Data Set Information
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| DATA_SET_NAME |
PHOENIX MARS ATMOSPHERIC STRUCTURE EXP REDUCED DATA V1.0
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| DATA_SET_ID |
PHX-M-ASE-5-EDL-RDR-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 dataset consists of data products derived from data collectedby an Inertial Measurement Unit (IMU) on the Phoenix spacecraftduring its entry into the martian atmosphere. The DATA/ directorycontains two data files (PHXPROFILE.TAB and PHXCOMPACT.TAB).PHXPROFILE.TAB contains time ordered records of smoothed acceleration,derived velocity, derived position, derived atmospheric properties andother derived quantities. PHXCOMPACT.TAB contains position andatmospheric properties at 1 km vertical intervals. PHXPROFILE.TAB isthe more comprehensive set of results. PHXCOMPACT.TAB is intended forthose users who are only interested in the atmospheric properties. Parameters: PHXPROFILE.TAB contains the following items. Time (relative to reference time, seconds) UTC_TIMERadial distance (m) RADIAL_DISTANCEAreocentric latitude (degrees north) LATITUDEAreocentric longitude (degrees east) LONGITUDEX-component of position (m) X_POSITIONY-component of position (m) Y_POSITIONZ-component of position (m) Z_POSITIONElement 0 of quaternion (dimensionless) Q0Element 1 of quaternion (dimensionless) Q1Element 2 of quaternion (dimensionless) Q2Element 3 of quaternion (dimensionless) Q3X-component of velocity (m/s) X_VELOCITYY-component of velocity (m/s) Y_VELOCITYZ-component of velocity (m/s) Z_VELOCITYSpeed of spacecraft relative to atmosphere (m/s) VRELX-component of acceleration (m s^(-2)) X_ACCELERATIONY-component of acceleration (m s^(-2)) Y_ACCELERATIONZ-component of acceleration (m s^(-2)) Z_ACCELERATIONAngle of attack (degrees) ALPHAAxial force coefficient, CA (dimensionless) CANormal force coefficient, CN (dimensionless) CNMach number (dimensionless) MAKnudsen number (dimensionless) KNDensity (kg m^(-3)) RHOPressure (Pa) PRESSTemperature (K) TEMP This data file also contains 1-sigma uncertainties for those items.Units for the uncertainties in item XXX are the same as for item XXX.Those names, which are derived from the above names, are as follows: SIGMA_UTC_TIMESIGMA_RADIAL_DISTANCESIGMA_LATITUDESIGMA_LONGITUDESIGMA_X_POSITIONSIGMA_Y_POSITIONSIGMA_Z_POSITIONSIGMA_Q0SIGMA_Q1SIGMA_Q2SIGMA_Q3SIGMA_X_VELOCITYSIGMA_Y_VELOCITYSIGMA_Z_VELOCITYSIGMA_VRELSIGMA_X_ACCELERATIONSIGMA_Y_ACCELERATIONSIGMA_Z_ACCELERATIONSIGMA_ALPHASIGMA_CASIGMA_CNSIGMA_MASIGMA_KNSIGMA_RHOSIGMA_PRESSSIGMA_TEMP PHXCOMPACT.TAB contains the following items. Radial distance (m) MRADIAL_DISTANCEAltitude (km) MALTITUDEDensity (kg m^(-3)) MRHOPressure (Pa) MPRESSTemperature (K) MTEMP This data file also contains 1-sigma uncertainties for those items.Units for the uncertainties in item XXX are the same as for item XXX.Those names, which are derived from the above names, are as follows: SIGMA_MRADIAL_DISTANCESIGMA_MALTITUDESIGMA_MRHOSIGMA_MPRESSSIGMA_MTEMP The contents of PHXCOMPACT.TAB are derived from the contents ofPHXPROFILE.TAB as described below. Timing: All data products in this dataset are derived from PDS volumePHXASE_0001 [CATLINGETAL2008], which expresses times with respectto a UTC reference time of 2008-05-25T23:30:47.918. All timesin this dataset are expressed relative to the UTC reference timeof 2008-05-25T23:00:00.000. Thus a time of 0.000 in [CATLINGETAL2008]would be written as 1847.918 seconds in this dataset. Coordinate Systems: All data products in this dataset are derived from 200 Hz IMUmeasurements in DATA/IMU_A_EDR_M.TAB of PDS volume PHXASE_0001[CATLINGETAL2008]. These acceleration measurements are given in anXYZ cartesian frame fixed relative to the spacecraft. Specifically,the Phoenix mechanical frame, also known as the PHX_LANDER frameor the M frame, which has NAIF ID -84001. This spacecraftframe is neither inertial nor fixed relative to Mars. The spacecraftis axisymmetric about the Z axis in this frame. The data products in PDS volume PHXASE_0001 [CATLINGETAL2008] weretransmitted to Earth in a different frame, the IMU frame, and thentransformed into the M frame before being archived. During the courseof the preparation of this dataset, it was discovered that a preliminaryversion of the appropriate transformation matrix had been used. Thepreliminary matrix corresponds to the spacecraft as designed, not asbuilt. The vector accelerations and angular velocities in DATA/IMU_A_EDR_M.TABof PDS volume PHXASE_0001 [CATLINGETAL2008] should be multiplied bythe following matrix to