Data Set Information
DATA_SET_NAME MESSENGER E/V/H MASCS 4 UVVS/VIRS DERIVED DATA V1.0
DATA_SET_ID MESS-E/V/H-MASCS-4-UVVS/VIRS-DDR-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview : This data set consists of the MESSENGER MASCS UVVS/VIRS combined derived data records (DDRs). Each UVVS+VIRS combined observation utilizes data extracted and derived from UVVS Surface DDRs and VIRS DDRs, described in their own SIS and *DS.CAT documents. Each combined DDR contains one UVVS observation from the middle ultraviolet (MUV) photomultiplier tube (sensitive from 160-320 nm, but utilizing 210-300 nm) and one VIRS spectrum composed of visible (VIS) detector (sensitive from 300-1050 nm but utilizing the range of 300-896 nm) and near infrared (NIR) (sensitive from 850-1450 nm but utilizing 898 nm to 1450 nm), with a resolution of 5 nm. VIRS spectra are matched by location, and where available, time, to the several thousand UVVS surface spectra obtained during Mercury orbit phases. Instrument Overview : The MASCS instrument consists of a small Cassegrain telescope that simultaneously feeds the UVVS and VIRS experiments. The MASCS VIRS experiment is a fixed concave grating spectrograph with a beam splitter that simultaneously disperses the spectrum onto two solid-state array detectors: a 512-element silicon photodiode array, with a sensitivity to visible wavelengths (300-1050 nm), and a 256-element indium-gallium-arsenide photodiode array, to measure near infrared wavelengths (850-1450 nm). The VIRS detector helped to measure the surface reflectance and search for ferrous bearing minerals, Fe-Ti bearing phases, and ferrous iron on the surface of Mercury. The MASCS UVVS experiment is a scanning grating monochromator equipped with three photomultiplier tubes, providing spectral information in the far ultraviolet (115-190 nm), middle ultraviolet (160-320 nm), and visible (250-600 nm) wavelength ranges. The UVVS detector helped to determine the composition of Mercury's exosphere by measuring the spatial and vertical distribution of known species as well as search for new ones. See the INST.CAT file for more information and [MCCLINTOCK&LANK2007] for full details. Parameters : The principal parameters when constructing the combined data set are as follows: * Component File IDs (UVVS Header File ID, UVVS Science File ID, VIRS VIS File ID, VIRS NIR File ID): The individual DDR files from which spectral and other information is extracted to make the combined DDR. * VIRS spectrum number: Which spectrum number from the matching observation that is the closest/best match to the UVVS spectrum of the DDR. * UVVS derived footprint parameters: UVVS drift distance and UVVS smear as a percentage of footprint size. * VIRS footprint parameters for VIRS spectrum. * Spatial relation between UVVS and VIRS footprints: Center to center distance between UVVS and VIRS in km and as a percentage of the UVVS footprint size. * Photometric angles of the UVVS and VIRS observations: Incidence, emission, and phase angles. * Quality factors for spectrum: Goodness of match, temperature flags, noncontempraneous VIRS observation flags, VIRS binning. * Spectral wavelengths, reflectance, and noise. Derived Product Overview : This data set consists of MASCS UVVS and VIRS Derived Data Records (DDRs) (calculated from the EDRs and CDRs as described in their respective SISs). The DDRs are the processed data records of derived surface reflectance used for scientific analysis. The science DDRs contain Mercury surface photometrically corrected reflectance measured by the UVVS and VIRS detectors. The processing steps from the individual DDR to the Combined DDR include: 1. Identify matching VIRS DDR and spectrum that is the closest, best fit in location, time and quality to each UVVS surface observation. 2. Derive smear, drift, and proximity and other parameters. 3. Combine spectra into a single contiguous spectrum from 210-1450 nm. The processing steps are detailed in the document MESSENGER MASCS UVVS+VIRS Combined Derived Data Record Specification, located in the DOCUMENT directory. Coordinate Systems : MASCS VIRS data are represented in the following coordinate systems: * Planetocentric body fixed: The MBF coordinate system is defined by the planetocentric position, Cartesian X, Y, Z coordinates related to the planetocentric distance, latitude measured positive northward from the equator, and longitude measured positive eastward from the prime meridian. * Cartographic: Surface observations use IAU planetocentric system with East longitudes being positive for planetary surfaces. The MESSENGER-derived reference system (pck00010_msgr_v21.tpc) for cartographic coordinates and rotational elements was used for computing latitude and longitude coordinates of planets. Data : There is a single combined UVVS+VIRS DDR data product - one per observation pair of UVVS and VIRS. UVVS surface data is taken from the set of UVVS observations, specifically targeting points on the Mercury surface for MUV spectral data taking, as described in the UVVS Surface DDR documentation. VIRS data is taken from the set of VIRS DDR observations. Where possible, matched, dedicated VIRS observations intended to target the same location as UVVS observations are used for matching. If those are not available, or were not taken, other proximate, but non-contemporaneous VIRS observations are used.
