Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 1 VIRTIS-VEx geometry files formatting VVX-LES-SW-2268 ??Issue 1.2 NAME FUNCTION SIGNATURE DATE Prepared by S. Erard 28/1/2008 K. Garceran Checked by P. Drossart G. Piccioni Approved by Authorized by Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 2 TABLE OF CONTENTS 1- Introduction ......................................................................................................................4 1.1 Applicable / Reference Documents................................................................................................. 4 2- Detailed specifications.......................................................................................................4 2.1 Data file labels .................................................................................................................................... 6 2.2 Geometric index................................................................................................................................. 6 2.3 Geometry files contents..................................................................................................................... 6 2.3.1 Observations intercepting the surface ......................................................................................................... 7 2.3.2 Limb observations and other geometries .................................................................................................. 10 2.4 Geometry files labels ....................................................................................................................... 11 Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 3 DOCUMENT CHANGE RECORD Issue Date # Old New Description of the Reason of the modification Paragraph Paragraph modification Draft 02 26/01/2006 1 Added label for VEX-H geometry files Draft 03 14/02/2006 2 Modified information in Deeper thinking geometric files Draft 16/03/2006 3 Modified information in Finalization after discussions at 0.4 geometric files team meeting Draft 20/03/2006 4 Modified information in Corrections 0.5 geometric files 0.6 5/05/2006 5 Draft 15/05/2006 6 General Update Related to actual 0.6b implementation 0.6c 16/05/2006 7 Correction of UTC encoding To preserve required accuracy 0.6d 17/05/2006 8 Various corrections Draft 4/06/2006 9 Change cube organization Space saving in M cubes 0.8 (~20%) + consistency for H (first planes are common). 10 Added slit orientation in H Information was previously not cubes available at the limb Draft first 11 Minor updates Corrections, precisions? 0.9/0.9b distribution Draft 25/7/2006 12 Added boresight-Sun angle For characterization of possible 0.10 projections along X and Y stray light. axes for both H and M. 13 Updated Fig. 1 14 Geometry files are According to orbital parameters / generated twice (*.PRE and time correlation generation at *.GEO) ESOC. 15 Changed offset in surface Previous value of 20,000 m was elevation for limb not practical. observations to 100,000 m 16 Modified definition of plane Now in accordance with actual 30 in limb observation computation (not set to 0) 17 Included estimated From ESOC information, accuracy on pointing confirmed by SPICAV direction 18 Updated labels 19 Added Figures 1 and 2 Draft 28/8/2006 20 Various Complete check and corrections 0.11 to fit actual computation Draft 25/10/2006 21 Sun position is now given in Consistency 0.12 the instrument frame (instead of the S/C frame) Draft 30/10/2006 22 Plane 30 modified for limb Removes duplicate and 0.13 observations preserve surface elevation info for limb observations Draft 10/11/2006 23 Various corrections in text Consistency, clarifications 0.14 Issue 1 18/6/2007 24 Various corrections in text, Consistency with final pipeline figures added and updated EGSE Issue 11/9/2007 25 Minor corrections Update after interaction with 1.1 PSA Issue 28/1/2008 26 Overall Updated after review 1.2 Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 4 1- Introduction This document defines the format and contents of the VIRTIS VEx geometrical files for both M and H channels. These files are distributed to the science team, and are part of the archive delivered to PSA. 1.1 Applicable / Reference Documents ? AD1 - VIRTIS VEx to Planetary Science Archive Interface Control Document (EAICD). Issue 1.2, 18 July2008. ??AD2 VIRTIS PDS/IDL software library VVX-LES-SW-2264, Issue 2.7.4 ? RD1 - Seidelman et al. (2000) Report of the IAU/IAG working group on cartographic coordinates and rotational elements of the planets and satellites. Celestial Mechanics and Dynamical Astronomy 82: 83?110, 2002. ? RD2 - Ford, P.G. and G.H. Pettengill (1992) Venus topography and kilometer-scale slopes. Journal of Geophysical Research, 97 13103. 