Model Mission: Magnetospheric Multiscale (MMS)

1. Model Mission:Magnetospheric Multiscale (MMS) • Mission Goal “To study the microphysics of three fundamental plasma processes: magnetic reconnection, energetic particle acceleration, and turbulence*” • Constellation composed of 4 identical spacecraft maintaining a tetrahedral formation in regions of scientific interest within the magnetosphere • Each spacecraft has a suite of 4 primary payload sensors/subsystems (FPI, FIELDS, HPCA, EPD) * SWRI MMS webpage http://mms.space.swri.edu/

2. MMS Mission (cont.) • Plasma processes under investigation are inherently transient (magnetic reconnection in particular) • Specific need for reactive on-board autonomyto enable high temporal and spatial resolution data acquisition during transient events (i.e. changes in particle, ion, and electromagnetic field measurements) • Limited intra-constellation communication dedicated to coordinating reactive data acquisition • Only a measure of the “quality” of scientific data is transmitted (1 byte every 10 seconds) by each spacecraft • Quality byte is used as a trigger for the other spacecraft in the constellation to start high resolution data acquisition

3. Operating Modes • Each spacecraft has three modes of operation • Slow Survey • Fast Survey • Burst • Slow Survey Mode is entered when a spacecraft is outside the regions of scientific interest (approx 60% of orbit) • Only a subset of payload sensors are active, providing a minimal amount of data (primarily for health monitoring) • Acquired data is not stored for downlink • Fast Survey Mode is entered when a spacecraft is inside a region of interest (approx 40% of orbital period) • All payload sensors are active, and data taken at moderate rates • Acquired data is analyzed for quality on-board and stored for later downlink • Quality data is communicated throughout the constellation

4. Operating Modes (cont.) • Burst Mode is initiated by time-triggered commands or autonomously when measured conditions satisfy a set of rules • It can only be triggered while the spacecraft is already in Fast Survey Mode • Approximately 40 min allowable per day (due to storage constraints) • All sensors acquire high temporal resolution data • Acquired data is analyzed for quality and stored for downlink • Transition to Burst Mode is communicated throughout the constellation via the quality byte • Does not necessarily force Burst Mode transition in other spacecraft • Transition based on weighted combination of conditions, local data quality, and communicated quality

5. Phases of MMS Mission • Three phases of operation targeting different regions of the magnetosphere • Priority of payload data dependent on phase of mission as well as location in orbit Image from SWRI MMS CSR p. F-16

6. Payload Sensor Specifications Image from SWRI MMS CSR p. E-18

7. Demonstration Scenarios based on MMS Mission Model • Simplifying assumptions • Only three spacecraft in a triangular formation (allowing potential use of Microbots as hardware testbed) • Simulate payload sensor data and orbital information for operating mode transitions • Use representative algorithms for compression, on-board processing, etc. • Three potential scenarios of increasing complexity • Nominal “Day in the Life” of MMS • Support of science community requests for alternate on-board processing • Management of solid-state storage overflow conditions

8. Demonstration Scenarios (cont.) • “Day in the Life” scenario will demonstrate several aspects of mission operations under nominal conditions • Mode transitions based on orbital location (Slow/Fast) • Mode transition based on burst trigger commands, measured conditions, and inter-constellation communication • Ground station interaction with the constellation • “User Request” scenario will demonstrate support for multiple scientific user requests beyond the nominal operations • Users can modify or add to the on-board processing • Alternate data rates • Compression schemes • Quality of data for downlink/storage • Users can set time triggered commands to control mode transitions based on time (i.e. location in orbit)

9. Demonstration Scenarios (cont.) • “Storage Overflow” scenario will demonstrate autonomous management of a fault or off-nominal conditions • Limited data storage space could be filled (by entering Burst Mode often) or fail, while sensors/processors still operational • Several potential methods of managing situation • Overwrite low quality or priority data • Balance stored data across constellation during Slow Survey Mode • Stream acquired data in realtime to other spacecraft for storage (assuming communication bandwidth sufficient) • Specific methods to be implemented still under consideration

10. Science Agent Architecture

11. Adaptive Network Architecture (ANA) Executive Agent CCM Layer Sensors Gizmo Agent CORBA Notification Service Component (Data/Message Filtering for Remote Delivery) Science Agent Actuators CCM Layer InterAgent Messages (FIPA ACL) CCM Layer SpaceWire/USB/ 802.11/Legacy GNC Agent Agent Registration CORBA Notification Service Component (Data/Message Filtering for local Delivery) CCM Layer CORBA Federated Naming Service (Agent Locator) Comm. Agent CCM Layer SpaceWire/ USB/ 802.11/Legacy Current LMCO ANA Configuration Science Payload Gizmo Agent CCM Layer Science Instrument e.g. Camera