"HST Scheduling System Two-Gyro Science, Phase I"
HST Scheduling System Two-Gyro Science, Phase I Operations Concept and Functional Requirements Review October 24, 2003 Agenda (1 of 2) Introduction C. Myers 9:00 – 9:10 Background Overview Operational scenarios M. Reinhart 9:10 – 9:35 TGS modes and scenarios Science impact studies Long-range planning (SPIKE) M. Giuliano 9:35 – 10:00 Prototype work Requirements summary Short-term scheduling (SPSS) S. Stallcup, 10:00 – 10:45 Requirements summary S. Speck Design concept 10/24/2003 2 Agenda (2 of 2) Short-term scheduling (PASS) 10:45 – 11:30 Requirements summary C. Darby Design concept R. McCutcheon Commanding / PRD 11:30 – 11:45 Command impacts A. Welty PRD impacts M. Bielefeld Testing planning L. Foor 11:45 – 11:55 Interfaces R. McCutcheon 11:55 – 12:10 Summary C. Myers 12:10 – 12:30 Risks / issues Schedule 10/24/2003 3 Introduction Carey Myers 10/24/2003 4 Purpose of Review Ensure that we have a feasible operations concept Ensure that we have a complete set of Phase I functional requirements that will enable implementation of a basic two-gyro science (TGS) capability Define an initial design concept that can provide the basis for a full end-to-end TGS mode of operations 10/24/2003 5 Problem Statement The HST Project has tasked us with developing a TGS mode The TGS mode is a means to provide spacecraft attitude control and slew capability, in the condition of only two remaining operational gyros, with sufficient accuracy to continue science gathering operations It is a contingency mode primarily targeted for use in the event the HST is in a two-gyro condition before SM4 It is also considered a degraded mode in that science operations will be capable of being performed, but with less efficiency and flexibility compared to normal operations with three gyros Particular classes of science observations likely will be heavily constrained or not possible 10/24/2003 6 HST Scheduling Process Proposal Implementation (APT) Visit V V Visit Visit Visit Visit Visit Long-Range Planning (TRANS, SPIKE) Long Range Plan (1 year +) Calendar(1 wk) Calendar(1 wk) Calendar(1 wk) SMS SMS SMS Short-Term Scheduling (SPSS / SCS, PASS) Mission Schedule Mission Schedule Mission Schedule CL CL CL 10/24/2003 7 HST Scheduling Systems Astronomer’s Proposal Tools (APT): Suite of tools enabling astronomers to design and submit detailed proposed science observations (visits) Transformation (TRANS): System that translates each proposed visit into a detailed plan for execution Science Planning Interactive Knowledge Environment (SPIKE): System that creates and manages the HST long-range science plan Science Planning and Scheduling System / Science Commanding System (SPSS / SCS): System that creates the weekly calendar and generates the science mission specification (SMS) POCC Applications Software Support (PASS): System that processes the SMS and generates the binary command loads for 10/24/2003 8 uplink to HST Phased Implementation Approach The scheduling system two-gyro science support will be a two-phased implementation Phase I will support TGS in the continuous viewing zone (CVZ) with limited support for full-sky science Requires reworked science visits and manual scheduling Impacts primarily SPSS and PASS: Enhancements to existing scheduling algorithms as opposed to major function replacement Phase II will incorporate enhancements to support automated TGS proposal submission and long-range planning Will incorporate lessons learned from Phase I Impacts primarily APT, TRANS, and SPIKE: Additional PI tools and incorporation of scheduling constraints 10/24/2003 9 TGS Implementation Team TGS Working Group Co-Chair: Larry Dunham Co-Chair: Mike Prior Secretary: Paul Finneran PCS STScI FSW Lead: Dan Smith y Lead: Rodger Doxse Lead: Brian Vreeland Satyan Anandakrishnan ESS ODM Joe Pollizzi Jim Etchison Carl Johnson Mark Abernathy SPB - Merle Reinhart MGSE - Carey Myers SSCB - Mary Galloway George Chapman Clif Darby Bob McCutcheon OPB - Alison Vick PSDB - Mark Giuliano Clif Darby Bob Boyer FSE - Alan Welty SSDB - Scott Stallcup Ron Pitts Scott Speck Ilana Dashevsky Mike Boyer TEST - Leslie Zimmerman Foor Danny Jones PRD - Mike Bielefeld John Boia 10/24/2003 10 Documentation Status Document Title Status Date Two-Gyro Science Mode System Baselined at Level 4 CCB; Oct. 2003 Requirements Document (Revision 1) submitted to Level 3 CCB Two-Gyro Science Planning and Draft available Oct. 2003 Scheduling Functional Requirements Document ST-ICD-11: Hubble Space Telescope Draft updates available Oct. 2003 (HST) Science Scheduling to Mission Scheduling Interface Control Document (Revision F) ST-ICD-26, Part 2: POCC Applications Draft updates in progress Dec. 2003 Software Support (PASS) to Project Data Base (PDB) Tape Interface Control Document (Revision B) HST-ICD-T1: Hubble Space Telescope Draft updates available Oct. 2003 (HST) Control Center System (CCS) to Planning and Scheduling System (P&S) Interface Control Document 10/24/2003 11 Operational Scenarios Merle Reinhart 10/24/2003 12 TGS Modes and Scenarios: Overview Currently, operations uses three gyros to provide rate control at all times; attitude errors are limited to nominally a couple of hundred arc-seconds worst case after very large vehicle slews Onboard attitude updates using FHST data are done to get errors within FGS search radius FGS data are used with gyro data to hold spacecraft position during science With only two gyros and MSS data, we may start with degrees of attitude error each orbit FHST and / or FGS data are needed to control the rates as well as correct the attitude 10/24/2003 13 TGS Modes and Scenarios: Concept Two active gyros are available; these measure the vehicle rates in the plane formed by the input axes of the two gyros Another sensor is required to estimate the vehicle rates normal to the two-gyro (input-axes) plane MSS Measures magnetic field vector Always available FHSTs Measure star vector Provide accuracy required to start using the FGSs FGSs Measure the guide star vector Provide