Data Set Information
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| DATA_SET_NAME |
VL1/VL2 MARS METEOROLOGY DATA CALIBRATED DATA PRESSURE V1.0
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| DATA_SET_ID |
VL1/VL2-M-MET-3-P-V1.0
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| NSSDC_DATA_SET_ID |
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| DATA_SET_TERSE_DESCRIPTION |
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| DATA_SET_DESCRIPTION |
Data Set Overview : This data set contains the martian surface atmospheric pressure readings obtained through much of the duration of the Viking Lander 1 and 2 missions (data are included for Viking Lander 1 sols 0 - 2245 and Viking Lander 2 sols 0 - 1050). The data are derived from the ambient pressure sensor carried onboard the Landers and values are presented on a point by point basis. The sampling rate was variable throughout the mission; the maximum sampling rate was one measurement per second, but ranged up to 65 minutes for Lander 1 and 105 minutes for Lander 2. For further background information on the Viking Meteorology Instrument System (VMIS) and results from this experiment, see CHAMBERLAIN_ETAL1976, HESS_ETAL_1976A, HESS_ETAL_1976B, and HESS_ETAL_1977. For discussions of analyses of experiment data, see also TILLMAN_1977, HESS_ETAL_1980, and TILLMAN_1988. An earlier version of this data set is archived at the NSSDC (NSSDC ID 75-075C-07D and 75-083C-07D). This data set is composed of the following fields (listed as the field name followed by a description): SC_ID Spacecraft id SOL_LON Areocentric longitude of the Sun (Ls), derived for the local time of each measurement VIKING_YEAR Viking mission year, starting at 1 when the Viking spacecraft reached Mars, and incremented at Ls : 0 every martian year MARTIAN_DAY The martian solar day (sol), starting at day 0 when each Lander touched down LOCAL_HOUR Local hour (Earth hour), beginning at midnight (hr 0) LOCAL_MINUTE Local minute (Earth minute) LOCAL_SECOND Local second (Earth second) PRESSURE Surface atmospheric pressure Processing Level Id : 3 Software Flag : Y Processing Start Time : UNK Processing Stop Time : UNK Native Start Time : 97.1 AREOCENTRIC SOL LON, EARTH YR 1976 Native Stop Time : 226.7 AREOCENTRIC SOL LON, EARTH YR 1982 Parameters : Data Set Parameter 'ATMOSPHERIC PRESSURE' ----------------------------------------- The force per unit area exerted by an atmosphere, measured in millibars (10**3 dyne cm**-2). Data Set Parameter Name : ATMOSPHERIC PRESSURE Data Set Parameter Unit : MILLIBAR Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : N/A Maximum Sampling Parameter : N/A Sampling Parameter Resolution : N/A Sampling Parameter Interval : N/A Minimum Available Sampling Int : 1.000000 Noise Level : N/A Source Instrument Parameters : Instrument Host ID : VL1 Data Set Parameter Name : ATMOSPHERIC PRESSURE Instrument Parameter Name : PRESSURE Important Instrument Parameters : 1 Instrument Host ID : VL2 Data Set Parameter Name : ATMOSPHERIC PRESSURE Instrument Parameter Name : PRESSURE Important Instrument Parameters : 1 Processing : Processing History ------------------ Source Data Set ID : MASTER DATA RECORD (MDR) Software : UNK Product Data Set ID : VL1/VL2-M-MET-3-P-V1.0
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| DATA_SET_RELEASE_DATE |
1989-11-01T00:00:00.000Z
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| START_TIME |
1976-07-20T12:00:00.000Z
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| STOP_TIME |
1982-11-13T12:00:00.000Z
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| MISSION_NAME |
VIKING
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| MISSION_START_DATE |
1975-08-20T12:00:00.000Z
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| MISSION_STOP_DATE |
1983-02-01T12:00:00.000Z
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| TARGET_NAME |
MARS
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| TARGET_TYPE |
PLANET
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| INSTRUMENT_HOST_ID |
VL1
VL2
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| INSTRUMENT_NAME |
VIKING METEOROLOGY INSTRUMENT SYSTEM
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| INSTRUMENT_ID |
MET
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| INSTRUMENT_TYPE |
METEOROLOGY
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| NODE_NAME |
Planetary Atmospheres
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| ARCHIVE_STATUS |
ARCHIVED
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| CONFIDENCE_LEVEL_NOTE |
Overview : The pressure transducers were calibrated to approximately 0.01 to 0.02 millibars accuracy over the ranges expected for martian atmospheric pressure variation. Calibrations to accuracies greater than allowed by the digitizing system were accomplished by test support instrumentation. Repeatability from year to year of the daily average pressures indicates that the transducers have remained stable to significantly better than 0.04 millibars throughout the mission, possibly maintaining stabilities on the order of 0.01 millibars. The pressure measurements were digitized into 255 approximately equal increments (digital numbers or DNs), giving a basic pressure digitization interval of 0.088 millibars. Raw DNs between 0 and 255 were converted to pressures by linear interpolation between calibration points. Due to the limited pressure range on Mars, the only calibration points used are those for DNs 100, 120, and 160. DN 140 was left out of the calibration table, producing a maximum error of 0.0425 millibar for VL1 and 0.008 millibar for VL2; corrections have been applied to the data set to correct for this missing calibration point. As the output of the pressure transducer is quantized in 0.088 millibar increments, the resolution of a single measurement is limited to 0.088 millibar. On average, half of the measurements producing a given pressure value are at least one half a quantum above the indicated value and that value is actually the lower bound of the actual value. By adding 0.044 millibar to each measurement, any estimate of the average pressure (generally having greater resolution than one DN) will not be biased (see HESS_ETAL_1980). Such accuracy is important as features of the annual pressure cycle repeat within 0.02 millibar or less and it is important to establish the actual value for comparison between years and for future missions to Mars.
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| CITATION_DESCRIPTION |
Citation TBD
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| ABSTRACT_TEXT |
This data set contains the martian surface atmospheric pressure readings obtained through much of the duration of the Viking Lander 1 and 2 missions (data are included for Viking Lander 1 sols 0 - 2245 and Viking Lander 2 sols 0 - 1050). The data are derived from the ambient pressure sensor carried onboard the Landers and values are presented on a point by point basis. The sampling rate was variable throughout the mission maximum sampling rate was one measurement per second, but ranged up to 65 minutes for Lander 1 and 105 minutes for Lander 2. For further background information on the Viking Meteorology Instrument System (VMIS) and results from this experiment, see CHAMBERLAIN_ETAL1976, HESS_ETAL_1976A, HESS_ETAL_1976B, and HESS_ETAL_1977. For discussions of analyses of experiment data, see also TILLMAN_1977, HESS_ETAL_1980, and TILLMAN_1988. An earlier version of this data set is archived at the NSSDC (NSSDC ID 75-075C-07D and 75-083C-07D).
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| PRODUCER_FULL_NAME |
JAMES E. TILLMAN
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| SEARCH/ACCESS DATA |
Atmospheres Online Archives
Atmospheres Online Archives
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