transform them into the actual M frame. [New X] : [ 0.99991267 -0.00087993926 -0.013188274 ] [Old X][New Y] : [ 0.00090164837 0.99999798 0.0016463352 ] [Old Y][New Z] : [ 0.013186473 -0.0016580001 0.99991177 ] [Old Z] Where the vector with components [New X, New Y, and New Z] is thecorrected vector, the vector with components [Old X, Old Y, and Old Z]is the vector from DATA/IMU_A_EDR_M.TAB in PDS volume PHXASE_0001,and the XYZ axes refer to the M frame. Further details are given inDOCUMENT/REPORT.LBL. Acceleration measurements included in this dataset (X_ACCELERATION,Y_ACCELERATION, Z_ACCELERATION and associated uncertainties) areexpressed in the Phoenix cruise frame, also known as thePHX_LANDER_CRUISE frame or the C frame, which has NAIF ID -84000.The spacecraft is axisymmetric about the X axis in this frame.The relationship between the M and C frames is stated inDOCUMENT/EDRSIS.LBL of PDS volume PHXASE_0001 [CATLINGETAL2008].Axial accelerations are parallel to the X axis of the C frame andnormal accelerations are perpendicular to the X axis of the C frame. Position and velocity (X_POSITION, Y_POSITION, Z_POSITION andassociated uncertainties; X_VELOCITY, Y_VELOCITY, Z_VELOCITY andassociated uncertainties) are given in an XYZ cartesian framewhose origin is at the center of mass of Mars. The +Z axispasses through the north pole and the +X axis passes through theequator at zero degrees east areocentric longitude at a specifiedtime. The +Y axis completes a right-handed set. The specified timeis the UTC reference time of 2008-05-25T23:00:00.000. Position isalso given as radial distance, areocentric latitude, andareocentric longitude. This is the standard spherical polarcoordinate system found in mathematical textbooks. Longitudeincreases to the east. Altitude is defined as radial distanceminus the radial distance from the center of mass of Mars tothe landing site, 3376.3 km. Altitude is not referenced to anyequipotential surface. The orientation of Phoenix is described by the quaternion thatrelates the C frame to the J2000 frame, which is defined by theEarth's mean equator and equinox at the J2000.0 epoch. Theconvention that quaternion [Q0, Q1, Q2, Q3] corresponds to arotation about the axis parallel to the vector QV : [Q1, Q2, Q3]by an angle 2 cos-1(Q0) was adopted. Data Processing: Data processing for PHXPROFILE.TAB is described in DOCUMENT/REPORT.LBL.Many aspects of the reconstruction were similar to the reconstructionreported in PDS volume MERIMU_2001 [WITHERS&MURPHY2009]. Not all data products are defined at all timesteps. Dataproducts derived in the atmospheric structure reconstruction arenot defined above about 130 km nor below about 15 km. Such dataproducts are given the null value -1 in the PHXPROFILE.TAB. The contents of PHXCOMPACT.TAB were derived from the contents ofPHXPROFILE.TAB. The dependent variable in PHXCOMPACT.TAB is altitude,which is defined as the difference between the radial distance toPhoenix and the radial distance to the landing site (3376.3 km). Theprefix M is used frequently in PHXCOMPACT.TAB to distinguish variablesin PHXCOMPACT.TAB from similar variables in PHXPROFILE.TAB. This Mstands for mean, since many of the values contained in PHXCOMPACT.TABare averages of values reported in PHXPROFILE.TAB. A series ofaltitude levels were defined as 1 km, 2 km, ..., 146 km andlabelled as MALTITUDE. Each value of MRADIAL_DISTANCE was defined asthe sum of the corresponding value of MALTITUDE and 3376.3 km.Each value of SIGMA_MRADIAL_DISTANCE was defined as the arithmeticmean of SIGMA_RADIAL_DISTANCE for all data points in PHXPROFILE.TABwhose value of RADIAL_DISTANCE is within 0.5 km of the relevant valueof MRADIAL_DISTANCE. SIGMA_MALTITUDE was defined to equalSIGMA_MRADIAL_DISTANCE. Each value of MRHO was defined as the geometricmean of all values of RHO whose value of RADIAL_DISTANCE is within0.5 km of the relevant value of MRADIAL_DISTANCE. Values of SIGMA_MRHO,MPRESS, SIGMA_MPRESS and SIGMA_MTEMP were defined similarly. MTEMP wascalculated from MRHO and MPRESS using the same ideal gas law as was usedto produce TEMP in PHXPROFILE.TAB. If all DENSITY values in PHXPROFILE.TABwhose values of RADIAL_DISTANCE are within 0.5 km of a given value ofMRADIAL_DISTANCE in PHXCOMPACT.TAB are null (-1), then all atmosphericproperties at this MRADIAL_DISTANCE in PHXCOMPACT.TAB are given the nullvalue -1. Acronyms: AAS American Astronautical SocietyAIAA American Institute of Aeronautics and AstronauticsASCII American Standard Code for Information InterchangeASE Atmospheric Structure ExperimentASTG Atmospheric Science