1.2 Acronyms and Abbreviations EDR: Experimental Data Record EGSE: Electrical Ground Support Equipment FPA: Focal Plane Arrays HK: HouseKeeping parameters IDL: Interactive Data Language IR: InfraRed ISIS: Integrated Software for Imagers and Spectrometers ME: Main Electronic MSB: Most Significant Byte first MTP: Medium Term Plan - basic period for observation planning (~1 month) OBT: On-Board Time PDS: Planetary Data System PSA: Planetary Science Archive RDR: Reduced Data Record SCET: SpaceCraft Elapsed Time (on-board time measured in s from launch) SAP: Science Activity Plan SI: Syst?me International d?unit?s TM: Telemetry UTC: Universal Time Corrected VEx: Venus-Express VIRTIS: Visible Infra Red Thermal Imaging Spectrometer 2- Detailed specifications The overall pipeline for VEx is described in the EAICD, and is summarized in Fig. 1. Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 5 Figure 1: VIRTIS VEx processing pipe-line The VIRTIS VEx data archive contains geometrical information together with the data at various processing levels. This includes: 1) General/averaged information contained in the PDS label of data files, pertaining to the overall session; 2) More detailed information stored in a general data catalogue, called GEO_VENUS.TAB. This file is a catalogue providing the footprint of the observing sessions. It is required by the PSA for long term archiving, and is intended to facilitate on-line cross-correlation between data sets. 3) Detailed information on a pixel basis, required to plot the data and analyze them in details. This information is stored in separated geometric files associated to the data files. The detailed information is stored in separate files, so as to decouple maintenance of the data on one hand, and of the geometry on the other hand. Practically, the geometric files have to be generated several times, as navigation Spice kernels are updated by ESA. This scheme also preserves the possibility to generate and maintain calibrated/derived data files easily. Consequently, there is one geometric file associated to each data file. This implies that the geometric files are relevant to one focal plane only (separated files for H, M-vis, M-IR). When processing a data file, only the corresponding geometry file needs to be loaded. The geometry computation is in general performed twice for each file: a first time when the raw data file is generated by the EGSE, using predicted orbital parameters; a second time about three weeks later, when the Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 6 final (reconstructed) orbital parameters and time correlation files become available. The first generation of geometry files have extension ?PRE?, whereas the final version have extension ?GEO?. The first generation is made available to the team for real time analysis, and is superseded by the final one when available. Only the .GEO files, which are the final versions, are included in the archive. Geometry computations are performed by a specific IDL library developed and maintained in Meudon (GeoVirtis), relying on the Spice toolkit for IDL (ICY, version N0061). The three types of information are described in the next sections. 2.1 Data file labels Data file labels are described in the current versions of the EAICD [AD 1], and related documents. These geometric quantities are computed with the SPICE system, then are included in the PDS labels of the data files written by the EGSE. This means that the raw data files are written in two steps (see Fig. 1): 1) Formatting in EGSE, with attached PDS labels. The geometrical keywords have dummy values ("NULL"). These files are not distributed outside the PI institutes in Rome and Meudon. 