Engineering Telemetry Hubble Space Telescope Tom Wheeler Chris Long TODAY WE ARE GOING TO SPEAK ABOUT “ENGINEERING TELEMETRY.” LET ME START BY EXPLAING JUST WHAT THAT IS. HUBBLE – SPACECRAFT – CANNOT PUT OUT HANDS ON IT, SPIN DIALS TO CONTROL IT, OR STICK PROBES INTO IT FOR TROUBLESHOOTING. EVERYTHING MUST BE DONE REMOTELY. THERE ARE THOUSANDS OF SENSORS MEASURING TEMPERATURE, PRESSURE, VOLTAGE, AND ETCETERAS. THE OUTPUT OF THOSE SENSORS, WHICH IS DOWNLINKED TO THE GROUND IS WHATR WE CALL ENGINEERING TELEMETRY. . Tom Wheeler Chris Long

Onboard Telemetry Systems (Tom) Agenda Onboard Telemetry Systems (Tom) Hardware Description Data Acquisition and Handling Limit Checking Science Data Headers Ground Systems & Archives (Chris) Data Characteristics Utilization Data Access Improvements (SMOV) Our seminar today will be split between Tom and myself. .

Telemetry Flow Tom will cover how the sensor data is acquired and processed onboard HST. I’ll talk about what happens after it arrives on the ground. So without further delay: here’s Tom.

Onboard Telemetry Systems Tom Wheeler

How is SI Engineering Data Acquired Onboard HST?

SI C&DH (Science Instrument Control and Data Handling) Hardware Description NASA Standard Spacecraft Computer-1 Remote Interface Units Multiplexed Data Bus Control Unit/Science Data Formatter This is a block diagram of the Science Instrument Control & Data Handling subsystem. Control Unit/Science Data Formatter is the hub of the SI C&DH. It handles the Master Timing Pulse from the Support Systems Module used for telemetry synchronization. Receives 16-bit commands from the SSM, and forwards them to the RIUs or the NSSC1. Receives 27-bit ground commands. Receives science data from the SIs and NSSC1 memory dumps, NASA Standard Spacecraft Computer1 is a general purpose computer that provides the function of input/output control, delayed command storage and execution, engineering data collection and limit checking. RIUs are the common communications interface between the SIC&DH and the SIs. Bus Couplers provide electrical isolation and fault tolerance. PCU performs power switching and distribution for all components of the SI C&DH. Support Systems Module Power Control Unit

SI C&DH2 Here is a photograph of the SI C&DH2 that will replace the ailing SI C&DH during SM4.

RIU (Remote Interface Unit) Hardware Description RIU’s are the common communication interface to the SIs (located within the SIs). RIU’s are implemented in redundant pairs, with seven pairs on HST: one pair for each of the five SI’s plus a pair the SI C&DH WFPC-2 has an additional RIU used for the AFMs. another pair was installed during SM-3B for the Cooling System only one of each pair is fully active at a time Each RIU provides: 8 lines for serial digital commands 64 lines for discrete commands 64 lines for sampling serial digital, analog, and bi-level telemetry points EUs (Expander Units), that piggy-back onto a RIU, add additional 64 telemetry inputs and are used on some SIs Can also provide 50 msec commands for relay open/close

Engineering Data Handling The SI C&DH has two telemetry collection modes. Fixed Format (NSSC-1 is safed) are: AF, FF, HF, PF, TF, XF, YF, ZF, C, D, E (rarely used except for Safe modes) Normal Format (NSSC-I is operating) are: AN, FN, HN, PN, TN, XN, YN, ZN Spacecraft Telemetry Distribution: Total 64 Words/minor frame 10 words each for SI = 50 words 14 words for SI C&DH Same for every operational format (regardless of 4 or 32K rates) Fixed mode – only a subset of telemetry collected. A fixed set of 64 telemetry words collected and output to the SSM every 500 msec. Normal mode – table driven 64 words/minor frame

Science Data Handling The CU/SDF collects science data from all five SIs for transmission to the SSR (in SSM) or processing within the NSSC1. Also collects memory dumps from the NSSC1 for transmission to the ground via the SSM. Output Rates: 1Mb (used for all current/future SIs science data) 32K (not used currently) 4K (ESB Dumps and SI Memory logs) Ability to add RS (Reed-Solomon, an error correcting code) or PN (Pseudorandom Noise) encoding to data.

SI Interfaces This is a block diagram of the SI interdace. Within a typical SI we have detectors, detector control electronics that communicate to the Control Section. Each SI also con a Support Electronics subsystem that provides the interface with the mechanisms and cal lamps. The CS communicates with the RIU. The RIU communicates with the SI C&DH. Science data flows form the CS directly to the Science Data formatter.