Theme GroupBWG Beam Wave GuideCA CaliforniaCD Compact DiscCD-ROM Compact Disc Read-Only MemoryCM Centre of MassCO ColoradoD/L DownlinkDSN Deep Space NetworkDVI Device Independent file formatEDL Entry, Descent and LandingEDR Experiment Data RecordEDT Eastern Daylight TimeEPS Encapsulated PostscriptET Ephemeris TimeFL FloridaHASI Huygens Atmospheric Structure InstrumentHEF High EfficiencyHIRISE High Resolution Imaging Science ExperimentID IdentifierIDL Interactive Data Language, a computer programming languageIMU Inertial Measurement UnitITAR International Traffic in Arms RegulationsJPG Joint Photographic Experts GroupJPL Jet Propulsion LaboratoryLM Lockheed MartinLMA Lockheed Martin AstronauticsLMST Local Mean Solar TimeLs The angle between the Mars-Sun line and the Mars-Sun line at the northern hemisphere vernal equinox, known as the areocentric longitude of the SunLSB Least Significant BitLST Local Solar TimeMA MassachusettsMECA Microscopy, Electrochemistry, and Conductivity AnalyzerMEGDR Mission Experiment Gridded Data RecordsMET MeteorologicalMEX Mars ExpressMGS Mars Global SurveyorMIMU Minature IMUMOLA Mars Orbiter Laser AltimeterMPL Mars Polar LanderMRO Mars Reconnaissance OrbiterMSP Mars Surveyor ProgramNAIF Navigation and Ancillary Information FacilityNASA National Aeronautics and Space AdministrationODY Mars OdysseyORT Operational Readiness TestPDF Portable Document FormatPDS Planetary Data SystemPDT Pacific Daylight TimePHX PhoenixPS PostscriptRA Robotic ArmRAC Robotic Arm CameraRLG Ring Laser GyroscopeSCLK Spacecraft ClockSIS Software Interface SpecificationSPICE An information system provided by the Navigation and Ancillary Information FacilitySSI Surface Stereo ImagerTEGA Thermal and Evolved Gas AnalyzerTCM Trajectory Correction ManeuverTBD To be determinedUA University of ArizonaUHF Ultra High FrequencyUSA United States of AmericaUTC Coordinated Universal TimeWA Washington
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| DATA_SET_RELEASE_DATE |
2010-04-05T00:00:00.000Z
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| START_TIME |
2008-05-25T11:30:47.918Z
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| STOP_TIME |
2008-05-25T11:38:36.899Z
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| MISSION_NAME |
PHOENIX
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| MISSION_START_DATE |
2008-05-25T12:00:00.000Z
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| MISSION_STOP_DATE |
2008-11-02T12:00:00.000Z
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| TARGET_NAME |
MARS
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| TARGET_TYPE |
PLANET
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| INSTRUMENT_HOST_ID |
PHX
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| INSTRUMENT_NAME |
ATMOSPHERIC STRUCTURE EXPERIMENT
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| INSTRUMENT_ID |
ASE
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| INSTRUMENT_TYPE |
INERTIAL MEASUREMENT UNIT
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| NODE_NAME |
Planetary Atmospheres
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| ARCHIVE_STATUS |
IN_PEER_REVIEW
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| CONFIDENCE_LEVEL_NOTE |
Data Coverage and Quality: Data coverage is excellent. The only minor gaps in the data seriesare discussed in DOCUMENT/REPORT.LBL. Uncertainties in the data usedin the reconstruction and in the resultant data products are discussedabove, in DOCUMENT/REPORT.LBL and in [CATLINGETAL2008]. Limitations and Caveats: As discussed in DOCUMENT/REPORT.LBL, the angle of attack can bedetermined by two different methods. The results obtained by the twomethods differ by 1-2 degrees, which is relatively large. This issue hasnot been resolved.
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| CITATION_DESCRIPTION |
P. Withers, D. C. Catling, J.R. Murphy, PHX-M-ASE-5-EDL-RDR-V1.0, NASA Planetary Data System, 2010.
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| ABSTRACT_TEXT |
The purpose of this report is to describe the methodology used to produce Reduced Data Records (RDRs) for the Phoenix Atmospheric Structure Experiment (ASE) from its Experimental Data Records (EDRs). These RDRs include vertical profiles of atmospheric density, pressure, and temperature.
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| PRODUCER_FULL_NAME |
PAUL WITHERS
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| SEARCH/ACCESS DATA |
Atmospheres Mars Archive
PHX ASE RDR Volume PHXASE_1XXX
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