accuracy required for science Rate of change of the measured vector is used to estimate vehicle rates normal to the two-gyro (input-axes) plane 10/24/2003 14 TGS Scenario 10/24/2003 15 Two-Gyro Mode: Overview TGS modes are based on an alternate sensor being used in place of a third gyro MSS / two-gyro (M2G) mode: Normal entry only from FHST / two-gyro mode FHST / two-gyro (T2G) mode: Default entry from safemode FGS / two-gyro (F2G) mode: Entry only from FHST / two-gyro mode Safe Mode Optional Default M2G Mode Mode T2G Mode Transition Rate Estimation based on 2 gyros Rate Estimation Rate Estimation + MSS and on- based on 2 gyros Failure board Mag field + FHST Transitions model Entry from F2G Mode Safemode Rate Estimation based on 2 gyros + FGS data (in FL or CT) 10/24/2003 16 Two-Gyro Mode: M2G Modes defined in M2G Attitude hold: Only path for normal transition to and from T2G Maneuver: Large vehicle (type 2) slews Hardware Sunpoint Mode M2G Mode Transition Attitude Ops Mode Transition Hold T2G Rate Estimation Failure Maneuver Transitions Entry from Safemode 10/24/2003 17 Two-Gyro Mode: T2G Modes defined in T2G Attitude hold / rate capture: Only path for Maneuver / attitude correction Normal transition to and from M2G Guide star acquisition Normal transition from F2G Only path for transition to F2G Attitude determination (OBAD) Spans T2G and F2G T2G Mode Mode Attitude Determination Transition Ops Mode M2G Maneuver / Att. Correction Transition Rate Estimation Failure Attitude Hold / Transitions Rate Capture Default Entry from Guide Star Acquisition Safe Mode Safemode (ZGSP/PSEA) F2G 10/24/2003 18 Two-Gyro Mode: F2G Modes defined in F2G Guide star acquisition Spans T2G and F2G Only entry path for F2G Maneuver / science slew Decenterline slew, error correction Profile slews, peakups, scans etc. Science Fine guidance F2G Mode Mode Transition Guide Star Acquisition Ops Mode Transition T2G Science Rate Estimation Failure Maneuver Transitions (Science Slews) 10/24/2003 19 What We Lose in Two-Gyro Mode Smallest aperture, highest spatial resolution science programs are likely to be infeasible No pointed gyro science observations (Earth calibrations may be an exception to this) No handoffs from guide star control to gyro control No guide star handoffs No single FGS guiding No target acquisition information carried over from orbit to orbit (i.e., must repeat the target acquisition in each orbit) No moving target observations (at least in Phase I) 10/24/2003 20 FHST Star Density Study (1 of 2) For the OBADWG, a star density study was conducted to determine if sufficient stars will be available for FHST rate control FHST onboard mapping, star identification, and attitude correction V1-Axis Pointing l (deg) b (deg) FHST Great Circle Description 0.0 0.0 Passes through north and south galactic poles (ngp and sgp, respectively), intersecting galactic plane at l = 90 deg and l = 270 deg 45.0 0.0 Passes through ngp and sgp, intersecting galactic plane at l = 135 deg and l = 315 deg 90.0 0.0 Passes through ngp and sgp, intersecting galactic plane at l = 0 deg and l = 180 deg 135.0 0.0 Passes through ngp and sgp, intersecting galactic plane at l = 45 deg and l = 225 deg 0.0 90.0 FHST great circle is in the galactic plane 10/24/2003 21 FHST Star Density Study (2 of 2) Star count analysis indicates that The chance of not finding a rate control star in one of the three FHSTs is exceedingly small Away from the galactic plane, there are regions where there are fewer than three stars available for a given tracker Thus there is a small chance that the FHST used as a mapping tracker will have fewer than three stars Due to the different orientations of the three FHSTs, it is unlikely that all three trackers will see fewer than three stars at a given time Conclusions FSW requires logic to switch between rate control and mapping trackers if the mapping tracker finds insufficient stars The planning systems should retain an optional capability to specify the mapping FHST based on star density expectations for the three FHSTs 10/24/2003 22 Science Impact Studies CVZ scheduling study All-sky target availability study Current cycle scheduling study 10/24/2003 23 CVZ Scheduling Study Status: Nearly complete; need to complete analysis of the effect of changing the timings and to write up the final results Built upon earlier work done to evaluate the potential of using the CVZ as a way of achieving relatively high observing efficiency Evaluated using the north and south CVZs for early operations Evaluated the ability to cover SAA passages with FHST availability Estimated how many orbits are schedulable and how many will be lost due to uncovered SAA passages Number of usable orbits varies from ~7 to 15 orbits per day A scheduling efficiency >~ 50% is implied Evaluated the level of scheduling flexibility available (via off-nominal roll, etc.) to adjust these uncovered periods Results of study can be used to evaluate potential early two-gyro science programs 10/24/2003 24 Northern FGS CVZ -Nominal Roll 10/24/2003 25 Southern FGS CVZ -Nominal Roll 10/24/2003 26 All-Sky Target Availability Study Status: In progress; proposals / targets to be used have been written; expect to be completed by the end of the year Assess the availability of targets across the entire sky Driven by FHST scheduling restrictions Provide basic information about when and how various portions of the sky are accessible Instantaneously, expect <50% of the sky to be available (predominantly due to FGS / FHST visibility synchronization) Perform schedulability sensitivity studies Vary worst case pointing error in M2G / T2G Vary FHST durations and timings for transitions from T2G to F2G Utilize SPIKE and other tools to evaluate a grid of targets over the entire sky, comparing the results to nominal operations Provides insight into how much of any pre-existing observational program could be supported 10/24/2003 27 FGS vs. FHST Visibility (1 of 2) Example of visibilities that are unusable with two-gyro science ops In this case, the target is