PART II OVERVIEW OF MARS EXPRESS SCIENCE OPERATIONS

Transcription

1 MASTER SCIENCE PLAN OVERVIEW DOCUMENTATION (MEX-EST-PL-11912, Draft Issue 1.5) PART II OVERVIEW OF MARS EXPRESS SCIENCE OPERATIONS Planetary Missions Division Research and Scientific Support Department

2 : 2 Document Issue Record Prepared by Affiliation Issue P. Martin SCI-SB, ESTEC Issue May 2003 P. Martin SCI-SB, ESTEC Draft Issue November 2004 Checked by Affiliation PST ESTEC August 2004 Mission Manager ESTEC September 2004 Applicable and Reference Documents Both applicable and reference documents provide additional supportive information for a better understanding of the information given in the present documentation. Applicable and reference documents are listed in Annex 1 and 2, respectively. Cross-references to applicable and reference documents are indicated throughout this document by a combination of a letter code and sequential numbers, such as ADxx for applicable documents and RDxx for reference documents. 2

3 : 3 Table of Contents 1. Concept for Mars Express Science Operations Responsibilities for the Science Planning Mission Planning Cycles Introduction Long-Term Planning Scope and Description of Activities Timing Inputs Outputs Medium-Term Planning Scope and Description of Activities Timing Inputs Outputs Short-Term Planning and Very Short-Term Planning Scope and Description of Activities Timing Contingency Planning Payload Operations Service Overview Introduction POS Planning Subsystem POS Commanding Subsystem POS Information Dissemination Subsystem Planning and Commanding Interfaces POS-PST Interface POS-PI Interface PST-PI Interface PST-MOC Interface POS-MOC Interface MOC-PI Interface Other Interfaces Interface Diagrams Planning Tools

4 : MEX Instrument Resource Analyzer (MIRA) Mapping And Planning of Payload Science (MAPPS) Strategic purpose and use of MIRA and MAPPS Terminology Used in the Science Planning Contact Information Payload Support Team (PST) Payload Operations Service (POS) Mission Operations Centre (MOC) Principle Investigators (PI) Other Useful Contacts

5 : 5 1. Concept for Mars Express Science Operations The concept developed for the implementation of the Mars Express science operations is described thereafter and summarized in Figure 4. The Science Working Team (SWT) advises ESA on science matters related to the mission and assists the Project Scientist in elaborating science strategies and optimizing the scientific return of Mars Express. The SWT establishes, through the Science Operations Working Group, the policy, strategy and guidelines for science operations, based on the Mars Express scientific requirements and objectives. The SOWG is composed of Principal Investigator (PI) team representatives assigned to address all science operations issues. At this point it is important to note that a basic principle of the Mars Express science operations, as clearly expressed in the Science Management Plan (AD1), is the requirement for a strong personnel commitment by each PI team for the preparation of the payload operations. The Payload Support Team (PST) merges the science goals (both high-level mission goals and individual instrument goals) with technical and operational constraints into a feasible operational plan. The essential goal of this mission planning process is to optimize the science output along the lines of the mission s science objectives and strategy outlined by the Project Scientist and the SWT. Following the long-term planning, this is achieved (i) on a medium-term basis (planning periods of 4 weeks prepared 2 to 3 months ahead) thanks to the super-frozen orbit concept with its accurate predictability (see Part IV), and (ii) by harmonizing through an iterative process all science-driven payload requests with the spacecraft resource budgets and constraints. The PST chairs and consults the SOWG for all science planning matters. PST also coordinates the medium-term planning process and all interfaces (see AD2 for further detail about PST s role and responsibilities in the Mars Express science operations). An essential task of the PST is to consolidate the detailed payload operations timelines. The Payload Operations Service (POS) at Rutherford Appleton Laboratory in the UK has been contracted to support the PST, the Principal Investigators, and the Mission Operations Centre (MOC) in conducting efficient operations of the mission s scientific instruments. The POS undertakes to develop, implement, test, and operate the system and tools required to provide adequate support to Mars Express for an extended period of up to several years during which payload commanding operations will be run in a quasiautomated way. For the detailed planning and for the transition to and implementation of the commanding of each instrument s operations, POS interfaces with the PST, the MOC and the PI institutes, as shown in Figure 4 below. The main tasks of the POS are (i) the generation of the pointing requests (PTR), (ii) the generation of the consolidated Payload Operations Request (POR) files for all Mars Express orbiter instruments in the format 5

6 : 6 specified in the CRID (RD28), and (iii) the onward transmission of the planning and commanding files to the MOC. The high-level scientific planning is performed by the SOWG, with adequate support from PST and POS. This leads to the production of the (MSP). The MSP is the result of the compilation of payload operations timelines and of their integration into a feasible, consolidated overall science timeline per orbit and for all science phases of the Mars Express mission. All critical activities such as early Mars commissioning operations or any activity during the Interplanetary Cruise phase which requires interaction with the ground segment, are normally handled via either Flight Control Procedures (FCP) or POR files. All routine payload operations will be requested via POR files. The payload operations for all science phases shall be executed using timelines and procedures documented within the ESOC Flight Operations Plan (FOP; RD15). Most information required for the elaboration of the and for the production by ESOC of the instruments commanding timelines and procedures is documented in the instruments Flight User Manuals (FUM). Spacecraft safety is considered a primary goal and could potentially lead to severe constraints on science operations. Figure 4: Overall organization of the interfaces for the Mars Express science operations. 6