2) Computation of geometrical quantities with the SPICE system, outside the EGSE. Files from the first step are edited and completed in this step with the proper values for the geometrical keywords. The calibrated or derived data files are written from these updated raw data files, with complete labels that include values associated to the geometrical keywords. No second step SPICE computation has to be performed when writing the calibrated or derived files. Some of this information cannot be derived from the SPICE system or the data, but is known from science planning (e.g., target names). Such information is collected in the data base in Meudon, and is included in the labels together with the geometric values. The update of the raw data files is triggered by the geometry software (GEOVIRTIS) as a by-product of geometry computation. 2.2 Geometric index The archive contains two different index files pertaining to the geometry: 1) The general index of the archive, named INDEX.TAB. It provides basic catalogue reference to all the data files, including some selected geometry keywords; 2) A more technical file named GEO_VENUS.TAB providing a general description of the footprint for each data file. The contents and structure of these files are defined according to PSA requirements. These files are used for cross-correlation with other data sets and data mining in the PSA. They are computed using the GEOLIB software provided by the PSA. 2.3 Geometry files contents The Virtis-VEx geometric files for the three focal planes are written by the GEOVIRTIS software. This system makes use of the SPICE kernels distributed by ESA, and of Virtis-M CK kernels computed in Rome to handle the scanning mirror angle on the M channel. These latter files are generated after observations from TM information, and reflect what has actually been done. Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 7 As mentioned above, geometry is computed and stored independently for each FPA. Virtis geometric files also contain a cube with structure related to the raw data file, so that there is a direct correspondence between the two: ??Data cube dimensions = (X, Y, Z), where X is the spectral dimension. X and Y depend on instrumental mode, and Z depends on session duration. The sideplane contains the housekeeping parameters. ??Geometric cube dimensions = (N, Y?, Z?), where N is the # of geometrical parameters for this FPA/channel. There is no sideplane associated to the cube core. For M cubes, Z? is equal to the number of spectral frames in the data cube, while Z is equal to the number of spectral frames + dark current frames. The same applies to H cubes in frame (backup) mode. In H nominal mode however, Z? = Z (dark frames are stored independently). M geometric cubes always have Y? = Y (the value depends on binning mode). H geometric cubes in nominal mode always have Y? = Y = 64. H geometric cubes in backup mode always have Y? = 1, whereas Y = 256 (each data frame contains a detector image, but is described by 1 single geometric column). The geometry cubes are stored as long signed integers with MSB encoding. A simple conversion coefficient is used to accommodate the data in this format whenever required to preserve accuracy (see below). The geometry files are handled directly by the VIRTIS IDL library and its front-end routine virtispds [AD 2]. Each observed pixel is projected on Venus, with coordinates of the IFOV corners and center written in the geometry files. Because most of the signal originates in the atmosphere and not from the surface, the IFOV is projected on Venus along the geometric line of sight with no correction for scattering, refraction, or surface topography. Two projection surfaces are used to allow for simple interpolation of the footprint at various altitudes in the atmosphere: ? The first projection surface is a sphere with 6051.8 km radius. This is the Venus reference surface used in SPICE kernels, derived from the Venus reference ellipsoid defined in the IAU 2000 standard (sphere with radius = 6051.8 ? 1.0 km; see [RD1]). ??The second projection surface is a sphere located 60 km above the reference ellipsoid. This particular altitude is selected to match approximately the upper cloud layer on the day side. The estimated accuracy on the pointing direction is ~0.02?. However two situations have been reported: ? The pointing direction of Virtis is affected by a small oscillation when the ASPERA mirror is moving during acquisition. This is particularly visible on limb sessions. The amplitude of oscillation is on the order of some pixels. At the time of writing, this translate into a pointing error of the same amplitude on some session acquired in the summer of 2007. In the future, the effect may be measured and compensated in the SPICE kernels. ??The M-IR FOV is not entirely aligned: the spatial direction is slightly bended, with an inflection of about 1 pixel at its center. The M-visible FOV may be deformed similarly. Again, this is mostly sensitive on the limb sessions. 