PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "2016-12-12 Lorenz; 20200817 RChen/EN ingest datasets in GEO but not in EN" RECORD_TYPE = STREAM OBJECT = DATA_SET DATA_SET_ID = "VL2-M-SEIS-5-RDR-V1.0" OBJECT = DATA_SET_INFORMATION DATA_SET_NAME = "VIKING LANDER 2 MARS SEISMOLOGY RESTORED DATA V1.0" DATA_SET_COLLECTION_MEMBER_FLG = "N" DATA_OBJECT_TYPE = TABLE START_TIME = 1976-09-04 STOP_TIME = 1978-03-17 DATA_SET_RELEASE_DATE = 2016-06-01 PRODUCER_FULL_NAME = "RALPH D. LORENZ" DETAILED_CATALOG_FLAG = "N" ARCHIVE_STATUS = ARCHIVED DATA_SET_TERSE_DESC = "Data from the Viking Lander 2 Seismology Experiment." CITATION_DESC = "Lorenz, R.D., Viking Lander 2 Seismology Data, VL2-M-SEIS-5-RDR-V1.0, NASA Planetary Data System, 2016." ABSTRACT_DESC = "The dataset comprises records in Event and High Rate modes for the three axes of the Viking Lander 2 Seismology Experiment. High rate data are raw velocity signals sampled at 20.2 Hz. Event mode data are 1.01 second records of the envelope (amplitude) and zero-crossings (frequency). Summary files of the key characteristics of these records, together with the nearest wind measurement data, are also given." DATA_SET_DESC = " Data Set Overview ================= The dataset comprises four file types, namely summary and raw for High Rate and Event Mode data respectively. The raw files allow close examination of the signal for individual events, whereas the summary files are intended as an index (to identify occasions where signals are anomalous) and for large-scale correlations. Parameters ========== The raw files, as comma-separated values extracted from an archive at University of Texas (the 'VUSA tapes', Viking Unscrambled Seismic ASCII), each comprise the data from the entire mission in a single axis (e.g. X-axis corresponds to the vertical sensor). Each line in the file corresponds to a single raw record, which (due to the memory in the instrument) corresponds to 51 samples in Event (i.e. approx 51 seconds long) or 83 samples (just over 4 seconds) in High rate mode. These readings are preceded by record number and acquisition time information (Sol, hour, minute, second) reconstructed from the lander clock. For the High rate data files, the readings are the instantaneous velocity signal in the relevant axis. For event mode data, the readings are either the amplitude or the frequency (a separate file for each). The summary files present statistics of each High or Event mode record - mean, deviation, maximum value etc., together with the nearest available meteorology readings. The record number at the start of each summary record allows the corresponding raw record to be readily identified. Additionally, the estimated time between the nearest meteorology data and the seismic record is noted - to allow filtering of only those occasions where the data were near-simultaneous, for example. Note that uncertainties in the relative time reconstruction (performed differently on the seismometer and meteorology instruments) may be as high as 100 seconds. Times are specified in Local Lander Time, where Sol 0 was landing sol. Landing occurred at 22:58:20 UT (9:49:05 a.m. local Mars time) on September 3, 1976. Note that the time in the record corresponds to the end of the record. Wind azimuths are directions towards which the wind is blowing, measured clockwise from north; thus 90 degrees is Eastwards. The instrument is a velocity-sensing instrument, and thus the displacement to which a given reading corresponds is frequency- dependent, and depends on filter settings and gain states which have not been recovered. In general the highest sensitivity settings were used, and one digital data unit (DU) corresponds to 2 nm of displacement at 3 Hz or 10nm at 1 Hz - see [ANDERSONETAL1977] where fuller details are given, note especially fig.6 in that paper. The response is also slightly dependent on the choice of event vs high rate mode. Processing ========== In the processing of the VUSA data, a small number of corrupted records were simply rejected. Thus a purely ordinal comparison of these PDS archive files with VUSA data should allow for a skipped entry. The VUSA line number indicated in the PDS summary record provides the correct location, however. Because the VUSA tapes may include multiple