7 : 7 2. Responsibilities for the Science Planning In order to fully understand the roles, various interactions and activities of the parties involved in the implementation of the, it is critical to state the overall responsibilities of the PST, POS, MOC and PIs and to clearly establish the respective interfaces between those parties. Overall responsibilities are summarized thereafter. The detailed share of responsibilities for the scientific operations of the Mars Express payload during the routine phase of the mission is defined in the Mars Express Scientific Ground Segment Management Plan (AD2). The ESA Mars Express Project Team, headed by the Project Manager, had the overall responsibility for the Mars Express project implementation and provided the programmatic, contractual and technical interface with the POS until the Mars Commissioning Review on 3 June After successful separation of the spacecraft from the launcher, ESOC assumed operational responsibility for the mission. The Spacecraft Operations Manager (SOM) at ESOC manages the spacecraft operations according to the Flight Operations Plan (FOP; see RD15). The FOP contains rules and constraints for operating the spacecraft and its payload. Liaison on all matters concerning in-orbit operations is with the SOM, via the Payload Support Team (PST) at ESTEC. The MOC is responsible for scheduling spacecraft and ground segment operations such that the requested payload activities can take place. It is also responsible for executing all nominal and contingency operations according to the pre-defined procedures contained in the FOP. Overall spacecraft safety is also under MOC responsibility. Further details about the MOC role and specific responsibilities are listed in the Science Operations Implementation Agreement (RD18). Following the handover of spacecraft and operations management from the Project to the Research and Scientific Support Department, the Mission Manager and the Project Scientist have the overall responsibility for the mission operations and scientific outcome, and for the POS contractual management and technical interface. During the routine phase, the orbiter PIs are responsible for planning the activities of their instruments within the assumptions and constraints of the overall Mars Express and other documentation relevant to planning assumptions, constraints and rules, and for ensuring that the instrument commanding prepared by POS is consistent with those constraints. PST has the responsibility of coordinating all the required inputs, respecting the mission constraints and safeguarding the balance in the scientific return of the Mars Express instruments. POS is responsible for the efficient and successful implementation of the science operations of the orbiter instruments. 7

8 : 8 3. Mission Planning Cycles 3.1. Introduction The planning of the science operations of the Mars Express orbiter payload complement follows a four-step cycle, implemented as long-term, medium-term, short-term, and very short-term planning. The essential aim of the mission planning approach for the Mars Express routine operations is to maximize the science output of the mission by implementing payload science requests from the Principal Investigators in an optimum way, i.e., by ensuring adequate balance between (i) some flexibility in the finalization of the science requests, (ii) some robustness in the elaboration of timelines compatible with operational aspects of the mission and the timeframe given by the Mission Planning Concept (RD24), and (iii) providing the basis to optimize the consolidation of the medium-term planning. At various stages of these four planning cycles, the allocation of resources needs to be approved in order to go ahead with the next stage of the planning. The Resource Allocation Board (RAB) performs this approval activity. The RAB comprises representatives of PST, POS, Flight Dynamics (FD), Flight Control Team (FCT), and Mission Planning Team. This board convenes via teleconference at specific milestones defined by the planning schedule and/or when required. The, a high-level consolidated timeline of payload activities, is the result of the long-term planning. Long-term planning is for the most part performed by the PST and the PI teams, as it deals with long-term scientific goals and priorities, while medium-term planning is performed by the PIs, PST and POS, in close collaboration with the MOC, and leads to the production of Payload Operations Requests (POR) for all orbiter instruments. The POR files, calling telecommand sequences, are transmitted from the POS to the MOC during the Mars Routine phase. Figure 5 illustrates the concept developed for the science planning, and describes the four distinct planning cycles. The following subsections briefly describe each planning cycle. For details, please refer to the Mission Planning Concept (RD24) as developed by ESOC, which gives the precursor approach to planning and operations philosophy in terms of activities, interfaces, processes, and schedules. The Mission Planning Concept has been revised through a technical note (RD44) summarizing the updates resulting from the Solar Array power anomaly and the introduction of the second ground station. It is strongly advised to read and acquire the knowledge from all following three documents, the Mission Planning Concept (RD24 and RD44), the POS Planning Scenario (RD22), and this MSP overview documentation, in order to fully understand the overall planning activity that will take place in the execution of the Mars Express science operations. 8

9 : 9 Figure 5: Concept for the Mars Express mission planning cycles. The various acronyms are explained in subsections below. 9

