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FIELDS Concept of Operations Team Meeting Dec 1, 2012

FIELDS Concept of Operations Team Meeting Dec 1, 2012. S. Harris (UCB). Orbit Phase 1 - 5. 100% inst duty cycle TPS to sun s/c +x near ram Momentum dumps. Ram S/C to Sun S/C Coord (translated to ~center of gravity, cg). Aphelion. 1.02AU – 0.88AU. x cg. z cg. Cruise/Downlink

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FIELDS Concept of Operations Team Meeting Dec 1, 2012

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  1. FIELDS Concept of OperationsTeam MeetingDec 1, 2012 S. Harris (UCB)

  2. Orbit Phase 1 - 5 • 100% inst duty cycle • TPS to sun • s/c +x near ram • Momentum dumps Ram S/C to Sun S/C Coord (translated to ~center of gravity, cg) Aphelion 1.02AU – 0.88AU xcg zcg Cruise/Downlink ~158-110 days Primary Science ~11 days • DL science data • TPS to sun except, slews • >0.82AU (thermal) • cooling system activation • >0.7AU (data DL) • s/c rotates about s/c-sun line • Power avail for inst <0.82AU if s/c not DL data, etc 0.25 AU Perihelion 35Rs – 28Rs 0.25 AU MDR charts: 12_Spacecraft – MKLockwood

  3. Orbit Phase 6 - 24 • 100% inst duty cycle • TPS to sun • s/c +x near ram • Momentum dumps Ram S/C to Sun S/C Coord (translated to ~center of gravity, cg) xcg Cruise/Downlink ~102-77 days Aphelion 0.82AU – 0.73AU zcg Primary Science ~11 days 0.25 AU • DL science data • TPS to sun except, slew • >0.7AU (data DL) • s/c rotates about s/c-sun line (momentum management) • Power avail for inst if s/c not DL data, etc Perihelion 20Rs – 9.5Rs 0.25 AU MDR charts: 12_Spacecraft – MKLockwood

  4. Instrument Operation (1 of 2) • Solar Encounter – solar distance < 0.25AU • FIELDS MEP will be ON • All Sensors ON • Survey data will flow directly to S/C SSR • Plan to create 3 levels of Survey Data • 1% data is decimated by 100, lowest resolution, given highest priority for Downlink • 10% data is decimated by 10, given mid-level D/L priority • 89% data is full resolution, given lowest level D/L priority • Why do this? To provide quick look at encounter • Enables us to uplink playlists for Select Data • Provides some flexibility in dealing with D/L schedule • Burst data, or “Select” data will flow to FIELDS Flash Memory • After reviewing Survey data, will decide which Select data to D/L • Total allocation, Survey + Select, is 20Gbit / encounter • Encounter – safe mode and recovery • If S/C enters Safe mode, instruments will be powered off • FIELDS must autonomously return to previous operational mode after recovery

  5. Instrument Operation (2 of 2) • Solar distance > 0.25AU • No requirement for science data for solar distance > 0.25AU • However, there is power for instruments for distances < 0.8AU • Must still operate within D/L data allocation • FIELDS MEP must be ON to transfer “Select” data to S/C SSR, however • MEP is OFF during Ka-band operation (power constraint to operate TWTAs) • MEP is OFF if S/C operations require more power, e.g. Side B health checks • MEP is OFF for Trajectory Correction Maneuvers • MEP is OFF for Venus flybys (Maybe) • Other times, as well • So, managing data transfer from MEP Flash Memory to S/C SSR requires some planning • S/C charging (primarily due to TPS) will deviate outside of 10V

  6. Ka-band Downlink Constraints • All science data is downlinked via Ka-band, no other channel • DSN passes are generally scheduled for 6 hours (8 including margin) • Despite this, instruments will remain OFF if D/L scheduled for consecutive days • On some orbits it creates a race condition for us to review data, upload playlists For example: Orbit 5: ~5 days to D/L Orbit 4 data ~9 days to D/L Orbit 5 data Assuming we want to transfer 10Gbits to S/C SSR, using 80kbps telemetry interface, would take 1.5days • Some orbits have very stretched out D/L periods, results in reduced opportunities for science data operation • e.g. Orbit 13, 17 • So, all orbits have to be planned individually, for science operation and data transfer

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