2.3.1 Observations intercepting the surface The cube planes are described in Table 1. In general, coordinates of the four pixel footprint corners and of the pixel central point are computed on both reference surfaces. All computations are performed in the planetocentric system (i.e.: relative to the local vertical) and using eastward longitudes. Planetographic coordinates are not provided (they are identical in absolute value because the reference ellipsoid is a sphere). The geographic frame is the one used in the SPICE kernels, and defined in the IAU 2000 system. The three observing angles (incidence, emergence, phase) are also computed on both surfaces. In addition, the spacecraft slant distance is computed from the surface ellipsoid (not including the topography) for each pixel. Right ascension and declination at pixel center are computed for each pixel in all observing modes. Local time at Venus is also provided for each pixel; it is measured from local midnight, and increases with UTC in a given location (although the planet rotation is retrograde). Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 8 A topographic model is used to provide the average surface elevation of the geometrical footprint at the intercepts of the line of sight with both reference surfaces. The point beneath the intercept with the cloud layer corresponds to the shortest atmospheric path, and is expected to be the main source of photons originating from the surface. The intercept with the ellipsoid roughly corresponds to the intercept with the actual surface; in most situations the difference can be ignored under the thick Venus atmosphere. The two points are identical in nadir pointing (see Fig.2). The topographic model used is the Magellan GTDR (RD2). Surface elevation information is converted to altitude above the reference ellipsoid. The pixel elevation is provided as the average value at the four corners and at center, or as the center value whenever one corner is missing in the GTDR; whenever the pixel center value is missing, a special error code is recorded in the file (the value -20 000 m is used; it is negative and lower than the minimal altitude on Venus). Other instrument-related information is stored in the geometric cubes, including SCET, UTC, and scanning mirror angle for M. SCET are copied directly from the data files, except in the case of H nominal mode where they are reconstructed for each spectrum from acquisition parameters. UTC are the corresponding values recomputed from the SPICE kernels (not using the DDS approximation attached to the TM data), then translated at mid-exposure (the offset is equal to half the repetition time). UTC is stored on two words, the first one providing the number of day since Jan. 1st, 2000 (starting at 1), the second one providing 10,000 x the number of seconds on this day, starting at 0h. For H, the slit orientation is provided as the angle between the ellipsoid normal and the longest slit direction (in the plan orthogonal to the line of sight, see Figure 3). For M the mirror angle is stored as the sine and cosine of this angle (HK parameters decoded using the adequate transfer function). Finally, the Sun direction is provided as the angle from the instrument boresight and its azimuth in the XY plane, counted from the X axis (Figure 4). For H, all quantities are computed on a pixel basis. For M, those which are common to a complete frame are stored in the same plane; they comprise SCET, UTC, sub-S/C coordinates, mirror angle and Sun-boresight direction in the orthogonal plane (10 words, whereas the minimum plane dimension is 64). All parameters are stored on 4 bytes as long signed integers. Angles (coordinates, viewing angles, and ?