10 : Long-Term Planning Scope and Description of Activities Two main goals can be set for the long-term planning, the first one being the establishment of payload objectives and priorities based on a defined science strategy (see Part VI), and the second one to ensure that the resulting planning will fit at Medium Term Plan (MTP)-level within the available envelope of spacecraft resources. During the long-term planning period, the PST prepares a skeleton of possible scientific windows and activities per orbit according to the science strategy, defined priorities and known constraints. This skeleton, in the form of an orbit activity table, is proposing a trade-off between the various possible observation and communication (NNO and DSN) windows. This leads to the process of PST sending out to the PI teams the information/guidelines to allow them to generate preliminary MIRA request files (MREQs) to be used by the MIRA tool (see the Planning Tools section below). Longterm planning activities (top of Figure 5) are largely performed by the PST, in interaction with the PI teams and POS, although POS involvement shall remain minimal in this planning cycle. The PI teams use the MAPPS tool (see the Planning Tools section below) and MIRA tool during the long-term planning, to visualize and prepare science requests. PST and POS shall ensure that (i) available spacecraft communications periods for data dumping, spacecraft health monitoring and uplinking of on-board command schedules are compatible with science observation and safety of the spacecraft, and (ii) that there are no violation of known constraints at this planning level based on the values provided in the FDS-POS constants file and on the rules and constraints specified in the OCD. The long-term planning process/cycle culminates in the generation of a Long-Term Plan (LTP), constituted by the orbit activity tables per MTP, over specific time segments as defined below. LTPs are therefore built based on a balance between both scientific objectives/priorities and various mission parameters/constraints. The science themes, as defined in the science strategy (Part VI), are used to implement the LTPs and check how the science goals of the mission are fulfilled once the relevant LTP payload activities have been implemented and executed Timing The long-term planning for Mars Express spans a time range of several weeks to several months, which is typical of a planetary orbiter mission and depends on the various constraints imposed on the spacecraft and payload resources. Therefore, Long Term Plans (LTPs) are defined as covering specific time segments corresponding to the relevant science subphases of the nominal routine mission. These time segments are 10

11 : 11 larger than MTP time segments (one science subphase or LTP covers several MTPs). From the definition of science subphases/ltps results scientific priorities based on the long-term analysis of science objectives and orbit, illumination, and downlink constraints Inputs The general inputs to the long-term planning process are (i) the science planning strategy as established in the overview documentation (Part VI), (ii) the spacecraft constraints from the spacecraft manufacturer as documented in the Spacecraft User Manual, (iii) the rules and constraints defined in the Operational Constraints and Budgets Document (OCD; RD25), and (iv) the Consolidated Report on Mission Analysis (CREMA; RD2). The OCD defines spacecraft, payload and ground segment activities to be managed by the Mission Planning System (MPS) and MIRA. In addition, the following input files shall be used by the SOWG as a basis for all science operations planning, in particular at long-term planning level. Long-term orbit file (ORMF) as produced by Flight Dynamics. Long-term event file (EVTF) as produced by Flight Dynamics (e.g., ground contacts, eclipses). Bit rate file (BRF) as produced by the Flight Control Team. The bit rate file is used for data balance calculations by POS/MIRA and ESOC/MPS. This file, under configuration control by FCT, will be updated if and when required to reflect the actual link performance. FECS file covering a specific science phase corresponding to several MTPs. The FECS contains the S/C maintenance windows reserved for orbit and attitude maintenance, and the tracking window, i.e. maximum communication opportunities. This information is extracted from ground station scheduling files provided by the ESOC Ground Station Scheduling Office, and updated as regularly as possible. Ground station activity periods for Mars Express are based on Mars visibility periods and requirements for sharing the station with other missions. Since ground station availability may only be known at a late stage in the long-term planning, PST shall investigate ways to generate a Long-Term FECS which would allow the PI teams to run MIRA and MAPPS at LTP level. Star occultation file (SOF) as produced by the MOC for the SPICAM team. FDS POS Constants File (FPC). This is a companion file to the FECS containing, amongst other information, the minimum duration of communications per day to ensure safety of the S/C (monitoring of uplink of the on-board TC schedule) and good navigation accuracy (tracking data). Science observation requests and priorities as sent by the PI teams to PST. 11

