Mission Operations

Planner

All of ELFIN’s nominal activities are planned using the Planner, ELFIN’s home-brew software that abstracts low level commanding and scheduling in an intuitive manner. The Planner allows for planning of science collections, data compression, automated downlinks, and spin/attitude control by aggregating/displaying useful information about the spacecraft orbit/status and providing a user-friendly interface to plan out the activities. These activities are constraint checked in real time against known spacecraft health limits, operational capabilities, and scheduling conflicts. Activity plans created in the Planner are converted into commands the spacecraft can understand through another custom software called the Translator. These commands are then put into Command Load Files, which are handled by the Commander (below).

Command and Control

The Commander is the direct method by which operators interface with the satellites; it's capable of sending/receiving commands with ELFIN satellites in real time, as well as display real time state data and telemetry in a helpful manner, which is crucial to off-nominal real time operations. The Commander also gives Spacecraft Operators an interface to turn the Translator Output from the Planner into Load Files, which is how we can streamline nominal ops to run without human supervision. At the center of the Command and Control process is the GSED (Ground Support Equipment Daemon), which interfaces with the SatTracker Daemon (responsible pointing the antennas at ELFIN and accounting for doppler shifting) for knowledge of ELFIN communication passes, and handles the loaded up command queue appropriately. Load files are usually generated 2-3 days in advance nominally, to allow for modification of planned activities in case anything needs to change, typically by request of the science team. C&C is also responsible for receiving parsing and handling real-time telemetry for display and for science data processing (below). This streamlined paradigm allows for fairly complex and robust C&C of the ELFIN satellites with ease.

Science Processing

The science processing team is responsible for developing a consistent and reliable pipeline that regularly handles packets from ELA and ELB, extracts and processes the contained data, and presents this information in NASA’s CDF format for scientific use. Science processing scripts must handle data from a variety of sensors and instruments, as well as data relating to each satellite’s status. Items generated by the pipeline are ultimately used in a variety of ways, from generating plots to tracking satellite position. Additionally, the science processing team is responsible for providing support to operators and other members of ELFIN by creating tools and investigating issues related to downlink completeness and operations. As a result, the science processing team provides an integral bridge between the operating and scientific sides of ELFIN.