/?) are stored in degrees and multiplied by 10,000. Distances are stored in meters. Sine and cosine of mirror angle are multiplied by 1000. Local time is stored in units of Venus period/24 (local hours) multiplied by 100,000. Parameters based on data or HK which are absent from the TM are replaced by value -2147483648 ('80000000' hexa; this actually occurs mainly for mirror angle parameters). Geometric information that can be considered constant in the time frame of one subsession is also stored in the label of the geometry files, including sub-solar point coordinates at the surface, solar distance, and solar longitude. Solar longitude is computed as the planetocentric longitude of the Sun, starting from Venus North hemisphere spring equinox. Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 9 Plane # Parameter description Comment 1-4 Longitudes of 4 pixel footprint corner points Geometrical projection on surface ellipsoid, with no correction for scattering or refraction 5-8 Latitudes of 4 pixel footprint corner points 9-10 Longitude & latitude of pixel footprint center on surface ellipsoid 11-13 Incidence, emergence & phase at footprint center, Angles relative to the reference surface (not relative to Venus center direction accounting for topography). Incidence angle is equal to solar zenithal angle. 14 Surface elevation (footprint corners average) From topographic model 15 Slant distance (line of sight from spacecraft to Does not include topographic model surface ellipsoid at pixel center) 16 Local time at footprint center 17-20 Longitudes of 4 corner points on cloud layer Geometrical projection on reference cloud layer (60km) 21-24 Latitudes of 4 corner points on cloud layer 25-26 Longitude & latitude of pixel center on cloud layer 27-29 Incidence, emergence & phase, relative to local Phase angle is the complement of the normal of cloud layer scattering angle. Incidence angle is equal to solar zenithal angle. 30 Surface elevation at the vertical of cloud layer From topographic model intercept 31-32 Right ascension and declination of pointing J2000 reference frame direction. For M: 33 One frame-common plane Provides 10 scalar quantities along the frame spatial dimension. The remainder is set to 0. 1-2 Original data SCET from TM The first value stores the SCET first two words (integer part), the second one stores the third SCET word (fractional part) 3-4 UTC Encoded UTC recomputed through the SPICE system. The first value contains the number of days since Jan. 1st, 2000, the second value contains the time of the day as 10,000 x seconds (starting from 0h) 5-6 Sub-spacecraft coordinates (longitude/latitude) 7-8 Sine and cosine of M mirror angle Converted into sin/cos values from HK Sun direction: 9: angle between Sun direction and Virtis Z axis; 10: azimuth of Sun direction in instrument XY plane (counted from 0? at X axis). For H: 9 supplementary planes 33-34 Original data SCET from TM Interpolated for each spectrum in nominal mode. The first plan stores the SCET first two words (integer part), the second one stores the third SCET word (fractional part) 35-36 UTC Encoded UTC recomputed through the SPICE system. See above (33.3-4) 37-38 Sub-spacecraft coordinates (longitude/latitude) 39 Slit orientation Relative to the pixel normal at footprint center 40-41 Sun direction: 40: angle between Sun direction and Virtis Z axis; 41: azimuth of Sun direction in instrument XY plane (counted from 0? at X axis). Table 1: contents of Virtis geometric files, for observations intercepting the surface Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 10 Figure 2: Observations intercepting the surface Figure 3: Slit orientation for Virtis-H Figure 4: Sun direction in the instrument frame 2.3.2 Limb observations and other geometries Whenever the line of sight does not intercept the surface, the above quantities are substituted by specific information (Figure 5): ? During limb observations surface elevation at the ellipsoid intercept (plane 14) is substituted by the tangent altitude (impact parameter above the surface) with the addition of a large offset (100,000 m). This offset is intended to select or filter limb observations easily inside a file. The 100,000 m offset must be subtracted from plane 14 to retrieve the tangent altitude. ??Surface elevation at the cloud layer intercept (plane 30) is maintained whenever possible. If the line of sight does not intercept the cloud layer, this plane provides the surface elevation at the vertical of the tangent point. A Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 11 surface elevation is therefore always available in the geometry cubes, although not necessarily below