12 : 12 POS shall ensure that the latest files issued by MOC for long-term planning purpose are made available within MIRA. PST shall ensure that the latest files issued by MOC for long-term planning purpose are made available within MAPPS Outputs Each LTP shall consist of the following output information: Table indicating orbits used for science or for communication (orbit activity table). Inputs (information and guidelines) for building preliminary MREQ files to be used for the relevant MTPs Medium-Term Planning Scope and Description of Activities The medium-term planning is the next level of planning after the availability of the relevant Long-Term Plan. During the medium-term planning cycle, the LTP is broken down and used to produce Medium-Term Plans (MTPs), which are then subject to detailed feasibility analysis - especially in terms of constraints on the proposed timeline of spacecraft pointing, power usage and data downlink. This planning is therefore done at more detailed level, subdividing each science subphase or LTP into smaller segments of 4 weeks each. With inputs from the long-term planning cycle (Figure 5), the preliminary MREQs and orbit activity table are iterated between PST and the PI teams, with further usage of MIRA and MAPPS by PI teams at this stage to identify and select their observations, set their measurement priorities, and resolve the conflicts. This leads to a new set of MIRA request files (MREQs), using which a detailed analysis of the proposed merged payload plan versus the available resources (e.g., pointing, power, data) is performed by PST and POS. This eventually leads to the production and availability of a set of resourceharmonized MREQs, which is the starting point for the medium-term planning (MTP) cycle at POS. The harmonized MIRA file is the result of the conflict resolution and subsequent harmonization of all individual MIRA request files for each instrument spanning a given period of time or number of orbits, equal to the considered MTP segment. It is used by POS to produce the pointing request file (PTR). 12

13 : 13 Following the production of resource-harmonized MIRA requests, the POS generates and forwards pointing timeline requests (PTR), POR-lite and DASH files to Mission Planning at the MOC for feasibility analysis using a full dynamical, thermal and power model check of the proposed slews. PST shall approve the PTR before it is sent to Mission Planning. If there is no conflict, Flight Dynamics generates the Flight Dynamics Timeline (FTL) in response to the validated PTR. The POS passes radio science requirements to the MOC via the PTR, and the MOC prepares the corresponding operations requests. This special activity handling is due to its criticality at system level and to the need to schedule ground station resources well in advance (up to several weeks ahead). In case of conflicts with spacecraft resources, the Resource Allocation Board (RAB), led by PST and composed of PST, POS, and MOC representatives, performs the decisionmaking regarding conflict resolution at MTP level, in particular for PTR approval. Conflict evidence (e.g., conflict summary, plots, DoD inputs, other inputs) shall be distributed in advance of the RAB meeting by the FCT or Mission Planning. Changes required to eliminate problems shall be handled by following predefined rules and according to the severity of the change. Potential changes of specific rules for a given timeframe shall be agreed by the RAB. Following a RAB decision, PST proposes solutions to the PIs for solving remaining conflicts and further iteration may be needed to consolidate the PTR. One essential role of PST and POS during this planning cycle is to ensure that all resource-harmonized segments are prepared for the medium-term planning assessment and approval by ESOC. Such spacecraft resource-checked timeline of instrument activities constitutes the main input for the POS commanding activities. The transition from planning to commanding is made at POS during the medium-term planning cycle. It entails the creation by POS of initial PI Observation Requests (PIOR) for each instrument for each of the four commanding periods within the MTP period. Each PIOR is iterated between POS and the corresponding PI team during the commanding cycle, through the PI Modification Request (PMRQ) process, in order to modify, add or delete command sequences and/or parameter values. Once PI teams have approved the PIOR files for a given commanding period, POS creates the consolidated POR files required by ESOC at the end of each MTP. The planning-to-commanding interface is described in RD21. The POS Planning-to-Commanding Interface Document (RD37) describes the transition from planning to commanding and concentrates on the data generated from the information gathered in the POS planning subsystem and stored in the POS planning database. Figures 6 and 7 illustrate the activities that take place during the medium-term planning process, both from a planning and commanding point of view. 13

14 : 14 Figure 6: Planning process at medium-term planning level. Figure 7: Commanding process at medium-term planning level. 14

15 : Timing The baseline is MTP segments of four weeks, which corresponds to a realistic planning period considering the dynamics of the knowledge and impact of the spacecraft resource constraints on the payload operations. The (MSP) is built by cumulative planning of subsequent MTPs. Therefore there is no detailed payload operations plan covering a longer period than an MTP. The iteration process for PTR consolidation is a major component of the overall elapsed time. The final MTP has to be ready long before the execution time to account for long periods before the next uplink opportunity. As a consequence, the deadline for the last inputs for changing resource allocation and ground segment or onboard storage schedule is of the order of 4 weeks before the execution time. The MTP must be ready no later than 1 month before execution of the first activity of the plan. The MTP cycle is based on an integer number of STP cycles (nominally 4, i.e. about a month). A typical schedule of an MTP planning and execution cycle is shown in Figure 8 below. PTR delivery POR-lite delivery PTR iteration FTL generation FTL consolidation TLIS generation 1 TLIS generation 2 TLIS generation 3 TLIS generation 4 PIOR cycle 1 PIOR cycle 2 PIOR cycle 3 PIOR cycle 4 POR delivery STP 1 STP 2 STP 3 STP 4 week Execution 1 Execution 2 Execution 3 Execution 4 Figure 8: Mission Planning Activities Flow From PTR Delivery to Command Execution. POS makes the DASH file delivery shortly after PTR delivery. From RD Inputs The inputs to the medium-term planning activities are as follows, some of these files already needed at long-term planning level: 15