Acquisition of Engineering Data from SIs The are 3 type of Engineering data collections Normal Engineering Data (NED) - digital serial data to RIU RIU direct - analog, bi-level Special Engineering Data (SED) - digital serial data to RIU Normal Engineering Data (NED) Consists of key instrument parameters (analog and digital) giving visibility into instrument state and operations Analog engineering data is sampled directly from A/D Electronics (includes temperatures, voltages, etc.) located in: SES A/D electronics (all new SIs) CEBs (ACS, STIS, and WFC3 CCD) A/D electronics DEB (WFC3 IR) A/D electronics Mechanism status and position information is collected MIE (ACS & STIS, DIB for COS) status is collected NED collection task runs every 2.0 sec. except 0.5 sec. for NICMOS Collected data is stored in current value table for subsequent transmission to the SI C&DH and is used by the CS’s limit checking task A circular A/D data buffer maintains approximately 2 minutes of data Analog engineering data is sampled directly from A/D electronics that include voltages, temperatures, etc. These A/Ds are located in the SES, CEBs and DEB. The MIEs DIB for COS)

Acquisition of Engineering Data from SIs RIU Direct Data Telemetry Analog and digital telemetry collected directly by the RIU. SI need not be operating. Used to monitor key telemetry while SI in SAFE mode but is also used during normal ops. Special Engineering Data Telemetry 28 (used to be 35) bytes sent to the NSSC-1 every minor frame (0.5 seconds) Contains information used by the NSSC-1 Safing requests, suspend requests, executive status buffer messages, checksum indicator, minor frame count, flight software state (boot/operate), slew requests and reason for last reset.

Limits Monitoring Two Types of limit monitoring NSSC Executive (Safing Application Processor) Once a minute Only monitors RIU direct telemetry points 3 strikes and you’re out will cause suspend/safing SI Control Section Limit Checking Done at the same rate as NED Done in Boot and in Operate Out of limits may cause suspend/safing (depends upon action in FSW) I just thought that I would mention limit checking and point out limit checking is performed in the CS and the NSSC.

Standard Header Packet The Standard Header Packet (SHP) is a fixed format data log generated by the NSSC-1 sent out prior to an instrument science data dump. The format of the SHP is shown in below. See DM-03D Rev M for BL9.0 for a complete description. Uplinked programmatic information for data identification Portions of each SI Current Value Table Copies of the most recent PIT tables Unique log for each SI, provided by that SI’s application processor Standard Header Packet Format Data Word Number Contents 1 Observation Number (least significant 8 bits of the 16-bit word), Requesting SI Source ID (most significant 8 bits of the 16-bit word) 2-130 ACS Portion of the Current Value Table (CVT) 131-259 NICMOS Portion of the CVT 260-388 STIS Portion of the CVT 389-517 COS Portion of the CVT 518-646 WFC3 Portion of the CVT 647-775 SI C&DH Portion of the CVT 776-795 SSM PIT 796-855 Forward Linked Data 856-877 ACS Unique Data 878-899 NICMOS Unique Data 900-921 STIS Unique Data 922-943 COS Unique Data 944-965 WFC3 Unique Data In the science stream just prior to a science dump, the NSSC1 inserts a SHP.

SI Internal Science Data Headers The SI internal science header is a fixed format data log generated by the CS and sent out as the first line (965 words) in an instrument science data dump. A complete description of the internal science header is contained in the DM-06 for each SI. An ACS example is shown below: 1-255 (255 words) contain exposure specific information, e.g., programmatic numbers, instrument configuration, TDF responses, detector information. Some keywords found in science data’s FITS header are derived from this data. 256-605 (350 words) Eng. snapshot 1 606-955 (350 words) Eng. snapshot 2 For most science data files, the 1st snapshot is taken prior to the exposure start and the 2nd is taken just after the exposure completes. The one exception is when one exposure extends over multiple science data dumps, i.e., time-tag exposures. In this case, the first dump contains the 1st snapshot before the exposure starts and 2nd prior to the start of the dump. Subsequent dumps will only have the 2nd snapshot populated. These two snapshots form the .SPT file

Other Lesser Known Telemetry NSSC-1 Executive Status Buffer Messages Reports when an error or out of limits violation occurs with the SIs or SI C&DH. This log is always downlinked. SI Instrument Error Logs Reports when an error or out-of-limits violation occurs within an SI. This log is sometimes sent to the ground. Engineering Reports Reports status and errors within the SI C&DH. Always downlinked in Normal mode.

Data Transmission Engineering telemetry and science data are passed from the SIC&DH to the SSM (Support Systems Module) for transmission to TDRSS or are recorded on the SSR (Solid State Recorder) for later transmission.

Ground Processing/Storage Chris Long ASK QUESTIONS.

Downlink WHAT HAPPENS TO DATA WHEN IT LEAVES THE SPACECRAFT? Hubble to constellation of NASA’s TDRSS satellites. TDRSS >> one of two ground stations >> control center at White Sands, New Mexico. Forwarded through ground links to Goddard Space Flight Center.