the tangent point. ? Angles, local time, and slant distance are computed at the intersection with the local vertical (tangent point). ? The H slit orientation cannot be retrieved from surface coordinates, but is available in plane 39 (computed at the tangent point). In some occasions, the target is a planet different from Venus (Mercury, Earth?). In such cases, the geometry is computed similarly with respect to the target using its ellipsoid shape, and no second reference surface. Planes 17-30 are therefore not used. Such targets are subpixel when observed from the Venus orbit, but a resolved observation of the Earth and the Moon was performed during cruise. If the target is not a planet (e.g., stars, comets?) it is not expected to produce any geometry files. Whenever such observations are performed in inertial mode, the bore sight direction is available in the file labels. Figure 5: Limb observations at Venus 2.4 Geometry file labels An example of PDS label for the geometry cubes is given in Table 2 for Virtis-H. This is essentially a shortened version of the raw data files labels. Extra geometric information such as SOLAR_DISTANCE and sub-solar point coordinates is included here (four extra keywords). Other differences are outlined in red. Solar distance and sub-solar point coordinates are computed at start of acquisition, and are about constant during a session. Slant distance is the average value encountered during observation. The other values are either minimum/maximum values (for coordinates) or start/stop values (for times). Four extra keywords are present in the Virtis-M geometry files. They are all related to the scanning mode, and are identical to those present in the data file labels. Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 12 Keyword SSE Type Possible values / range Description PDS_VERSION_ID SC ID PDS3 Version of PDS standard used, constant LABEL_REVISION_NOTE SC CHAR "SE, 07/06/2007" ID of label version (blank line) /* File format and length */ PRODUCT_ID SC CHAR "xxx.GEO" Current file name with extension RECORD_TYPE SC ID FIXED_LENGTH File formatting info RECORD_BYTES SC INT 512 Record length in bytes, constant FILE_RECORDS SC INT nn1 Total file length / RECORD_BYTES (closest integer greater than or equal to this value) LABEL_RECORDS SC INT 7 Smallest integer large enough to accommodate the label up to the END keyword (ie., label length in byte ? LABEL_RECORDS * 512) FILE_STATE SC ID CLEAN Flag for incomplete files, constant (blank line) /* Pointers to data objects */ ^QUBE SC PT nn2 LABEL_RECORDS + 1 (blank line) /* Producer information */ PRODUCER_ID SC ID VEX_VIRTIS_TEAM (constant) PRODUCER_FULL_NAME SC CHAR "DROSSART-PICCIONI" (constant) PRODUCER_INSTITUTION_N SC CHAR "OBSERVATOIRE DE PARIS-LESIA" (constant) AME PRODUCT_CREATION_TIME SC TIME yyyy-mm-ddThh:mm:ss.fff Time when the PDS file is written TELEMETRY_SOURCE_ID SC CHAR "VIRTIS_EGSE" EGSE ID ( is the version number of EGSE itself) SOFTWARE_VERSION_ID SET CHAR { "VirtisVEX SW v.2.50", Versions ID of software used to "EGSE_SOFT_", process this file, including on- "PDS_CONVERTER_

", board software and conversion "GEOVIRTIS_", "V_GEOLABEL_2"} routines. ,

and are the version numbers of EGSE and GEOVIRTIS software (blank line) /* Data description parameters */ DATA_SET_NAME SC CHAR "VENUS EXPRESS VENUS VIRTIS 2/3 (Same as raw data) V1.0" DATA_SET_ID SC CHAR "VEX-V-VIRTIS-2/3-V1.0 " (Same as raw data) RELEASE_ID SC INT 0001 Delivery # to PSA, related to observation date REVISION_ID SC INT 0000 Version # for this release, may be incremented PRODUCT_TYPE SC ID EDR (constant) PROCESSING_LEVEL_ID SC INT 2 As in DATA_SET_ID STANDARD_DATA_PRODUC SC CHAR "VIRTIS GEOMETRY" Identifies data versus geometry T_ID MISSION NAME SC CHAR "VENUS EXPRESS" (constant) MISSION_ID SC ID VEX (constant) INSTRUMENT_HOST_NAME SC ID VENUS_EXPRESS (constant) Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 13 INSTRUMENT_HOST_ID SC ID VEX (constant) MISSION_PHASE_NAME SC CHAR "xxx? String, as defined by PSA PI_PDS_USER_ID SC CHAR "DROSSART-PICCIONI" (constant) INSTRUMENT_NAME SC CHAR "VISIBLE AND INFRARED THERMAL (constant) IMAGING SPECTROMETER" INSTRUMENT_ID SC ID "VIRTIS" (constant) INSTRUMENT_TYPE SC CHAR "IMAGING SPECTROMETER" (constant) ^INSTRUMENT_DESC SC PT "VIRTIS_EAICD.TXT" (constant) VEX:CHANNEL_ID SC ID "VIRTIS_H" (constant) DATA_QUALITY_ID