16 : 16 Long-term orbit file Long-term event file FECS file Bit rate file Star occultation file FDS-POS constants file Long-Term Plan Instrument science requests in MIRA format Outputs The outputs of the medium-term planning activities are as follows: Validated Pointing Timeline Request (PTR) or FTL Payload Operations Requests (POR) 3.4. Short-Term Planning and Very Short-Term Planning Scope and Description of Activities The POS transmits POR files to the MOC, after validation with the PIs and PST. During the short-term planning the outputs from the MTP are refined and undergo detailed resource and constraints checks using the Mission Planning System (Figure 5). While the orbit configuration cannot change any more at this stage, the timeline of instrument activity may in case of unforeseen events or payload conditions, which could require late changes to the POR files. Such late changes are only possible on an exceptional basis and if they do not impact the spacecraft resources. Late modifications requested after submission of the final commanding timeline to the MOC must obtain approval from the SOM. The very short-term planning deals, on a daily basis, with detailed operations requests to perform attitude maneuvers, wheel off-loading, orbit maintenance and data recovery. All these requests are consolidated within the master operations plan during this cycle. The telecommands are instantiated and a schedule generated. The commands are transferred to the spacecraft master timeline buffer during the ground station communications period Timing The short-term planning activity is performed by the MOC on a time scale of 1 week. 16

17 : 17 Inputs and outputs for these planning cycles are detailed in the Mission Planning Concept (RD24; RD44). 4. Contingency Planning Contingency planning applies following unforeseen events in the mission that imply changes to the current plans. Contingency planning is necessary at all levels of the planning. Although contingency handling may mostly be necessary and performed at short-term planning level, it also likely affects the medium-term planning. At higher level (LTP/MSP), contingency scenarios shall be drawn in order to respond to specific situations for which solutions can be found in advance. If the baseline of the science operations planning has to be interrupted due to unforeseen events occurring during any of the mission s science phases, contingency handling procedures or scenarios shall be followed and implemented for some or the entire payload. The two main cases that can unfold are: In case the unforeseen events have an impact on the whole mission, it is necessary to follow a specific contingency scenario that involves a complete revision of the science operations planning, likely up to LTP/MSP level. This contingency scenario shall be defined by the SWT. During pre-launch and pre-moi activities, the SWT, in collaboration with the Mission Analysis team at ESOC, has established backup orbits for the Mars Express mission. This contingency planning shall be used and/or revised if the eq100 orbit currently flown cannot be maintained. In case the impact of the unforeseen events does affect the payload complement in a limited way and/or in a limited duration, several options can be envisaged: (i) A major re-planning activity for one or more MTP cycles, likely to be time-consuming and to have an impact on spacecraft resource handling and subsequent planning activities. Restart of commanding would be as soon as possible. (ii) The contingency approach may be not to try to catch up with the adopted operations plan but rather to ignore the lost activities and pick up operations at whatever command was planned for the time when normal operations are resumed, as dictated by the Master Science Plan. (iii) Use of a prepared backup plan. Procedures for contingency handling must be implemented and provided by instrument teams, in the form of a number of contingency plans, and coordinated by PST via the SOWG. The PST has established in this documentation some contingency procedures in cooperation with the MOC (Part VI). Other information is available in RD24. 17

18 : Payload Operations Service Overview 5.1. Introduction POS has a key role in supporting the Mission Planning Concept. The POS planning function is designed to verify and merge PI inputs prior to the detailed planning consolidation that ESOC carries out during the medium-term planning cycle. This consolidation is essential for reliable routine operations in order to ensure that science operations are consistent with the complex set of mission constraints that must be respected in order to ensure spacecraft safety. The need for this planning consolidation has been amply demonstrated during commissioning where the short-term planning necessary during commissioning repeatedly led to cases where observations were cancelled. The POS system is designed to sustain high quality operations over the long term, to support evolution of science aims and instruments over that term and to ensure that all this can be accomplished under a severely constrained mission budget. The system has a high level of automation so as to focus limited staff effort on the added value that can be provided by human intervention, e.g. procedural checks on quality. Configuration control of interfaces, software and data is critical to POS operations. The Payload Operations Service produces the consolidated Payload Operations Requests (POR) contributing to the successful implementation of the Mars Express science operations. POS was declared fully operational following (i) a POS Readiness Review declared successful and (ii) the Mars Express Commissioning Results Review. For further details about the POS system, please refer to subsections below and to the documents RD21, RD22, and RD23. Details in some of the following figures are explained in RD21. The Mars Express POS can be decomposed into three main sub-systems, which are the planning sub-system, the commanding sub-system, and the information dissemination sub-system. These sub-systems are briefly described below, the detail of which can be found in the POS System Specification (RD21). An overview of the overall POS planning-commanding system is presented in Figure 9 below. 18