east of the Sun 10/24/2003 28 FGS vs. FHST Visibility (2 of 2) Example of visibilities that support two-gyro science ops In this case, the target is west of the Sun 10/24/2003 29 Current Cycle Scheduling Study Status: Start early next year Evaluate what fraction of an entire cycle could be scheduled using a representative pool of observations Results will help determine the observing policies that the STScI would put in place to support two-gyro mode If only a few typical cycle observations can be scheduled as originally requested, then it is likely that development of a new observing program would be necessary ASAP (while carrying out an interim CVZ campaign) If a substantial fraction can be scheduled in two-gyro mode, then more time to respond will be available, and potentially a new program could simply be brought in with the next planned observing cycle Details are to be defined as previous studies are completed 10/24/2003 30 Long-Range Planning: SPIKE Mark Giuliano 10/24/2003 31 HST Scheduling Systems RPS2 / APT TRANS / ASSIST SPIKE MOSS PMDB SPSS GSC SCS CMD PRD NGSS SMS PASS FRSS ODBs PROCESS FLOW DATA FLOW 10/24/2003 32 SPIKE Background Science Planning Interactive Knowledge Environment (SPIKE) is a highly adaptable constraint-based software system for planning and scheduling astronomical observations SPIKE works in terms of constraint windows and plan windows Constraint windows: Intervals in which an observation can satisfy all its physical (e.g., Sun / Moon avoidance) and observer-specified (e.g., ob1 after ob2 by 10-20 days) constraints Plan windows Subset of constraint windows (nominally 8 weeks) Selected via heuristic search to optimize resource usage and user-tunable criteria Used by SPSS to create a pool of candidate SUs for building an SMS SPIKE is run under various guises by various HST user communities Observers run SPIKE through APT to determine and analyze visit schedulability STScI staff use SPIKE to build and maintain the HST Long-Range Plan (LRP) 10/24/2003 33 TRANS Background Transformation (TRANS) is a knowledge-based software system that takes proposal observation descriptions and generates a detailed plan for executing the observations on HST TRANS creates support activities (e.g., buffer dumps), models instrument overheads (e.g., filter moves), and groups activities into a hierarchy based on exposure pointing and engineering concerns A TRANS observations plan is used by observers to pack orbits (as part of APT) and by downstream systems for planning, scheduling, and data analysis 10/24/2003 34 SPIKE Prototyping Efforts Since July 2003 the SPIKE team has been developing prototype two-gyro scheduling capabilities The purpose of this effort is to provide tools that can be used to characterize and analyze the impact of two-gyro constraints on HST scheduling The tools will support the science impact studies described earlier The prototype will also form the basis of the final implementation of SPIKE two-gyro support 10/24/2003 35 SPIKE TGS Design Concept Divide the implementation of two-gyro constraints into two portions Model the required FHST overlaps The exact requirements for the overlaps are expected to be volatile Integrate an FHST visibility constraint into SPIKE Integration with existing GUI, constraint infrastructure, and roll angle code Nonvolatile Determine how much (if any) of an orbit is available for FHST scheduling by incorporating the FHST overlap model into the FHST visibility constraint Feed the resulting orbit structure into the existing SPIKE orbital viewing constraint (code reuse) Sample FHST visibility over legal roll ranges for a day 10/24/2003 36 Schedulable FHST Overlaps FHST RATE FHST OVERLAP 1 FHST OVERLAP 2 FGS OVERLAP FGS FHST 3 FHST 2 FHST 1 T2G COMBINE M2G COMBINE 10/24/2003 37 Unschedulable FHST Overlaps FGS FHST3 FHST2 FHST1 T2G COMBINE M2G COMBINE 10/24/2003 38 SPIKE GUI Snapshot 10/24/2003 39 SPIKE TGS Requirements Summary SPIKE will provide two-gyro scheduling constraints for APT proposal processing and long-range planning SPIKE will model FHST visibilities SPIKE will implement two-gyro constraints based on FHST overlaps SPIKE will integrate two-gyro constraints with existing constraint infrastructure and visualization tools SPIKE will model FHST / SAA impacts SPIKE will integrate FHST roll restrictions with existing roll constraints 10/24/2003 40 SPIKE Study Support Status (1 of 2) FHST visibility study support – Completed SPIKE already modeled FHST visibility Verified correctness of the model All-sky target availability study support - Completed Working on configuration and delivery issues Added FHST overlap constraints to SPIKE Integrated with SPIKE constraint and visualization tools Integrated with orientation restrictions 10/24/2003 41 SPIKE Study Support Status (2 of 2) Current cycle scheduling study support (Nov. 2003 - Jan. 2004) Complete SAA modeling Perform TRANS preparation work to account for less visibility time due to extended PCS acquisition times Requires no TRANS code changes Model times via input parameters Use existing TRANS orbit fill capability to shrink orbits Rebuild TRANS with new visibility model table 10/24/2003 42 Short-Term Scheduling: SPSS / SCS Scott Stallcup Scott Speck 10/24/2003 43 HST Scheduling Systems RPS2 / APT TRANS / ASSIST SPIKE MOSS PMDB SPSS GSC SCS CMD PRD NGSS SMS PASS FRSS ODBs PROCESS FLOW DATA FLOW 10/24/2003 44 SPSS Background (1 of 2) Science Planning and Scheduling System (SPSS) Short-term scheduler for HST science observations Schedules activities to the nearest second Scheduling constraints include Bright / dark Earth avoidance Sun / Moon avoidance SAA avoidance Target visibility (input from MOSS) Power constraints Thermal constraints SI state restrictions Guide star constraints (input from NGSS) 10/24/2003 45 SPSS Background (2 of 2) Scheduled activities include Slews Small-angle maneuvers Track 51 scans PCS acquisitions / reacquisitions Guide star handoffs Target acquisitions FHST updates Science instrument reconfigurations Science activities Calibrations