IMPACT Conjunction andSidelobeOperations
Janet Luhmann, Dave Curtis, Peter Schroeder, Dick Mewaldt and the IMPACT TeamJuly 2, 2014
Instrument Power States inSidelobesand Conjunction PeriodsSSR requirementsFirstsidelobetelemetrySecondsidelobetelemetryScience to be done during this period
Instrument Power States
BothsidelobesPowered onIDPU/MAGSEPMAG heaterSWEA survival heaterPowered offSWEA/STE-DSuperior ConjunctionIMPACT powered off but MAG heater and survival heaters powered on
Store IMPACT beacon (ApID270, 1 packet/minute)Total bitrate of 36.3bpsTotal volume of ~1.03Gbits, ~24% of available 4.294GbitsSSR space for science (dumped after we return to normal operations)Maybe add some margin in case we don’t get back to operations on schedule.Just one partition needed.
At a minimum for monitoring instrument health and safety we need housekeeping (ApID200-203, 240-241, average total housekeeping bitrate 76.2bps) and beacon (ApID270, 36.3bps). Beacon is also being written to the recorder.In addition, we would like to send some real time science from MAG (ApID208, normally 414bps @ 8 samples/sec) and SEP (ApID244-268, normally 1.3kbps). We can reduce the bitrate by averaging, decimation, and excluding someApIDs. Tell us what bitrate we can get and we will configure the instrument accordingly.It would be good to get an allocated bitrate soon so we can divide it amongst the instruments and build and test the corresponding instrument configuration commands.
Again,at a minimum for monitoring instrument health and safety we need housekeeping (ApID200-203, 240-241, average total housekeeping bitrate 76.2bps) and beacon (ApID270, 36.3bps). Beacon is also being written to the recorder.We anticipate reducing science by lowering MAG time resolution and decimating and eliminating other science packet types.Again, we need to know soon what our allocation will be so we can test the configuration.
Candidate IMPACT Bitrates
White is normal rates, Green are some candidateSidelobe1 cases, Blue are some candidatesidelobe2 cases.
Main Goal: To recover some of theheliosphere-wide space weatherin-situ observational coverage (mainly MAG and SEP) originally intendedfor Far-side Science and planetary mission science support during theunforeseen period of reduced operations.Priorities:Record beacon MAG and SEP data on SSR throughout allsidelobeperiods to provide continuous coverage of conditions on thefarside(excepting periods of superior conjunction when IMPACT will be off).Real time telemetry of HK and beacon data to monitor instrumenthealth and obtain snapshots offarsidespace weather once/day3. Additional MAG and SEP data as possible within therealtimecontacts-
Somefarsidescience details:-MAVEN will be at mid-prime-missionin mid-2015, and will rely on STEREOfor approaching space weather eventinformation (realtime) and later forretrospective event studies (SSRBeacon data).-Rosetta will be approachingperihelion and will be observing thecometaryresponse to solar windconditions, including IMF sectorboundary crossings and ICMEs
May 15, 2015 ‘where’ plot
July 1, 2015
Farsidescience withsidelobeand SSR IMPACT data (continued)-Further SEP event longitudinal spread information(the topic of an LWS Science Focus) will be obtained-Trends in interplanetary magnetic field, ICME and SEP events inthis unusual solar cycle will be tracked as solar activity declines(often considered a phase during which major CMEs occur)-In-situ support for SWAVES, PLASTIC and SECCHI scienceobservations-In-situ support forfarsidespaceweather data users(eg. NOAASWPC, NASA GSFC)
Note on IMPACT use of extrasidelobereal-timedata volume:
>> Allows for more detailed and more continuous IMPACThealth checks during thesidelobeperiods>> Allows for more real-time space weather data coveragefor uses in forecasts and planetary mission needs>> Allows us to obtain a more substantial sampling of thesidelobeperiod-especially in the event the SSR beacondata cannot, for some reason, be retrieved