19 : 19 Figure 9: POS planning-commanding system overview. From RD POS Planning Subsystem The planning sub-system includes the ingestion of orbit and event data from ESOC, and the production of planning support products files and graphical outputs for the orbiter PIs and the PST. The major external output from this sub-system is the Master Science Plan (MSP), produced by the PST, the SOWG and the POS under the lead and control of the PST. The major internal output from this sub-system is the Top Level Instrument Schedule (TLIS) used for the commanding sub-system. The POS planning scenario (RD22) outlines the functions that POS will develop in the framework of this sub-system and, in particular, explores the conceptual framework on which those functions will be built. The planning data ingestion is explained in RD21. The main processes carried out in this sub-system are: Data acquisition and ingestion that encompasses the receipt of predicted orbit and event files from ESOC, the processing and ingestion of this information into the POS, which includes the Flight Dynamics Events and Communications Skeleton (FECS) and the baseline pointing modes. MSP and MTP preparation and implementation, using planning inputs as well as supplementary information supplied by the individual orbiter PIs concerning the activities and operational constraints applicable to their instrument. This 19

20 : 20 particular information will be encoded within Instrument Rule Processor Tables to be used by a core component of the planning sub-system the Instrument Rule Processor. Additional planning support products may be generated. Planning support tools will be used to aid the process of building the MSP. Orbit and event analysis which uses rules and constraints and the ingested predicted orbit and event data, generates value-added products which show where the science gathering periods are, and produces orbit and event displays, listings and graphics. Timeline generation, which encompasses the production of the baseline instrument command timeline, the Top Level Instrument Schedule (TLIS), and the production of the corresponding pointing timeline (PTR). The need to plan the pointing of the Mars Express spacecraft was identified as a fundamental difference from the ESA Cluster mission at an early stage and quickly led to the development of the MIRA planning tool. It also brought a requirement for the planning tool to check how the planned pointing affects other resources such as power and data return. Following the power constraints discovered after launch, this issue became more important and a major effort has been devoted to harmonizing MIRA modeling of resource usage with the equivalent modeling in the MPS system at ESOC POS Commanding Subsystem POS has been developed as a cost-effective adaptation from the JSOC system, which has supported Cluster science operations since January This has proved beneficial with many JSOC concepts and components being re-used in particular those used for commanding and database management (data structures, data ingestion and data output). Nonetheless a range of changes were necessary to meet the full set of Mars Express requirements in particular, for science planning. The scope of re-use and of new features is described in the POS system specification (RD21). POS has also developed the pcc (POS command centre) tool, which generates the timeline of command sequences that must be sent to the MOC to command the orbiter instruments. This commanding sub-system includes the production of baseline instrument command schedules or PI Operations Requests (PIOR), based on the TLIS, and the provision for iteration of these with the orbiter PIs. Preparation of the consolidated POR files and their transfer to ESOC is also part of this sub-system. Pcc first generates a draft set of command sequences (PIOR) based on the knowledge (provided by PIs and stored in a database at POS) of how to command the instrument activities specified in the MIRA planning requests. This draft is made available to PIs for review and revision. After PI approval, the sequences are delivered as POR files to ESOC for execution. Pcc includes comprehensive facilities for automatically tracking these deliveries and their acknowledgement by ESOC. 20

21 : 21 To support the conversion of planning into commanding, the POS planning-commanding interface ingests the products from MIRA into a database and processes this data to generate the inputs needed by pcc, in particular a timeline of instrument modes to be converted into sequences. The planning-commanding interface is also responsible for delivering MIRA products (e.g., DASH file) to ESOC and for tracking those deliveries. The POS commanding scenario (RD23) outlines the functions that POS developed in the framework of this sub-system. A high-level overview of the commanding process, showing the most important internal interfaces and products, is shown in Figure POS Information Dissemination Subsystem This sub-system provides a secure system for uploading, cataloguing, and dissemination of planning and commanding information derived from the POS databases and other operational files to the relevant parties (PIs, PST, ESOC) via the POS Internet site. Figure 10: POS commanding process. From RD21. 21

22 : Planning and Commanding Interfaces Figure 4 presented an overview of the interface structure put in place for Mars Express routine science operations. In this section are given details about each interface (see also AD2). The relevant Interface Control Documents are made available with this documentation as a complement to the information presented below POS-PST Interface The Mars Express Mission Manager, Project Scientist and the PST act as the formal interface for all scientific matters and science operations. This includes pre-launch science planning, support during payload commissioning, and support and provision of planning inputs going through the POS once POS has been phased in. During the preroutine and routine (operational) phases of interaction with POS, the POS shall work closely with the PST to ensure the achievement of the scientific objectives and to maximize the scientific return of the mission. POS is a contractually based service to the PST. As such, there is no formal interface and corresponding ICD between POS and PST. The operational interface is described thereafter. The POS system is being built and operated in compliance with its statement of work and associated technical requirements, the POS to ESOC Interface Control Document (RD17), the Science Operations Implementation Agreement (RD18), the POS to PI Interface Control Document (RD19), the POS to Flight Dynamics Interface Control Document (RD42), and the (this documentation). All activities related to coordination of the payload operations planning, and conflict resolution, are performed by the PST, with support from POS. The implementation of the scientific goals and requirements are monitored and checked by PST. The interactions between PST and POS mainly consist of exchange of information and planning inputs necessary for the implementation of the. This includes the provision of planning software and relevant files to the PST and SOWG (MIRA tool, see Section 7). It also includes, but is not limited to, the following activities: Supervision of the interface testing between POS, MOC and the PIs. Appropriate response to specific requests (e.g., unforeseen planning changes). Verification of the correct development, implementation and validation of the planning sub-system and relevant planning tools. 22