Recorder activities Written in F77, C++, and Java in 520,000 lines, 54 applications 10/24/2003 46 SCS Background Science Commanding System (SCS) Takes “calendar” of observations from SPSS and produces a science mission specification (SMS) for input to PASS by interpreting command instructions Generates high-level HST commands from the SPSS “calendar” of science and other activities Written in F77, C++, and Java in 220,000 lines, 19 applications 10/24/2003 47 Proposal Management Data Base Proposal Management Data Base (PMDB) Relational data base that contains all observation proposal data Observation structure Proposal Scheduling unit (visit) Observation set Alignment Exposure Also contains ephemeris data, linkset data, and other items 10/24/2003 48 SSPS Calendar and Candidate List Calendar and Candidate (C&C) List File and data structure Contains a candidate pool of observations from the PMDB Contains a calendar of scheduled observations for a given time period Generally covers 1 week of observations SPSS scheduling commands work only with C&C list files, not the PMDB 10/24/2003 49 SPSS Scheduling Concept (1 of 2) SPSS scheduling begins with an empty calendar and a pool of candidate observations (scheduling units - SUs) to be scheduled Candidate SUs may be scheduled automatically as a group or individually using SPSS commands Scheduling is attempted for a particular time span If the candidate can be scheduled within constraints, it will be, and the scheduled efficiency will be reported If the candidate cannot be scheduled, the reasons for the failure are reported 10/24/2003 50 SPSS Scheduling Concept (2 of 2) As the software adds activities within an SU, it checks all constraints and, if required, delays activities until the constraints are clear; it continues this process with all necessary activities until all activities are scheduled or the end time is reached SPSS does not schedule SU activities in time order from beginning to end; the scheduling order for each alignment is Science activities PCS activities SI activities Slews FHST updates 10/24/2003 51 SPSS TGS Requirements Summary: Data Base and C&C List SPSS will query the PMDB for all parameters for two-gyro operation and store these data in the C&C list SPSS will designate a new C&C list as either two-gyro or non-two-gyro; only two-gyro observations will be added to a two-gyro C&C list and vice versa for a non-two-gyro C&C list SPSS will issue errors when a moving-target observation is set to use a two-gyro PCS scenario 10/24/2003 52 SPSS TGS Requirements Summary: Scheduling (1 of 3) In two-gyro mode, gyro scheduling units will be scheduled only in M2G mode When scheduling an alignment, SPSS will first determine whether the HST is in M2G or T2G mode For the HST to be in T2G mode, FHST windows must exist from the previous FGS loss-of-usability through the resumption of F2G mode; SPSS will calculate these windows using a small attitude uncertainty In M2G mode, FHST windows will be calculated using a large attitude uncertainty, from the end of the previous slew to the start of F2G mode 10/24/2003 53 SPSS TGS Requirements Summary: Scheduling (2 of 3) To transition the HST from M2G to T2G mode, an initial FHST rate control activity will be scheduled SPSS will schedule initial FHST map and attitude correction activities at the earliest time when two FHSTs are visible for the required duration SPSS will calculate FHST windows using a medium attitude uncertainty after the first attitude correction to determine the next place where two FHSTs are visible for a second map and attitude correction SPSS will schedule a second FHST map and attitude correction, ending as close as possible to the start of the FGS PCS acquisition 10/24/2003 54 SPSS TGS Requirements Summary: Scheduling (3 of 3) SPSS will calculate FHST windows using a small attitude uncertainty to determine when one FHST is visible until F2G mode is achieved SPSS will schedule an FHST observer mode activity that ends partway through the FGS PCS acquisition, when F2G mode is established; no FHST handoffs will be permitted during this observer mode activity When more targeted alignments need to be scheduled after FGS loss-of-usability, a full FGS acquisition will be scheduled if the HST is in T2G mode; otherwise, a full set of FHST maps and attitude corrections will be scheduled before the FGS acquisition 10/24/2003 55 SPSS TGS Requirements Summary: Utility SPSS will display the new FHST activity types on a calendar, as well as the FHST visibility windows on a calendar using any of the HST pointing uncertainties associated with two-gyro scheduling 10/24/2003 56 SPSS TGS Requirements Summary: SMS Generation The SMS generation (SMSG) process will recognize the new FHST activity types FHST tracker identification will be provided via SCPL pseudo-instruction if set by SPSS scheduling for FHST or guide star acquisition activities FHST mode information will be available via SCPL pseudo-instruction Where practicable existing pseudo-instructions will be enhanced to provide this additional information 10/24/2003 57 SPSS / SCS TGS Design Concept (1 of 3) SPSS will operate in two general modes: two-gyro and three-gyro modes controlled by a flag in the PMDB Users will be able to create C&C lists and SMSs in either mode, depending on the state of the flag There will be no user interface changes required for SPSS / SCS, though the displayed items with the display tools will change slightly In three-gyro mode, SPSS schedules FGS acquisitions and reacquisitions; in two-gyro mode, it schedules only acquisitions No FGS specific code changes will be required because FGS operations in SPSS are table driven based on named guiding scenarios, although overlapping FHST visibility will be needed through the first part of FGS activities 10/24/2003 58 SPSS / SCS TGS Design Concept (2 of 3) Most of the software changes will be isolated to the FHST processing components in SPSS In three-gyro mode, FHST updates will be scheduled as they are today In two-gyro mode, FHST updates will