The SWT will set the overall science policy and direction for mission operations, set priorities, resolve conflicts and disputes, and consider Guest Investigator observing proposals. During SOHO science operations, the SWT will meet every three months to consider the quarter starting in one month's time and form a general scientific plan. If any non-standard DSN contacts are required, the requests must be formulated at this quarterly meeting. The three-month plan will then be refined during the monthly planning meetings (see 2.1.2) of the Science Operations Team (SOT), composed of those PIs or their team members with IWSs at the EOF, which will allocate observing sessions to specific programs. At weekly meetings of the SOT (2.1.3) , coordinated timelines will be produced for the instruments, together with detailed plans for spacecraft operations. Daily meetings of the SOT (2.1.4) will optimize fine pointing targets in response to solar conditions and adjust operations if DSN anomalies occur.
While the Project Scientist (PS) will be responsible for the implementation of the scientific operations plan, execution of the plan will be carried out by the SOT. On a rotating basis, one of the PIs or their representatives at the EOF will serve as the Science Operations Leader (SOL). The SOL will serve for approximately 10 days, starting with the weekly planning meeting and continuing through the week of operations. The SOL will
To provide operational continuity over the course of the SOHO mission, and from one SOL's tenure to the next, a Science Operations Coordinator (SOC), who is not a member of any of the PI teams, will work daily with the SOL and SOT. The SOC's role is to
There will be two full-time SOC's and two Science Data Coordinators (SDC). The SDC's role is to
On a monthly time scale the SOT will meet to assess progress in achieving the scientific goals of their investigation and to discuss the objectives for operations starting in a month's time. This gives time for coordinated observations to be set up, arrangements for Guest Investigators to be made, and any deficiencies in observing sequences to be identified.
Approximately 2 weeks later a SOT meeting will discuss instrument health, solar activity and consider the operations for the month under consideration. SOL's will be appointed for each week and they will be responsible during the month for identifying any conflicts between the planned operations and the DSN schedule as they become available.
Inputs to the monthly meeting are made by each instrument team and common objectives are identified. The output of this meeting is a schedule showing when each instrument will be operating, whether joint or individual observations are being made, the types of solar features being observed, ground observatory support and a backup plan if these conditions are not met. Requirements for telemetry rate switching should be identified together with any spacecraft operations which may affect the observations, for example momentum dumping and station keeping. Conflicts between instruments for resources are resolved and disturbances identified.
A weekly meeting considers the week starting in approximately three days time and this is when the detailed plans for all the SOHO instruments are synchronised. It will be convened by the SOL designated to lead that week. The intention is to lay out a definitive plan with timings, flag status, disturbances, etc., so that the daily meetings only consider deviations from the weekly plan. This meeting will have the conflict-free DSN schedule available.
The weekly meeting will also be the forum for instrument teams to give advance notice of any special operations or changes to the plan for future weeks. The DSN forecast schedule will be available for the week commencing in 10 days time and the strawman proposal will be available for the week following that.
Table 2.1: Schedule for SOHO planning meetings
The daily meeting convenes to hear about the state of the Sun, discusses fine pointing targets and whether any changes are necessary in view of yesterday's operations. On the nominal timeline which follows, this meeting would take place early in the long real time contact, at approximately 10:00 GSFC local time, so that recent images from other SOHO instruments and ground observatories will be available and allow optimisation of observations, particularly pointing targets, for the current pass and also those planned for the next 24 hours. A ``SOHO planning day'' will start towards the end of the long real time pass, at approximately 15:00, so routine commands for the next 24 hours should be uplinked by 15:00 to allow for checking and contingency. Figure 2.1 and 2.2 summarize the SOHO planning cycle activities.
Figure 2.1: SOHO planning cycle
Figure 2.2: SOHO telemetry and real time operation plan
Fig 2.2 shows the proposed overall time line of operations. The time of the long real-time operation (MDI high data rate) has been chosen to be day-light in GSFC and to overlap about half time with the Canary Islands observatories and with the USA western observatories. The 2-month continuous operation is arbitrary selected. It is expected that both the time of the day and the period of the year for the MDI high data rate will have to be adapted to DSN capabilities both for technical and scheduling reasons.
It is also expected that the Soho SWT will, on certain occasions, for correlative studies with particular ground observations or with other space missions, request modifications to the baseline operations schedule for limited periods of time.
During the real time operation periods the individual investigators will send their commands as needed from their workstations. It is required that the command processing time from WS to spacecraft be less than one minute. Real-time commanding rate will be typically less than 100 per hour, with peaks of about 10-20 per minute.
Figure 2.3: One day SOHO observing plan (Coronal instruments), Day D
Figure 2.4: One day SOHO observing plan (Coronal instruments), Day D+1
This two day timeline is intended to show the degree of interaction and coordination between the instruments during a ``typical'' day (Fig. 2.3 and 2.4). At some times all of the instruments will be addressing a common objective, at other times joint science will be carried out by smaller number and there will be occasions when instruments will be working individually. Naturally there is a tremendous scope for variation.
03:25 MDI make a magnetogram.
07:00 Telemetry format 2 is used to enable EIT and LASCO to make full Sun images. MDI make magnetogram.
07:30 - 09:00 CDS and SUMER make a series of short interactive observations to identify features to be studied during the rest of the real time pass and features to be studied collectively during the following SOHO day. EIT carry out a bright point survey. LASCO continue synoptic studies.
10:00 Daily SOHO meeting which optimises the plan for the day starting at 15:00 and considers the plan for the day after.
14:00 EIT repeat their bright point survey.
15:00 SOHO observing day starts. All instruments concentrating on the same area with the same objectives.
20:00 CDS and SUMER check instrument performance and optimise observing programs (particularly pointing) for the next session. Every 2 days SUMER will make a full Sun scan to give intensity and velocity maps. EIT, UVCS and LASCO start synoptic observations.
During agreed periods one or several experiment teams and, if agreed, teams from other spacecraft or ground observatories will run, in collaboration, observation campaigns to address specific topics. The periods of two-months continuous near real-time observation will probably be the most convenient for campaigns that require continuous observation during more than 8 hours, or that require coordination with ground observations only feasible from particular observatories around the world. For each campaign a campaign leader will be responsible for the coordination.
With ground-based observatories
If the ground-based observatory is one that has electronic links that allow near real-time imaging transmission to and from the EOF, the coordination will be no different than if the ground based observatory were one of the SOHO experiments.
If no real-time data transmission is needed or possible, the coordinated operation will be an agreed time of simultaneous observations.
Generally speaking the coordinated observations with ground observatories will need a longer time lead in their planning to insure availability of the facility and coincidence of the SOHO real-time coverage.