playbacks, occasional duplicate records may appear. The raw files report the readings or zero crossings as integers, which are simply reproduced, together with the reconstructed acquisition time. The summary files indicate an ordinal record number (identifying the corresponding raw record in the raw files) the acquisition time in decimal sols, as well as the original VUSA location (file, line number) followed by the first X-axis value in that record, the maximum and minimum X-values, then the rms variation in each axis (multiplied by 100) and the mean number of X,Y,Z zero crossings indicating frequency. These are then followed by the mission time in decimal sols corresponding to the meteorology datapoint acquired closest in time, and the meteorology data itself and the time difference between the start of the seismic record and the meteorology reading. The meteorology data were provided by J. Murphy of New Mexico State University, and comprise wind speed, direction, pressure and air temperature data. Data ==== Event mode data in fact comprise the largest fraction of the archive (256,087 records, against 47,361 High rate records). Event data were acquired for much of the day during the first ~60 sols, and in the night hours (~20-23 hrs until ~3 hrs) for most of the mission. Naming Conventions ================== The raw files are named vpds_MMMM_ATYP.CSV where MMMM is event or high, A is the axis (X,Y,Z) and TYP is DAT (for High rate mode, the raw velocity readings), or for Event mode, AMP or FREQ for the envelope amplitude or frequency. The summary files are EVENT_WIND_SUMMARY.TAB and HIGH_WIND_SUMMARY.TAB respectively. " CONFIDENCE_LEVEL_NOTE = " Overview ======== The data are believed to be generally of good quality, but is dominated by wind-generated signals [e.g. NAKAMURA&ANDERSO1979]. Users should consult [ANDERSONETAL1976, ANDERSONETAL1977] to ensure familiarity with the instrument, operations and the character of wind noise and calibration signals etc. Review ====== This archive has passed a peer review according to PDS requirements. Data Coverage and Quality ========================= Data coverage is summarized in [LORENZ&NAKAMURA2014]. In brief, due to data limitations (of storage on the lander, as well as the overall downlink data rate) High rate data were acquired relatively sporadically. A number of sessions were performed in early mission (Sols 30-60). Brief sessions of early morning data (~2 or 3 hrs local time, where wind noise was at a minimum) were obtained throughout the mission. Normal mode data were acquired for much of the day for much of the mission but are of very limited utility. The data include lander disturbances as well as wind noise, calibration signals, and (perhaps) real seismic events. These lander disturbances include documented activities (operation of the sampling arm, and the agitator of the X-ray fluorescence experiment - these are documented in [MOOREETAL1987] and [BAIRDETAL1977] respectively). Additional disturbances result from slewing of the S-band telecommunications antenna, and operations of the camera and lander tape recorder. Some electrical noise is also suspected in the record, due to switching of heaters in the lander meteorological instumentation, and thermal 'pops' of the lander occur, up to 25 per day [ANDERSONETAL1976]. Limitations =========== Because of the timing uncertainties, 1:1 correlation of meteorology and seismic data should be performed with caution. Offsets of a few tens of seconds may be possible. " END_OBJECT = DATA_SET_INFORMATION OBJECT = DATA_SET_TARGET TARGET_NAME = MARS END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_HOST INSTRUMENT_HOST_ID = VL2 INSTRUMENT_ID = "VL2-SEIS" END_OBJECT = DATA_SET_HOST OBJECT = DATA_SET_MISSION MISSION_NAME = "VIKING" END_OBJECT = DATA_SET_MISSION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "LAZAREWICZETAL1981" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "ANDERSONETAL1976" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "ANDERSONETAL1977" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "MOOREETAL1987" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BAIRDETAL1977" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "LORENZ&NAKAMURA2014" END_OBJECT = DATA_SET_REFERENCE_INFORMATION END_OBJECT = DATA_SET END