not be scheduled; instead, onboard maps and attitude corrections will be scheduled Currently, FHST visibility windows are computed with a constant HST pointing uncertainty; under two-gyro mode, three separate FHST visibility window calculations will be needed Different pointing uncertainties will be associated with the first and second map / attitude correction activities and the FHST / FGS observer mode activity 10/24/2003 59 SPSS / SCS TGS Design Concept (3 of 3) The most significant change to the scheduling algorithm involves the need to schedule FHST maps, attitude corrections, and FGS activities with one or two FHSTs simultaneously visible as required Existing event display tools (“calendar display” and “sgs”) will be updated to display the three sets of FHST visibility windows when in two-gyro mode SMS changes will be minimal and isolated to the FHST statements; new arguments (described in the interface section of this presentation) will be added to handle the maps and attitude corrections 10/24/2003 60 Short-Term Scheduling: PASS Clif Darby Bob McCutcheon 10/24/2003 61 HST Scheduling Systems RPS2 / APT TRANS / ASSIST SPIKE MOSS PMDB SPSS GSC SCS CMD PRD NGSS SMS PASS FRSS ODBs PROCESS FLOW DATA FLOW 10/24/2003 62 PASS Background PASS is run weekly as the last step of HST short-term scheduling to accept, verify, and expand the weekly science plan (SMS) into stored command loads for uplink to the spacecraft Major PASS functionality includes Verifying vehicle pointing control activities Selecting FHST reference stars Managing antennas and solar arrays Managing science and engineering data recording Generating weekly TDRSS communication schedule requests Generating stored command loads Generating ancillary reports PASS FHST Reference Star Selection System (FRSS) is used by the guide star selection system for determining roll ranges with valid FHST support 10/24/2003 63 PASS TGS Requirements Summary: Vehicle Control Determination PASS will determine whether an SMS is in three- gyro (nominal) mode or two-gyro (degraded) mode based on a data base parameter Two-gyro mode further consists of three types of vehicle control modes M2G control mode (default) T2G control mode when under FHST rate control F2G control mode when in FGS fine lock 10/24/2003 64 PASS TGS Requirements Summary: SMS Statements PASS will accept FHST statements to support two-gyro mode (described in the interface section of this presentation) FHST OAD to perform onboard attitude determination and attitude correction FHST GOB to perform two-gyro FHST observer control PASS will not allow the following SMS statements in two-gyro mode: FHST(MAN) - FHST maneuver update FHST(DEL) - FHST delay update FHST(OBS) - FHST observer GSACQ,CPNAME(REACQ) - Guide star reacquisition SLEW,SLEWRATE - Any vehicle slew that specifies the SLEWRATE parameter 10/24/2003 65 PASS TGS Requirements Summary: Attitude Uncertainty PASS will use SMS statements and data base values to determine three levels of attitude uncertainty Large uncertainty always exists during M2G Small uncertainty always exists during F2G T2G transitions between large, medium, and small uncertainty PASS will account for attitude uncertainty when calculating constraints for FHST, V1, off-nominal roll, and solar array (shadowing and incidence angle) 10/24/2003 66 PASS TGS Requirements Summary: Initial FHST Rate Control PASS will verify that an initial rate control period exists An initial rate control period is a time when a single FHST has continuous visibility before the first FHST OAD statement following a period of M2G control 10/24/2003 67 PASS TGS Requirements Summary: Systemic FHST Visibility PASS will calculate the periods of systemic FHST visibility for use in verifying FHST OAD and GSACQ statements Systemic FHST visibility is the entire time covered by a collection of FHST visibility windows that overlap by a data-base-specified time 10/24/2003 68 PASS TGS Requirements Summary: FHST Map / Attitude Correction (1 of 2) PASS will determine whether an FHST OAD SMS statement is an initial or a second onboard map / attitude correction PASS will verify that an optional second FHST OAD is separated from the initial FHST OAD by a data-base- specified time (start to start) PASS will verify that systemic FHST visibility exists from the initial rate control period through a data-base- specified time after the start of the FHST OAD PASS will verify FHST visibility and issue FHST OAD commanding 10/24/2003 69 PASS TGS Requirements Summary: FHST Map / Attitude Correction (2 of 2) If the FHST OAD statement does not specify the FHST PASS will verify that at least two FHSTs have continuous simultaneous visibility throughout the FHST OAD map PASS will verify that at least two FHSTs have visibility throughout the FHST OAD attitude correction PASS will optionally populate the FHST OAD command with the PASS-selected FHST If the FHST OAD statement specifies the mapping FHST PASS will verify the visibility of that FHST and one other PASS will populate the FHST OAD command with the specified FHST 10/24/2003 70 PASS TGS Requirements Summary: FHST Observer Commanding The FHST GOB statement for observer mode commanding may optionally specify the FHST; if an FHST is not specified, PASS will select an FHST PASS will verify continuous FHST visibility for the observer mode and specify the FHST in the command PASS will verify that an FHST GOB statement accompanies every GSACQ statement and is offset by a data-base-specified time 10/24/2003 71 PASS TGS Requirements Summary: FGS Acquisition Commanding PASS will process GSACQ statements as is done currently (reacquisitions not permitted) PASS will verify that systemic FHST visibility exists from the initial rate control period through a data- base-specified time after the start of GSACQ If no FHST OAD statements have occurred since the previous GSACQ, PASS will verify that systemic FHST exists from the previous FGS loss-of-usability 10/24/2003 72 PASS TGS Requirements Summary: FHST Maps PASS will optionally generate FHST map commands