Collection planning for the OrbView-3 high resolution imaging satellite

Abstract

Commercial imaging satellites must respond to thousands of requests to image different areas of the earth within tight time constraints. To effectively satisfy and manage these requests, geodynamic, camera, and spacecraft constraints must be reconciled within a matter of minutes to create a workable plan for capturing images during a particular spacecraft pass. These constraints include customer-defined target viewing constraints, spacecraft power limitations, data storage attributes, pointing constraints, spacecraft agility limitations, high gain antenna blockages, cloud cover and more. Orbit Logic developed and delivered a high fidelity spacecraft simulator that is tightly integrated with scheduling optimization algorithms to meet this challenge. Dubbed the OrbView Tasking System (OTS), it is used today by GeoEye for OrbView-3 image collection planning. OTS incorporates spacecraft slew, scan, and other models, reconciles all constraints and efficiently generates valid collection plans using multiple optimization algorithms and/or manual planning inputs. It also incorporates innovative visualization capabilities for intuitive assessment of collection plans. This system is being upgraded for use with GeoEye-1, in addition to OrbView- 3, and will be incorporated into a new system called the Collection Planning System (CPS). CPS includes a planning server that will manage multiple instances of OTS for increased computational performance and system scalability. This paper will describe the OTS and the overall approach to optimizing collection planning for OrbView-3 as well as the system's overall applicability for use with any imagery, radar, or remote sensing mission. The OTS is designed to support rapid collection plan optimization over a user-defined timeframe (generally a specified portion of one satellite orbit). In addition to the myriad of physical system and target constraints noted above, quality of previously planned images and priority of targets are critical factors in collection optimization for future passes. The system provides a userconfigurable filter for choosing those constraints most important to the satellite operator or system user, with the result being a more qualified list of candidates for in-depth computation and planning. Once this filtered group of target areas is ascertained, the OTS then competes multiple optimization algorithms against each other to determine the "best" collection plan. The quality of each candidate plan is judged using a common user-configurable figure-of-merit equation. Each algorithm employs a different approach to solving the collection problem and, importantly, each algorithm will always return a plan consistent with spacecraft constraints and performance. Whether performed manually or in an automated fashion, the plan is output to the ground command and control system for uplink to the spacecraft. For a single orbit, an optimized collection plan can be computed in a matter of minutes with specific performance being dependent upon several factors including the number and density of targets within the field-of-regard during the planning window, spacecraft agility, and the number of constraints configured as "hard" constraints. OTS uses an agile and flexible user interface to provide parameter specification and visual verification of the plan. The user has the ability to specify various parameters for each image collection included in the plan (including scan start time, imaging mode, scan direction, line rate, and more). OTS incorporates Satellite Tool Kit (STK) from Analytical Graphics, Inc. for user map displays and visualization of the optimized collection plan. STK provides a visual verification of the optimized imaging plan as well as assists the user in understanding system constraints and spacecraft behavior. This visual capability combined with OTS's adaptable architecture and extensive modeling results in a robust system that can be easily tailored for any spacecraft mission that must accommodate large target decks with numerous physical constraints and unique spacecraft capabilities. © 2006 by Orbit Logic Incorporated.