Melbourne Florida., June 1999 -- Earthwatch uses their Quickbird satellite for multi-spectral imaging of the planet Earth.  The Quickbird satellite utilizes intelligent Mission Planning & Tasking (P&T) modules built by Interface & Control Systems.  Planning and Tasking a satellite to obtain maximum utility and functionality is a complex process, performed every time a new task (in this case, a new imaging request) is initiated for the satellite. 

The process begins with a user defining the geographical location of the desired image, any temporal requirements, and other parameters.  This set of parameters is passed to P&T, which then performs orbital propagation to determine when imaging opportunities will occur that satisfy the requirements.  These calculations include considerations of maneuvering the spacecraft (slewing) to optimize an imaging opportunity.  Working from a known spacecraft orientation at a known time, known minimal and maximal spacecraft slew rates, and other physical factors, possible “task windows” are defined that include actual slew start time, slew rate, and other critical variables.

Possible task windows are compared to the current Spacecraft Plan to search for conflicts such as overlapping task windows.  How a conflict is resolved may be affected by factors such as the prioritization assigned to each customer and each task, and the need to maximize satellite utilization by minimizing gaps where the satellite is not in use. 

Even when “clear” windows are found, estimates must be made of the availability of onboard resources, such as onboard memory space for the images and battery power to operate the imaging payload.  Resource evaluation includes assessment of connectivity with ground stations and the Mission Control Center for imaging downloads.  If one or more critical spacecraft resources are not available at the time of a window, then that window becomes invalid – unless task-prioritization dictates that already-scheduled activities be altered such that the necessary resources become available, a complex process called “shoehorning”.

ICS is a product development and engineering services company specializing in the development of Open Source real-time, embedded, and autonomous command and control software systems.  Services include software systems engineering, integration and test, and project and software life cycle management. ICS is a privately held company with main offices in Columbia, MD, and Melbourne, FL.

Contact information:

info@interfacecontrol.com Interface & Control Systems, Inc. 877-404-CONTROL