on a single FHST and only when that FHST and at least one other have visibility PASS will schedule automaps to begin as soon as possible after the first GSACQ following a type 2 slew; additional automaps may follow subsequent GSACQs if requested PASS will, for FHST MAP SMS statements, verify that FHST visibility exists for one more FHST than is requested in the MAP statement 10/24/2003 73 PASS TGS Requirements Summary: FHST Availability Commanding PASS will issue FHST shutter open and close commands at the start and end of FHST visibility, as calculated using the appropriate attitude uncertainty PASS will set the FHST available coincident with the open shutter command PASS will set the FHST as unavailable before the close shutter command PASS will use the autogroup feature to control these commands 10/24/2003 74 PASS TGS Requirements Summary: PASS Reporting PASS will expand existing reports to include Calculated FHST visibility windows Transition times between M2G, T2G, and F2G FHST commanding Constraint violations PASS will generate error messages when constraint violations occur and continue processing if possible 10/24/2003 75 PASS TGS Requirements Summary: Star Catalog for Flight Software PASS will provide the SKYMAP star catalog to flight software for onboard star identification and attitude determination 10/24/2003 76 TGS Scenario 1 - M2G-T2G-F2G Transition TGS Mode M2G M2G T2G T2G F2G F2G FGS Visibility FHST -- Systemic FHST-1 FHST-2 FHST-3 Attitude Uncertainty LARGE (LAU) MEDIUM (MAU) SMALL (SAU) IRC SLEW 2 FHST(OAD) FHST(OAD) FHST(GOB) SMS GSACQ TGS_DUROAD(1) TGS_DUROAD(4) TGS_DUROAD(6) (~3 min) (7 min) (5 min) TGS_DUROAD(8) (8-9 min) TGS_DUROAD(3) TGS_DUROAD(5) TGS_DUROAD(7) (3 min) (3 min) (~1-5 min) = FHST hand-off Systemic = No hand-off restriction Legend: SMS not allowed Visibility = 1 FHST available satisfied 77 = 2 FHSTs available TGS Scenario 2 - F2G-T2G-F2G Transition TGS Mode T2G F2G F2G T2G F2GF2G FGS Visibility FHST -- Systemic FHST-1 FHST-2 FHST-3 TGS_DUROAD(2) (~1 min) Attitude Uncertainty SMALL (SAU) FHST(GOB) FHST(GOB) SMS GSACQ GSACQ TGS_DUROAD(8) TGS_DUROAD(8) (8-9 min) (8-9 min) TGS_DUROAD(7) TGS_DUROAD(7) (~1-5 min) (~1-5 min) = FHST hand-off Systemic = No hand-off restriction Legend: SMS not allowed Visibility = 1 FHST available satisfied 78 = 2 FHSTs available PASS TGS Design Concept: Overview PASS two-gyro support is consistent with overall system design and functionality Mission scheduling subsystem has most of the software changes Pointing control area Occultation processing FHST processing Autogroup area Data management subsystem has some software changes SKYMAP star catalog generation PDB processing FHST Reference Star Selection System has minimal software changes 10/24/2003 79 PASS TGS Design Concept: Mission Scheduling Subsystem (1 of 3) Data structure initialization Accept additional SCHF / CRPF data base parameters for two-gyro mode (thus minimizing operational impact for transition to two-gyro control) Populate internally used parameters with proper values, based on the two- gyro or three-gyro data base flag (thus minimizing software algorithm changes) Determination of FHST and V1 occultation times Invoke the occultation subsystem three times to compute occultation times for the entire SMS at each attitude uncertainty level Invert occultation times into visibility times Use visibility times to verify SMS statements and determine M2G, T2G, and F2G modes Form one set of visibility times based on calculated M2G, T2G, and F2G modes 10/24/2003 80 PASS TGS Design Concept: Mission Scheduling Subsystem (2 of 3) FHST processing Expand FHST SMS statement processing to accept new two-gyro FHST OAD and GOB requests Verify FHST statements using appropriate visibility times Select FHST for use Issue commanding using expanded data base templates Disable FHST MAN, OBS, DEL requests, thereby bypassing reference star selection Modify FHST map area to handle additional two-gyro constraints Pointing control constraints No changes needed; handled by proper two- or three-gyro data base population 10/24/2003 81 PASS TGS Design Concept: Mission Scheduling Subsystem (3 of 3) Autogroup processing Add new FHST visibility orbital events for use in generation of FHST shutter open / close and FHST availability commanding Apply optional + / - delta for determination of command times Allow an optional event identifier for SMS on / off control of a subset of commands for a given event; e.g., turn FHST availability commanding off, but leave FHST shutter commanding on 10/24/2003 82 PASS TGS Design Concept: Other Subsystems Modify project data base subsystem Add two-gyro parameters to SCHF and CRPF Add new entries in the GREX and DFSC files to define FHST commanding parameters Expand the autogroup file format to support FHST shutter and availability commanding Generate a SKYMAP reference star catalog for the flight software by modifying input generation options for limiting star magnitude and proper motion reference time Modify FRSS to make reference star selection optional 10/24/2003 83 Commanding / PRD Alan Welty Mike Bielefeld 10/24/2003 84 Commanding Role Create and maintain “instructions” for SMS commanding An instruction is invoked by each calendar activity, including FHST updates and GSACQs Guided by information on the PMDB, the instruction outputs statements required by the activity to the SMS Instructions are written in “Science Commanding Programming Language,” part of SPSS Maintain SMS Review Tool (SRT) 10/24/2003 85 Commanding Impacts Preserve current FHST and GSACQ commanding Develop new instructions for new FHST activities New activity types expected for OAD and GOB modes Adapt existing instructions for new guide star acquisition scenarios New scenarios expected for two-gyro mode May require new instructions as well Incorporate two-gyro checks into SRT 10/24/2003 86 PRD Data Types Commands, telemetry, symbols: Support CCS PRD PLCPs, CCLs, and GRPs: Support command scripts TFPF tables: Support HST486 personnel CRPF and SCHF: Support PASS, SPSS, and