in which case IESIS appears to function much like any other interactive question-answering system (fig. 2.3).
Frequently, however, requests will require satellite observation data not yet available, in which case appropriate observations are scheduled by the on-ground processor. These instructions are uplinked via geosynchronous
