Page:Advanced Automation for Space Missions.djvu/31



103 pixel?

AVERAGE 30 niches CHARACTERISTICS 1 SENSOR VICTORIA, AUSTRALIA 106 pixels VS. 450 CHARACTERISTICS 2,222 : 1 REDUCTION Figure 2.9. - Sample niche features map of Mildura City; alteration in boundaries of the River Murray due to flooding.

terrestrial niches, sensor characteristics, and subsidiary characteristics. The ground model thus constitutes a full working library. A land agent, for instance, easily could retrieve moisture content on all corn acreage in southwest Iowa from the master files.

In addition to a physical database memory onboard and on the ground, the world model requires extensive artificial intelligence software including expert systems which use the database in controlling sensing, image location and rectification, data processing, labeling, anomaly search, and decisionmaking on board the satellite and on the ground. A set of expert systems is needed to handle overall coordination, observation scheduling and user-generated processing tasks (fig. 2.11).

2.3.2 Onboard Memory

Present predictions for onboard memory in the year 2000 for Earth-sensing satellites are on the order of 1014 bits (Opportunity for Space Exploration to Year 2000. Address delivered by A. Adelman at Goddard Space Flight Center, 1980). In this section, these projections are compared with the storage capacity required for IESIS abstracting and onboard processing. The following estimates emphasize image processing because this is the type of data transmitted at the highest rates - on the order of 650 Mb/sec for SAR and 320 Mb/sec for the multilinear array (Nagler and Sherry, 1978).

The bits stored aboard the satellite or satellites for use in immediate processing tasks presumably are substantially less than the number stored on the ground in IESIS. The on-ground world model is a continually updated version of the Earth model. Future feasibility experiments plus new developments in computer science and technology will dictate the specific allocations of memory required in space and on the ground. Hence, the following are only crude estimates of the storage requirements under a range of plausible assumptions.

For the present work it is assumed that a correlation is to be performed between the incoming image and its image description stored in the onboard world model. Significant