TRANS GREX, DFSC, and AGCF: PASS only DBDF: Support ST-ICD-11 syntax modifications 10/24/2003 87 PRD Impacts Impact similar to normal software build-related PRD change Value changes: Normal process Data structure changes ICD modifications Output specs by receiving party (e.g., SPSS, TRANS) IMTOOL changes Regenerate PASS ODBs Determine data item owner, then values Coordinate installation for tests and operations 10/24/2003 88 Test Planning Leslie Zimmerman Foor 10/24/2003 89 Planning and Scheduling System Testing The modifications to each of the planning and scheduling systems will be tested using the normal testing process This testing will be successfully completed before starting the integration testing of the entire planning and scheduling system Test cases will be generated for each requirement, and their verification will be tracked using the DOORS requirements management tool 10/24/2003 90 Requirements Traceability and Verification Requirements and test cases for two-gyro mode will be managed using DOORS; the following diagram illustrates how the test cases and requirements will be linked: DOORS DOORS DOORS Requirements Module Verification Module Test Case Module Title TestCase Desc A1 . Status Link to Requirement Verification Proc. Description Primary A A Title TestCase Desc. A2 Status Secondary Link to Proc. Title TestCase Desc. B1 Status Link to Requirement Verification Primary Proc. Description B B Title TestCase Desc. B2 Status Link to Proc. Secondary Title TestCase Desc. C1 Status Link to Requirement Verification Proc. Description Primary C C Title TestCase Desc. C2 Status Link to Proc. 10/24/2003 91 Integration Testing Determine scenarios and create test cases and observations for each of them Schedule observations on test flight calendars and generate SMSs and PASS products Verify that no unexpected errors / warnings occur during the processing Analyze intermediate output to verify that it meets expected results Perform further verification of the final products using an HST simulator (e.g., VEST) 10/24/2003 92 Test Environment Integration testing will take place in the integrated test environment Complete HST planning and scheduling system from APT SMS generation Coming soon: PASS processing on Unix Separation from subsystem testing data Flexibility in P&S subsystem versions Supports multiple data bases, .i.e., multiple versions of ASSIST and PMDB data bases 10/24/2003 93 Interfaces Bob McCutcheon 10/24/2003 94 Interface Control Documents System Component STScI SPSS / CCS / ICD Name Changes SCS CMD PASS SAC FSW Status ICD-11 HST Science Sched- Modify FHST state- X X X Draft changes uling to Mission ment; expand AUTO available Scheduling statement ICD-26, Pt 2 PASS to PDB Update for two-gyro X X Draft changes in spacecraft charac- progress; will teristics, constraints evolve through- and restrictions, and out design commanding process ICD-T1 HST CCS to P&S Add SAC and FSW X X X Draft changes star catalogs available Note: ICD updates may be viewed at http://hst.nasa.gov/sepg/web/dev/2gyrotab.htm 10/24/2003 95 Science Scheduling to Mission Scheduling (ST-ICD-11) (1 of 2) Modify FHST statement for two-gyro operations Add new modes for two-gyro control only OAD: Perform onboard attitude determination consisting of an FHST map followed by onboard star identification, attitude determination, and an onboard sized vehicle maneuver to correct the vehicle attitude Optional parameter: FHST map tracker ID GOB: Designate FHST to be used as an observer during two-gyro FGS guide star acquisition Required new parameter: FHST observer support end time Optional parameter: FHST observer tracker ID 10/24/2003 96 Science Scheduling to Mission Scheduling (ST-ICD-11) (2 of 2) Restrict existing maneuver (MAN), delay (DEL), and observer (OBS) updates to three-gyro control only Permit existing map (MAP) and standby (SBY) modes during both three-gyro and two-gyro control Expand AUTO statement to include optional event identifier to provide on / off control for a subset of command groups associated with an orbital event Add new attitude-dependent orbital events for use in autogroup commanding FxVISBEG indicates start of FHST-x visibility FxVISEND indicates end of FHST-x visibility 10/24/2003 97 PASS to Project Data Base (ST-ICD-26, Part 2) (1 of 4) Files affected: SCHF, CRPF, DFSC, GREX, and AGCF SCHF: Add new spacecraft parameters Flag to indicate that two-gyro control is in effect Minimum times to establish FHST rate control When transitioning from M2G to T2G mode When already in T2G mode or when transitioning from F2G to T2G mode Defines minimum FHST / FHST visibility overlap for FHST rate- control handoff in T2G mode Defines minimum FGS / FHST visibility overlap for transition from F2G to T2G mode 10/24/2003 98 PASS to Project Data Base (ST-ICD-26, Part 2) (2 of 4) For OADs (separate entries for first and second OADs) Minimum time for FHST map Minimum time for attitude correction For FHST observer support of FGS guide star acquisition Minimum time for FHST observer to settle Minimum FHST / FGS visibility overlap during initial phase of guide star acquisition CRPF: Expand constraint / restriction parameters Add support for three levels of attitude uncertainty FHST and V1 Moon angle constraints FHST and V1 Earth bright limb angle constraints 10/24/2003 99 PASS to Project Data Base (ST-ICD-26, Part 2) (3 of 4) FHST and V1 Earth dark limb angle constraints FHST Sun angle constraint (shutter open) FHST Sun angle constraint (shutter closed) V1 Sun angle constraint (aperture door open) V1 Sun angle constraint (aperture door closed) Allow separate sets of two-gyro and three-gyro input HST roll parameters (off-nominal roll and SA shadowing constraints) Solar array parameters (SA off-nominal incidence angle checking and type 28 command management) Note: No CRPF changes for HGA / LGA management 10/24/2003 100 PASS to Project Data Base (ST-ICD-26, Part 2) (4 of 4) DFSC and GREX: Add new command templates and PLCP command group names Onboard FHST map, star ID, attitude