23 : 23 Verification of the timely implementation of the commanding database and software system. POS support to PST in the identification and resolution of conflicts following the delivery of preliminary MIRA request files by the PI teams. Consolidation of the pointing requests (PTR) with POS. Communication of the generated PTR to PST for approval before its formal export to MOC. PST monitoring of the PIOR/PMRQ cycle between POS and the PI teams. Verification of the proper implementation, consolidation, processing and validation of the Payload Operations Requests before transfer to the MOC. Further details on POS requirements, interfaces, and activities to be performed with PST support are given in the POS Statement of Work and Requirements Specification document (RD43) POS-PI Interface The POS generates the planning (e.g., PTR) and commanding information needed for operating the orbiter payload, and the updates of instrument operational databases and documentation. The POS-PI interactions involve: Providing planning support to the PI teams during the pre-routine and routine (operational) phases of the mission. Defining, and requesting, all relevant information required from the PIs in order to build the POS command structures and databases for all payload instruments. Ensuring interface verification and testing at technical level. Providing technical information about the POS commanding system on request from the PI teams. Providing PI teams with the generated planning files (e.g., pointing requests) and instrument commanding files. Ensuring instrument commanding database maintenance (e.g., IBAT, ALUT, VAL, PISI, & DEPV). Ingesting harmonized MIRA requests provided by PI teams for PTR production. Generating the PI Operations Requests (PIOR) and sending them to the PI teams. PI teams to generate PIOR Modification Request (PMRQ) and send them to POS. POS to ingest and process the PMRQ files. 23

24 : 24 Providing conflict files generated during PTR, PIOR and POR production. Finalizing the Payload Operations Requests (POR) with the PI teams. The interfaces between the POS and PI teams are detailed in the relevant ICD (RD19) PST-PI Interface There is no specific PST-to-PI ICD describing the interface between the PST and the orbiter Principle Investigators. This interface is described thereafter. Previous subsections gave the overall concept within which the PST and PIs responsibilities and interactions are listed. The PIs and their representatives interact with PST in the framework of the SWT and its SOWG and DAWG subgroups in order to establish the strategy and guidelines for successfully conducting the tasks dealing with science operations and data handling/archiving. Concerning the planning of payload operations, the orbiter instrument teams interact with the PST for the implementation of the. The PIs provide PST with all necessary and/or requested planning information (e.g., detailed scientific objectives and rationale, scientific requirements and priorities, detailed lists of surface targets) and take part in the negotiations that will lead to the successful and timely implementation of the Master Science Plan and MTP segments. The PI teams also provide support to PST for the commissioning of the payload instruments, and help PST in preparing the guidelines for science data handling and archiving and in building the Mars Express science data archive for the scientific community. See RD16 where details about data archiving for Mars Express are documented. The essential interactions between PST and the PI teams are: PI teams provide PST with and maintain the payload scientific objectives for the purpose of defining a long-term science planning strategy. PST and PI teams interact within the SOWG to merge technical and operational constraints and scientific goals into a long-term plan. PST provides an outline of the constraints and guidelines to the PI teams to be used for the generation of the initial MIRA request files. Interactions required for the resolution of conflicts before MTP consolidation. PI teams to provide the products from the complete mission (in the agreed format) to PST for their ingestion into the Planetary Science Archive (PSA). 24

25 : PST-MOC Interface During the pre-routine and routine mission phases, PST is in close interaction with the mission planning team (Mission Planning) at ESOC with regard to: Specific queries relevant to planning constraints and activities. Preparation of detailed planning inputs (PTR; POR files during commissioning). Data downlink and retrieval. Coordination of the detailed planning activities and deliveries. Running the Resource Allocation Board (RAB). Following the phasing-in of the POS, PST will still interact with the mission planning team, but on a lower level as POS will take the lead in preparing PTR and POR files. Note that the formal interface between the PI teams and the MOC is via the PST (e.g. for requests of special operations). PST will also be in close interaction with the Flight Dynamics (FD) team for collecting information about PTR preparation and for any queries relevant to orbit configuration, orbit and event files delivery, and spacecraft attitude. PST will interact with the Flight Control Team (FCT) in general for all types of activities and with the SOM and/or his deputy when important decisions need to be taken that would affect the status or operation of the payload. The FCT will contact PST for any decision regarding the modification of the payload status or operation POS-MOC Interface The Mission Operations Centre is the interface between the POS and the spacecraft, and the POS plays a central role within the overall Ground Segment. The POS interface with the MOC at ESOC is described in RD17. In summary, it deals with: Interface verification and testing at technical level Predicted orbit and event data from Mission Planning / Flight Dynamics. Flight Dynamics Event and Communication Skeleton (FECS) file from Mission Planning / Flight Dynamics. Bit Rate File (BRF) provided to PST and POS. Pointing Timeline Request (PTR) files interchanged between POS and Mission Planning. Verification by Mission Planning of all planning inputs and respect of FOP and OCD rules before the scheduling of operations with the Mission Planning System. Consolidated Payload Operations Request (POR) files sent to Mission Planning 25