Telemetry Pipeline Local Archive 100% SI Monitors Data Warehouse Science data >> Institute. Proprietary. Goddard intercepts only during SM. Engineering data processed by CCS Command and Control System. Displayed in real time and stored in the Data Warehouse. DW inefficient for trending or analysis cover large time scales. Local repository containing all of the SI telemetry since launch. Local Archive 100% SI Monitors Data Warehouse 100% Mission Central Store Science Inst. FOF

Data Quality (Gaps) Real-time: Viewable with gaps. Recent: All-points w/gaps. Historical: Change only, no gaps. DATA QUALITY DEPENDS UPON THE TIME FRAME. HST downlinks data through the TDRSS satellites. As the TDRSS in use drops below the horizon, HST looks for the next one. COMMUNICATION WITH THE GROUND HAS GAPS. Shows up in the real time record but all of the data is stored on the HST recorder. STORED DATA IS DOWNLINKED LATER AND MERGED INTO THE EXISTING DATA STREAM.

Data Utilization Analysis Tracking Monitoring Trending Random data extraction and manipulation. Tracking Following evolutions in real-time. May include rapid turnaround plotting. Monitoring Regular products of systems of known interest. Trending Periodic long-term visualization Unrecognized performance variation. Consumable statistics. So what do we use engineering telemetry for?

Archive Access CCS Data Warehouse Local SI Data Archive Official HST engineering archive. Requires software and HSTnet/CCS accounts. ITAR and support issues. Local SI Data Archive Engineers maintain SI monitor archive. No access limitations. But, no tools… SAY YOU WANT TELEMETRY FOR YOUR ANALYSIS. MESSAGE FROM THIS SLIDE: VAST REPOSITORIES...BUT DIFFICULT TO ACCESS.

No Such Thing. Monitors Listed As: Directory of Monitors No Such Thing. Monitors Listed As: Spacecraft 1000’s maintained by systems engineers. Observatory MSID U169 Mnemonic: USCADCLK FOC 205 COSTAR 157 ACS 823 FOS 200 WFPC2 255 COS GHRS 315 NICMOS 479 WFC3 HSP 208 STIS 607 WFPC 217 NCS 790 MESSAGE FROM THIS SLIDE: DOCUMENTATION OF MONITOR POINTS IS LACKING.

Products (but no standards) Content All-points or change-only. Merging recorded data into ongoing analysis.. Time MJD, UTC, Day of Year. Output File Delimited/interleaved/multiple independent files. Products Flat file, preload Excel, statistics, or plots. MESSAGE FROM THIS SLIDE: PRODUCTS ARE NOT STANDARDIZED.

SPACE TELESCOPE SCIENCE INSTITUTE 27 HST TELEMETRY SYSTEMS SO FROM YOUR POINT OF VIEW (YOU BEING THE CUSTOMER): DIFFICULT TO ACCESS THE DATA. (2) MONITORS POOLY DOCUMENTED. (3) NO PRODUCT STANDARDS. So that’s the bad news. The good news is there is a lot of room for incremental, and relatively easy solutions. NOW I’M GUESSING MOST OF YOU: would rather not have to come to an engineer at all. YOU’D LIKE TO GO TO YOUR “AUTOMATIC TELEMETRY MACHINE”… SPACE TELESCOPE SCIENCE INSTITUTE 27 HST TELEMETRY SYSTEMS HST TELEMETRY SYSTEMS

Telemetry ATM Directory SPACE TELESCOPE SCIENCE INSTITUTE 28 WE HAVE HUBBLE. WE HAVE THIS COOL THING CALLED THE INTERNET. You should be able to sit down…BRING UP INTERFACE WITH A WELL-DOCUMENTED DIRECTORY LISTING. PICK YOUR POINTS OF INTEREST, ENTER A TIMEFRAME, AND HIT ENTER A short time later your data file is seamlessly delivered to your desktop. I’ll go further in betting that you rather not have to do the work of importing and plotting data yourself, YOU’D RATHER HIT THE PLOT BUTTON AND HAVE THE RESULT APPEAR ON YOUR SCREEN. SPACE TELESCOPE SCIENCE INSTITUTE 28 HST TELEMETRY SYSTEMS HST TELEMETRY SYSTEMS

Improvements SMOV Forward Plan Telemetry directory Post products Extraction interface Visualization interface SMOV Proactive monitor program Improved analysis tools Well, we aren’t their yet. SO WHAT SHOULD BE DONE? I THINK WE SHOULD…. WHY NOW? SMOV WITH A MUCH SMALLER TEAM…. THIS ISN’T ROCKET SCIENCE. SPACE TELESCOPE SCIENCE INSTITUTE 29 HST TELEMETRY SYSTEMS HST TELEMETRY SYSTEMS

Engineering Support Questions? That’s it. Thanks for listening. We have time for questions about this or anything else related to HST systems engineering. SPACE TELESCOPE SCIENCE INSTITUTE 30 HST TELEMETRY SYSTEMS HST TELEMETRY SYSTEMS