1. EMC Quiet Planning During Science Operations Andrew Walsh & Chris Watson Solar Orbiter SOC, ESAC, Madrid EMC Working Group #12, Imperial College, 15-16 July 2015

2. Introduction EIDA R-699: The Prime Contractor shall ensure that electromagnetically quiet phases amount to at least 70% of the operational orbit duration. During these EMC quiet phases contiguous intervals of quietness shall last at least one hour. EIDA R-795: The PIs shall ensure their instrument operations are coordinated with other units and platform events as defined in R- 679 and R-794 and minimise their disturbances to the electromagnetically quiet phases. During these EMC quiet phases, contiguous intervals of quietness shall last at least one hour. GOAL: Meet 70% requirement without overly constraining science operations

3. Two Extremes of Approach (Neither Will Work) 1.Completely proactive approach: Model EMC in detail and treat it as a hard constraint, rejecting IORs at MTP if the 70% requirement is not met. Whose IORs do we reject? Will require far more iterations than anyone has the time and resources for. 2.Completely reactive approach: Let instruments plan how they like but restrict subsequent operations of excessively noisy instruments via the SOWG/SWT. Won’t provide coordinated science. Unlikely to reach 70% quiet. We think a combination of the approaches will work

4. Some Definitions EMC Noisy Events Events or operations that aren’t EMC Quiet (according to EIDA definition) Three Subcategories: Platform Noisy Events (planned first) E.g. an HGA Movement or wheel offloading These can’t be rescheduled by SOC. MOC will stack them as best they can to minimise disruption. ‘Fixed’ Payload Noisy Events Events that need to occur at a specific time for meaningful science operations. Movable Payload Noisy Events Events whose precise timing is not critically important. Not tightly interwoven with normal operations

5. EMC Noisy Events Catalogue SOC will hold a catalogue of noisy events, identifying payload events as fixed noisy or movable noisy. Also contains platform noisy events. First version will be produced before launch by SOC + EMC-WG based on EMC test results. Updates after NECP and Cruise phase RS Checkouts Ad-hoc updates thereafter. Events can be added or reclassified with SOWG agreement. Events can be removed with agreement of affected PIs.

6. Planning Approach – Proactive Part SOC will schedule Mandatory Quiet Windows at LTP: These will have to fit around Platform Noisy Events. IORs that include Any Noisy Events during these windows will be rejected. There will be at least one every day (even during RSWs). They will be a minimum of 1 hour long. Exact durations will be decided based on science goals & experience in flight.

7. Planning Approach – Proactive Part time Mandatory quiet window No EMC Noisy Operations Permitted In Principle 100% Contribution to quiet time Platform Noisy Event Not to scale (!)

8. Planning Approach – Proactive Part SOC will schedule ‘Preferred Noisy Windows’ at LTP: These will nominally be centred on platform noisy events. In principle additional ‘Preferred Noisy Windows’ could be scheduled where there are no platform noisy events. ITs are encouraged to schedule as many noisy events as possible in these windows ITs are obliged to schedule movable payload noisy events during these windows. Probably near 0% contribution to quiet time.

9. Planning Approach – Proactive Part time Mandatory quiet window No EMC Noisy Operations Permitted In Principle 100% Contribution to quiet time Platform Noisy Event Preferred Noisy Window All Movable noisy events must be scheduled here Likely 0% contribution to quiet time Not to scale (!)

10. Planning Approach – Proactive Part The rest of the time: No platform noisy events IORs scheduling movable payload noisy events will be rejected. Other noisy events allowed, but discouraged. TBD contribution to quiet time (won’t be 100%, but won’t be 0% either).

11. Planning Approach – Proactive Part time Mandatory Quiet Window No EMC Noisy Operations Permitted In Principle 100% Contribution to quiet time Platform Noisy Event Preferred Noisy Window All Movable noisy events must be scheduled here Likely 0% contribution to quiet time Undefined period No Easily movable events here Medium density of EMC noisy events TBD contribution to quiet time Not to scale (!)

12. Planning Approach – Reactive Part Reactive in that to reach 70% we will need to tune this approach as we better understand performance. Two aspects: 1.Setting window frequencies and durations. –Science driven, SWT decisions –Based on science goals of a planning period and past EMC performance 2.Noisy events catalogue maintenance (SOWG & PIs) –Add events that turn out to be noisy –Remove events that turn out to be quiet –Reclassify events when necessary

13. Handling Autonomous Behaviour Autonomous behaviour from platform and payload can’t be predicted in advance, so can’t be completely excluded from mandatory quiet times. Two possible ways around this: Disable noisy payload autonomous behaviour that isn’t critical for instrument safety during mandatory quiet times to minimise the potential impact. Allow it, but if mandatory quiet time is broken by autonomous behaviour, schedule more mandatory quiet time in the next panning period to compensate. The best choice will depend on how noisy autonomous operations end up being.

14. Communication of Window Times At LTP, SOC, with input from MOC, will produce & distribute a planning file (E-FECS) that contains scheduled platform activities for a 6 month period: Thruster firings Antenna and Solar Array Movements etc. This will also include times of Mandatory Quiet and Preferred Noisy Windows XML Format Instrument teams expected to write their IORs based on this input.

15. Summary Tunable, window-based EMC Quiet planning scheme. We think this is the best way to reach 70% quiet without 1.Imposing an unmanageable planning overhead 2.Compromising coordinated science Details can be adapted based on science goals and in flight EMC performance Fully described in SOL-SGS-ICD-0006, E-FECS ICD (Draft in the SOC Documents Area) Happy to distribute to EMC Working Group for comment. We will need your input to the events catalogue to make it work.