SC INT 0 0 if TM data paquets are missing 1 when writing PDS data "NULL" 1 otherwise "NULL" is no diagnostic (may be used to store other error codes) DATA_QUALITY_DESC SC CHAR "0:INCOMPLETE ; 1:COMPLETE" (constant) (blank line) /* Science operations information */ TARGET_TYPE SC CHAR "PLANET" As defined by PSA "CALIBRATION" "SKY" TARGET_NAME SC CHAR "EARTH" As defined by PSA "VENUS" "CALIBRATION" "SKY" START_TIME SC TIME yyyy-mm-ddThh:mm:ss.fff UTC of first acquisition STOP_TIME SC TIME yyyy-mm-ddThh:mm:ss.fff UTC of last acquisition SPACECRAFT_CLOCK_STAR SC CHAR "n/sssssssssss.fffff" Formatted, from TM packet data T_COUNT field header. n is increased after each resynchronization of the S/C clock, starting from 1 SPACECRAFT_CLOCK_STOP SC CHAR "n/sssssssssss.fffff" Formatted, from TM packet data _COUNT field header. n is increased after each resynchronization of the S/C clock, starting from 1 ORBIT_NUMBER SC INT xxxx Follows ESA convention, see EAICD VEX:SCIENCE_CASE_ID SC INT 1 to 8 Science case, encoded. From VEX science case definition document (VEX-RSSD-TN-001) OBSERVATION_TYPE SC CHAR "xxx" From VEX document VEX-RSSD- LI-004 SPACECRAFT_ORIENTATION VEC REAL (0.0,-1.0,0.0) or Provides scanning orientation (0.0,1.0,0.0) (descending or ascending branch of orbit) ^SPACECRAFT_ORIENTATIO SC PT "VEX_ORIENTATION_DESC.TXT" (constant) Pointer to description N_DESC file SPACECRAFT_POINTING_MO SC CHAR "NADIR" ID of pointing mode DE "INERTIAL" Values as provided by PSA "LIMB" "EARTH_POINTING" "STAR_OCCULTATION" "SUN" "SPECULAR" "ALONGTRACK" "ACROSSTRACK" "SPOT" Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 14 ? ^SPACECRAFT_POINTING_M SC PT "VEX_POINTING_MODE_DESC.TXT" Pointer to description file, ODE_DESC constant DECLINATION SC REAL 0.0 RIGHT_ASCENSION SC REAL 0.0 MAXIMUM_LATITUDE SC REAL 000.000 In decimal degrees MINIMUM_LATITUDE SC REAL 000.000 In decimal degrees EASTERNMOST_LONGITUDE SC REAL 000.000 In decimal degrees, Eastward longitudes WESTERNMOST_LONGITUDE SC REAL 000.000 In decimal degrees, Eastward longitudes SLANT_DISTANCE SC REAL 0000.000 Average value in km SOLAR_DISTANCE SC REAL 0000.000 Sun-target distance in km SOLAR_LONGITUDE SC REAL 0000.000 Counted from vernal equinox, in decimal degrees SUB_SOLAR_LONGITUDE SC REAL 0000.000 Longitude of sub-solar point, in decimal degrees SUB_SOLAR_LATITUDE SC REAL 0000.000 Latitude of sub-solar point, in decimal degrees (blank line) /* Instrument status */ (constant) INSTRUMENT_MODE_ID SC INT 1 H_Off H channel functioning mode 2 H_Cool_Down 3 H_Idle 4 H_Annealing 5 H_PEM_On 6 H_Test 7 H_Calibration 8 H_Nominal_Simulation 9 H_Science_Maximum_Data_Rate 10 H_Science_Nominal_Data_Rate 11 H_Science_Minimum_Data_Rate 12 (deleted) 13 H_Science_Backup 14 H_User_Defined 15 (deleted) 16 (deleted) 17 (deleted) 18 H_Spectral_Calibration_Simulation 19 H_Degraded 63 H_ME_Test ^INSTRUMENT_MODE_DESC SC CHAR "VIRTIS_EAICD.TXT" (constant) (blank line) /* Pointer to navigation data files*/ SPICE_FILE_NAME SET CHAR {"xxx", ?,"xxx"} or "NULL" List of Spice files used in computation (blank line) /* Cube keywords */ OBJECT SC ID QUBE (constant) AXES SC INT 3 (constant) AXIS_NAME EN ID (BAND,SAMPLE,LINE) (constant, provides data structure) CORE_ITEMS EN INT (x,y,z) Cube dimensions: y, z same as data cube. x constant (# of geometrical values stored = 41 for H or 33 for M) Doc: VVX-LES-SW-2268 Issue: 1.2 VIRTIS Date: 18/7/2008 Page: 15 CORE_ITEM_BYTES SC INT 4 (constant) CORE_ITEM_TYPE SC ID MSB_INTEGER (constant) CORE_BASE SC REAL 0.0 (constant) CORE_MULTIPLIER SC REAL 1.0 (constant) CORE_VALID_MINIMUM SC INT -2147483648 (constant) CORE_NULL SC INT -2147483648 (constant) '80000000' hexa CORE_LOW_REPR_SATURA SC INT -2147483648 (constant) TION CORE_LOW_INSTR_SATURA SC INT -2147483648 (constant) TION CORE_HIGH_REPR_SATURA SC INT 2147483647 (constant) TION CORE_HIGH_INSTR_SATURA SC INT 2147483647 (constant) TION CORE_NAME SC ID "GEOMETRIC PARAMETERS" (constant) CORE_UNIT SC ID "UNK" (constant) Depends on parameter CORE_DESC SC CHAR "Parameters are defined in EAICD" (constant) (blank line) SUFFIX_BYTES SC INT 4 (constant) SUFFIX_ITEMS EN INT (0, 0 ,0) No suffix present END_OBJECT SC ID QUBE (constant) (blank line) END SC ID Table 2: Label for Virtis-H on VEx. Extra or modified lines relative to the raw data labels are outlined in red (several lines present in the data labels are also canceled).