determination, and attitude correction events FHST observer support of FGS guide star acquisitions AGCF Modify format to include optional + / - delta time and event identifier that are used to Adjust command times by a + / - delta relative to their associated orbital events Provide on / off control for a subset of command groups associated with a given orbital event Add new autogroup commanding FHST shutter open and shutter close commands FHST start and end availability commands 10/24/2003 101 CCS to P&S (HST-ICD-T1) Add SKYMAP star catalog definitions Ground reference star catalog used by PASS for FHST reference star selection SAC for FHST calibration and fine attitude star identification Flight software reference star catalog used for onboard star identification 10/24/2003 102 Summary Carey Myers 10/24/2003 103 Risks (1 of 2) SPSS scheduling algorithms are complex, and there are many event scenarios to consider; some scenarios may be missed Mitigation: Begin design process with definition of scenarios; develop test cases for each Overlap of flight software two-gyro work with scheduling system software implementation might cause late-breaking requirement changes Mitigation: Incorporate flexibility into design; parameterize data; implement software in phases, with well-defined areas first Onboard testing of two-gyro mode operations does not occur until late in the scheduling system software implementation; unanticipated design changes may be needed Mitigation: Incorporate flexibility into design; parameterize data; incorporate updates in Phase II 10/24/2003 104 Risks (2 of 2) Different occultation algorithms between SPIKE, SPSS, and PASS scheduling systems could limit the capability to generate two-gyro science plans. Under three-gyro mode, FHST visibility mismatches have been minor; for two-gyro mode, they may become a significant problem Mitigation: Start with CVZ observations to minimize mismatches; ensure that SPSS is more restrictive than PASS; review the study on algorithmic differences; consider integrating SPSS algorithm into PASS (Phase II) Pointing error inherent under two-gyro control may cause antenna / communications problems Mitigation: Consider applying attitude uncertainty to antenna area in PASS; minimize time under large attitude uncertainty 10/24/2003 105 Issues Scheduling system issues currently being worked through OBADWG Handling of type 2 slew FHST shutter / availability commanding Placement of type 4 slews (Are they allowed before GSACQ?) FHST maps / automaps: Are they needed? Should duration be limited? Is the second OAD always required? (Currently assuming so) FHST / GOB Is it required for every GSACQ, or only the first in the sequence, or at all? Is it before, at, or after GSACQ? GSACQ scenario changes unknown Earth calibrations: Are they needed in two-gyro? How will they be scheduled? 10/24/2003 106 TGS Project Schedule (1 of 4) 10/24/2003 107 TGS Project Schedule (2 of 4) 10/24/2003 108 TGS Project Schedule (3 of 4) 10/24/2003 109 TGS Project Schedule (4 of 4) 10/24/2003 110 TGS Implementation Schedule (1 of 2) 10/24/2003 111 TGS Implementation Schedule (2 of 2) 10/24/2003 112 Acronyms (1 of 2) AGCF auto-group command data file FSE Flight Systems Engineering APT Astronomer’s Proposal Tools FSW Flight Software ASAP as soon as possible GOB FHST two-gyro observer mode asec arc-seconds GREX group expansion file ASSIST relational data base for proposals GRP CCS real-time command group C&C Calendar & Candidate GSACQ guide star acquisition CCB Configuration Control Board GSC guide star catalog CCL CCS command language GUI graphical user interface CCS Control Center System HGA high-gain antenna CL command loader HST Hubble Space Telescope CMD Command Maintenance and Development ICD interface control document CRPF constraints and restrictions parameters file ID identifier CT coarse track IMTOOL instruction management tool CVZ continuous viewing zone LGA low-gain antenna DBDF data block definition file LRP Long-Range Plan DEL FHST delay mode M2G MSS / two-gyro (mode) DFSC DF-224 / HST486 scenario data file MAN FHST maneuver mode DOORS Dynamic Object Oriented Requirements masec milliarc-seconds System MGSE Mission Ground System Engineering ESS Engineering and Software Services MOSS Moving Object Support System F2G FGS / two-gyro (mode) MSS magnetic sensing system FGS fine guidance sensor ngp north galactic pole FHST fixed-head star tracker NGSS New Guide Star System FL fine lock OAD FHST onboard attitude determination mode FRSS FHST Reference Star Selection System OBAD onboard attitude determination 10/24/2003 113 Acronyms (2 of 2) OBADWG OBAD working group SCS Science Commanding System OBS observer sgp south galactic pole ODB operational data base SI Scientific Instrument ODM Operations and Data Management SM4 servicing mission 4 OPB Observation Planning Branch SMS science mission specification P&S planning and scheduling system SMSG SMS generation PASS Payload Operations Control Center (POCC) SPB Science Projects Branch Applications Software Support SPIKE Science Planning Interactive Knowledge PCS pointing control system Environment PDB project data base SPSS Science Planning and Scheduling System PI principal investigator SRT SMS Review Tool PLCP planning command pool file SSCB Spacecraft Scheduling and Commanding PMDB Proposal Management Data Base Branch PRD project reference data SSDB Scheduling Systems Development Branch PSDB Planning Systems Development Branch STScI Space Telescope Science Institute PSEA pointing and safemode electronics assembly SU scheduling unit RPS2 Remote Proposal Submission Two T2G FHST / two-gyro (mode) SA solar array TDRSS Tracking and Data Relay Satellite System SAA South Atlantic Anomaly TEST Test Engineering at Space Telescope SAC Sensor Analysis and Calibration TFPF table formats and parameters file SBY FHST standby mode TGS two-gyro science SCHF spacecraft characteristics file TRANS Transformation SCPL Science Commanding Programming VEST Vehicle Electrical System Test Language ZGSP zero-gyro Sun point 10/24/2003 114