26 : 26 Response files from the Mission Planning System (MPS). ESOC command database exports for synchronization of POS command database. MOC to provide to POS updated FDS-POS constant file (FPC), FD software routines for slew time prediction, Operations Constraints & Budget Document (OCD), operational command database (ODB) MOC-PI Interface PIs interface directly with the MOC during the commissioning phases (see RD14 for details). After the Mars commissioning phase, interactions between the MOC and PI teams decrease, as the POS-PI interface is phased in, but there shall still be the need for: Retrieval of data by PI teams from the Data Disposition System (DDS) at ESOC. Maintenance of PI teams inputs to the MOC Operational Database (ODB). Support for investigations of the instrument anomalies. Delivery from PI teams of upgraded instruments On-Board S/W Other Interfaces Other interfaces within the science operations structure, mentioned for completeness, include: An on-line data delivery interface between ESOC and the PST, the POS, and the orbiter PIs for the delivery of raw data and auxiliary data (RD29). The PI teams collect science and housekeeping auxiliary data from the Data Disposition System (DDS) at ESOC for calibration and processing, and further scientific data analysis and distribution/archiving. A planning interface between the PST/MOC and the NASA Jet Propulsion Laboratory (JPL) for the delivery to PST/MOC of predicted Odyssey and MER contact periods. A spacecraft navigation interface between ESOC and JPL (RD34) Interface Diagrams This subsection gives further detail and insight into the mission planning interfaces of the Mars Express mission, in the form of flow diagrams. Figures 11, 12, and 13 detail the interfaces for the long-term planning, the medium-term planning, and the maintenance activities. The description of the various input or product files mentioned in these flow 26

27 : 27 charts can be found in Section 8 below or in the Mission Planning Concept (RD24; RD44) and separate ICD documents given as annex to this documentation. Figure 11: Long-term planning interfaces. 27

28 : 28 Figure 12: Medium-term planning interfaces. 28

29 : 29 Figure 13: Maintenance activities and related interfaces. 29

30 : Planning Tools Two planning software tools have been developed for the purpose of supporting the planning activities of the PIs and PST. These are the Mars Express Instrument Resource Analyzer (MIRA), and the MAPPS tool (Mapping And Planning of Payload Science). The role, tasks, and brief description of these two software tools are given in the subsections below MEX Instrument Resource Analyzer (MIRA) An essential role and activity of the POS in planning the science operations for Mars Express is the provision and support of a software tool that allows analysis of the planned instrument activities versus spacecraft resource envelopes. The instrument activities represent the science objectives and requirements that form the (MSP) and MIRA allows the science requirements to be balanced with spacecraft operations (e.g., communication windows for TT&C and data downlink, momentum wheel offloading, and orbit maintenance) and resource constraints (e.g., power, OBDH bandwidth, data volume). The role of MIRA is an extension of that pioneered by the ESA Science Timeline Analysis Tool (STAT) but it also provides facilities for editing, for handling standard orbit plans for each instrument, and for checking the validity of each entry or change as it is entered. With an available planning database, MIRA is able to model the payload activities over more than the 2000 orbits of the nominal mission around Mars. Figure 14 explains the structure of the MIRA process, with its inputs and outputs. The inputs to MIRA are two supporting datasets, (i) a database containing the relevant orbit and event information (RD45), and (ii) the instrument profiles. The Flight Dynamics data such as orbit and event files, and the FECS file, constitute essential inputs to MIRA. Operational constraints and rules as given by the MPS Operations Constraints and Budget Document (OCD; RD25) represent other parameters essential to MIRA. The scientific inputs are the orbiter PI requests derived from payload science objectives and strategy and expressed in a standard format recorded in the MIRA documentation (RD40). MIRA, developed under IDL, can yield information about any orbit in the database, but its main purpose is the analysis of a series of request files that are intended to form the Mars Express scientific plan. The main timeline plot is displayed for each orbit for a commanding-plan period (1 week), as shown in Figure 15 below, and various parameters such as data volumes are calculated for each downlink session. Various indicators in the display and listings are used to show where the combined PI requests conflict with the constraints. The requests must then be tailored to fit the available resources. See MIRA User Manual (RD26). The power modeling used by MIRA is described in RD46. 30