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EDSN Autonomous Planner Completes Pre-Flight Test

The EDSN planning and scheduling software was tested as part of EDSN's flight qualification. The EDSN mission is designed to be fully autonomous; no ground commanding of the spacecraft is expected as part of the nominal mission. As a result, each spacecraft needs a fully autonomous planner to make key decisions during the mission.

Every 25 hours, each spacecraft receives a GPS update, refines its estimate of its position and orbit, and then uses this new prediction to compute schedule windows for key spacecraft activities. There are four classes of activity: time constrained (e.g. crosslink), location constrained (e.g., downlink), both (e.g., science data collection), and frequency constrained (e.g., GPS reading). Activities are also prioritized. The scheduler's task is to ensure 1) activities occur inside their corresponding opportunity windows, 2) no two activities overlap in time and a specified minimum separation is maintained so that the spacecraft executive can process them reliably, and 3) activities that may conflict are either separated in time or preference is given to the highest priority activity. The scheduler design ensured EDSN could meet its mission objectives of autonomous operations with no ground commanding. The complete mission concept enables a 'sensor-web' like science capability comprising small autonomous spacecraft.

BACKGROUND: EDSN is a space flight demonstration of a small swarm of satellites capable of collecting multi-point science data and transferring the data to ground. The mission objectives are 1) flight demonstration of a one-way space-to-space data transfer, where at least two satellites transfer data to a third satellite, which then transfers the data to ground; 2) fight demonstration of a system to collect multi-point science measurements, and transfer science measurements to the ground; 3) flight demonstration of a reaction wheel based pointing system, and 4) assess the viability of satellites built with COTS components to operate for 60 days.

TEAM: Javier Barreiro (SGT), Mike Dalal (SGT), with support from Douglas Forman (MEI), John Schreiner (ARC-TI), and the EDSN engineering staff

NASA PROGRAM FUNDING: STMD; Technology Demonstration Mission Program

Contact: K. Michael Dalal

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