DATA_SET_RELEASE_DATE 2017-05-12T00:00:00.000Z
START_TIME 1965-01-01T12:00:00.000Z
STOP_TIME N/A (ongoing)
MISSION_NAME MESSENGER
MISSION_START_DATE 2004-08-03T12:00:00.000Z
MISSION_STOP_DATE 2015-04-30T12:00:00.000Z
TARGET_NAME MERCURY
TARGET_TYPE PLANET
INSTRUMENT_HOST_ID MESS
INSTRUMENT_NAME MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER
INSTRUMENT_ID MASCS
INSTRUMENT_TYPE VISIBLE/INFRARED SPECTROGRAPH
UV/VISIBLE SPECTROMETER
NODE_NAME Geosciences
ARCHIVE_STATUS ARCHIVED - ACCUMULATING
CONFIDENCE_LEVEL_NOTE Confidence Level Overview : The MASCS UVVS+VIRS Combined Derived Data Record (DDR) consists of the derived data converted to units of reflectance and represented in physical coordinate systems. Data presented here are an accurate representation of the UVVS and VIRS data as received from the spacecraft, and reflect the processing steps from the MASCS UVVS and VIRS Calibrated Data Records (CDRs) to DDR level detailed in the documents UVVS_CDR2DDR.*, VIRS_CDR2DDR.*, and UVVSVIRS_DDR2DDR_COMBINED.* located in the DOCUMENT directory. Review : The UVVS+VIRS Combined DDR was reviewed internally by the MASCS team prior to release to the PDS. PDS also performed an external review of the MASCS UVVS+VIRS Combined DDRs. Data Coverage and Quality : Data reported are the derived data received from the spacecraft during the orbital mission phases: Mercury Orbit, Mercury Orbit Year 2, Mercury Orbit Year 3, Mercury Orbit Year 4, and Mercury Orbit Year 5. These mission phases are defined as: Start time End time Phase Name Date (DOY) Date (DOY) ------------------------- ----------------- ---------------- ORB: Mercury Orbit 04 Mar 2011 (063) 17 Mar 2012 (077) OB2: Mercury Orbit Year 2 18 Mar 2012 (078) 17 Mar 2013 (076) OB3: Mercury Orbit Year 3 18 Mar 2013 (077) 17 Mar 2014 (076) OB4: Mercury Orbit Year 4 18 Mar 2014 (077) 17 Mar 2015 (076) OB5: Mercury Orbit Year 5 18 Mar 2015 (077) 30 Apr 2015 (120) To validate the initial DDR dataset, the MASCS team did the following: * Examined several combined observations in detail. - Checked all data columns for format and sanity numbers. - Compared calibration numbers for earlier independent analysis before DDR development. - Compared reflectance and photometric conversions to previous independent solutions. The Combined DDR dataset was evaluated on an iterative basis, checking for completeness and data integrity. MASCS UVVS surface and VIRS data were collected during all Mercury orbit phases, but contemporary, co-targeted VIRS observations were not made for all UVVS observations, and earlier (OB3 and earlier) UVVS observations tended to have higher drift and smear than later (OB4 and later) observations. Limitations : This data set is derived data. The data are received from the spacecraft telemetry and ingested into the MESSENGER Science Operations Center (SOC), then run through the MASCS pipeline. No data uncharacterized gaps have been identified for any of the MASCS operational periods.
CITATION_DESCRIPTION Izenberg, N., MESSENGER E/V/H MASCS 4 UVVS/VIRS DERIVED DATA V1.0, MESS-E/V/H-MASCS-4-UVVS/VIRS-DDR-V1.0, NASA Planetary Data System, 2017.
ABSTRACT_TEXT Abstract : This data set consists of the MESSENGER MASCS UVVS+VIRS combined derived data records, also known as DDRs. The UVVS+VIRS DDRs consist of derived data from UVVS' middle ultraviolet (MUV) photomultiplier tube, and VIRS. Spatially proximate UVVS and VIRS spectra are combined to create a single extended wavelength surface reflectance spectrum from 210 nm to 1450 nm. The combination is conducted by software that locates automatically or with human assistance, the closest best matching VIRS spectrum to a given UVVS spectrum, and combines the two data sets into a single spectrum for that location.
PRODUCER_FULL_NAME NOAM IZENBERG
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